Merge remote-tracking branch 'extensions_package_manager/REWRITE'

extensions/package-manager/.editorconfig

@@ -0,0 +1,19 @@
+# EditorConfig helps developers define and maintain consistent
+# coding styles between different editors and IDEs
+# editorconfig.org
+
+root = true
+
+[*]
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+indent_style = space
+indent_size = 2
+
+[*.{diff,md}]
+trim_trailing_whitespace = false
+
+[*.{php,xml,json}]
+indent_size = 4

extensions/package-manager/.gitattributes

@@ -0,0 +1,19 @@
+.gitattributes export-ignore
+.gitignore export-ignore
+.gitmodules export-ignore
+.github export-ignore
+.travis export-ignore
+.travis.yml export-ignore
+.editorconfig export-ignore
+.styleci.yml export-ignore
+
+phpunit.xml export-ignore
+tests export-ignore
+
+js/dist/* -diff
+js/dist/* linguist-generated
+js/dist-typings/* linguist-generated
+js/yarn.lock -diff
+js/package-lock.json -diff
+
+* text=auto eol=lf

extensions/package-manager/.github/workflows/backend.yml

@@ -0,0 +1,17 @@
+name: Package Manager PHP
+
+on: [workflow_dispatch, push, pull_request]
+
+# The reusable workflow definitions will be moved to the `flarum/framework` repo soon.
+# This will break your current script.
+# When this happens, run `flarum-cli audit infra --fix` to update your infrastructure.
+
+jobs:
+  run:
+    uses: flarum/.github/.github/workflows/REUSABLE_backend.yml@as/support-npm-yarn
+    with:
+      enable_backend_testing: true
+
+      backend_directory: .
+
+      php_versions: '["7.4", "8.0"]'

extensions/package-manager/.github/workflows/frontend.yml

@@ -0,0 +1,23 @@
+name: Package Manager JS
+
+on: [workflow_dispatch, push, pull_request]
+
+# The reusable workflow definitions will be moved to the `flarum/framework` repo soon.
+# This will break your current script.
+# When this happens, run `flarum-cli audit infra --fix` to update your infrastructure.
+
+jobs:
+  run:
+    uses: flarum/.github/.github/workflows/REUSABLE_frontend.yml@as/support-npm-yarn
+    with:
+      enable_bundlewatch: false
+      enable_prettier: true
+      enable_typescript: true
+
+      frontend_directory: ./js
+      backend_directory: .
+      package_manager: yarn
+      main_git_branch: main
+
+    secrets:
+      bundlewatch_github_token: ${{ secrets.BUNDLEWATCH_GITHUB_TOKEN }}

extensions/package-manager/.gitignore

@@ -0,0 +1,12 @@
+/vendor
+composer.lock
+composer.phar
+
+.DS_Store
+Thumbs.db
+tests/.phpunit.result.cache
+/tests/integration/tmp
+.vagrant
+.idea/*
+.vscode
+js/coverage-ts

extensions/package-manager/.styleci.yml

@@ -0,0 +1,14 @@
+preset: recommended
+
+enabled:
+  - logical_not_operators_with_successor_space
+
+disabled:
+  - align_double_arrow
+  - blank_line_after_opening_tag
+  - multiline_array_trailing_comma
+  - new_with_braces
+  - phpdoc_align
+  - phpdoc_order
+  - phpdoc_separation
+  - phpdoc_types

extensions/package-manager/LICENSE.md

@@ -0,0 +1,21 @@
+The MIT License (MIT)
+
+Copyright (c) Sami Mazouz
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

extensions/package-manager/README.md

@@ -0,0 +1,5 @@
+# Package Manager
+
+*An Experiment.*
+
+Read: https://github.com/flarum/package-manager/wiki

extensions/package-manager/assets/flarum.svg

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg width="100px" height="100px" viewBox="0 0 100 100" version="1.1" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">
+    <title>only symbol</title>
+    <defs>
+        <linearGradient x1="50%" y1="0%" x2="50%" y2="100%" id="linearGradient-1">
+            <stop stop-color="#D22929" offset="0%"></stop>
+            <stop stop-color="#B71717" offset="100%"></stop>
+        </linearGradient>
+        <linearGradient x1="50%" y1="0%" x2="50%" y2="100%" id="linearGradient-2">
+            <stop stop-color="#E7762E" offset="0%"></stop>
+            <stop stop-color="#E7562E" offset="100%"></stop>
+        </linearGradient>
+    </defs>
+    <g id="Page-1-Copy" stroke="none" stroke-width="1" fill="none" fill-rule="evenodd">
+        <g id="symbol" transform="translate(19.000000, 14.000000)">
+            <polygon id="Rectangle-7" fill="url(#linearGradient-1)" transform="translate(18.992475, 60.055970) scale(1, -1) translate(-18.992475, -60.055970) " points="3.28100097 67.7843544 3.25585284 71.4179104 34.729097 71.4179104 34.729097 48.6940299"></polygon>
+            <path d="M1.50233444,0 C0.67261804,0 -6.34784439e-15,0.673057357 -4.66645372e-15,1.50356766 L8.86811991e-14,47.6119403 C0.0903997122,49.1366194 0.0127042007,50.726258 4.86812431,53.3284828 C4.86812431,53.3284828 0.110480342,48.7194253 7.59698997,48.6940299 L60.7759197,48.6940299 L60.7759197,0 L1.50233444,0 Z" id="Rectangle-6" fill="url(#linearGradient-2)"></path>
+        </g>
+    </g>
+</svg>

extensions/package-manager/composer.json

@@ -0,0 +1,100 @@
+{
+    "name": "flarum/package-manager",
+    "description": "A Flarum Package Manager.",
+    "keywords": [
+        "extensions",
+        "composer",
+        "packages",
+        "manager",
+        "updater"
+    ],
+    "type": "flarum-extension",
+    "license": "MIT",
+    "authors": [
+        {
+            "name": "Flarum",
+            "email": "info@flarum.org",
+            "homepage": "https://flarum.org/team"
+        }
+    ],
+    "support": {
+        "issues": "https://github.com/flarum/package-manager/issues",
+        "source": "https://github.com/flarum/package-manager"
+    },
+    "require": {
+        "flarum/core": "^1.0.0",
+        "composer/composer": "^2.0"
+    },
+    "require-dev": {
+        "flarum/testing": "^1.0.0",
+        "flarum/tags": "*"
+    },
+    "extra": {
+        "flarum-extension": {
+            "title": "Package Manager",
+            "icon": {
+                "name": "fas fa-box-open",
+                "backgroundColor": "#117187",
+                "color": "#fff"
+            }
+        },
+        "flarum-cli": {
+            "excludeScaffolding": [
+                ".github/workflows/backend.yml",
+                "js/src/admin/index.ts",
+                "tests/phpunit.integration.xml",
+                "tests/integration/setup.php"
+            ],
+            "excludeScaffoldingConfigKeys": {
+                "composer.json": [
+                    "scripts.test:setup"
+                ]
+            },
+            "modules": {
+                "admin": true,
+                "forum": false,
+                "js": true,
+                "jsCommon": false,
+                "css": true,
+                "gitConf": true,
+                "githubActions": true,
+                "prettier": true,
+                "typescript": true,
+                "bundlewatch": false,
+                "backendTesting": true,
+                "editorConfig": true,
+                "styleci": true
+            }
+        }
+    },
+    "autoload": {
+        "psr-4": {
+            "Flarum\\PackageManager\\": "src/"
+        }
+    },
+    "autoload-dev": {
+        "psr-4": {
+            "Flarum\\PackageManager\\Tests\\": "tests/"
+        }
+    },
+    "scripts": {
+        "test": [
+            "@test:unit",
+            "@test:integration"
+        ],
+        "test:unit": "phpunit -c tests/phpunit.unit.xml",
+        "test:integration": "phpunit -c tests/phpunit.integration.xml",
+        "test:setup": [
+            "@php tests/integration/setup.php",
+            "cd $FLARUM_TEST_TMP_DIR_LOCAL && composer install"
+        ]
+    },
+    "scripts-descriptions": {
+        "test": "Runs all tests.",
+        "test:unit": "Runs all unit tests.",
+        "test:integration": "Runs all integration tests.",
+        "test:setup": "Sets up a database for use with integration tests. Execute this only once."
+    },
+    "minimum-stability": "dev",
+    "prefer-stable": true
+}

extensions/package-manager/extend.php

@@ -0,0 +1,63 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager;
+
+use Flarum\Extend;
+use Flarum\Foundation\Paths;
+use Flarum\Frontend\Document;
+use Flarum\PackageManager\Exception\ComposerCommandFailedException;
+use Flarum\PackageManager\Exception\ExceptionHandler;
+use Flarum\PackageManager\Exception\ComposerRequireFailedException;
+use Flarum\PackageManager\Exception\ComposerUpdateFailedException;
+use Flarum\PackageManager\Exception\MajorUpdateFailedException;
+use Flarum\PackageManager\Settings\LastUpdateCheck;
+use Flarum\PackageManager\Settings\LastUpdateRun;
+
+return [
+    (new Extend\Routes('api'))
+        ->post('/package-manager/extensions', 'package-manager.extensions.require', Api\Controller\RequireExtensionController::class)
+        ->patch('/package-manager/extensions/{id}', 'package-manager.extensions.update', Api\Controller\UpdateExtensionController::class)
+        ->delete('/package-manager/extensions/{id}', 'package-manager.extensions.remove', Api\Controller\RemoveExtensionController::class)
+        ->post('/package-manager/check-for-updates', 'package-manager.check-for-updates', Api\Controller\CheckForUpdatesController::class)
+        ->post('/package-manager/why-not', 'package-manager.why-not', Api\Controller\WhyNotController::class)
+        ->post('/package-manager/minor-update', 'package-manager.minor-update', Api\Controller\MinorUpdateController::class)
+        ->post('/package-manager/major-update', 'package-manager.major-update', Api\Controller\MajorUpdateController::class)
+        ->post('/package-manager/global-update', 'package-manager.global-update', Api\Controller\GlobalUpdateController::class),
+
+    (new Extend\Frontend('admin'))
+        ->css(__DIR__ . '/less/admin.less')
+        ->js(__DIR__ . '/js/dist/admin.js')
+        ->content(function (Document $document) {
+            $paths = resolve(Paths::class);
+
+            $document->payload['isRequiredDirectoriesWritable'] = is_writable($paths->vendor)
+                && is_writable($paths->storage.'/.composer')
+                && is_writable($paths->base.'/composer.json')
+                && is_writable($paths->base.'/composer.lock');
+        }),
+
+    new Extend\Locales(__DIR__ . '/locale'),
+
+    (new Extend\Settings())
+        ->default(LastUpdateCheck::key(), json_encode(LastUpdateCheck::default()))
+        ->default(LastUpdateRun::key(), json_encode(LastUpdateRun::default())),
+
+    (new Extend\ServiceProvider)
+        ->register(PackageManagerServiceProvider::class),
+
+    (new Extend\ErrorHandling)
+        ->handler(ComposerCommandFailedException::class, ExceptionHandler::class)
+        ->handler(ComposerRequireFailedException::class, ExceptionHandler::class)
+        ->handler(ComposerUpdateFailedException::class, ExceptionHandler::class)
+        ->handler(MajorUpdateFailedException::class, ExceptionHandler::class)
+        ->status('extension_already_installed', 409)
+        ->status('extension_not_installed', 409)
+        ->status('no_new_major_version', 409),
+];

extensions/package-manager/js/.gitignore

@@ -0,0 +1,9 @@
+.pnp.*
+.yarn/*
+!.yarn/patches
+!.yarn/plugins
+!.yarn/releases
+!.yarn/sdks
+!.yarn/versions
+
+node_modules

extensions/package-manager/js/admin.ts

@@ -0,0 +1 @@
+export * from './src/admin';

extensions/package-manager/js/dist-typings/components/ExtensionItem.d.ts

@@ -0,0 +1,20 @@
+import Mithril from 'mithril';
+import Component, { ComponentAttrs } from 'flarum/common/Component';
+import { Extension as BaseExtension } from 'flarum/admin/AdminApplication';
+import { UpdatedPackage } from './Updater';
+export declare type Extension = BaseExtension & {
+    name: string;
+};
+export interface ExtensionItemAttrs extends ComponentAttrs {
+    extension: Extension;
+    updates: UpdatedPackage;
+    onClickUpdate: CallableFunction;
+    whyNotWarning?: boolean;
+    isCore?: boolean;
+    updatable?: boolean;
+    isDanger?: boolean;
+}
+export default class ExtensionItem<Attrs extends ExtensionItemAttrs = ExtensionItemAttrs> extends Component<Attrs> {
+    view(vnode: Mithril.Vnode<Attrs, this>): Mithril.Children;
+    private version;
+}

extensions/package-manager/js/dist-typings/components/Installer.d.ts

@@ -0,0 +1,11 @@
+import type Mithril from 'mithril';
+import Component from 'flarum/common/Component';
+import Stream from 'flarum/common/utils/Stream';
+export default class Installer<Attrs> extends Component<Attrs> {
+    packageName: Stream<string>;
+    isLoading: boolean;
+    oninit(vnode: Mithril.Vnode<Attrs, this>): void;
+    view(): Mithril.Children;
+    data(): any;
+    onsubmit(): void;
+}

extensions/package-manager/js/dist-typings/components/MajorUpdater.d.ts

@@ -0,0 +1,15 @@
+import Component, { ComponentAttrs } from 'flarum/common/Component';
+import Mithril from 'mithril';
+import { UpdatedPackage, UpdateState } from './Updater';
+interface MajorUpdaterAttrs extends ComponentAttrs {
+    coreUpdate: UpdatedPackage;
+    updateState: UpdateState;
+}
+export default class MajorUpdater<T extends MajorUpdaterAttrs = MajorUpdaterAttrs> extends Component<T> {
+    isLoading: string | null;
+    updateState: UpdateState;
+    oninit(vnode: Mithril.Vnode<T, this>): void;
+    view(vnode: Mithril.Vnode<T, this>): Mithril.Children;
+    update(dryRun: boolean): void;
+}
+export {};

extensions/package-manager/js/dist-typings/components/Updater.d.ts

@@ -0,0 +1,47 @@
+import Mithril from 'mithril';
+import Component from 'flarum/common/Component';
+import { Extension } from './ExtensionItem';
+export declare type UpdatedPackage = {
+    name: string;
+    version: string;
+    latest: string;
+    'latest-minor': string | null;
+    'latest-major': string | null;
+    'latest-status': string;
+    description: string;
+};
+export declare type ComposerUpdates = {
+    installed: UpdatedPackage[];
+};
+export declare type LastUpdateCheck = {
+    checkedAt: Date | null;
+    updates: ComposerUpdates;
+};
+declare type UpdateType = 'major' | 'minor' | 'global';
+declare type UpdateStatus = 'success' | 'failure' | null;
+export declare type UpdateState = {
+    ranAt: Date | null;
+    status: UpdateStatus;
+    limitedPackages: string[];
+    incompatibleExtensions: string[];
+};
+export declare type LastUpdateRun = {
+    [key in UpdateType]: UpdateState;
+} & {
+    limitedPackages: () => string[];
+};
+export default class Updater<Attrs> extends Component<Attrs> {
+    isLoading: string | null;
+    packageUpdates: Record<string, UpdatedPackage>;
+    lastUpdateCheck: LastUpdateCheck;
+    get lastUpdateRun(): LastUpdateRun;
+    oninit(vnode: Mithril.Vnode<Attrs, this>): void;
+    view(): (JSX.Element | null)[];
+    getExtensionUpdates(): Extension[];
+    getCoreUpdate(): UpdatedPackage | undefined;
+    checkForUpdates(): void;
+    updateCoreMinor(): void;
+    updateExtension(extension: any): void;
+    updateGlobally(): void;
+}
+export {};

extensions/package-manager/js/dist-typings/components/WhyNotModal.d.ts

@@ -0,0 +1,15 @@
+/// <reference path="../../../vendor/flarum/core/js/src/common/translator-icu-rich.d.ts" />
+import Mithril from 'mithril';
+import Modal, { IInternalModalAttrs } from 'flarum/common/components/Modal';
+export interface WhyNotModalAttrs extends IInternalModalAttrs {
+    package: string;
+}
+export default class WhyNotModal<Attrs extends WhyNotModalAttrs = WhyNotModalAttrs> extends Modal<Attrs> {
+    loading: boolean;
+    whyNot: string | null;
+    className(): string;
+    title(): import("@askvortsov/rich-icu-message-formatter").NestedStringArray;
+    oncreate(vnode: Mithril.VnodeDOM<Attrs, this>): void;
+    content(): JSX.Element;
+    requestWhyNot(): void;
+}

