<?php
/**
 * Class GhWebHook
 */
class GhWebHook
{

    /**
     * Hook key
     * @var string
     */
    protected $key = '';

    /**
     * @param $key
     */
    public function __construct($key)
    {
        $this->key = (string)$key;
    }

    /**
     * Run commands
     * @param $commands
     */
    public function run($commands)
    {
        if (!$this->validateUserAgent()) {
            static::response('error', 'User agent validation fail');
        }

        if (!$this->validateSig()) {
            static::response('error', 'Sig validation fail');
        }

        system(implode('&&', $commands));
        static::response('success', 'Deploy success');
    }

    /**
     * Response
     * @param $status
     * @param $message
     */
    public static function response($status, $message)
    {
        header('Content-Type: application/json');
        die(json_encode([$status => $message]));
    }

    public static function init($configs)
    {
        if (!file_exists($configs)) {
            static::response('error', 'Can not find configuration file');
        }

        $config = require($configs);

        if (!isset($config['deploykey'])) {
            static::response('error', 'Deploy key not exists');
        }

        return $config['deploykey'];
    }


    /**
     * User Agent must be a GitHub-Hookshot/****
     * @return bool
     */
    protected function validateUserAgent()
    {
        return isset($_SERVER['HTTP_USER_AGENT']) &&
            preg_match('/GitHub\-Hookshot\/[0-9]+/is', $_SERVER['HTTP_USER_AGENT']);
    }

    /**
     * Signature must be sha1 of raw content and key
     * @return bool
     */
    protected function validateSig()
    {
        $input  = file_get_contents('php://input');

        return isset($_SERVER['HTTP_X_HUB_SIGNATURE']) &&
            ('sha1=' . hash_hmac('sha1', $input, $this->key)) === $_SERVER['HTTP_X_HUB_SIGNATURE'];
    }
}



$key  = GhWebHook::init(__DIR__ . '/../app/config/app.php');

(new GhWebHook($key))
    ->run([
        'cd ../',
        'git checkout -f',
        'composer update',
    ]);