Rocketeer PHP check strategy replacement

PhpExtensionCheckStrategy.php

<?php
/**
 * This is a drop-in replacement for the default PhpStrategy.
 *
 * Instead of checking for `mcrypt` as a required extension, it checks for PHP extensions required in composer.json
 * (e.g. `ext-mcrypt`)
 *
 * - Save the file as `.rocketeer/strategies/PhpCheckStrategy.php`
 * - Change your strategy setting from 'Php' to `PhpExtensionCheck`
 *
 * @link https://getcomposer.org/doc/02-libraries.md
 * @link https://github.com/rocketeers/rocketeer/issues/602
 */

namespace Rocketeer\Strategies\Check;

use Illuminate\Container\Container;
use Rocketeer\Abstracts\Strategies\AbstractCheckStrategy;
use Rocketeer\Interfaces\Strategies\CheckStrategyInterface;
use Rocketeer\Strategies\Check\PhpStrategy;

class PhpExtensionCheckStrategy extends PhpStrategy implements CheckStrategyInterface
{
    /**
     * Check for the required extensions.
     *
     * @return array
     */
    public function extensions()
    {
        $extensions = [
            'database' => ['checkDatabaseDriver', $this->app['config']->get('database.default')],
            'cache'    => ['checkCacheDriver', $this->app['config']->get('cache.driver')],
            'session'  => ['checkCacheDriver', $this->app['config']->get('session.driver')],
        ];

        foreach ($this->getRequiredExtensionsFromComposer() as $extension) {
            $extensions[$extension] = ['checkPhpExtension', $extension];
        }

        // Check PHP extensions
        $errors = [];
        foreach ($extensions as $check) {
            list($method, $extension) = $check;

            if (!$this->$method($extension)) {
                $errors[] = $extension;
            }
        }

        return $errors;
    }

    /**
     * @return array
     */
    private function getRequiredExtensionsFromComposer()
    {
        $extensions = [];

        if (!$manifest = $this->manager->getManifestContents()) {
            return $extensions;
        }

        $data = json_decode($manifest, true);

        if (!array_key_exists('require', $data)) {
            return $extensions;
        }

        foreach ($data['require'] as $package => $version) {
            if ('ext-' === substr($package, 0, 4)) {
                $extensions[] = substr($package, 4);
            }
        }

        return $extensions;
    }
}