extensions/package-manager/js/dist-typings/index.d.ts

@@ -0,0 +1 @@
+export {};

extensions/package-manager/js/dist-typings/utils/errorHandler.d.ts

@@ -0,0 +1 @@
+export default function (e: any): void;

extensions/package-manager/js/package.json

@@ -0,0 +1,28 @@
+{
+    "name": "@flarum/package-manager",
+    "version": "0.0.0",
+    "private": true,
+    "prettier": "@flarum/prettier-config",
+    "devDependencies": {
+        "prettier": "^2.5.1",
+        "flarum-webpack-config": "^2.0.0",
+        "webpack": "^5.65.0",
+        "webpack-cli": "^4.9.1",
+        "@flarum/prettier-config": "^1.0.0",
+        "flarum-tsconfig": "^1.0.2",
+        "typescript": "^4.5.4",
+        "typescript-coverage-report": "^0.6.1"
+    },
+    "scripts": {
+        "dev": "webpack --mode development --watch",
+        "build": "webpack --mode production",
+        "format": "prettier --write src",
+        "format-check": "prettier --check src",
+        "ci": "yarn install --immutable --immutable-cache",
+        "analyze": "cross-env ANALYZER=true yarn run build",
+        "clean-typings": "npx rimraf dist-typings && mkdir dist-typings",
+        "build-typings": "yarn run clean-typings && tsc && [ -e src/@types ] && cp -r src/@types dist-typings/@types",
+        "check-typings": "tsc --noEmit --emitDeclarationOnly false",
+        "check-typings-coverage": "typescript-coverage-report"
+    }
+}

extensions/package-manager/js/src/admin/components/ExtensionItem.tsx

@@ -0,0 +1,89 @@
+import Mithril from 'mithril';
+import app from 'flarum/admin/app';
+import Component, { ComponentAttrs } from 'flarum/common/Component';
+import classList from 'flarum/common/utils/classList';
+import icon from 'flarum/common/helpers/icon';
+import Tooltip from 'flarum/common/components/Tooltip';
+import Button from 'flarum/common/components/Button';
+import { Extension as BaseExtension } from 'flarum/admin/AdminApplication';
+import { UpdatedPackage } from './Updater';
+import WhyNotModal from './WhyNotModal';
+
+/*
+ * @todo fix in core
+ */
+export type Extension = BaseExtension & {
+  name: string;
+};
+
+export interface ExtensionItemAttrs extends ComponentAttrs {
+  extension: Extension;
+  updates: UpdatedPackage;
+  onClickUpdate: CallableFunction;
+  whyNotWarning?: boolean;
+  isCore?: boolean;
+  updatable?: boolean;
+  isDanger?: boolean;
+}
+
+export default class ExtensionItem<Attrs extends ExtensionItemAttrs = ExtensionItemAttrs> extends Component<Attrs> {
+  view(vnode: Mithril.Vnode<Attrs, this>): Mithril.Children {
+    const { extension, updates, onClickUpdate, whyNotWarning, isCore, isDanger } = this.attrs;
+
+    return (
+      <div
+        className={classList({
+          'PackageManager-extension': true,
+          'PackageManager-extension--core': isCore,
+          'PackageManager-extension--danger': isDanger,
+        })}
+      >
+        <div className="PackageManager-extension-icon ExtensionIcon" style={extension.icon}>
+          {extension.icon ? icon(extension.icon.name) : ''}
+        </div>
+        <div className="PackageManager-extension-info">
+          <div className="PackageManager-extension-name">{extension.extra['flarum-extension'].title}</div>
+          <div className="PackageManager-extension-version">
+            <span className="PackageManager-extension-version-current">{this.version(extension.version)}</span>
+            {updates['latest-minor'] ? (
+              <span className="PackageManager-extension-version-latest PackageManager-extension-version-latest--minor">
+                {this.version(updates['latest-minor']!)}
+              </span>
+            ) : null}
+            {updates['latest-major'] && !isCore ? (
+              <span className="PackageManager-extension-version-latest PackageManager-extension-version-latest--major">
+                {this.version(updates['latest-major']!)}
+              </span>
+            ) : null}
+          </div>
+        </div>
+        <div className="PackageManager-extension-controls">
+          {onClickUpdate ? (
+            <Tooltip text={app.translator.trans('flarum-package-manager.admin.extensions.update')}>
+              <Button
+                icon="fas fa-arrow-alt-circle-up"
+                className="Button Button--icon Button--flat"
+                onclick={onClickUpdate}
+                aria-label={app.translator.trans('flarum-package-manager.admin.extensions.update')}
+              />
+            </Tooltip>
+          ) : null}
+          {whyNotWarning ? (
+            <Tooltip text={app.translator.trans('flarum-package-manager.admin.extensions.check_why_it_failed_updating')}>
+              <Button
+                icon="fas fa-exclamation-circle"
+                className="Button Button--icon Button--flat Button--danger"
+                onclick={() => app.modal.show(WhyNotModal, { package: extension.name })}
+                aria-label={app.translator.trans('flarum-package-manager.admin.extensions.check_why_it_failed_updating')}
+              />
+            </Tooltip>
+          ) : null}
+        </div>
+      </div>
+    );
+  }
+
+  private version(v: string): string {
+    return 'v' + v.replace('v', '');
+  }
+}

extensions/package-manager/js/src/admin/components/Installer.tsx

@@ -0,0 +1,71 @@
+import type Mithril from 'mithril';
+import app from 'flarum/admin/app';
+import Component from 'flarum/common/Component';
+import Button from 'flarum/common/components/Button';
+import Stream from 'flarum/common/utils/Stream';
+import LoadingModal from 'flarum/admin/components/LoadingModal';
+import errorHandler from '../utils/errorHandler';
+
+export default class Installer<Attrs> extends Component<Attrs> {
+  packageName!: Stream<string>;
+  isLoading: boolean = false;
+
+  oninit(vnode: Mithril.Vnode<Attrs, this>): void {
+    super.oninit(vnode);
+
+    this.packageName = Stream('');
+  }
+
+  view(): Mithril.Children {
+    return (
+      <div className="Form-group">
+        <label htmlFor="install-extension">{app.translator.trans('flarum-package-manager.admin.extensions.install')}</label>
+        <p className="helpText">
+          {app.translator.trans('flarum-package-manager.admin.extensions.install_help', {
+            extiverse: <a href="https://extiverse.com">extiverse.com</a>,
+          })}
+        </p>
+        <div className="FormControl-container">
+          <input className="FormControl" id="install-extension" placeholder="vendor/package-name" bidi={this.packageName} />
+          <Button className="Button" icon="fas fa-download" onclick={this.onsubmit.bind(this)} loading={this.isLoading}>
+            {app.translator.trans('flarum-package-manager.admin.extensions.proceed')}
+          </Button>
+        </div>
+      </div>
+    );
+  }
+
+  data(): any {
+    return {
+      package: this.packageName(),
+    };
+  }
+
+  onsubmit(): void {
+    this.isLoading = true;
+    app.modal.show(LoadingModal);
+
+    app
+      .request({
+        method: 'POST',
+        url: `${app.forum.attribute('apiUrl')}/package-manager/extensions`,
+        body: {
+          data: this.data(),
+        },
+        errorHandler,
+      })
+      .then((response) => {
+        const extensionId = response.id;
+        app.alerts.show(
+          { type: 'success' },
+          app.translator.trans('flarum-package-manager.admin.extensions.successful_install', { extension: extensionId })
+        );
+        window.location.href = `${app.forum.attribute('adminUrl')}#/extension/${extensionId}`;
+        window.location.reload();
+      })
+      .finally(() => {
+        this.isLoading = false;
+        m.redraw();
+      });
+  }
+}

extensions/package-manager/js/src/admin/components/MajorUpdater.tsx

@@ -0,0 +1,109 @@
+import app from 'flarum/admin/app';
+import Component, { ComponentAttrs } from 'flarum/common/Component';
+import Mithril from 'mithril';
+import Button from 'flarum/common/components/Button';
+import Tooltip from 'flarum/common/components/Tooltip';
+import { UpdatedPackage, UpdateState } from './Updater';
+import LoadingModal from 'flarum/admin/components/LoadingModal';
+import errorHandler from '../utils/errorHandler';
+import Alert from 'flarum/common/components/Alert';
+import WhyNotModal from './WhyNotModal';
+import RequestError from 'flarum/common/utils/RequestError';
+import ExtensionItem, { Extension } from './ExtensionItem';
+
+interface MajorUpdaterAttrs extends ComponentAttrs {
+  coreUpdate: UpdatedPackage;
+  updateState: UpdateState;
+}
+
+export default class MajorUpdater<T extends MajorUpdaterAttrs = MajorUpdaterAttrs> extends Component<T> {
+  isLoading: string | null = null;
+  updateState!: UpdateState;
+
+  oninit(vnode: Mithril.Vnode<T, this>) {
+    super.oninit(vnode);
+
+    this.updateState = this.attrs.updateState;
+  }
+
+  view(vnode: Mithril.Vnode<T, this>): Mithril.Children {
+    // @todo move Form-group--danger class to core for reuse
+    return (
+      <div className="Form-group Form-group--danger PackageManager-majorUpdate">
+        <img alt="flarum logo" src={app.forum.attribute('baseUrl') + '/assets/extensions/flarum-package-manager/flarum.svg'} />
+        <label>{app.translator.trans('flarum-package-manager.admin.major_updater.title', { version: this.attrs.coreUpdate['latest-major'] })}</label>
+        <p className="helpText">{app.translator.trans('flarum-package-manager.admin.major_updater.description')}</p>
+        <div className="PackageManager-updaterControls">
+          <Tooltip text={app.translator.trans('flarum-package-manager.admin.major_updater.dry_run_help')}>
+            <Button className="Button" icon="fas fa-vial" onclick={this.update.bind(this, true)}>
+              {app.translator.trans('flarum-package-manager.admin.major_updater.dry_run')}
+            </Button>
+          </Tooltip>
+          <Button className="Button Button--danger" icon="fas fa-play" onclick={this.update.bind(this, false)}>
+            {app.translator.trans('flarum-package-manager.admin.major_updater.update')}
+          </Button>
+        </div>
+        {this.updateState.incompatibleExtensions.length ? (
+          <div className="PackageManager-majorUpdate-incompatibleExtensions PackageManager-extensions-grid">
+            {this.updateState.incompatibleExtensions.map((extension: string) => (
+              <ExtensionItem
+                extension={app.data.extensions[extension.replace('flarum-', '').replace('flarum-ext-', '').replace('/', '-')]}
+                updates={{}}
+                onClickUpdate={null}
+                isDanger={true}
+              />
+            ))}
+          </div>
+        ) : null}
+        {this.updateState.status === 'failure' ? (
+          <Alert
+            type="error"
+            className="PackageManager-majorUpdate-failure"
+            dismissible={false}
+            controls={[
+              <Button
+                className="Button Button--text PackageManager-majorUpdate-failure-details"
+                icon="fas fa-question-circle"
+                onclick={() => app.modal.show(WhyNotModal, { package: 'flarum/core' })}
+              >
+                {app.translator.trans('flarum-package-manager.admin.major_updater.failure.why')}
+              </Button>,
+            ]}
+          >
+            <p className="PackageManager-majorUpdate-failure-desc">
+              {app.translator.trans('flarum-package-manager.admin.major_updater.failure.desc')}
+            </p>
+          </Alert>
+        ) : null}
+      </div>
+    );
+  }
+
+  update(dryRun: boolean) {
+    this.isLoading = `update-${dryRun ? 'dry-run' : 'run'}`;
+    app.modal.show(LoadingModal);
+
+    app
+      .request({
+        method: 'POST',
+        url: `${app.forum.attribute('apiUrl')}/package-manager/major-update`,
+        body: {
+          data: { dryRun },
+        },
+        errorHandler,
+      })
+      .then(() => {
+        app.alerts.show({ type: 'success' }, app.translator.trans('flarum-package-manager.admin.update_successful'));
+        window.location.reload();
+      })
+      .catch((e: RequestError) => {
+        app.modal.close();
+        this.updateState.status = 'failure';
+        this.updateState.incompatibleExtensions = e.response?.errors?.pop()?.incompatible_extensions as string[];
+      })
+      .finally(() => {
+        this.isLoading = null;
+        m.redraw();
+      });
+  }
+}

