Extract installation prerequisites into composable classes and use those in the web-based installer

src/Install/Actions/IndexAction.php

@@ -10,6 +10,7 @@
 
 namespace Flarum\Install\Actions;
 
+use Flarum\Install\Prerequisites\Prerequisite;
 use Flarum\Support\HtmlAction;
 use Psr\Http\Message\ServerRequestInterface as Request;
 use Illuminate\Contracts\View\Factory;
@@ -22,11 +23,18 @@ class IndexAction extends HtmlAction
     protected $view;
 
     /**
-     * @param Factory $view
+     * @var Prerequisite
      */
-    public function __construct(Factory $view)
+    protected $prerequisite;
+
+    /**
+     * @param Factory $view
+     * @param Prerequisite $prerequisite
+     */
+    public function __construct(Factory $view, Prerequisite $prerequisite)
     {
         $this->view = $view;
+        $this->prerequisite = $prerequisite;
     }
 
     /**
@@ -38,38 +46,8 @@ class IndexAction extends HtmlAction
     {
         $view = $this->view->make('flarum.install::app');
 
-        $errors = [];
-
-        if (version_compare(PHP_VERSION, '5.5.0', '<')) {
-            $errors[] = [
-                'message' => '<strong>PHP 5.5+</strong> is required.',
-                'detail' => 'You are running version '.PHP_VERSION.'. Talk to your hosting provider about upgrading to the latest PHP version.'
-            ];
-        }
-
-        foreach (['mbstring', 'pdo_mysql', 'openssl', 'json', 'gd', 'dom', 'fileinfo'] as $extension) {
-            if (! extension_loaded($extension)) {
-                $errors[] = [
-                    'message' => 'The <strong>'.$extension.'</strong> extension is required.'
-                ];
-            }
-        }
-
-        $paths = [
-            public_path(),
-            public_path().'/assets',
-            public_path().'/extensions',
-            storage_path()
-        ];
-
-        foreach ($paths as $path) {
-            if (! is_writable($path)) {
-                $errors[] = [
-                    'message' => 'The <strong>'.realpath($path).'</strong> directory is not writable.',
-                    'detail' => 'Please chmod this directory '.($path !== public_path() ? ' and its contents' : '').' to 0775.'
-                ];
-            }
-        }
+        $this->prerequisite->check();
+        $errors = $this->prerequisite->getErrors();
 
         if (count($errors)) {
             $view->content = $this->view->make('flarum.install::errors');

src/Install/InstallServiceProvider.php

@@ -11,6 +11,10 @@
 namespace Flarum\Install;
 
 use Flarum\Http\RouteCollection;
+use Flarum\Install\Prerequisites\PhpExtensions;
+use Flarum\Install\Prerequisites\PhpVersion;
+use Flarum\Install\Prerequisites\WritablePaths;
+use Flarum\Install\Prerequisites\Composite;
 use Flarum\Support\ServiceProvider;
 use Psr\Http\Message\ServerRequestInterface;
 
@@ -24,6 +28,17 @@ class InstallServiceProvider extends ServiceProvider
     public function register()
     {
         $this->app->register('Flarum\Locale\LocaleServiceProvider');
+
+        $this->app->bind(
+            'Flarum\Install\Prerequisites\Prerequisite',
+            function() {
+                return new Composite(
+                    new PhpVersion(),
+                    new PhpExtensions(),
+                    new WritablePaths()
+                );
+            }
+        );
     }
 
     /**

src/Install/Prerequisites/AbstractPrerequisite.php

@@ -0,0 +1,23 @@
+<?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\Install\Prerequisites;
+
+abstract class AbstractPrerequisite implements Prerequisite
+{
+    protected $errors = [];
+
+    abstract public function check();
+
+    public function getErrors()
+    {
+        return $this->errors;
+    }
+}

src/Install/Prerequisites/Composite.php

@@ -0,0 +1,45 @@
+<?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\Install\Prerequisites;
+
+class Composite implements Prerequisite
+{
+    /**
+     * @var AbstractPrerequisite[]
+     */
+    protected $prerequisites = [];
+
+    public function __construct(Prerequisite $first)
+    {
+        foreach (func_get_args() as $prerequisite)
+        {
+            $this->prerequisites[] = $prerequisite;
+        }
+    }
+
+    public function check()
+    {
+        return array_reduce(
+            $this->prerequisites,
+            function ($previous, Prerequisite $prerequisite) {
+                return $prerequisite->check() && $previous;
+            },
+            true
+        );
+    }
+
+    public function getErrors()
+    {
+        return collect($this->prerequisites)->map(function(Prerequisite $prerequisite) {
+            return $prerequisite->getErrors();
+        })->reduce('array_merge', []);
+    }
+}

src/Install/Prerequisites/PhpExtensions.php

@@ -0,0 +1,25 @@
+<?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\Install\Prerequisites;
+
+class PhpExtensions extends AbstractPrerequisite
+{
+    public function check()
+    {
+        foreach (['mbstring', 'pdo_mysql', 'openssl', 'json', 'gd', 'dom', 'fileinfo'] as $extension) {
+            if (! extension_loaded($extension)) {
+                $this->errors[] = [
+                    'message' => "The <strong>$extension</strong> extension is required.",
+                ];
+            }
+        }
+    }
+}

src/Install/Prerequisites/PhpVersion.php

@@ -0,0 +1,24 @@
+<?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\Install\Prerequisites;
+
+class PhpVersion extends AbstractPrerequisite
+{
+    public function check()
+    {
+        if (version_compare(PHP_VERSION, '5.5.0', '<')) {
+            $this->errors[] = [
+                'message' => '<strong>PHP 5.5+</strong> is required.',
+                'detail' => 'You are running version '.PHP_VERSION.'. Talk to your hosting provider about upgrading to the latest PHP version.'
+            ];
+        }
+    }
+}

src/Install/Prerequisites/Prerequisite.php

@@ -0,0 +1,18 @@
+<?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\Install\Prerequisites;
+
+interface Prerequisite
+{
+    public function check();
+
+    public function getErrors();
+}

src/Install/Prerequisites/WritablePaths.php

@@ -0,0 +1,33 @@
+<?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\Install\Prerequisites;
+
+class WritablePaths extends AbstractPrerequisite
+{
+    public function check()
+    {
+        $paths = [
+            public_path(),
+            public_path().'/assets',
+            public_path().'/extensions',
+            storage_path()
+        ];
+
+        foreach ($paths as $path) {
+            if (! is_writable($path)) {
+                $this->errors[] = [
+                    'message' => 'The <strong>'.realpath($path).'</strong> directory is not writable.',
+                    'detail' => 'Please chmod this directory '.($path !== public_path() ? ' and its contents' : '').' to 0775.'
+                ];
+            }
+        }
+    }
+}