Apply fixes from StyleCI

One thing that has been very frustrating while developing extensions is
that you cannot easily create a feature that you would like to allow
disabling through the permission grid.

This Proof of Concept PR is a question, whether I'm the only one running
into this limitation for Flarum.

It does:

- introduce a fake permission, similar to Guest
- removes the whole permission entry from the db when selected
- restores the permission visually on the frontend

It has to:

- confirm admins also cannot use the permission if selected
- not break v1.x functionality or be moved to v2.0
- appeal to core and community

framework/core/js/src/admin/components/PermissionDropdown.tsx

@@ -52,11 +52,14 @@ export default class PermissionDropdown<CustomAttrs extends IPermissionDropdownA
 
     groupIds = filterByRequiredPermissions(groupIds, this.attrs.permission);
 
+    const no_one = groupIds.length === 0;
     const everyone = groupIds.includes(Group.GUEST_ID);
     const members = groupIds.includes(Group.MEMBER_ID);
     const adminGroup = app.store.getById<Group>('groups', Group.ADMINISTRATOR_ID)!;
 
-    if (everyone) {
+    if (this.attrs.allowNoOne && no_one) {
+      this.attrs.label = Badge.component({ icon: 'fas fa-user-slash' });
+    } else if (everyone) {
       this.attrs.label = Badge.component({ icon: 'fas fa-globe' });
     } else if (members) {
       this.attrs.label = Badge.component({ icon: 'fas fa-user' });
@@ -65,6 +68,17 @@ export default class PermissionDropdown<CustomAttrs extends IPermissionDropdownA
     }
 
     if (this.showing) {
+      if (this.attrs.allowNoOne) {
+        children.push(
+          Button.component(
+            {
+              icon: no_one ? 'fas fa-check' : true,
+              onclick: () => this.save([Group.NO_ONE_ID]),
+            },
+            [Badge.component({ icon: 'fas fa-user-slash' }), ' ', app.translator.trans('core.admin.permissions_controls.no_one_button')]
+          )
+        );
+      }
       if (this.attrs.allowGuest) {
         children.push(
           Button.component(

framework/core/js/src/admin/components/PermissionGrid.tsx

@@ -12,6 +12,7 @@ export interface PermissionConfig {
   icon: string;
   label: Mithril.Children;
   allowGuest?: boolean;
+  allowNoOne?: boolean;
 }
 
 export interface PermissionSetting {
@@ -435,6 +436,7 @@ export default class PermissionGrid<CustomAttrs extends IPermissionGridAttrs = I
             return PermissionDropdown.component({
               permission: item.permission,
               allowGuest: item.allowGuest,
+              allowNoOne: item.allowNoOne,
             });
           }
 

framework/core/js/src/common/models/Group.ts

@@ -1,6 +1,7 @@
 import Model from '../Model';
 
 export default class Group extends Model {
+  static NO_ONE_ID = '-1';
   static ADMINISTRATOR_ID = '1';
   static GUEST_ID = '2';
   static MEMBER_ID = '3';

framework/core/locale/core.yml

@@ -235,6 +235,7 @@ core:
       members_button: => core.group.members
       signup_closed_button: Closed
       signup_open_button: Open
+      no_one_button: No one
 
     # These translations are used generically in setting fields.
     settings:

framework/core/src/Api/Controller/SetPermissionController.php

@@ -9,6 +9,7 @@
 
 namespace Flarum\Api\Controller;
 
+use Flarum\Group\Group;
 use Flarum\Group\Permission;
 use Flarum\Http\RequestUtil;
 use Illuminate\Support\Arr;
@@ -32,6 +33,11 @@ class SetPermissionController implements RequestHandlerInterface
 
         Permission::where('permission', $permission)->delete();
 