extensions/package-manager/js/src/admin/components/Updater.tsx

@@ -0,0 +1,254 @@
+import Mithril from 'mithril';
+import app from 'flarum/admin/app';
+import Component from 'flarum/common/Component';
+import Button from 'flarum/common/components/Button';
+import humanTime from 'flarum/common/helpers/humanTime';
+import LoadingModal from 'flarum/admin/components/LoadingModal';
+import errorHandler from '../utils/errorHandler';
+import LoadingIndicator from 'flarum/common/components/LoadingIndicator';
+import MajorUpdater from './MajorUpdater';
+import ExtensionItem, { Extension } from './ExtensionItem';
+
+export type UpdatedPackage = {
+  name: string;
+  version: string;
+  latest: string;
+  'latest-minor': string | null;
+  'latest-major': string | null;
+  'latest-status': string;
+  description: string;
+};
+
+export type ComposerUpdates = {
+  installed: UpdatedPackage[];
+};
+
+export type LastUpdateCheck = {
+  checkedAt: Date | null;
+  updates: ComposerUpdates;
+};
+
+type UpdateType = 'major' | 'minor' | 'global';
+type UpdateStatus = 'success' | 'failure' | null;
+export type UpdateState = {
+  ranAt: Date | null;
+  status: UpdateStatus;
+  limitedPackages: string[];
+  incompatibleExtensions: string[];
+};
+
+export type LastUpdateRun = {
+  [key in UpdateType]: UpdateState;
+} & {
+  limitedPackages: () => string[];
+};
+
+export default class Updater<Attrs> extends Component<Attrs> {
+  isLoading: string | null = null;
+  packageUpdates: Record<string, UpdatedPackage> = {};
+  lastUpdateCheck: LastUpdateCheck = JSON.parse(app.data.settings['flarum-package-manager.last_update_check']) as LastUpdateCheck;
+  get lastUpdateRun(): LastUpdateRun {
+    const lastUpdateRun = JSON.parse(app.data.settings['flarum-package-manager.last_update_run']) as LastUpdateRun;
+
+    lastUpdateRun.limitedPackages = () => [
+      ...lastUpdateRun.major.limitedPackages,
+      ...lastUpdateRun.minor.limitedPackages,
+      ...lastUpdateRun.global.limitedPackages,
+    ];
+
+    return lastUpdateRun;
+  }
+
+  oninit(vnode: Mithril.Vnode<Attrs, this>) {
+    super.oninit(vnode);
+  }
+
+  view() {
+    const extensions = this.getExtensionUpdates();
+    let coreUpdate: UpdatedPackage | undefined = this.getCoreUpdate();
+    let core: any;
+
+    if (coreUpdate) {
+      core = {
+        id: 'flarum-core',
+        name: 'flarum/core',
+        version: app.data.settings.version,
+        icon: {
+          backgroundImage: `url(${app.forum.attribute('baseUrl')}/assets/extensions/flarum-package-manager/flarum.svg`,
+        },
+        extra: {
+          'flarum-extension': {
+            title: app.translator.trans('flarum-package-manager.admin.updater.flarum'),
+          },
+        },
+      };
+    }
+
+    return [
+      <div className="Form-group">
+        <label>{app.translator.trans('flarum-package-manager.admin.updater.updater_title')}</label>
+        <p className="helpText">{app.translator.trans('flarum-package-manager.admin.updater.updater_help')}</p>
+        {this.lastUpdateCheck?.checkedAt && (
+          <p className="PackageManager-lastUpdatedAt">
+            <span className="PackageManager-lastUpdatedAt-label">
+              {app.translator.trans('flarum-package-manager.admin.updater.last_update_checked_at')}
+            </span>
+            <span className="PackageManager-lastUpdatedAt-value">{humanTime(this.lastUpdateCheck.checkedAt)}</span>
+          </p>
+        )}
+        <div className="PackageManager-updaterControls">
+          <Button
+            className="Button"
+            icon="fas fa-sync-alt"
+            onclick={this.checkForUpdates.bind(this)}
+            loading={this.isLoading === 'check'}
+            disabled={this.isLoading !== null && this.isLoading !== 'check'}
+          >
+            {app.translator.trans('flarum-package-manager.admin.updater.check_for_updates')}
+          </Button>
+          <Button
+            className="Button"
+            icon="fas fa-play"
+            onclick={this.updateGlobally.bind(this)}
+            loading={this.isLoading === 'global-update'}
+            disabled={this.isLoading !== null && this.isLoading !== 'global-update'}
+          >
+            {app.translator.trans('flarum-package-manager.admin.updater.run_global_update')}
+          </Button>
+        </div>
+        {this.isLoading !== null ? (
+          <div className="PackageManager-extensions">
+            <LoadingIndicator />
+          </div>
+        ) : extensions.length || core ? (
+          <div className="PackageManager-extensions">
+            <div className="PackageManager-extensions-grid">
+              {core ? (
+                <ExtensionItem
+                  extension={core}
+                  updates={coreUpdate}
+                  isCore={true}
+                  onClickUpdate={this.updateCoreMinor.bind(this)}
+                  whyNotWarning={this.lastUpdateRun.limitedPackages().includes('flarum/core')}
+                />
+              ) : null}
+              {extensions.map((extension: Extension) => (
+                <ExtensionItem
+                  extension={extension}
+                  updates={this.packageUpdates[extension.id]}
+                  onClickUpdate={this.updateExtension.bind(this, extension)}
+                  whyNotWarning={this.lastUpdateRun.limitedPackages().includes(extension.name)}
+                />
+              ))}
+            </div>
+          </div>
+        ) : null}
+      </div>,
+      coreUpdate && coreUpdate['latest-major'] ? <MajorUpdater coreUpdate={coreUpdate} updateState={this.lastUpdateRun.major} /> : null,
+    ];
+  }
+
+  getExtensionUpdates(): Extension[] {
+    this.lastUpdateCheck?.updates?.installed?.filter((composerPackage: UpdatedPackage) => {
+      const id = composerPackage.name.replace('/', '-').replace(/(flarum-ext-)|(flarum-)/, '');
+
+      const extension = app.data.extensions[id];
+      const safeToUpdate = ['semver-safe-update', 'update-possible'].includes(composerPackage['latest-status']);
+
+      if (extension && safeToUpdate) {
+        this.packageUpdates[extension.id] = composerPackage;
+      }
+
+      return extension && safeToUpdate;
+    });
+
+    return (Object.values(app.data.extensions) as Extension[]).filter((extension: Extension) => this.packageUpdates[extension.id]);
+  }
+
+  getCoreUpdate(): UpdatedPackage | undefined {
+    return this.lastUpdateCheck?.updates?.installed?.filter((composerPackage: UpdatedPackage) => composerPackage.name === 'flarum/core').pop();
+  }
+
+  checkForUpdates() {
+    this.isLoading = 'check';
+
+    app
+      .request({
+        method: 'POST',
+        url: `${app.forum.attribute('apiUrl')}/package-manager/check-for-updates`,
+        errorHandler,
+      })
+      .then((response) => {
+        this.lastUpdateCheck = response as LastUpdateCheck;
+      })
+      .finally(() => {
+        this.isLoading = null;
+        m.redraw();
+      });
+  }
+
+  updateCoreMinor() {
+    if (confirm(app.translator.trans('flarum-package-manager.admin.minor_update_confirmation.content'))) {
+      app.modal.show(LoadingModal);
+      this.isLoading = 'minor-update';
+
+      app
+        .request({
+          method: 'POST',
+          url: `${app.forum.attribute('apiUrl')}/package-manager/minor-update`,
+          errorHandler,
+        })
+        .then(() => {
+          app.alerts.show({ type: 'success' }, app.translator.trans('flarum-package-manager.admin.update_successful'));
+          window.location.reload();
+        })
+        .finally(() => {
+          this.isLoading = null;
+          m.redraw();
+        });
+    }
+  }
+
+  updateExtension(extension: any) {
+    app.modal.show(LoadingModal);
+    this.isLoading = 'extension-update';
+
+    app
+      .request({
+        method: 'PATCH',
+        url: `${app.forum.attribute('apiUrl')}/package-manager/extensions/${extension.id}`,
+        errorHandler,
+      })
+      .then(() => {
+        app.alerts.show(
+          { type: 'success' },
+          app.translator.trans('flarum-package-manager.admin.extensions.successful_update', { extension: extension.extra['flarum-extension'].title })
+        );
+        window.location.reload();
+      })
+      .finally(() => {
+        this.isLoading = null;
+        m.redraw();
+      });
+  }
+
+  updateGlobally() {
+    app.modal.show(LoadingModal);
+    this.isLoading = 'global-update';
+
+    app
+      .request({
+        method: 'POST',
+        url: `${app.forum.attribute('apiUrl')}/package-manager/global-update`,
+        errorHandler,
+      })
+      .then(() => {
+        app.alerts.show({ type: 'success' }, app.translator.trans('flarum-package-manager.admin.updater.global_update_successful'));
+        window.location.reload();
+      })
+      .finally(() => {
+        this.isLoading = null;
+        m.redraw();
+      });
+  }
+}

extensions/package-manager/js/src/admin/components/WhyNotModal.tsx

@@ -0,0 +1,51 @@
+import app from 'flarum/admin/app';
+import Mithril from 'mithril';
+import Modal, { IInternalModalAttrs } from 'flarum/common/components/Modal';
+import LoadingIndicator from 'flarum/common/components/LoadingIndicator';
+import errorHandler from '../utils/errorHandler';
+
+export interface WhyNotModalAttrs extends IInternalModalAttrs {
+  package: string;
+}
+
+export default class WhyNotModal<Attrs extends WhyNotModalAttrs = WhyNotModalAttrs> extends Modal<Attrs> {
+  loading: boolean = true;
+  whyNot: string | null = null;
+
+  className() {
+    return 'Modal--large WhyNotModal';
+  }
+
+  title() {
+    return app.translator.trans('flarum-package-manager.admin.why_not_modal.title');
+  }
+
+  oncreate(vnode: Mithril.VnodeDOM<Attrs, this>) {
+    super.oncreate(vnode);
+
+    this.requestWhyNot();
+  }
+
+  content() {
+    return <div className="Modal-body">{this.loading ? <LoadingIndicator /> : <pre className="WhyNotModal-contents">{this.whyNot}</pre>}</div>;
+  }
+
+  requestWhyNot(): void {
+    app
+      .request({
+        method: 'POST',
+        url: `${app.forum.attribute('apiUrl')}/package-manager/why-not`,
+        body: {
+          data: {
+            package: this.attrs.package,
+          },
+        },
+        errorHandler,
+      })
+      .then((response: any) => {
+        this.loading = false;
+        this.whyNot = response.data.whyNot;
+        m.redraw();
+      });
+  }
+}

extensions/package-manager/js/src/admin/index.tsx

@@ -0,0 +1,73 @@
+import { extend } from 'flarum/common/extend';
+import app from 'flarum/admin/app';
+import Alert from 'flarum/common/components/Alert';
+import ExtensionPage from 'flarum/admin/components/ExtensionPage';
+import Button from 'flarum/common/components/Button';
+import LoadingModal from 'flarum/admin/components/LoadingModal';
+import Installer from './components/Installer';
+import Updater from './components/Updater';
+import isExtensionEnabled from 'flarum/admin/utils/isExtensionEnabled';
+
+app.initializers.add('flarum-package-manager', (app) => {
+  app.extensionData
+    .for('flarum-package-manager')
+    .registerSetting(() => {
+      if (!app.data.isRequiredDirectoriesWritable) {
+        return (
+          <div className="Form-group">
+            <Alert type="warning" dismissible={false}>
+              {app.translator.trans('flarum-package-manager.admin.file_permissions')}
+            </Alert>
+          </div>
+        );
+      }
+
+      return null;
+    })
+    .registerSetting(() => {
+      if (app.data.isRequiredDirectoriesWritable) {
+        return <Installer />;
+      }
+
+      return null;
+    })
+    .registerSetting(() => {
+      if (app.data.isRequiredDirectoriesWritable) {
+        return <Updater />;
+      }
+
+      return null;
+    });
+
+  extend(ExtensionPage.prototype, 'topItems', function (items) {
+    if (this.extension.id === 'flarum-package-manager' || isExtensionEnabled(this.extension.id)) {
+      return;
+    }
+
+    items.add(
+      'remove',
+      <Button
+        className="Button Button--danger"
+        icon="fas fa-times"
+        onclick={() => {
+          app.modal.show(LoadingModal);
+
+          app
+            .request({
+              url: `${app.forum.attribute('apiUrl')}/package-manager/extensions/${this.extension.id}`,
+              method: 'DELETE',
+            })
+            .then(() => {
+              app.alerts.show({ type: 'success' }, app.translator.trans('flarum-package-manager.admin.extensions.successful_remove'));
+              window.location = app.forum.attribute('adminUrl');
+            })
+            .finally(() => {
+              app.modal.close();
+            });
+        }}
+      >
+        Remove
+      </Button>
+    );
+  });
+});

extensions/package-manager/js/src/admin/utils/errorHandler.ts

@@ -0,0 +1,29 @@
+import app from 'flarum/admin/app';
+
+export default function (e: any) {
+  const error = e.response.errors[0];
+
+  if (!['composer_command_failure', 'extension_already_installed', 'extension_not_installed'].includes(error.code)) {
+    throw e;
+  }
+
+  switch (error.code) {
+    case 'composer_command_failure':
+      if (error.guessed_cause) {
+        app.alerts.show({ type: 'error' }, app.translator.trans(`flarum-package-manager.admin.exceptions.guessed_cause.${error.guessed_cause}`));
+        app.modal.close();
+      } else {
+        app.alerts.show({ type: 'error' }, app.translator.trans('flarum-package-manager.admin.exceptions.composer_command_failure'));
+      }
+      break;
+
+    case 'extension_already_installed':
+      app.alerts.show({ type: 'error' }, app.translator.trans('flarum-package-manager.admin.exceptions.extension_already_installed'));
+      app.modal.close();
+      break;
+
+    case 'extension_not_installed':
+      app.alerts.show({ type: 'error' }, app.translator.trans('flarum-package-manager.admin.exceptions.extension_not_installed'));
+      app.modal.close();
+  }
+}

extensions/package-manager/js/tsconfig.json

@@ -0,0 +1,16 @@
+{
+  // Use Flarum's tsconfig as a starting point
+  "extends": "flarum-tsconfig",
+  // This will match all .ts, .tsx, .d.ts, .js, .jsx files in your `src` folder
+  // and also tells your Typescript server to read core's global typings for
+  // access to `dayjs` and `$` in the global namespace.
+  "include": ["src/**/*", "../vendor/flarum/core/js/dist-typings/@types/**/*", "@types/**/*"],
+  "compilerOptions": {
+    // This will output typings to `dist-typings`
+    "declarationDir": "./dist-typings",
+    "baseUrl": ".",
+    "paths": {
+      "flarum/*": ["../vendor/flarum/core/js/dist-typings/*"]
+    }
+  }
+}

extensions/package-manager/js/webpack.config.js

@@ -0,0 +1 @@
+module.exports = require('flarum-webpack-config')();

extensions/package-manager/less/admin.less

@@ -0,0 +1,157 @@
+.FormControl-container {
+  display: flex;
+  align-items: center;
+  flex-wrap: wrap;
+  gap: 4px;
+}
+
+.ComposerFailureModal-output {
+  white-space: break-spaces;
+}
+
+.flarum-package-manager-Page .ExtensionPage-settings .Form-group:last-child {
+  display: none;
+}
+
+.PackageManager-lastUpdatedAt {
+  color: var(--control-color);
+
+  &-label {
+    font-weight: bold;
+  }
+}
+
+.PackageManager-updaterControls {
+  display: flex;
+  flex-wrap: wrap;
+  gap: 8px;
+  grid-area: controls;
+}
+
+.PackageManager-extensions {
+  &-grid {
+    --gap: 12px;
+    display: grid;
+    grid-template-columns: repeat(auto-fit, calc(~"100% / 3 - var(--gap)"));
+    gap: var(--gap);
+    margin-top: 16px;
+  }
+}
+
+.PackageManager-extension {
+  display: flex;
+  align-items: center;
+  gap: 8px;
+  background-color: var(--control-bg);
+  padding: 8px;
+  border-radius: var(--border-radius);
+
+  &-controls {
+    margin-left: auto;
+  }
+
+  &-icon {
+    --size: 40px;
+  }
+
+  &-name {
+    font-weight: bold;
+  }
+
+  &-version {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+
+    &-latest {
+      border-radius: 30px;
+      padding: 0 6px;
+      font-weight: bold;
+
+      &--minor {
+        background-color: var(--alert-success-bg);
+        color: var(--alert-success-color);
+      }
+
+      &--major {
+        background-color: var(--alert-bg);
+        color: var(--alert-color);
+      }
+    }
+  }
+
+  &--core {
+    --bg-hover: darken(#e7672e, 5);
+    background-color: #e7672e;
+    color: #fff;
+    --button-color: #fff;
+    --button-bg-hover: var(--bg-hover);
+
+    .Button--danger {
+      color: #fff;
+      --button-bg-hover: var(--bg-hover);
+    }
+  }
+
+  &--core &-icon {
+    background-size: 100%;
+    background-color: transparent;
+    filter: grayscale(1) brightness(3.5);
+  }
+
+  &--danger {
+    background-color: var(--control-danger-bg);
+  }
+}
+
+.PackageManager-majorUpdate {
+  --space: 16px;
+  padding: var(--space);
+  display: grid;
+  grid-template-areas:
+    "title logo"
+    "helpText logo"
+    "controls logo"
+    "extensions extensions"
+    "failure failure";
+  grid-gap: 0 var(--space);
+  align-items: center;
+
+  > img {
+    grid-area: logo;
+  }
+
+  > label {
+    grid-area: title;
+  }
+
+  > .helpText {
+    grid-area: helpText;
+  }
+
+  &-failure {
+    --border-radius: 0;
+    grid-area: failure;
+    margin: calc(~"0px - var(--space)");
+    margin-top: var(--space);
+  }
+
+  &-incompatibleExtensions {
+    grid-area: extensions;
+    margin-top: var(--space);
+    padding-top: var(--space);
+    border-top: 1px solid var(--control-bg);
+  }
+}
+
+.Form-group--danger {
+  border: 2px solid var(--alert-error-bg);
+  border-radius: var(--border-radius);
+  background-color: transparent;
+}
+
+.WhyNotModal {
+  &-contents {
+    overflow-x: auto;
+  }
+}

extensions/package-manager/locale/en.yml

@@ -0,0 +1,53 @@
+flarum-package-manager:
+  admin:
+    exceptions:
+      composer_command_failure: Failed to execute. Check the composer logs in storage/logs/composer.
+      extension_already_installed: Extension is already installed.
+      extension_not_installed: Extension not found.
+
+      guessed_cause:
+        extension_incompatible_with_instance: The extension is most likely incompatible with your current Flarum instance.
+        extensions_incompatible_with_new_major: >
+          Some installed extensions are not compatible with the newest major release.
+          Please wait until the extensions are updated to be compatible by the authors, or remove them before proceeding.
+
+    extensions:
+      check_why_it_failed_updating: Show why it did not update to the latest.
+      install: Install a new extension
+      install_help: Fill in the extension package name to proceed. Visit {extiverse} to browse extensions.
+      proceed: Proceed
+      successful_install: "{extension} was installed successfully, redirecting.."
+      successful_remove: Extension removed successfully.
+      successful_update: "{extension} was updated successfully, redirecting.."
+      update: Update
+
+    file_permissions: >
+      The package manager requires read and write permissions on the following files and directories: composer.json, composer.lock, vendor, storage/.composer
+
+    major_updater:
+      description: Major Flarum updates are not backwards compatible, meaning that some of your currently installed extensions, and manually made modifications might not work with this new version.
+      dry_run: Dry Run
+      dry_run_help: A dry run emulates the update to see if your current setup can safely update, this does not mean that your manual made custom modifications will work in the newer version.
+      failure:
+        desc: The last major update failed, some installed extensions are not compatible with the new major release.
+        why: Find out more
+
+      title: Flarum {version} Major Update Available
+      update: Update
+
+    minor_update_confirmation:
+      content: This will also update any other extensions/packages with availabe updates.
+
+    updater:
+      check_for_updates: Check for updates
+      flarum: Flarum Core
+      global_update_successful: Successfully updated all packages.
+      last_update_checked_at: "Last Update Check: "
+      run_global_update: Run Global Update
+      updater_title: Updates
+      updater_help: Runs a check for new extension and Flarum updates.
+
+    update_successful: Flarum successfully updated.
+
+    why_not_modal:
+      title: Why Won't it Update

extensions/package-manager/migrations/2017_04_09_000000_create_bazaar_tasks_table.php

