<?php

namespace Vimeography;

class Cache {

  /**
   * The user's cache expiration setting for the current gallery.
   *
   * @var int | NULL
   */
  private $_expiration;

  /**
   * The path to the cache file, built in the constructor based on the
   * provided gallery id.
   *
   * @var string
   */
  private $_cache_file;


  /**
   * [__construct description]
   * @param [type] $settings [description]
   */
  public function __construct( $engine ) {

    wp_mkdir_p( VIMEOGRAPHY_CACHE_PATH );
    $scope = is_multisite() ? get_current_blog_id() . '-' . $engine->gallery_id : $engine->gallery_id;
    $this->_cache_file = VIMEOGRAPHY_CACHE_PATH . 'vimeography-gallery-' . $scope . '.cache';

    if ( isset( $engine->gallery_settings['cache'] ) ) {
      $this->_expiration = intval( $engine->gallery_settings['cache'] );
    }

  }

  /**
   * Checks if a cache file exists.
   *
   * @param  string $file Path to the cache file.
   * @return bool         true if exists, false if not.
   */
  public function exists() {
    return file_exists( $this->_cache_file );
  }


  /**
   * Check if the cache is expired
   *
   * @return bool
   */
  public function expired() {

    if ( ! isset( $this->_expiration ) ) {
      return false;
    }

    $last_modified = @filemtime( $this->_cache_file );
    $expires = $last_modified + $this->_expiration;

    if ( $expires < time() ) {
      // The cache is expired, but we don't want to remove it here,
      // We only want to remove it if we do not receive a 304 response or the user forces a cache refresh.

      // Set $last_modified to make the request along with the modified time in the header.
      $this->last_modified = date( DATE_ISO8601, $last_modified );

      return true;
    }

    return false;
  }

  /**
   * Get the serialized data stored in the Vimeography cache
   *
   * @access public
   * @static
   * @param string  A cache filename
   * @return object/bool
   */
  public function get() {
    if ( file_exists( $this->_cache_file ) ) {
      return unserialize( file_get_contents( $this->_cache_file ) );
    } else {
      return false;
    }
  }

  /**
   * Writes the video set to a cache file.
   *
   * @access public
   * @static
   * @param string $file      A cache filename, equal to tokenized shortcode settings.
   * @param object $video_set Vimeo collection data
   */
  public function set($data) {
    return @file_put_contents( $this->_cache_file, serialize( $data ) );
  }

  /**
   * If there is a 304 Not Changed, update the modified time to reset the expiration
   * Changes the file modified time to current
   *
   * @param  string $file A cache filename, equal to tokenized shortcode settings.
   * @return bool Whether the file was updated or not.
   */
  public function renew() {
    if ( touch( $this->_cache_file ) ) {
      return $this;
    } else {
      return false;
    }
  }

  /**
   * Delete a cache file if it is old or the user forces a refresh.
   *
   * @param  string $token A cache filename, equal to tokenized shortcode settings.
   * @return bool          Success or failure deleting file.
   */
  public function delete() {
    if ( substr( $this->_cache_file, -6 ) === '.cache' ) {
      return @unlink( $this->_cache_file );
    }
  }

  /**
   * Remove any expired cache files from the cache directory.
   * We can safely do this after the request was made, but we really shouldn't
   * get rid of valid, expired files if the 304 is working properly.
   *
   * @return void
   */
  protected function cleanup() {
    $files = scandir( VIMEOGRAPHY_CACHE_PATH );

    foreach ($files as $file) {
      $last_modified = @filemtime( VIMEOGRAPHY_CACHE_PATH . $file );

      if ( substr($file, -6) === '.cache' && ( $last_modified + $this->_expiration ) < time() ) {
        unlink( VIMEOGRAPHY_CACHE_PATH . $file );
      }
    }
  }
}