+        // Permission set to no one.
+        if (count($groupIds) === 1 && intval($groupIds[0]) === Group::NO_ONE_ID) {
+            return new EmptyResponse(204);
+        }
+
         Permission::insert(array_map(function ($groupId) use ($permission) {
             return [
                 'permission' => $permission,

framework/core/src/Extend/Permission.php

@@ -0,0 +1,29 @@
+<?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\Extend;
+
+use Flarum\Extension\Extension;
+use Flarum\User\Access\AdminPolicy;
+use Illuminate\Contracts\Container\Container;
+
+class Permission implements ExtenderInterface
+{
+    public function extend(Container $container, Extension $extension = null)
+    {
+        // TODO: Implement extend() method.
+    }
+
+    public function allowsNoOne(string $permission): self
+    {
+        AdminPolicy::allowNoOneOnPermission($permission);
+
+        return $this;
+    }
+}

framework/core/src/Group/Group.php

@@ -32,6 +32,11 @@ class Group extends AbstractModel
     use EventGeneratorTrait;
     use ScopeVisibilityTrait;
 
+    /**
+     * The temporary ID for when no one can do something.
+     */
+    const NO_ONE_ID = -1;
+
     /**
      * The ID of the administrator group.
      */

framework/core/src/User/Access/AdminPolicy.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\User\Access;
+
+use Flarum\User\User;
+
+class AdminPolicy extends AbstractPolicy
+{
+    public static array $allowNoOnePermissions = [];
+
+    /**
+     * @param string|array<string> $permissions
+     * @return void
+     */
+    public static function allowNoOneOnPermission($permissions)
+    {
+        self::$allowNoOnePermissions[] = array_merge(
+            static::$allowNoOnePermissions,
+            (array) $permissions
+        );
+    }
+
+    /**
+     * @param User $actor
+     * @param string $ability
+     * @return bool|null
+     */
+    public function can(User $actor, $ability)
+    {
+        if (! in_array($ability, static::$allowNoOnePermissions)
+            && $actor->isAdmin()) {
+            return $this->forceAllow();
+        }
+    }
+}

framework/core/src/User/Access/Gate.php

@@ -87,11 +87,7 @@ class Gate
         // If no policy covered this permission query, we will only grant
         // the permission if the actor's groups have it. Otherwise, we will
         // not allow the user to perform this action.
-        if ($actor->isAdmin() || $actor->hasPermission($ability)) {
-            return true;
-        }
-
-        return false;
+        return $actor->hasPermission($ability);
     }
 
     /**

framework/core/src/User/User.php

@@ -380,10 +380,6 @@ class User extends AbstractModel
      */
     public function hasPermission($permission)
     {
-        if ($this->isAdmin()) {
-            return true;
-        }
-
         return in_array($permission, $this->getPermissions());
     }
 
@@ -396,10 +392,6 @@ class User extends AbstractModel
      */
     public function hasPermissionLike($match)
     {
-        if ($this->isAdmin()) {
-            return true;
-        }
-
         foreach ($this->getPermissions() as $permission) {
             if (substr($permission, -strlen($match)) === $match) {
                 return true;

framework/core/src/User/UserServiceProvider.php

@@ -20,6 +20,7 @@ use Flarum\Http\AccessToken;
 use Flarum\Post\Access\PostPolicy;
 use Flarum\Post\Post;
 use Flarum\Settings\SettingsRepositoryInterface;
+use Flarum\User\Access\AdminPolicy;
 use Flarum\User\Access\ScopeUserVisibility;
 use Flarum\User\DisplayName\DriverInterface;
 use Flarum\User\DisplayName\UsernameDriver;
@@ -49,7 +50,7 @@ class UserServiceProvider extends AbstractServiceProvider
 
         $this->container->singleton('flarum.policies', function () {
             return [
-                Access\AbstractPolicy::GLOBAL => [],
+                Access\AbstractPolicy::GLOBAL => [AdminPolicy::class],
                 AccessToken::class => [AccessTokenPolicy::class],
                 Discussion::class => [DiscussionPolicy::class],
                 Group::class => [GroupPolicy::class],