@@ -0,0 +1,19 @@
+<?php
+
+use Flarum\Database\Migration;
+use Illuminate\Database\Schema\Blueprint;
+
+return Migration::createTable(
+    'generic_tasks',
+    function (Blueprint $table) {
+        $table->increments('id');
+        $table->string('status', 50)->nullable();
+        $table->string('command', 50);
+        $table->string('command_class')->nullable();
+        $table->string('package', 100)->nullable();
+        $table->mediumText('output');
+        $table->dateTime('created_at');
+        $table->dateTime('started_at')->nullable();
+        $table->dateTime('finished_at')->nullable();
+    }
+);

extensions/package-manager/src/Api/Controller/CheckForUpdatesController.php

@@ -0,0 +1,43 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Api\Controller;
+
+use Flarum\Http\RequestUtil;
+use Illuminate\Contracts\Bus\Dispatcher;
+use Illuminate\Support\Arr;
+use Laminas\Diactoros\Response\JsonResponse;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use Flarum\PackageManager\Command\CheckForUpdates;
+
+class CheckForUpdatesController implements RequestHandlerInterface
+{
+    /**
+     * @var Dispatcher
+     */
+    protected $bus;
+
+    public function __construct(Dispatcher $bus)
+    {
+        $this->bus = $bus;
+    }
+
+    public function handle(ServerRequestInterface $request): ResponseInterface
+    {
+        $actor = RequestUtil::getActor($request);
+
+        $lastUpdateCheck = $this->bus->dispatch(
+            new CheckForUpdates($actor)
+        );
+
+        return new JsonResponse($lastUpdateCheck);
+    }
+}

extensions/package-manager/src/Api/Controller/GlobalUpdateController.php

@@ -0,0 +1,45 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Api\Controller;
+
+use Flarum\Bus\Dispatcher;
+use Flarum\Http\RequestUtil;
+use Laminas\Diactoros\Response\EmptyResponse;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Flarum\PackageManager\Command\GlobalUpdate;
+
+class GlobalUpdateController implements RequestHandlerInterface
+{
+    /**
+     * @var Dispatcher
+     */
+    protected $bus;
+
+    public function __construct(Dispatcher $bus)
+    {
+        $this->bus = $bus;
+    }
+
+    /**
+     * @throws \Flarum\User\Exception\PermissionDeniedException
+     */
+    public function handle(ServerRequestInterface $request): ResponseInterface
+    {
+        $actor = RequestUtil::getActor($request);
+
+        $this->bus->dispatch(
+            new GlobalUpdate($actor)
+        );
+
+        return new EmptyResponse(200);
+    }
+}

extensions/package-manager/src/Api/Controller/ListTaskController.php

@@ -0,0 +1,32 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Api\Controller;
+
+use Flarum\Http\RequestUtil;
+use Flarum\PackageManager\Api\Serializer\TaskSerializer;
+use Flarum\PackageManager\Task;
+use Flarum\Api\Controller\AbstractListController;
+use Psr\Http\Message\ServerRequestInterface;
+use Tobscure\JsonApi\Document;
+
+class ListTaskController extends AbstractListController
+{
+    public $serializer = TaskSerializer::class;
+
+    /**
+     * @throws \Flarum\User\Exception\PermissionDeniedException
+     */
+    protected function data(ServerRequestInterface $request, Document $document)
+    {
+        RequestUtil::getActor($request)->assertAdmin();
+
+        return Task::query()->orderBy('created_at', 'desc')->get();
+    }
+}

extensions/package-manager/src/Api/Controller/MajorUpdateController.php

@@ -0,0 +1,44 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Api\Controller;
+
+use Flarum\Bus\Dispatcher;
+use Flarum\Http\RequestUtil;
+use Laminas\Diactoros\Response\EmptyResponse;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use Illuminate\Support\Arr;
+use Psr\Http\Message\ServerRequestInterface;
+use Flarum\PackageManager\Command\MajorUpdate;
+
+class MajorUpdateController implements RequestHandlerInterface
+{
+    /**
+     * @var Dispatcher
+     */
+    protected $bus;
+
+    public function __construct(Dispatcher $bus)
+    {
+        $this->bus = $bus;
+    }
+
+    public function handle(ServerRequestInterface $request): ResponseInterface
+    {
+        $actor = RequestUtil::getActor($request);
+        $dryRun = (bool) (int) Arr::get($request->getParsedBody(), 'data.dryRun', 0);
+
+        $this->bus->dispatch(
+            new MajorUpdate($actor, $dryRun)
+        );
+
+        return new EmptyResponse(200);
+    }
+}

extensions/package-manager/src/Api/Controller/MinorUpdateController.php

@@ -0,0 +1,45 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Api\Controller;
+
+use Flarum\Bus\Dispatcher;
+use Flarum\Http\RequestUtil;
+use Laminas\Diactoros\Response\EmptyResponse;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Flarum\PackageManager\Command\MinorUpdate;
+
+class MinorUpdateController implements RequestHandlerInterface
+{
+    /**
+     * @var Dispatcher
+     */
+    protected $bus;
+
+    public function __construct(Dispatcher $bus)
+    {
+        $this->bus = $bus;
+    }
+
+    /**
+     * @throws \Flarum\User\Exception\PermissionDeniedException
+     */
+    public function handle(ServerRequestInterface $request): ResponseInterface
+    {
+        $actor = RequestUtil::getActor($request);
+
+        $this->bus->dispatch(
+            new MinorUpdate($actor)
+        );
+
+        return new EmptyResponse(200);
+    }
+}

extensions/package-manager/src/Api/Controller/RemoveExtensionController.php

@@ -0,0 +1,44 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Api\Controller;
+
+use Flarum\Bus\Dispatcher;
+use Flarum\Http\RequestUtil;
+use Illuminate\Support\Arr;
+use Laminas\Diactoros\Response\EmptyResponse;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Flarum\PackageManager\Command\RemoveExtension;
+use Psr\Http\Server\RequestHandlerInterface;
+
+class RemoveExtensionController implements RequestHandlerInterface
+{
+    /**
+     * @var Dispatcher
+     */
+    protected $bus;
+
+    public function __construct(Dispatcher $bus)
+    {
+        $this->bus = $bus;
+    }
+
+    public function handle(ServerRequestInterface $request): ResponseInterface
+    {
+        $actor = RequestUtil::getActor($request);
+        $extensionId = Arr::get($request->getQueryParams(), 'id');
+
+        $this->bus->dispatch(
+            new RemoveExtension($actor, $extensionId)
+        );
+
+        return new EmptyResponse(200);
+    }
+}

extensions/package-manager/src/Api/Controller/RequireExtensionController.php

@@ -0,0 +1,48 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Api\Controller;
+
+use Flarum\Bus\Dispatcher;
+use Laminas\Diactoros\Response\JsonResponse;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use Flarum\PackageManager\Api\Serializer\ExtensionSerializer;
+use Flarum\PackageManager\Command\RequireExtension;
+use Flarum\PackageManager\Extension\ExtensionUtils;
+use Flarum\Api\Controller\AbstractCreateController;
+use Flarum\Http\RequestUtil;
+use Illuminate\Support\Arr;
+use Psr\Http\Message\ServerRequestInterface;
+use Tobscure\JsonApi\Document;
+
+class RequireExtensionController implements RequestHandlerInterface
+{
+    /**
+     * @var Dispatcher
+     */
+    protected $bus;
+
+    public function __construct(Dispatcher $bus)
+    {
+        $this->bus = $bus;
+    }
+
+    public function handle(ServerRequestInterface $request): ResponseInterface
+    {
+        $actor = RequestUtil::getActor($request);
+        $package = Arr::get($request->getParsedBody(), 'data.package');
+
+        $data = $this->bus->dispatch(
+            new RequireExtension($actor, $package)
+        );
+
+        return new JsonResponse($data);
+    }
+}

extensions/package-manager/src/Api/Controller/UpdateExtensionController.php

@@ -0,0 +1,44 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Api\Controller;
+
+use Flarum\Bus\Dispatcher;
+use Flarum\Http\RequestUtil;
+use Laminas\Diactoros\Response\EmptyResponse;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use Illuminate\Support\Arr;
+use Psr\Http\Message\ServerRequestInterface;
+use Flarum\PackageManager\Command\UpdateExtension;
+
+class UpdateExtensionController implements RequestHandlerInterface
+{
+    /**
+     * @var Dispatcher
+     */
+    protected $bus;
+
+    public function __construct(Dispatcher $bus)
+    {
+        $this->bus = $bus;
+    }
+
+    public function handle(ServerRequestInterface $request): ResponseInterface
+    {
+        $actor = RequestUtil::getActor($request);
+        $extensionId = Arr::get($request->getQueryParams(), 'id');
+
+        $this->bus->dispatch(
+            new UpdateExtension($actor, $extensionId)
+        );
+
+        return new EmptyResponse(200);
+    }
+}

extensions/package-manager/src/Api/Controller/WhyNotController.php

@@ -0,0 +1,47 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Api\Controller;
+
+use Flarum\Bus\Dispatcher;
+use Flarum\Http\RequestUtil;
+use Flarum\PackageManager\Command\WhyNot;
+use Illuminate\Support\Arr;
+use Laminas\Diactoros\Response\JsonResponse;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use Psr\Http\Message\ServerRequestInterface;
+
+class WhyNotController implements RequestHandlerInterface
+{
+    /**
+     * @var Dispatcher
+     */
+    protected $bus;
+
+    public function __construct(Dispatcher $bus)
+    {
+        $this->bus = $bus;
+    }
+
+    public function handle(ServerRequestInterface $request): ResponseInterface
+    {
+        $actor = RequestUtil::getActor($request);
+        $package = Arr::get($request->getParsedBody(), 'data.package', '');
+        $version = Arr::get($request->getParsedBody(), 'data.version', '*');
+
+        $whyNot = $this->bus->dispatch(
+            new WhyNot($actor, $package, $version)
+        );
+
+        return new JsonResponse([
+            'data' => compact('whyNot')
+        ]);
+    }
+}

extensions/package-manager/src/Command/CheckForUpdates.php

@@ -0,0 +1,25 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\User\User;
+
+class CheckForUpdates
+{
+    /**
+     * @var \Flarum\User\User
+     */
+    public $actor;
+
+    public function __construct(User $actor)
+    {
+        $this->actor = $actor;
+    }
+}

extensions/package-manager/src/Command/CheckForUpdatesHandler.php

@@ -0,0 +1,127 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\PackageManager\Composer\ComposerAdapter;
+use Flarum\PackageManager\Exception\ComposerCommandFailedException;
+use Flarum\PackageManager\Settings\LastUpdateCheck;
+use Symfony\Component\Console\Input\ArrayInput;
+
+class CheckForUpdatesHandler
+{
+    /**
+     * @var ComposerAdapter
+     */
+    protected $composer;
+
+    /**
+     * @var \Flarum\PackageManager\Settings\LastUpdateCheck
+     */
+    protected $lastUpdateCheck;
+
+    public function __construct(ComposerAdapter $composer, LastUpdateCheck $lastUpdateCheck)
+    {
+        $this->composer = $composer;
+        $this->lastUpdateCheck = $lastUpdateCheck;
+    }
+
+    /**
+     * We run two commands here
+     *
+     * `composer outdated -D --format json`
+     * This queries latest versions for all direct packages, so it can include major updates,
+     * that are not necessarily compatible with the current flarum version.
+     * That includes flarum/core itself, so for example if we are on flarum/core v1.8.0
+     * and there are v1.8.1 and v2.0.0 available, the command would only let us know of v2.0.0.
+     *
+     * `composer outdated -D --minor-only --format json`
+     * This only lists latest minor updates, we need to run this as well not only to be able to know
+     * of these minor versions in addition to major ones, but especially for the flarum/core, as explained above
+     * we need to know of minor core updates, even if there is a major version available.
+     *
+     * The results from both commands are properly processed and merged to have new key values `latest-minor` and `latest-major`.
+     *
+     * @throws \Flarum\User\Exception\PermissionDeniedException|ComposerCommandFailedException
+     * @todo integration test
+     */
+    public function handle(CheckForUpdates $command)
+    {
+        $actor = $command->actor;
+
+        $actor->assertAdmin();
+
+        $firstOutput = $this->runComposerCommand(false);
+        $firstOutput = json_decode($firstOutput, true);
+
+        $majorUpdates = false;
+
+        foreach ($firstOutput['installed'] as $package) {
+            if ($package['latest-status'] === 'update-possible') {
+                $majorUpdates = true;
+                break;
+            }
+        }
+
+        if ($majorUpdates) {
+            $secondOutput = $this->runComposerCommand(true);
+            $secondOutput = json_decode($secondOutput, true);
+        }
+
+        if (! isset($secondOutput)) {
+            $secondOutput = ['installed' => []];
+        }
+
+        foreach ($firstOutput['installed'] as &$mainPackageUpdate) {
+            $mainPackageUpdate['latest-minor'] = $mainPackageUpdate['latest-major'] = null;
+
+            if ($mainPackageUpdate['latest-status'] === 'update-possible') {
+                $mainPackageUpdate['latest-major'] = $mainPackageUpdate['latest'];
+
+                $minorPackageUpdate = array_filter($secondOutput['installed'], function ($package) use ($mainPackageUpdate) {
+                    return $package['name'] === $mainPackageUpdate['name'];
+                })[0] ?? null;
+
+                if ($minorPackageUpdate) {
+                    $mainPackageUpdate['latest-minor'] = $minorPackageUpdate['latest'];
+                }
+            } else {
+                $mainPackageUpdate['latest-minor'] = $mainPackageUpdate['latest'];
+            }
+        }
+
+        return $this->lastUpdateCheck
+            ->with('installed', $firstOutput['installed'])
+            ->save();
+    }
+
+    /**
+     * @throws ComposerCommandFailedException
+     */
+    protected function runComposerCommand(bool $minorOnly): string
+    {
+        $input = [
+            'command' => 'outdated',
+            '-D' => true,
+            '--format' => 'json',
+        ];
+
+        if ($minorOnly) {
+            $input['--minor-only'] = true;
+        }
+
+        $output = $this->composer->run(new ArrayInput($input));
+
+        if ($output->getExitCode() !== 0) {
+            throw new ComposerCommandFailedException('', $output->getContents());
+        }
+
+        return $output->getContents();
+    }
+}

extensions/package-manager/src/Command/GlobalUpdate.php

@@ -0,0 +1,25 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\User\User;
+
+class GlobalUpdate
+{
+    /**
+     * @var \Flarum\User\User
+     */
+    public $actor;
+
+    public function __construct(User $actor)
+    {
+        $this->actor = $actor;
+    }
+}

extensions/package-manager/src/Command/GlobalUpdateHandler.php

@@ -0,0 +1,64 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\Bus\Dispatcher as FlarumDispatcher;
+use Flarum\PackageManager\Composer\ComposerAdapter;
+use Illuminate\Contracts\Events\Dispatcher;
+use Flarum\PackageManager\Event\FlarumUpdated;
+use Flarum\PackageManager\Exception\ComposerUpdateFailedException;
+use Symfony\Component\Console\Input\StringInput;
+
+class GlobalUpdateHandler
+{
+    /**
+     * @var ComposerAdapter
+     */
+    protected $composer;
+
+    /**
+     * @var Dispatcher
+     */
+    protected $events;
+
+    /**
+     * @var FlarumDispatcher
+     */
+    protected $commandDispatcher;
+
+    public function __construct(ComposerAdapter $composer, Dispatcher $events, FlarumDispatcher $commandDispatcher)
+    {
+        $this->composer = $composer;
+        $this->events = $events;
+        $this->commandDispatcher = $commandDispatcher;
+    }
+
+    /**
+     * @throws \Flarum\User\Exception\PermissionDeniedException|ComposerUpdateFailedException
+     */
+    public function handle(GlobalUpdate $command)
+    {
+        $command->actor->assertAdmin();
+
+        $output = $this->composer->run(
+            new StringInput("update --prefer-dist --no-dev -a --with-all-dependencies")
+        );
+
+        if ($output->getExitCode() !== 0) {
+            throw new ComposerUpdateFailedException('*', $output->getContents());
+        }
+
+        $this->events->dispatch(
+            new FlarumUpdated($command->actor, FlarumUpdated::GLOBAL)
+        );
+
+        return true;
+    }
+}

