Get rid of Server classes for Admin, API and Forum

The various middleware can be registered in the service provider,
and the rest of the logic can all go through one single front
controller (index.php in flarum/flarum, and Flarum\Http\Server in
flarum/core).

This will also simplify the necessary server setup, as only one
rewrite rule remains.

src/Http/Server.php

@@ -0,0 +1,159 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Http;
+
+use Flarum\Foundation\AbstractServer;
+use Flarum\Foundation\Application;
+use Flarum\Http\Middleware\DispatchRoute;
+use Flarum\Http\Middleware\HandleErrors;
+use Flarum\Http\Middleware\StartSession;
+use Flarum\Install\InstallServiceProvider;
+use Flarum\Update\UpdateServiceProvider;
+use Flarum\User\AuthToken;
+use Flarum\User\EmailToken;
+use Flarum\User\PasswordToken;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Zend\Diactoros\Response\HtmlResponse;
+use Zend\Diactoros\Server as DiactorosServer;
+use Zend\Stratigility\MiddlewareInterface;
+use Zend\Stratigility\MiddlewarePipe;
+use Zend\Stratigility\NoopFinalHandler;
+
+class Server extends AbstractServer
+{
+    public function listen()
+    {
+        DiactorosServer::createServer(
+            $this,
+            $_SERVER,
+            $_GET,
+            $_POST,
+            $_COOKIE,
+            $_FILES
+        )->listen(new NoopFinalHandler());
+    }
+
+    /**
+     * Use as PSR-7 middleware.
+     *
+     * @param ServerRequestInterface $request
+     * @param ResponseInterface $response
+     * @param callable $out
+     * @return ResponseInterface
+     */
+    public function __invoke(ServerRequestInterface $request, ResponseInterface $response, callable $out)
+    {
+        $app = $this->getApp();
+
+        $this->collectGarbage($app);
+
+        $middleware = $this->getMiddleware($app, $request->getUri()->getPath());
+
+        return $middleware($request, $response, $out);
+    }
+
+    /**
+     * @param Application $app
+     * @param string $requestPath
+     * @return MiddlewareInterface
+     */
+    protected function getMiddleware(Application $app, $requestPath)
+    {
+        $pipe = new MiddlewarePipe;
+        $pipe->raiseThrowables();
+
+        if (! $app->isInstalled()) {
+            return $this->getInstallerMiddleware($pipe, $app);
+        } else if ($app->isDownForMaintenance()) {
+            return $this->getMaintenanceMiddleware($pipe);
+        } else if (! $app->isUpToDate()) {
+            return $this->getUpdaterMiddleware($pipe, $app);
+        }
+
+        $forum = parse_url($app->url(''), PHP_URL_PATH) ?: '/';
+        $admin = parse_url($app->url('admin'), PHP_URL_PATH);
+        $api = parse_url($app->url('api'), PHP_URL_PATH);
+
+        if ($this->pathStartsWith($requestPath, $api)) {
+            $pipe->pipe($api, $app->make('flarum.api.middleware'));
+        } else if ($this->pathStartsWith($requestPath, $admin)) {
+            $pipe->pipe($admin, $app->make('flarum.admin.middleware'));
+        } else {
+            $pipe->pipe($forum, $app->make('flarum.forum.middleware'));
+        }
+
+        return $pipe;
+    }
+
+    private function pathStartsWith($path, $prefix)
+    {
+        return $path === $prefix || starts_with($path, "$prefix/");
+    }
+
+    protected function getInstallerMiddleware(MiddlewarePipe $pipe, Application $app)
+    {
+        $app->register(InstallServiceProvider::class);
+
+        $pipe->pipe(new HandleErrors($this->getErrorDir(), $app->make('log'), true));
+
+        $pipe->pipe($app->make(StartSession::class));
+        $pipe->pipe($app->make(DispatchRoute::class, ['routes' => $app->make('flarum.install.routes')]));
+
+        return $pipe;
+    }
+
+    protected function getMaintenanceMiddleware(MiddlewarePipe $pipe)
+    {
+        $pipe->pipe(function () {
+            return new HtmlResponse(file_get_contents($this->getErrorDir().'/503.html', 503));
+        });
+
+        // TODO: FOR API render JSON-API error document for HTTP 503
+
+        return $pipe;
+    }
+
+    protected function getUpdaterMiddleware(MiddlewarePipe $pipe, Application $app)
+    {
+        $app->register(UpdateServiceProvider::class);
+
+        $pipe->pipe($app->make(DispatchRoute::class, ['routes' => $app->make('flarum.update.routes')]));
+
+        // TODO: FOR API render JSON-API error document for HTTP 503
+
+        return $pipe;
+    }
+
+    private function collectGarbage()
+    {
+        if ($this->hitsLottery()) {
+            AccessToken::whereRaw('last_activity <= ? - lifetime', [time()])->delete();
+
+            $earliestToKeep = date('Y-m-d H:i:s', time() - 24 * 60 * 60);
+
+            EmailToken::where('created_at', '<=', $earliestToKeep)->delete();
+            PasswordToken::where('created_at', '<=', $earliestToKeep)->delete();
+            AuthToken::where('created_at', '<=', $earliestToKeep)->delete();
+        }
+    }
+
+    private function getErrorDir()
+    {
+        return __DIR__.'/../../error';
+    }
+
+    private function hitsLottery()
+    {
+        return mt_rand(1, 100) <= 2;
+    }
+}