<?php

/*

 * This file is part of the Assetic package, an OpenSky project.

 *

 * (c) 2010-2011 OpenSky Project Inc

 *

 * For the full copyright and license information, please view the LICENSE

 * file that was distributed with this source code.

 */

namespace Assetic\Cache;

/**

 * A config cache stores values using var_export() and include.

 *

 * @author Kris Wallsmith <kris.wallsmith@gmail.com>

 */

class ConfigCache

{

    private $dir;

    /**

     * Construct.

     *

     * @param string $dir The cache directory

     */

    public function __construct($dir)

    {

        $this->dir = $dir;

    }

    /**

     * Checks of the cache has a file.

     *

     * @param string $resource A cache key

     *

     * @return Boolean True if a file exists

     */

    public function has($resource)

    {

        return file_exists($this->getSourcePath($resource));

    }

    /**

     * Writes a value to a file.

     *

     * @param string $resource A cache key

     * @param mixed  $value    A value to cache

     */

    public function set($resource, $value)

    {

        $path = $this->getSourcePath($resource);

        if (!is_dir($dir = dirname($path)) && false === @mkdir($dir, 0777, true)) {

            // @codeCoverageIgnoreStart

            throw new \RuntimeException('Unable to create directory '.$dir);

            // @codeCoverageIgnoreEnd

        }

        if (false === @file_put_contents($path, sprintf("<?php\n\n// $resource\nreturn %s;\n", var_export($value, true)))) {

            // @codeCoverageIgnoreStart

            throw new \RuntimeException('Unable to write file '.$path);

            // @codeCoverageIgnoreEnd

        }

    }

    /**

     * Loads and returns the value for the supplied cache key.

     *

     * @param string $resource A cache key

     *

     * @return mixed The cached value

     */

    public function get($resource)

    {

        $path = $this->getSourcePath($resource);

        if (!file_exists($path)) {

            throw new \RuntimeException('There is no cached value for '.$resource);

        }

        return include $path;

    }

    /**

     * Returns a timestamp for when the cache was created.

     *

     * @param string $resource A cache key

     *

     * @return integer A UNIX timestamp

     */

    public function getTimestamp($resource)

    {

        $path = $this->getSourcePath($resource);

        if (!file_exists($path)) {

            throw new \RuntimeException('There is no cached value for '.$resource);

        }

        if (false === $mtime = @filemtime($path)) {

            // @codeCoverageIgnoreStart

            throw new \RuntimeException('Unable to determine file mtime for '.$path);

            // @codeCoverageIgnoreEnd

        }

        return $mtime;

    }

    /**

     * Returns the path where the file corresponding to the supplied cache key can be included from.

     *

     * @param string $resource A cache key

     *

     * @return string A file path

     */

    private function getSourcePath($resource)

    {

        $key = md5($resource);

        return $this->dir.'/'.$key[0].'/'.$key.'.php';

    }

}