extensions/package-manager/src/Command/MajorUpdate.php

@@ -0,0 +1,31 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\User\User;
+
+class MajorUpdate
+{
+    /**
+     * @var \Flarum\User\User
+     */
+    public $actor;
+
+    /**
+     * @var bool
+     */
+    public $dryRun;
+
+    public function __construct(User $actor, bool $dryRun)
+    {
+        $this->actor = $actor;
+        $this->dryRun = $dryRun;
+    }
+}

extensions/package-manager/src/Command/MajorUpdateHandler.php

@@ -0,0 +1,129 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\PackageManager\Composer\ComposerAdapter;
+use Flarum\PackageManager\Composer\ComposerJson;
+use Flarum\PackageManager\Exception\MajorUpdateFailedException;
+use Flarum\PackageManager\Exception\NoNewMajorVersionException;
+use Illuminate\Contracts\Events\Dispatcher;
+use Flarum\PackageManager\Event\FlarumUpdated;
+use Flarum\PackageManager\Settings\LastUpdateCheck;
+use Symfony\Component\Console\Input\ArrayInput;
+
+class MajorUpdateHandler
+{
+    /**
+     * @var ComposerAdapter
+     */
+    protected $composer;
+
+    /**
+     * @var LastUpdateCheck
+     */
+    protected $lastUpdateCheck;
+
+    /**
+     * @var Dispatcher
+     */
+    protected $events;
+
+    /**
+     * @var ComposerJson
+     */
+    protected $composerJson;
+
+    /**
+     * @param ComposerAdapter $composer
+     * @param LastUpdateCheck $lastUpdateCheck
+     * @param Dispatcher $events
+     * @param ComposerJson $composerJson
+     */
+    public function __construct(ComposerAdapter $composer, LastUpdateCheck $lastUpdateCheck, Dispatcher $events, ComposerJson $composerJson)
+    {
+        $this->composer = $composer;
+        $this->lastUpdateCheck = $lastUpdateCheck;
+        $this->events = $events;
+        $this->composerJson = $composerJson;
+    }
+
+    /**
+     * Set the version constraint for all directly required packages in the root composer.json to *.
+     * Set flarum/core version constraint to new major version.
+     * Run composer update --prefer-dist --no-plugins --no-dev -a --with-all-dependencies.
+     * Clear cache.
+     * Run migrations.
+     *
+     * @throws \Flarum\User\Exception\PermissionDeniedException
+     * @throws NoNewMajorVersionException|MajorUpdateFailedException
+     */
+    public function handle(MajorUpdate $command)
+    {
+        $command->actor->assertAdmin();
+
+        $majorVersion = $this->lastUpdateCheck->getNewMajorVersion();
+
+        if (! $majorVersion) {
+            throw new NoNewMajorVersionException();
+        }
+
+        $this->updateComposerJson($majorVersion);
+
+        $this->runCommand($command->dryRun, $majorVersion);
+
+        if ($command->dryRun) {
+            $this->composerJson->revert();
+
+            return true;
+        }
+
+        $this->events->dispatch(
+            new FlarumUpdated($command->actor, FlarumUpdated::MAJOR)
+        );
+
+        return true;
+    }
+
+    /**
+     * @todo change minimum stability to 'stable' and any other similar params
+     */
+    protected function updateComposerJson(string $majorVersion): void
+    {
+        $versionNumber = str_replace('v', '', $majorVersion);
+
+        $this->composerJson->require('*', '*');
+        $this->composerJson->require('flarum/core', '^'.$versionNumber);
+    }
+
+    /**
+     * @throws MajorUpdateFailedException
+     */
+    protected function runCommand(bool $dryRun, string $majorVersion): void
+    {
+        $input = [
+            'command' => 'update',
+            '--prefer-dist' => true,
+            '--no-plugins' => true,
+            '--no-dev' => true,
+            '-a' => true,
+            '--with-all-dependencies' => true,
+        ];
+
+        if ($dryRun) {
+            $input['--dry-run'] = true;
+        }
+
+        $output = $this->composer->run(new ArrayInput($input));
+
+        if ($output->getExitCode() !== 0) {
+            throw new MajorUpdateFailedException('*', $output->getContents(), $majorVersion);
+        }
+    }
+}

extensions/package-manager/src/Command/MinorUpdate.php

@@ -0,0 +1,25 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\User\User;
+
+class MinorUpdate
+{
+    /**
+     * @var \Flarum\User\User
+     */
+    public $actor;
+
+    public function __construct(User $actor)
+    {
+        $this->actor = $actor;
+    }
+}

extensions/package-manager/src/Command/MinorUpdateHandler.php

@@ -0,0 +1,77 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\PackageManager\Composer\ComposerAdapter;
+use Flarum\PackageManager\Composer\ComposerJson;
+use Illuminate\Contracts\Events\Dispatcher;
+use Flarum\PackageManager\Event\FlarumUpdated;
+use Flarum\PackageManager\Exception\ComposerUpdateFailedException;
+use Flarum\PackageManager\Settings\LastUpdateCheck;
+use Symfony\Component\Console\Input\StringInput;
+
+class MinorUpdateHandler
+{
+    /**
+     * @var ComposerAdapter
+     */
+    protected $composer;
+
+    /**
+     * @var \Flarum\PackageManager\Settings\LastUpdateCheck
+     */
+    protected $lastUpdateCheck;
+
+    /**
+     * @var Dispatcher
+     */
+    protected $events;
+
+    /**
+     * @var ComposerJson
+     */
+    protected $composerJson;
+
+    public function __construct(ComposerAdapter $composer, LastUpdateCheck $lastUpdateCheck, Dispatcher $events, ComposerJson $composerJson)
+    {
+        $this->composer = $composer;
+        $this->lastUpdateCheck = $lastUpdateCheck;
+        $this->events = $events;
+        $this->composerJson = $composerJson;
+    }
+
+    /**
+     * @throws \Flarum\User\Exception\PermissionDeniedException
+     * @throws ComposerUpdateFailedException
+     */
+    public function handle(MinorUpdate $command)
+    {
+        $command->actor->assertAdmin();
+
+        $coreRequirement = $this->composerJson->get()['require']['flarum/core'];
+
+        $this->composerJson->require('*', '*');
+        $this->composerJson->require('flarum/core', $coreRequirement);
+
+        $output = $this->composer->run(
+            new StringInput("update --prefer-dist --no-dev -a --with-all-dependencies")
+        );
+
+        if ($output->getExitCode() !== 0) {
+            throw new ComposerUpdateFailedException('flarum/*', $output->getContents());
+        }
+
+        $this->events->dispatch(
+            new FlarumUpdated($command->actor, FlarumUpdated::MINOR)
+        );
+
+        return true;
+    }
+}

extensions/package-manager/src/Command/RemoveExtension.php

@@ -0,0 +1,31 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\User\User;
+
+class RemoveExtension
+{
+    /**
+     * @var User
+     */
+    public $actor;
+
+    /**
+     * @var string
+     */
+    public $extensionId;
+
+    public function __construct(User $actor, string $extensionId)
+    {
+        $this->actor = $actor;
+        $this->extensionId = $extensionId;
+    }
+}

extensions/package-manager/src/Command/RemoveExtensionHandler.php

@@ -0,0 +1,70 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\Extension\ExtensionManager;
+use Flarum\PackageManager\Composer\ComposerAdapter;
+use Illuminate\Contracts\Events\Dispatcher;
+use Flarum\PackageManager\Exception\ComposerCommandFailedException;
+use Flarum\PackageManager\Exception\ExtensionNotInstalledException;
+use Flarum\PackageManager\Extension\Event\Removed;
+use Symfony\Component\Console\Input\StringInput;
+
+class RemoveExtensionHandler
+{
+    /**
+     * @var ComposerAdapter
+     */
+    protected $composer;
+
+    /**
+     * @var ExtensionManager
+     */
+    protected $extensions;
+
+    /**
+     * @var Dispatcher
+     */
+    protected $events;
+
+    public function __construct(ComposerAdapter $composer, ExtensionManager $extensions, Dispatcher $events)
+    {
+        $this->composer = $composer;
+        $this->extensions = $extensions;
+        $this->events = $events;
+    }
+
+    /**
+     * @throws \Flarum\User\Exception\PermissionDeniedException
+     * @throws \Exception
+     */
+    public function handle(RemoveExtension $command)
+    {
+        $command->actor->assertAdmin();
+
+        $extension = $this->extensions->getExtension($command->extensionId);
+
+        if (empty($extension)) {
+            throw new ExtensionNotInstalledException($command->extensionId);
+        }
+
+        $output = $this->composer->run(
+            new StringInput("remove $extension->name")
+        );
+
+        if ($output->getExitCode() !== 0) {
+            throw new ComposerCommandFailedException($extension->name, $output->getContents());
+        }
+
+        $this->events->dispatch(
+            new Removed($extension)
+        );
+    }
+}

extensions/package-manager/src/Command/RequireExtension.php

@@ -0,0 +1,31 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\User\User;
+
+class RequireExtension
+{
+    /**
+     * @var User
+     */
+    public $actor;
+
+    /**
+     * @var string
+     */
+    public $package;
+
+    public function __construct(User $actor, string $package)
+    {
+        $this->actor = $actor;
+        $this->package = $package;
+    }
+}

extensions/package-manager/src/Command/RequireExtensionHandler.php

@@ -0,0 +1,90 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\Extension\ExtensionManager;
+use Flarum\PackageManager\Composer\ComposerAdapter;
+use Illuminate\Contracts\Events\Dispatcher;
+use Flarum\PackageManager\Exception\ComposerRequireFailedException;
+use Flarum\PackageManager\Exception\ExtensionAlreadyInstalledException;
+use Flarum\PackageManager\Extension\Event\Installed;
+use Flarum\PackageManager\Extension\ExtensionUtils;
+use Flarum\PackageManager\RequirePackageValidator;
+use Symfony\Component\Console\Input\StringInput;
+
+class RequireExtensionHandler
+{
+    /**
+     * @var ComposerAdapter
+     */
+    protected $composer;
+
+    /**
+     * @var ExtensionManager
+     */
+    protected $extensions;
+
+    /**
+     * @var RequirePackageValidator
+     */
+    protected $validator;
+
+    /**
+     * @var Dispatcher
+     */
+    protected $events;
+
+    public function __construct(ComposerAdapter $composer, ExtensionManager $extensions, RequirePackageValidator $validator, Dispatcher $events)
+    {
+        $this->composer = $composer;
+        $this->extensions = $extensions;
+        $this->validator = $validator;
+        $this->events = $events;
+    }
+
+    /**
+     * @throws \Flarum\User\Exception\PermissionDeniedException
+     * @throws \Exception
+     */
+    public function handle(RequireExtension $command)
+    {
+        $command->actor->assertAdmin();
+
+        $this->validator->assertValid(['package' => $command->package]);
+
+        $extensionId = ExtensionUtils::nameToId($command->package);
+        $extension = $this->extensions->getExtension($extensionId);
+
+        if (! empty($extension)) {
+            throw new ExtensionAlreadyInstalledException($extension);
+        }
+
+        $packageName = $command->package;
+
+        // Auto append :* if not requiring a specific version.
+        if (strpos($packageName, ':') === false) {
+            $packageName .= ":*";
+        }
+
+        $output = $this->composer->run(
+            new StringInput("require $packageName")
+        );
+
+        if ($output->getExitCode() !== 0) {
+            throw new ComposerRequireFailedException($packageName, $output->getContents());
+        }
+
+        $this->events->dispatch(
+            new Installed($extensionId)
+        );
+
+        return ['id' => $extensionId];
+    }
+}

extensions/package-manager/src/Command/UpdateExtension.php

@@ -0,0 +1,31 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\User\User;
+
+class UpdateExtension
+{
+    /**
+     * @var User
+     */
+    public $actor;
+
+    /**
+     * @var string
+     */
+    public $extensionId;
+
+    public function __construct(User $actor, string $extensionId)
+    {
+        $this->actor = $actor;
+        $this->extensionId = $extensionId;
+    }
+}

extensions/package-manager/src/Command/UpdateExtensionHandler.php

@@ -0,0 +1,93 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\Extension\ExtensionManager;
+use Flarum\PackageManager\Composer\ComposerAdapter;
+use Illuminate\Contracts\Events\Dispatcher;
+use Flarum\PackageManager\Exception\ComposerUpdateFailedException;
+use Flarum\PackageManager\Exception\ExtensionNotInstalledException;
+use Flarum\PackageManager\Extension\Event\Updated;
+use Flarum\PackageManager\UpdateExtensionValidator;
+use Flarum\PackageManager\Settings\LastUpdateCheck;
+use Symfony\Component\Console\Input\StringInput;
+
+class UpdateExtensionHandler
+{
+    /**
+     * @var ComposerAdapter
+     */
+    protected $composer;
+
+    /**
+     * @var ExtensionManager
+     */
+    protected $extensions;
+
+    /**
+     * @var UpdateExtensionValidator
+     */
+    protected $validator;
+
+    /**
+     * @var LastUpdateCheck
+     */
+    protected $lastUpdateCheck;
+
+    /**
+     * @var Dispatcher
+     */
+    protected $events;
+
+    public function __construct(
+        ComposerAdapter $composer,
+        ExtensionManager $extensions,
+        UpdateExtensionValidator $validator,
+        LastUpdateCheck $lastUpdateCheck,
+        Dispatcher $events)
+    {
+        $this->composer = $composer;
+        $this->extensions = $extensions;
+        $this->validator = $validator;
+        $this->lastUpdateCheck = $lastUpdateCheck;
+        $this->events = $events;
+    }
+
+    /**
+     * @throws \Flarum\User\Exception\PermissionDeniedException
+     * @throws \Exception
+     */
+    public function handle(UpdateExtension $command)
+    {
+        $command->actor->assertAdmin();
+
+        $this->validator->assertValid(['extensionId' => $command->extensionId]);
+
+        $extension = $this->extensions->getExtension($command->extensionId);
+
+        if (empty($extension)) {
+            throw new ExtensionNotInstalledException($command->extensionId);
+        }
+
+        $output = $this->composer->run(
+            new StringInput("require $extension->name:*")
+        );
+
+        if ($output->getExitCode() !== 0) {
+            throw new ComposerUpdateFailedException($extension->name, $output->getContents());
+        }
+
+        $this->events->dispatch(
+            new Updated($command->actor, $extension)
+        );
+
+        return true;
+    }
+}

extensions/package-manager/src/Command/WhyNot.php

@@ -0,0 +1,37 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\User\User;
+
+class WhyNot
+{
+    /**
+     * @var User
+     */
+    public $actor;
+
+    /**
+     * @var string
+     */
+    public $package;
+
+    /**
+     * @var string
+     */
+    public $version;
+
+    public function __construct(User $actor, string $package, string $version)
+    {
+        $this->actor = $actor;
+        $this->package = $package;
+        $this->version = $version;
+    }
+}

extensions/package-manager/src/Command/WhyNotHandler.php

@@ -0,0 +1,65 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Command;
+
+use Flarum\PackageManager\Composer\ComposerAdapter;
+use Illuminate\Contracts\Events\Dispatcher;
+use Flarum\PackageManager\Exception\ComposerRequireFailedException;
+use Flarum\PackageManager\WhyNotValidator;
+use Symfony\Component\Console\Input\StringInput;
+
+class WhyNotHandler
+{
+    /**
+     * @var ComposerAdapter
+     */
+    protected $composer;
+
+    /**
+     * @var WhyNotValidator
+     */
+    protected $validator;
+
+    /**
+     * @var Dispatcher
+     */
+    protected $events;
+
+    public function __construct(ComposerAdapter $composer, WhyNotValidator $validator, Dispatcher $events)
+    {
+        $this->composer = $composer;
+        $this->validator = $validator;
+        $this->events = $events;
+    }
+
+    /**
+     * @throws \Flarum\User\Exception\PermissionDeniedException
+     * @throws \Exception
+     */
+    public function handle(WhyNot $command)
+    {
+        $command->actor->assertAdmin();
+
+        $this->validator->assertValid([
+            'package' => $command->package,
+            'version' => $command->version
+        ]);
+
+        $output = $this->composer->run(
+            new StringInput("why-not $command->package $command->version")
+        );
+
+        if ($output->getExitCode() !== 0) {
+            throw new ComposerRequireFailedException($command->package, $output->getContents());
+        }
+
+        return $output->getContents();
+    }
+}

