<?php
/**
 * PHPCI - Continuous Integration for PHP
 *
 * @copyright    Copyright 2014, Block 8 Limited.
 * @license      https://github.com/Block8/PHPCI/blob/master/LICENSE.md
 * @link         https://www.phptesting.org/
 */

namespace PHPCI\Helper;

/**
 * Helper class for dealing with SSH keys.
 * @package PHPCI\Helper
 */
class SshKey
{
    /**
     * Uses ssh-keygen to generate a public/private key pair.
     * @return array
     */
    public function generate()
    {
        $tempPath = sys_get_temp_dir() . '/';

        // FastCGI fix for Windows machines, where temp path is not available to
        // PHP, and defaults to the unwritable system directory.  If the temp
        // path is pointing to the system directory, shift to the 'TEMP'
        // sub-folder, which should also exist, but actually be writable.
        if (IS_WIN && $tempPath == getenv("SystemRoot") . '/') {
            $tempPath = getenv("SystemRoot") . '/TEMP/';
        }

        $keyFile = $tempPath . md5(microtime(true));

        if (!is_dir($tempPath)) {
            mkdir($tempPath);
        }

        $return = array('private_key' => '', 'public_key' => '');

        if ($this->canGenerateKeys()) {
            shell_exec('ssh-keygen -q -t rsa -b 2048 -f '.$keyFile.' -N "" -C "deploy@phpci"');

            $pub = file_get_contents($keyFile . '.pub');
            $prv = file_get_contents($keyFile);

            if (!empty($pub)) {
                $return['public_key'] = $pub;
            }

            if (!empty($prv)) {
                $return['private_key'] = $prv;
            }
        }

        return $return;
    }

    /**
     * Checks whether or not we can generate keys, by quietly test running ssh-keygen.
     * @return bool
     */
    public function canGenerateKeys()
    {
        $keygen = @shell_exec('ssh-keygen --help');
        $canGenerateKeys = !empty($keygen);

        return $canGenerateKeys;
    }
}