<?php

/**
 * Concrete class for file caching strategy.
 *
 * @instantiator new
 * @author       Time.ly Network, Inc.
 * @since        2.0
 * @package      Ai1EC
 * @subpackage   Ai1EC.Cache.Strategy
 */
class Ai1ec_Cache_Strategy_File extends Ai1ec_Cache_Strategy {

    /**
     * @var string
     */
    private $_cache_dir;

    private $_cache_url;

    public function __construct( Ai1ec_Registry_Object $registry, array $cache_dir ) {
        parent::__construct( $registry );
        $this->_cache_dir = $cache_dir['path'];
        $this->_cache_url = $cache_dir['url'];
    }

    /**
     *
     * @see Ai1ec_Get_Data_From_Cache::get_data()
     *
     */
    public function get_data( $file ) {
        $file = $this->_get_file_name( $file );
        if ( ! $file || ! file_exists( $this->_cache_dir . $file ) ) {
            throw new Ai1ec_Cache_Not_Set_Exception(
                'File \'' . $file . '\' does not exist'
            );
        }
        return maybe_unserialize(
            file_get_contents( $this->_cache_dir . $file )
        );
    }

    /**
     *
     * @see Ai1ec_Write_Data_To_Cache::write_data()
     *
     */
    public function write_data( $filename, $value ) {
        $filename = $this->_safe_file_name( $filename );
        $value    = maybe_serialize( $value );

        $result = $this->_registry->get( 'filesystem.checker' )->put_contents(
            $this->_cache_dir . $filename,
            $value
        );
        if ( false === $result ) {
            $message = 'An error occured while saving data to \'' .
                $this->_cache_dir . $filename . '\'';
            throw new Ai1ec_Cache_Write_Exception( $message );
        }
        return array(
            'path' => $this->_cache_dir . $filename,
            'url'  => $this->_cache_url . $filename,
            'file' => $filename,
        );
    }

    /**
     * (non-PHPdoc)
     * @see Ai1ec_Write_Data_To_Cache::delete_data()
     */
    public function delete_data( $filename ) {
        // Check if file exists. It might not exists if you switch themes
        // twice without never rendering the CSS
        $filename = $this->_safe_file_name( $filename );
        if (
            file_exists( $this->_cache_dir . $filename ) &&
            false === unlink( $this->_cache_dir . $filename )
        ) {
            return false;
        }
        return true;
    }

    /**
     *
     * @see Ai1ec_Write_Data_To_Cache::delete_matching()
     */
    public function delete_matching( $pattern ) {
        $dirhandle = opendir( $this->_cache_dir );
        if ( false === $dirhandle ) {
            return 0;
        }
        $count = 0;
        while ( false !== ( $entry = readdir( $dirhandle ) ) ) {
            if ( '.' !== $entry{0} && false !== strpos( $entry, $pattern ) ) {
                if ( unlink( $this->_cache_dir . $entry ) ) {
                    ++$count;
                }
            }
        }
        closedir( $dirhandle );
        return $count;
    }

    /**
     * Get the extension for the file if required
     *
     * @param string $file
     *
     * @return string
     */
    protected function _get_extension_for_file( $file ) {
        $extensions = array(
            'ai1ec_parsed_css' => '.css'
        );
        if ( isset( $extensions[$file] ) ) {
            return $extensions[$file];
        }
        return '';
    }

    /**
     * Tries to get the stored filename
     *
     * @param string $file
     *
     * @return boolean | string
     */
    protected function _get_file_name( $file ) {
        static $file_map = array(
            'ai1ec_parsed_css' => 'ai1ec_filename_css',
        );
        if ( isset ( $file_map[$file] ) ) {
            return $this->_registry->get( 'model.option' )->get( $file_map[$file] );
        }
        return false;
    }

    /**
     * _safe_file_name method
     *
     * Generate safe file name for any storage case.
     *
     * @param string $file File name currently supplied
     *
     * @return string Sanitized file name
     */
    protected function _safe_file_name( $file ) {
        static $prefix = null;
        $extension = $this->_get_extension_for_file( $file );
        if ( null === $prefix ) {
            // always include site_url when there is more than one
            $pref_string = ai1ec_site_url();
            if ( ! AI1EC_DEBUG ) {
                // address multiple re-saves for a single version
                // i.e. when theme settings are being edited
                $pref_string .= mt_rand();
            }
            $prefix = substr( md5( $pref_string ), 0, 8 );
        }
        $length = strlen( $file );
        if ( ! ctype_alnum( $file ) ) {
            $file = preg_replace(
                '|_+|',
                '_',
                preg_replace( '|[^a-z0-9\-,_]|', '_', $file )
            );
        }
        if ( 0 !== strncmp( $file, $prefix, 8 ) ) {
            $file = $prefix . '_' . $file;
        }
        return $file . $extension;
    }

}