extensions/package-manager/src/Composer/ComposerAdapter.php

@@ -0,0 +1,67 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Composer;
+
+use Composer\Console\Application;
+use Flarum\Foundation\Paths;
+use Flarum\PackageManager\OutputLogger;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\BufferedOutput;
+
+/**
+ * @internal
+ */
+class ComposerAdapter
+{
+    /**
+     * @var Application
+     */
+    private $application;
+
+    /**
+     * @var OutputLogger
+     */
+    private $logger;
+
+    /**
+     * @var BufferedOutput
+     */
+    private $output;
+
+    /**
+     * @var Paths
+     */
+    private $paths;
+
+    public function __construct(Application $application, OutputLogger $logger, Paths $paths)
+    {
+        $this->application = $application;
+        $this->logger = $logger;
+        $this->paths = $paths;
+        $this->output = new BufferedOutput();
+    }
+
+    public function run(InputInterface $input): ComposerOutput
+    {
+        $this->application->resetComposer();
+
+        // This hack is necessary so that relative path repositories are resolved properly.
+        $currDir = getcwd();
+        chdir($this->paths->base);
+        $exitCode = $this->application->run($input, $this->output);
+        chdir($currDir);
+
+        $outputContents = $this->output->fetch();
+
+        $this->logger->log($input->__toString(), $outputContents, $exitCode);
+
+        return new ComposerOutput($exitCode, $outputContents);
+    }
+}

extensions/package-manager/src/Composer/ComposerJson.php

@@ -0,0 +1,90 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Composer;
+
+use Flarum\Foundation\Paths;
+use Illuminate\Filesystem\Filesystem;
+use Illuminate\Support\Str;
+
+class ComposerJson
+{
+    /**
+     * @var Paths
+     */
+    protected $paths;
+
+    /**
+     * @var Filesystem
+     */
+    protected $filesystem;
+
+    /**
+     * @var array
+     */
+    protected $initialJson;
+
+    public function __construct(Paths $paths, Filesystem $filesystem)
+    {
+        $this->paths = $paths;
+        $this->filesystem = $filesystem;
+    }
+
+    public function require(string $packageName, string $version): void
+    {
+        $composerJson = $this->get();
+
+        if (strpos($packageName, '*') === false) {
+            $composerJson['require'][$packageName] = $version;
+        } else {
+            foreach ($composerJson['require'] as $p => $v) {
+                if ($version === '*@dev') {
+                    continue;
+                }
+
+                $wildcardPackageName = str_replace('\*', '.*', preg_quote($packageName, '/'));
+
+                if (Str::of($p)->test("/($wildcardPackageName)/")) {
+                    $composerJson['require'][$p] = $version;
+                }
+            }
+        }
+
+        $this->set($composerJson);
+    }
+
+    public function revert(): void
+    {
+        $this->set($this->initialJson);
+    }
+
+    protected function getComposerJsonPath(): string
+    {
+        return $this->paths->base . '/composer.json';
+    }
+
+    /**
+     * @throws \Illuminate\Contracts\Filesystem\FileNotFoundException
+     */
+    public function get(): array
+    {
+        $json = json_decode($this->filesystem->get($this->getComposerJsonPath()), true);
+
+        if (! $this->initialJson) {
+            $this->initialJson = $json;
+        }
+
+        return $json;
+    }
+
+    protected function set(array $json): void
+    {
+        $this->filesystem->put($this->getComposerJsonPath(), json_encode($json, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES));
+    }
+}

extensions/package-manager/src/Composer/ComposerOutput.php

@@ -0,0 +1,39 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Composer;
+
+class ComposerOutput
+{
+    /**
+     * @var int
+     */
+    protected $exitCode;
+
+    /**
+     * @var string
+     */
+    protected $contents;
+
+    public function __construct(int $exitCode, string $contents)
+    {
+        $this->exitCode = $exitCode;
+        $this->contents = $contents;
+    }
+
+    public function getExitCode(): int
+    {
+        return $this->exitCode;
+    }
+
+    public function getContents(): string
+    {
+        return $this->contents;
+    }
+}

extensions/package-manager/src/Event/FlarumUpdated.php

@@ -0,0 +1,35 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Event;
+
+use Flarum\User\User;
+
+class FlarumUpdated
+{
+    public const GLOBAL = 'global';
+    public const MINOR = 'minor';
+    public const MAJOR = 'major';
+
+    /**
+     * @var User
+     */
+    public $actor;
+
+    /**
+     * @var string
+     */
+    public $type;
+
+    public function __construct(User $actor, string $type)
+    {
+        $this->actor = $actor;
+        $this->type = $type;
+    }
+}

extensions/package-manager/src/Exception/ComposerCommandFailedException.php

@@ -0,0 +1,42 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Exception;
+
+use Exception;
+
+class ComposerCommandFailedException extends Exception
+{
+    /**
+     * @var string
+     */
+    public $packageName;
+
+    /**
+     * @var array
+     */
+    public $details = [];
+
+    public function __construct(string $packageName, string $output)
+    {
+        $this->packageName = $packageName;
+
+        parent::__construct($output);
+    }
+
+    public function guessCause(): ?string
+    {
+        return null;
+    }
+
+    protected function getRawPackageName(): string
+    {
+        return preg_replace('/^([A-z0-9-_\/]+)(?::.*|)$/i', '$1', $this->packageName);
+    }
+}

extensions/package-manager/src/Exception/ComposerRequireFailedException.php

@@ -0,0 +1,30 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Exception;
+
+class ComposerRequireFailedException extends ComposerCommandFailedException
+{
+    protected const INCOMPATIBLE_REGEX = '/(?:(?: +- {PACKAGE_NAME}(?: v[0-9A-z.-]+ requires|\[[^\[\]]+\] require) flarum\/core)|(?:Could not find a version of package {PACKAGE_NAME} matching your minim)|(?: +- Root composer.json requires {PACKAGE_NAME} [^,]+, found {PACKAGE_NAME}\[[^\[\]]+\]+ but it does not match your minimum-stability))/m';
+
+    public function guessCause(): ?string
+    {
+        $hasMatches = preg_match(
+            str_replace('{PACKAGE_NAME}', preg_quote($this->getRawPackageName(), '/'), self::INCOMPATIBLE_REGEX),
+            $this->getMessage(),
+            $matches
+        );
+
+        if ($hasMatches) {
+            return 'extension_incompatible_with_instance';
+        }
+
+        return null;
+    }
+}

extensions/package-manager/src/Exception/ComposerUpdateFailedException.php

@@ -0,0 +1,15 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Exception;
+
+class ComposerUpdateFailedException extends ComposerCommandFailedException
+{
+    // ...
+}

extensions/package-manager/src/Exception/ExceptionHandler.php

@@ -0,0 +1,44 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Exception;
+
+use Flarum\Foundation\ErrorHandling\HandledError;
+
+class ExceptionHandler
+{
+    public function handle(ComposerCommandFailedException $e): HandledError
+    {
+        return (new HandledError(
+            $e,
+            'composer_command_failure',
+            409
+        ))->withDetails($this->errorDetails($e));
+    }
+
+    protected function errorDetails(ComposerCommandFailedException $e): array
+    {
+        $details = [];
+
+        if ($guessedCause = $this->guessCause($e)) {
+            $details['guessed_cause'] = $guessedCause;
+        }
+
+        if (! empty($e->details)) {
+            $details = array_merge($details, $e->details);
+        }
+
+        return [$details];
+    }
+
+    protected function guessCause(ComposerCommandFailedException $e): ?string
+    {
+        return $e->guessCause();
+    }
+}

extensions/package-manager/src/Exception/ExtensionAlreadyInstalledException.php

@@ -0,0 +1,27 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Exception;
+
+use Exception;
+use Flarum\Extension\Extension;
+use Flarum\Foundation\KnownError;
+
+class ExtensionAlreadyInstalledException extends Exception implements KnownError
+{
+    public function __construct(Extension $extension)
+    {
+        parent::__construct("Extension {$extension->getTitle()} is already installed.");
+    }
+
+    public function getType(): string
+    {
+        return 'extension_already_installed';
+    }
+}

extensions/package-manager/src/Exception/ExtensionNotInstalledException.php

@@ -0,0 +1,26 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Exception;
+
+use Exception;
+use Flarum\Foundation\KnownError;
+
+class ExtensionNotInstalledException extends Exception implements KnownError
+{
+    public function __construct(string $extensionId)
+    {
+        parent::__construct("Extension {$extensionId} is not installed.");
+    }
+
+    public function getType(): string
+    {
+        return 'extension_not_installed';
+    }
+}

extensions/package-manager/src/Exception/MajorUpdateFailedException.php

@@ -0,0 +1,54 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Exception;
+
+use Composer\Semver\Semver;
+use Flarum\PackageManager\Event\FlarumUpdated;
+use Flarum\PackageManager\Settings\LastUpdateRun;
+
+class MajorUpdateFailedException extends ComposerCommandFailedException
+{
+    private const INCOMPATIBLE_REGEX = '/^ +- (?<ext>[A-z0-9\/-]+) [A-z0-9.-_\/]+ requires flarum\/core (?<coreReq>(?:[A-z0-9.><=_ -](?!->))+)/m';
+
+    /**
+     * @var string
+     */
+    private $majorVersion;
+
+    public function __construct(string $packageName, string $output, string $majorVersion)
+    {
+        $this->majorVersion = $majorVersion;
+
+        parent::__construct($packageName, $output);
+    }
+
+    public function guessCause(): ?string
+    {
+        if (preg_match_all(self::INCOMPATIBLE_REGEX, $this->getMessage(), $matches) !== false) {
+            $this->details['incompatible_extensions'] = [];
+
+            foreach ($matches['ext'] as $k => $name) {
+                if (! Semver::satisfies($this->majorVersion, $matches['coreReq'][$k])) {
+                    $this->details['incompatible_extensions'][] = $name;
+                }
+            }
+
+            resolve(LastUpdateRun::class)
+                ->for(FlarumUpdated::MAJOR)
+                ->with('status', LastUpdateRun::FAILURE)
+                ->with('incompatibleExtensions', $this->details['incompatible_extensions'])
+                ->save();
+
+            return 'extensions_incompatible_with_new_major';
+        }
+
+        return null;
+    }
+}

extensions/package-manager/src/Exception/NoNewMajorVersionException.php

@@ -0,0 +1,26 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Exception;
+
+use Exception;
+use Flarum\Foundation\KnownError;
+
+class NoNewMajorVersionException extends Exception implements KnownError
+{
+    public function __construct()
+    {
+        parent::__construct("No new major version known of. Try checking for updates first.");
+    }
+
+    public function getType(): string
+    {
+        return 'no_new_major_version';
+    }
+}

extensions/package-manager/src/Extension/Event/Installed.php

@@ -0,0 +1,23 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Extension\Event;
+
+class Installed
+{
+    /**
+     * @var string
+     */
+    public $extensionId;
+
+    public function __construct(string $extensionId)
+    {
+        $this->extensionId = $extensionId;
+    }
+}

extensions/package-manager/src/Extension/Event/Removed.php

@@ -0,0 +1,25 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Extension\Event;
+
+use Flarum\Extension\Extension;
+
+class Removed
+{
+    /**
+     * @var Extension
+     */
+    public $extension;
+
+    public function __construct(Extension $extension)
+    {
+        $this->extension = $extension;
+    }
+}

extensions/package-manager/src/Extension/Event/Updated.php

@@ -0,0 +1,32 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Extension\Event;
+
+use Flarum\Extension\Extension;
+use Flarum\User\User;
+
+class Updated
+{
+    /**
+     * @var User
+     */
+    public $actor;
+
+    /**
+     * @var Extension
+     */
+    public $extension;
+
+    public function __construct(User $actor, Extension $extension)
+    {
+        $this->actor = $actor;
+        $this->extension = $extension;
+    }
+}

extensions/package-manager/src/Extension/ExtensionUtils.php

@@ -0,0 +1,21 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Extension;
+
+class ExtensionUtils
+{
+    public static function nameToId(string $name): string
+    {
+        [$vendor, $package] = explode('/', $name);
+        $package = str_replace(['flarum-ext-', 'flarum-'], '', $package);
+
+        return "$vendor-$package";
+    }
+}

extensions/package-manager/src/Listener/ClearCacheAfterUpdate.php

@@ -0,0 +1,52 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Listener;
+
+use Composer\Command\ClearCacheCommand;
+use Flarum\Database\Console\MigrateCommand;
+use Flarum\Foundation\Console\AssetsPublishCommand;
+use Flarum\PackageManager\Event\FlarumUpdated;
+use Symfony\Component\Console\Input\ArrayInput;
+use Symfony\Component\Console\Output\NullOutput;
+
+class ClearCacheAfterUpdate
+{
+    /**
+     * @var ClearCacheCommand
+     */
+    private $clearCache;
+
+    /**
+     * @var AssetsPublishCommand
+     */
+    private $publishAssets;
+
+    /**
+     * @var MigrateCommand
+     */
+    private $migrate;
+
+    public function __construct(ClearCacheCommand $clearCache, AssetsPublishCommand $publishAssets, MigrateCommand $migrate)
+    {
+        $this->clearCache = $clearCache;
+        $this->publishAssets = $publishAssets;
+        $this->migrate = $migrate;
+    }
+
+    /**
+     * @throws \Exception
+     */
+    public function handle(FlarumUpdated $event): void
+    {
+        $this->clearCache->run(new ArrayInput([]), new NullOutput());
+        $this->migrate->run(new ArrayInput([]), new NullOutput());
+        $this->publishAssets->run(new ArrayInput([]), new NullOutput());
+    }
+}

extensions/package-manager/src/Listener/ReCheckForUpdates.php

@@ -0,0 +1,68 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Listener;
+
+use Flarum\Bus\Dispatcher;
+use Flarum\PackageManager\Command\CheckForUpdates;
+use Flarum\PackageManager\Event\FlarumUpdated;
+use Flarum\PackageManager\Extension\Event\Updated;
+use Flarum\PackageManager\Settings\LastUpdateCheck;
+use Flarum\PackageManager\Settings\LastUpdateRun;
+
+class ReCheckForUpdates
+{
+    /**
+     * @var LastUpdateRun
+     */
+    private $lastUpdateRun;
+    /**
+     * @var LastUpdateCheck
+     */
+    private $lastUpdateCheck;
+
+    /**
+     * @var Dispatcher
+     */
+    private $bus;
+
+    public function __construct(LastUpdateRun $lastUpdateRun, LastUpdateCheck $lastUpdateCheck, Dispatcher $bus)
+    {
+        $this->lastUpdateRun = $lastUpdateRun;
+        $this->lastUpdateCheck = $lastUpdateCheck;
+        $this->bus = $bus;
+    }
+
+    /**
+     * @param FlarumUpdated|Updated $event
+     */
+    public function handle($event): void
+    {
+        $previousUpdateCheck = $this->lastUpdateCheck->get();
+
+        $lastUpdateCheck = $this->bus->dispatch(
+            new CheckForUpdates($event->actor)
+        );
+
+        if ($event instanceof FlarumUpdated) {
+            $mapPackageName = function (array $package) {
+                return $package['name'];
+            };
+
+            $previousPackages = array_map($mapPackageName, $previousUpdateCheck['updates']['installed']);
+            $lastPackages = array_map($mapPackageName, $lastUpdateCheck['updates']['installed']);
+
+            $this->lastUpdateRun
+                ->for($event->type)
+                ->with('status', LastUpdateRun::SUCCESS)
+                ->with('limitedPackages', array_intersect($previousPackages, $lastPackages))
+                ->save();
+        }
+    }
+}

extensions/package-manager/src/OutputLogger.php

@@ -0,0 +1,36 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager;
+
+use Psr\Log\LoggerInterface;
+
+class OutputLogger
+{
+    /**
+     * @var LoggerInterface
+     */
+    protected $logger;
+
+    public function __construct(LoggerInterface $logger)
+    {
+        $this->logger = $logger;
+    }
+
+    public function log(string $input, string $output, int $exitCode): void
+    {
+        $content = "$input\n$output";
+
+        if ($exitCode === 0) {
+            $this->logger->info($content);
+        } else {
+            $this->logger->error($content);
+        }
+    }
+}

extensions/package-manager/src/PackageManagerServiceProvider.php

@@ -0,0 +1,97 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager;
+
+use Composer\Config;
+use Composer\Console\Application;
+use Flarum\Extension\ExtensionManager;
+use Flarum\Foundation\AbstractServiceProvider;
+use Flarum\Foundation\Paths;
+use Flarum\Frontend\RecompileFrontendAssets;
+use Flarum\Locale\LocaleManager;
+use Flarum\PackageManager\Composer\ComposerAdapter;
+use Flarum\PackageManager\Listener\ReCheckForUpdates;
+use Illuminate\Contracts\Container\Container;
+use Illuminate\Contracts\Events\Dispatcher;
+use Monolog\Formatter\LineFormatter;
+use Monolog\Handler\RotatingFileHandler;
+use Monolog\Logger;
+use Flarum\PackageManager\Event\FlarumUpdated;
+use Flarum\PackageManager\Extension\Event\Updated;
+use Flarum\PackageManager\Listener\ClearCacheAfterUpdate;
+
+class PackageManagerServiceProvider extends AbstractServiceProvider
+{
+    public function register()
+    {
+        $this->container->singleton(ComposerAdapter::class, function (Container $container) {
+            // This should only ever be resolved when running composer commands,
+            // because we modify other environment configurations.
+            $composer = new Application();
+            $composer->setAutoExit(false);
+
+            /** @var Paths $paths */
+            $paths = $container->make(Paths::class);
+
+            putenv("COMPOSER_HOME={$paths->storage}/.composer");
+            putenv("COMPOSER={$paths->base}/composer.json");
+            putenv("COMPOSER_DISABLE_XDEBUG_WARN=1");
+            Config::$defaultConfig['vendor-dir'] = $paths->vendor;
+
+            // When running simple require, update and remove commands on packages,
+            // composer 2 doesn't really need this much unless the extensions are very loaded dependency wise,
+            // but this is necessary for running flarum updates.
+            @ini_set('memory_limit', '1G');
+            @set_time_limit(5 * 60);
+
+            return new ComposerAdapter($composer, $container->make(OutputLogger::class), $container->make(Paths::class));
+        });
+
+        $this->container->alias(ComposerAdapter::class, 'flarum.composer');
+
+        $this->container->singleton(OutputLogger::class, function (Container $container) {
+            $logPath = $container->make(Paths::class)->storage.'/logs/composer/output.log';
+            $handler = new RotatingFileHandler($logPath, Logger::INFO);
+            $handler->setFormatter(new LineFormatter(null, null, true, true));
+
+            $logger = new Logger('composer', [$handler]);
+
+            return new OutputLogger($logger);
+        });
+    }
+
+    public function boot(Container $container)
+    {
+        /** @var Dispatcher $events */
+        $events = $container->make('events');
+
+        $events->listen(
+            [Updated::class],
+            function (Updated $event) use ($container) {
+                /** @var ExtensionManager $extensions */
+                $extensions = $container->make(ExtensionManager::class);
+
+                if ($extensions->isEnabled($event->extension->getId())) {
+                    $recompile = new RecompileFrontendAssets(
+                        $container->make('flarum.assets.forum'),
+                        $container->make(LocaleManager::class)
+                    );
+                    $recompile->flush();
+
+                    $extensions->migrate($event->extension);
+                    $event->extension->copyAssetsTo($container->make('filesystem')->disk('flarum-assets'));
+                }
+            }
+        );
+
+        $events->listen(FlarumUpdated::class, ClearCacheAfterUpdate::class);
+        $events->listen([FlarumUpdated::class, Updated::class], ReCheckForUpdates::class);
+    }
+}

extensions/package-manager/src/RequirePackageValidator.php

@@ -0,0 +1,24 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager;
+
+use Flarum\Foundation\AbstractValidator;
+
+class RequirePackageValidator extends AbstractValidator
+{
+    public const PACKAGE_NAME_REGEX = '/^[A-z0-9-_]+\/[A-z-0-9]+(?::[A-z-0-9.->=<_]+){0,1}$/i';
+
+    /**
+     * {@inheritdoc}
+     */
+    protected $rules = [
+        'package' => ['required', 'string', 'regex:'.self::PACKAGE_NAME_REGEX]
+    ];
+}

extensions/package-manager/src/Settings/JsonSetting.php

@@ -0,0 +1,23 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Settings;
+
+interface JsonSetting
+{
+    public function with(string $key, $value): self;
+
+    public function save(): array;
+
+    public function get(): array;
+
+    public static function key(): string;
+
+    public static function default(): array;
+}

extensions/package-manager/src/Settings/LastUpdateCheck.php

@@ -0,0 +1,78 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Settings;
+
+use Carbon\Carbon;
+use Flarum\Settings\SettingsRepositoryInterface;
+use Illuminate\Support\Arr;
+use Illuminate\Support\Str;
+
+class LastUpdateCheck implements JsonSetting
+{
+    /**
+     * @var SettingsRepositoryInterface
+     */
+    protected $settings;
+
+    protected $data = [];
+
+    public function __construct(SettingsRepositoryInterface $settings)
+    {
+        $this->settings = $settings;
+    }
+
+    public function with(string $key, $value): JsonSetting
+    {
+        $this->data[$key] = $value;
+
+        return $this;
+    }
+
+    public function save(): array
+    {
+        $lastUpdateCheck = [
+            'checkedAt' => Carbon::now(),
+            'updates' => $this->data,
+        ];
+
+        $this->settings->set($this->key(), json_encode($lastUpdateCheck));
+
+        return $lastUpdateCheck;
+    }
+
+    public function get(): array
+    {
+        return json_decode($this->settings->get($this->key()), true);
+    }
+
+    public static function key(): string
+    {
+        return 'flarum-package-manager.last_update_check';
+    }
+
+    public static function default(): array
+    {
+        return [
+            'checkedAt' => null,
+            'updates' => [
+                'installed' => [],
+            ],
+        ];
+    }
+
+    public function getNewMajorVersion(): ?string
+    {
+        $core = Arr::first(Arr::get($this->get(), 'updates.installed', []), function ($package) {
+            return $package['name'] === 'flarum/core';
+        });
+
+        return $core ? $core['latest-major'] : null;
+    }
+}

extensions/package-manager/src/Settings/LastUpdateRun.php

@@ -0,0 +1,97 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Settings;
+
+use Carbon\Carbon;
+use Flarum\PackageManager\Event\FlarumUpdated;
+use Flarum\Settings\SettingsRepositoryInterface;
+
+class LastUpdateRun implements JsonSetting
+{
+    public const SUCCESS = 'success';
+    public const FAILURE = 'failure';
+
+    /**
+     * @var SettingsRepositoryInterface
+     */
+    protected $settings;
+
+    protected $data;
+
+    /**
+     * @var {'major'|'minor'|'global'}
+     */
+    protected $activeUpdate;
+
+    public function __construct(SettingsRepositoryInterface $settings)
+    {
+        $this->settings = $settings;
+        $this->data = self::default();
+    }
+
+    public function for(string $update): self
+    {
+        if (! in_array($update, [FlarumUpdated::MAJOR, FlarumUpdated::MINOR, FlarumUpdated::GLOBAL])) {
+            throw new \InvalidArgumentException("Last update runs can only be for one of: minor, major, global");
+        }
+
+        $this->activeUpdate = $update;
+
+        return $this;
+    }
+
+    public function with(string $key, $value): JsonSetting
+    {
+        $this->data[$this->activeUpdate][$key] = $value;
+
+        return $this;
+    }
+
+    public function save(): array
+    {
+        $this->data[$this->activeUpdate]['ranAt'] = Carbon::now();
+
+        $this->settings->set(self::key(), json_encode($this->data));
+
+        return $this->data;
+    }
+
+    public function get(): array
+    {
+        $lastUpdateRun = json_decode($this->settings->get(self::key()), true);
+
+        if ($this->activeUpdate) {
+            return $lastUpdateRun[$this->activeUpdate];
+        }
+
+        return $lastUpdateRun;
+    }
+
+    public static function key(): string
+    {
+        return 'flarum-package-manager.last_update_run';
+    }
+
+    public static function default(): array
+    {
+        $defaultState = [
+            'ranAt' => null,
+            'status' => null,
+            'limitedPackages' => [],
+            'incompatibleExtensions' => [],
+        ];
+
+        return [
+            FlarumUpdated::GLOBAL => $defaultState,
+            FlarumUpdated::MINOR => $defaultState,
+            FlarumUpdated::MAJOR => $defaultState,
+        ];
+    }
+}

extensions/package-manager/src/UpdateExtensionValidator.php

@@ -0,0 +1,22 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager;
+
+use Flarum\Foundation\AbstractValidator;
+
+class UpdateExtensionValidator extends AbstractValidator
+{
+    /**
+     * {@inheritdoc}
+     */
+    protected $rules = [
+        'extensionId' => 'required|string'
+    ];
+}

extensions/package-manager/src/WhyNotValidator.php

@@ -0,0 +1,23 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager;
+
+use Flarum\Foundation\AbstractValidator;
+
+class WhyNotValidator extends AbstractValidator
+{
+    /**
+     * {@inheritdoc}
+     */
+    protected $rules = [
+        'package' => ['required', 'string', 'regex:'.RequirePackageValidator::PACKAGE_NAME_REGEX],
+        'version' => ['sometimes', 'string', 'regex:/(?:\*|[A-z0-9.-]+)/i']
+    ];
+}

extensions/package-manager/tests/integration/ChangeComposerConfig.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace Flarum\PackageManager\Tests\integration;
+
+trait ChangeComposerConfig
+{
+    protected function setComposerConfig(array $requirements): void
+    {
+        $composerSetup = new SetupComposer($requirements);
+        $composerSetup->run();
+
+        $this->composer('install');
+    }
+}

extensions/package-manager/tests/integration/DummyExtensions.php

@@ -0,0 +1,32 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Tests\integration;
+
+use Flarum\Foundation\Paths;
+
+trait DummyExtensions
+{
+    protected function makeDummyExtensionCompatibleWith(string $name, string $coreVersions): void
+    {
+        $dirName = $this->tmpDir() . "/packages/" . str_replace('/', '-', $name);
+
+        if (! file_exists($dirName)) {
+            mkdir($dirName);
+        }
+
+        file_put_contents($dirName."/composer.json", json_encode([
+            'name' => $name,
+            'version' => '1.0.0',
+            'require' => [
+                'flarum/core' => $coreVersions
+            ],
+        ], JSON_UNESCAPED_SLASHES | JSON_PRETTY_PRINT));
+    }
+}

extensions/package-manager/tests/integration/RefreshComposerSetup.php

@@ -0,0 +1,55 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Tests\integration;
+
+use FilesystemIterator;
+use Flarum\PackageManager\Composer\ComposerAdapter;
+use RecursiveDirectoryIterator;
+use RecursiveIteratorIterator;
+
+trait RefreshComposerSetup
+{
+    public function tearDown(): void
+    {
+        $composerSetup = new SetupComposer();
+        @unlink($this->tmpDir().'/composer.lock');
+
+        $this->deleteDummyExtensions();
+
+        $composerSetup->run();
+
+        $this->composer('install');
+
+        parent::tearDown();
+    }
+
+    private function deleteDummyExtensions(): void
+    {
+        $dir = $this->tmpDir().'/packages';
+
+        $it = new RecursiveDirectoryIterator($dir, FilesystemIterator::SKIP_DOTS);
+        $files = new RecursiveIteratorIterator($it, RecursiveIteratorIterator::CHILD_FIRST);
+
+        foreach($files as $file) {
+            if ($file->isDir()){
+                rmdir($file->getRealPath());
+            } else {
+                unlink($file->getRealPath());
+            }
+        }
+
+        rmdir($dir);
+    }
+
+    protected function forgetComposerApp(): void
+    {
+        $this->app()->getContainer()->instance(ComposerAdapter::class, null);
+    }
+}

extensions/package-manager/tests/integration/SetupComposer.php

@@ -0,0 +1,57 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Tests\integration;
+
+use Flarum\Testing\integration\UsesTmpDir;
+
+class SetupComposer
+{
+    use UsesTmpDir;
+
+    private $config = [
+        'require' => [
+            'flarum/core' => '1.0.0',
+            'flarum/tags' => '1.0.3',
+            'flarum/lang-english' => '*',
+        ],
+        'config' => [
+            'preferred-install' => 'dist',
+            'sort-packages' => true,
+        ],
+        'repositories' => [
+            [
+                'type' => 'path',
+                'url' => __DIR__.'/tmp/packages/*',
+            ]
+        ]
+    ];
+
+    public function __construct(array $config = null)
+    {
+        $this->config = array_merge($this->config, $config ?? []);
+    }
+
+    public function run()
+    {
+        $composerJson = $this->tmpDir().'/composer.json';
+        $composerLock = $this->tmpDir().'/composer.lock';
+        $packages = $this->tmpDir().'/packages';
+
+        file_put_contents($composerJson, json_encode($this->config, JSON_UNESCAPED_SLASHES | JSON_PRETTY_PRINT));
+
+        if (! file_exists($packages)) {
+            mkdir($packages);
+        }
+
+        if (file_exists($composerLock)) {
+            unlink($composerLock);
+        }
+    }
+}

extensions/package-manager/tests/integration/TestCase.php

@@ -0,0 +1,99 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Tests\integration;
+
+use Flarum\Foundation\Paths;
+use Flarum\PackageManager\Composer\ComposerAdapter;
+use Flarum\PackageManager\Composer\ComposerJson;
+use Flarum\PackageManager\Extension\ExtensionUtils;
+use Flarum\Testing\integration\RetrievesAuthorizedUsers;
+use Illuminate\Support\Arr;
+use Psr\Http\Message\ResponseInterface;
+use Symfony\Component\Console\Input\StringInput;
+
+class TestCase extends \Flarum\Testing\integration\TestCase
+{
+    use RetrievesAuthorizedUsers;
+
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->extension('flarum-package-manager', 'flarum-tags');
+
+        $tmp = realpath($this->tmpDir());
+
+        $this->app()->getContainer()->instance('flarum.paths', new Paths([
+            'base' => $tmp,
+            'public' => "$tmp/public",
+            'storage' => "$tmp/storage",
+            'vendor' => "$tmp/vendor",
+        ]));
+    }
+
+    protected function assertExtension(string $id, bool $exists)
+    {
+        $installed = json_decode(file_get_contents($this->app()->getContainer()->make(Paths::class)->vendor.'/composer/installed.json'), true);
+        $installedExtensions = Arr::where($installed['packages'] ?? $installed, function (array $package) {
+            return $package['type'] === 'flarum-extension';
+        });
+        $installedExtensionIds = array_map(function (string $name) {
+            return ExtensionUtils::nameToId($name);
+        }, Arr::pluck($installedExtensions, 'name'));
+
+        if ($exists) {
+            $this->assertTrue(in_array($id, $installedExtensionIds), "Failed asserting that extension $id is installed");
+        } else {
+            $this->assertFalse(in_array($id, $installedExtensionIds), "Failed asserting that extension $id is not installed");
+        }
+    }
+
+    protected function assertExtensionExists(string $id)
+    {
+        $this->assertExtension($id, true);
+    }
+
+    protected function assertExtensionNotExists(string $id)
+    {
+        $this->assertExtension($id, false);
+    }
+
+    protected function assertPackageVersion(string $packageName, string $version)
+    {
+        $composerJson = $this->app()->getContainer()->make(ComposerJson::class)->get();
+
+        $this->assertArrayHasKey($packageName, $composerJson['require'], "$packageName is not required.");
+        $this->assertEquals($version, $composerJson['require'][$packageName], "Expected $packageName to be $version, found {$composerJson['require'][$packageName]} instead.");
+    }
+
+    protected function requireExtension(string $package)
+    {
+        $this->composer("require $package");
+    }
+
+    protected function removeExtension(string $package)
+    {
+        $this->composer("remove $package");
+    }
+
+    protected function composer(string $command): void
+    {
+        /** @var ComposerAdapter $composer */
+        $composer = $this->app()->getContainer()->make(ComposerAdapter::class);
+        $composer->run(new StringInput($command));
+    }
+
+    protected function errorDetails(ResponseInterface $response): array
+    {
+        $json = json_decode((string) $response->getBody(), true);
+
+        return $json['errors'] ? ($json['errors'][0] ?? []) : [];
+    }
+}

extensions/package-manager/tests/integration/api/CheckForUpdatesTest.php

@@ -0,0 +1,42 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Tests\integration\api;
+
+use Flarum\PackageManager\Tests\integration\ChangeComposerConfig;
+use Flarum\PackageManager\Tests\integration\RefreshComposerSetup;
+use Flarum\PackageManager\Tests\integration\TestCase;
+use Illuminate\Support\Arr;
+
+class CheckForUpdatesTest extends TestCase
+{
+    use RefreshComposerSetup, ChangeComposerConfig;
+
+    /**
+     * @test
+     */
+    public function can_check_for_updates()
+    {
+        $this->setComposerConfig([
+            'require' => [
+                'flarum/core' => '^1.0.0',
+                'flarum/tags' => '1.0.0',
+            ]
+        ]);
+
+        $response = $this->send(
+            $this->request('POST', '/api/package-manager/check-for-updates', [
+                'authenticatedAs' => 1,
+            ])
+        );
+
+        $this->assertEquals(200, $response->getStatusCode());
+        $this->assertEquals(['flarum/tags'], Arr::pluck(json_decode((string) $response->getBody(), true)['updates']['installed'], 'name'));
+    }
+}

extensions/package-manager/tests/integration/api/GlobalUpdateTest.php

@@ -0,0 +1,32 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Tests\integration\api;
+
+use Flarum\PackageManager\Tests\integration\RefreshComposerSetup;
+use Flarum\PackageManager\Tests\integration\TestCase;
+
+class GlobalUpdateTest extends TestCase
+{
+    use RefreshComposerSetup;
+
+    /**
+     * @test
+     */
+    public function can_global_update()
+    {
+        $response = $this->send(
+            $this->request('POST', '/api/package-manager/global-update', [
+                'authenticatedAs' => 1,
+            ])
+        );
+
+        $this->assertEquals(200, $response->getStatusCode());
+    }
+}

extensions/package-manager/tests/integration/api/MajorUpdateTest.php

@@ -0,0 +1,127 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Tests\integration\api;
+
+use Flarum\PackageManager\Tests\integration\ChangeComposerConfig;
+use Flarum\PackageManager\Tests\integration\DummyExtensions;
+use Flarum\PackageManager\Tests\integration\RefreshComposerSetup;
+use Flarum\PackageManager\Tests\integration\TestCase;
+
+class MajorUpdateTest extends TestCase
+{
+    use RefreshComposerSetup, ChangeComposerConfig, DummyExtensions;
+
+    /**
+     * @test
+     */
+    public function cannot_update_when_no_update_check_ran()
+    {
+        $this->makeDummyExtensionCompatibleWith("flarum/dummy-incompatible-extension", ">=0.1.0-beta.15 <=0.1.0-beta.16");
+        $this->setComposerConfig([
+            'require' => [
+                'flarum/core' => '^0.1.0-beta.15',
+                'flarum/tags' => '^0.1.0-beta.15',
+                'flarum/dummy-incompatible-extension' => '^1.0.0'
+            ],
+            'minimum-stability' => 'beta',
+        ]);
+
+        $response = $this->send(
+            $this->request('POST', '/api/package-manager/major-update', [
+                'authenticatedAs' => 1,
+            ])
+        );
+
+        $this->assertEquals(409, $response->getStatusCode());
+        $this->assertEquals('no_new_major_version', $this->errorDetails($response)['code']);
+    }
+
+    /**
+     * @test
+     */
+    public function can_update_when_major_update_available()
+    {
+        $this->makeDummyExtensionCompatibleWith("flarum/dummy-compatible-extension", "^0.1.0-beta.15 | ^1.0.0");
+        $this->setComposerConfig([
+            'require' => [
+                'flarum/core' => '^0.1.0-beta.15',
+                'flarum/tags' => '^0.1.0-beta.15',
+                'flarum/dummy-compatible-extension' => '^1.0.0'
+            ],
+            'minimum-stability' => 'beta',
+        ]);
+
+        $lastUpdateCheck = $this->send(
+            $this->request('POST', '/api/package-manager/check-for-updates', [
+                'authenticatedAs' => 1,
+            ])
+        );
+
+        $this->forgetComposerApp();
+
+        $response = $this->send(
+            $this->request('POST', '/api/package-manager/major-update', [
+                'authenticatedAs' => 1,
+            ])
+        );
+
+        $newMinorCoreVersion = array_filter(
+            json_decode((string) $lastUpdateCheck->getBody(), true)['updates']['installed'],
+            function ($package) {
+                return $package['name'] === 'flarum/core';
+            }
+        )[0]['latest-major'];
+
+        $this->assertEquals(200, $response->getStatusCode());
+        $this->assertPackageVersion("flarum/core", str_replace('v', '^', $newMinorCoreVersion));
+        $this->assertPackageVersion("flarum/tags", "*");
+        $this->assertPackageVersion("flarum/dummy-compatible-extension", "*");
+    }
+
+    /**
+     * @test
+     */
+    public function cannot_update_with_incompatible_extensions()
+    {
+        $this->makeDummyExtensionCompatibleWith("flarum/dummy-incompatible-extension-a", ">=0.1.0-beta.16 <0.1.0-beta.17");
+        $this->makeDummyExtensionCompatibleWith("flarum/dummy-incompatible-extension-b", ">=0.1.0-beta.16 <=0.1.0-beta.17");
+        $this->makeDummyExtensionCompatibleWith("flarum/dummy-incompatible-extension-c", "0.1.0-beta.16");
+        $this->setComposerConfig([
+            'require' => [
+                'flarum/core' => '^0.1.0-beta.16',
+                'flarum/tags' => '^0.1.0-beta.16',
+                'flarum/dummy-incompatible-extension-a' => '^1.0.0',
+                'flarum/dummy-incompatible-extension-b' => '^1.0.0',
+                'flarum/dummy-incompatible-extension-c' => '^1.0.0',
+            ],
+            'minimum-stability' => 'beta',
+        ]);
+
+        $this->send(
+            $this->request('POST', '/api/package-manager/check-for-updates', [
+                'authenticatedAs' => 1,
+            ])
+        );
+
+        $response = $this->send(
+            $this->request('POST', '/api/package-manager/major-update', [
+                'authenticatedAs' => 1,
+            ])
+        );
+
+        $this->assertEquals(409, $response->getStatusCode());
+        $this->assertEquals('extensions_incompatible_with_new_major', $this->errorDetails($response)['guessed_cause']);
+        $this->assertEquals([
+            'flarum/dummy-incompatible-extension-a',
+            'flarum/dummy-incompatible-extension-b',
+            'flarum/dummy-incompatible-extension-c'
+        ], $this->errorDetails($response)['incompatible_extensions']);
+    }
+}

extensions/package-manager/tests/integration/api/MinorUpdateTest.php

@@ -0,0 +1,95 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Tests\integration\api;
+
+use Flarum\PackageManager\Event\FlarumUpdated;
+use Flarum\PackageManager\Settings\LastUpdateRun;
+use Flarum\PackageManager\Tests\integration\ChangeComposerConfig;
+use Flarum\PackageManager\Tests\integration\DummyExtensions;
+use Flarum\PackageManager\Tests\integration\RefreshComposerSetup;
+use Flarum\PackageManager\Tests\integration\TestCase;
+
+class MinorUpdateTest extends TestCase
+{
+    use RefreshComposerSetup, ChangeComposerConfig, DummyExtensions;
+
+    /**
+     * @test--
+     */
+    public function can_update_to_next_minor_version()
+    {
+        $this->makeDummyExtensionCompatibleWith("flarum/dummy-compatible-extension", "^1.0.0");
+        $this->setComposerConfig([
+            'require' => [
+                // The only reason we don't set this to `^1.0.0` and let it update to latest minor,
+                // is because migrations that run DDL queries might be introduced in future versions,
+                // therefore breaking the test transaction.
+                'flarum/core' => '>=1.0.0 <= 1.1.0',
+                // We leave tags fixed to a version,
+                // the update handler must be able to set it to `*`.
+                'flarum/tags' => '1.0.3',
+                'flarum/lang-english' => '*',
+                'flarum/dummy-compatible-extension' => '^1.0.0'
+            ]
+        ]);
+
+        $response = $this->send(
+            $this->request('POST', '/api/package-manager/minor-update', [
+                'authenticatedAs' => 1,
+            ])
+        );
+
+        $this->assertEquals(200, $response->getStatusCode());
+        $this->assertPackageVersion('flarum/tags', '*');
+        $this->assertPackageVersion('flarum/dummy-compatible-extension', '*');
+    }
+
+    /**
+     * @test
+     */
+    public function can_update_with_latest_ext_incompatible_with_latest_core()
+    {
+        $this->makeDummyExtensionCompatibleWith("flarum/dummy-extension", "1.0.0");
+        $this->setComposerConfig([
+            'require' => [
+                'flarum/core' => '>=1.0.0 <=1.1.0',
+                'flarum/tags' => '1.0.3',
+                'flarum/lang-english' => '*',
+                'flarum/dummy-extension' => '^1.0.0'
+            ]
+        ]);
+
+        $this->send(
+            $this->request('POST', '/api/package-manager/check-for-updates', [
+                'authenticatedAs' => 1,
+            ])
+        );
+
+        $this->forgetComposerApp();
+
+        $response = $this->send(
+            $this->request('POST', '/api/package-manager/minor-update', [
+                'authenticatedAs' => 1,
+            ])
+        );
+
+        /** @var LastUpdateRun $lastUpdateRun */
+        $lastUpdateRun = $this->app()->getContainer()->make(LastUpdateRun::class);
+
+        $this->assertEquals(200, $response->getStatusCode());
+        $this->assertPackageVersion("flarum/tags", "*");
+        $this->assertPackageVersion("flarum/dummy-extension", "*");
+        $this->assertEquals([
+            'flarum/core',
+            'flarum/lang-english',
+            'flarum/tags'
+        ], $lastUpdateRun->for(FlarumUpdated::MINOR)->get()['limitedPackages']);
+    }
+}

extensions/package-manager/tests/integration/api/extensions/RemoveExtensionTest.php

@@ -0,0 +1,55 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Tests\integration\api\extensions;
+
+use Flarum\PackageManager\Tests\integration\RefreshComposerSetup;
+use Flarum\PackageManager\Tests\integration\TestCase;
+
+class RemoveExtensionTest extends TestCase
+{
+    use RefreshComposerSetup;
+
+    /**
+     * @test
+     */
+    public function extension_installed_by_default()
+    {
+        $this->assertExtensionExists('flarum-tags');
+    }
+
+    /**
+     * @test
+     */
+    public function removing_an_extension_works()
+    {
+        $response = $this->send(
+            $this->request('DELETE', '/api/package-manager/extensions/flarum-tags', [
+                'authenticatedAs' => 1
+            ])
+        );
+
+        $this->assertEquals(200, $response->getStatusCode());
+        $this->assertExtensionNotExists('flarum-tags');
+    }
+
+    /**
+     * @test
+     */
+    public function removing_a_non_existant_extension_fails()
+    {
+        $response = $this->send(
+            $this->request('DELETE', '/api/package-manager/extensions/flarum-potato', [
+                'authenticatedAs' => 1
+            ])
+        );
+
+        $this->assertEquals(409, $response->getStatusCode());
+    }
+}

extensions/package-manager/tests/integration/api/extensions/RequireExtensionTest.php

@@ -0,0 +1,125 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Tests\integration\api\extensions;
+
+use Flarum\PackageManager\Tests\integration\RefreshComposerSetup;
+use Flarum\PackageManager\Tests\integration\TestCase;
+
+class RequireExtensionTest extends TestCase
+{
+    use RefreshComposerSetup;
+
+    /**
+     * @test
+     */
+    public function extension_uninstalled_by_default()
+    {
+        $this->assertExtensionNotExists('v17development-blog');
+    }
+
+    /**
+     * @test
+     */
+    public function requiring_an_existing_extension_fails()
+    {
+        $response = $this->send(
+            $this->request('POST', '/api/package-manager/extensions', [
+                'authenticatedAs' => 1,
+                'json' => [
+                    'data' => [
+                        'package' => 'flarum/tags'
+                    ]
+                ]
+            ])
+        );
+
+        $this->assertEquals(409, $response->getStatusCode());
+    }
+
+    /**
+     * @test
+     */
+    public function requiring_a_compatible_extension_works()
+    {
+        $response = $this->send(
+            $this->request('POST', '/api/package-manager/extensions', [
+                'authenticatedAs' => 1,
+                'json' => [
+                    'data' => [
+                        'package' => 'v17development/flarum-blog'
+                    ]
+                ]
+            ])
+        );
+
+        $this->assertEquals(200, $response->getStatusCode());
+        $this->assertExtensionExists('v17development-blog');
+    }
+
+    /**
+     * @test
+     */
+    public function requiring_a_compatible_extension_with_specific_version_works()
+    {
+        $response = $this->send(
+            $this->request('POST', '/api/package-manager/extensions', [
+                'authenticatedAs' => 1,
+                'json' => [
+                    'data' => [
+                        'package' => 'v17development/flarum-blog:0.4.0'
+                    ]
+                ]
+            ])
+        );
+
+        $this->assertEquals(200, $response->getStatusCode());
+        $this->assertExtensionExists('v17development-blog');
+    }
+
+    /**
+     * @test
+     */
+    public function requiring_an_uncompatible_extension_fails()
+    {
+        $response = $this->send(
+            $this->request('POST', '/api/package-manager/extensions', [
+                'authenticatedAs' => 1,
+                'json' => [
+                    'data' => [
+                        'package' => 'flarum/auth-github'
+                    ]
+                ]
+            ])
+        );
+
+        $this->assertEquals(409, $response->getStatusCode());
+        $this->assertEquals('extension_incompatible_with_instance', $this->errorDetails($response)['guessed_cause']);
+    }
+
+    /**
+     * @test
+     */
+    public function requiring_an_uncompatible_extension_with_specific_version_fails()
+    {
+        $response = $this->send(
+            $this->request('POST', '/api/package-manager/extensions', [
+                'authenticatedAs' => 1,
+                'json' => [
+                    'data' => [
+                        'package' => 'flarum/auth-github:0.1.0-beta.9'
+                    ]
+                ]
+            ])
+        );
+
+        $this->assertEquals(409, $response->getStatusCode());
+        $this->assertEquals('extension_incompatible_with_instance', $this->errorDetails($response)['guessed_cause']);
+    }
+}

extensions/package-manager/tests/integration/api/extensions/UpdateExtensionTest.php

@@ -0,0 +1,55 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * For detailed copyright and license information, please view the
+ * LICENSE file that was distributed with this source code.
+ */
+
+namespace Flarum\PackageManager\Tests\integration\api\extensions;
+
+use Flarum\PackageManager\Tests\integration\RefreshComposerSetup;
+use Flarum\PackageManager\Tests\integration\TestCase;
+
+class UpdateExtensionTest extends TestCase
+{
+    use RefreshComposerSetup;
+
+    /**
+     * @test
+     */
+    public function extension_installed_by_default()
+    {
+        $this->assertExtensionExists('flarum-tags');
+    }
+
+    /**
+     * @test
+     */
+    public function updating_an_existing_extension_works()
+    {
+        $response = $this->send(
+            $this->request('PATCH', '/api/package-manager/extensions/flarum-tags', [
+                'authenticatedAs' => 1,
+            ])
+        );
+
+        $this->assertEquals(200, $response->getStatusCode());
+        $this->assertExtensionExists('flarum-tags');
+    }
+
+    /**
+     * @test
+     */
+    public function updating_a_non_existing_extension_fails()
+    {
+        $response = $this->send(
+            $this->request('PATCH', '/api/package-manager/extensions/flarum-potato', [
+                'authenticatedAs' => 1,
+            ])
+        );
+
+        $this->assertEquals(409, $response->getStatusCode());
+    }
+}