<?php

/*
Copyright 2016-2016 Amazon.com, Inc. or its affiliates. All Rights Reserved.

Licensed under the GNU General Public License as published by the Free Software Foundation,
Version 2.0 (the "License"). You may not use this file except in compliance with the License.
A copy of the License is located in the "license" file accompanying this file.

This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
either express or implied. See the License for the specific language governing permissions
and limitations under the License.
*/

/**
 * Hepler class for commonly used functions in the plugin.
 *
 * @since      1.0.0
 * @package    AmazonAssociatesLinkBuilder
 * @subpackage AmazonAssociatesLinkBuilder/includes
 */
class Aalb_Helper{

  /**
   * Build key for storing rendered template in cache.
   *
   * @since     1.0.0
   * @param     string    $asins          List of hyphen separated asins.
   * @param     string    $marketplace    Marketplace of the asin to look into.
   * @param     string    $store          The identifier of the store to be used for current adunit
   * @param     string    $template       Template to render the display unit.
   * @return    string                    Template cache key.
   */
  public function build_template_cache_key($asins, $marketplace, $store, $template) {
    return 'aalb' . '-' . $asins . '-' . $marketplace . '-' . $store . '-' . $template;
  }

  /**
   * Build key for storing product information in cache.
   *
   * @since     1.0.0
   * @param     string    $asins          List of hyphen separated asins.
   * @param     string    $marketplace    Marketplace of the asin to look into.
   * @param     string    $store          The identifier of the store to be used for current adunit
   * @return    string                    Products information cache key.
   */
  public function build_products_cache_key($asins, $marketplace, $store) {
    return 'aalb' . '-' . $asins . '-' . $marketplace . '-' . $store;
  }

  /**
   * Clears the cache for the given template name
   *
   * @since    1.0.0
   * @param    string    $template    The template to clear the cache for
   */
  public function clear_cache_for_template($template) {
    $this->clear_cache_for_substring($template);
  }

  /**
   * Clear the cache for keys which contain the given substring
   *
   * @since    1.0.0
   * @param    string    $substring    The subtring which is a part of the keys to be cleared
   */
  public function clear_cache_for_substring($substring) {
    global $wpdb;
    $table_prefix = $wpdb->prefix;
    $statement = 'DELETE from ' . $table_prefix . 'options
        WHERE option_name like %s or option_name like %s';
    $transient_timeout_cache = '_transient_timeout_aalb%' . $substring . '%';
    $transient_cache = '_transient_aalb%' . $substring . '%';
    $prepared_statement = $wpdb->prepare($statement, $transient_timeout_cache, $transient_cache);

    try {
      $wpdb->query($prepared_statement);
    } catch(Exception $e) {
      error_log('Unable to clear cache. Query to clear cache for substring ' . $substring . ' failed with the Exception ' . $e->getMessage());
    }
  }

  /**
   * Clear the dead expired transients from cache at intervals
   *
   * @since    1.0.0
   */
  public function clear_expired_transients_at_intervals() {
    $randomNumber = rand(1,50);
    // Clear the expired transients approximately once in 50 requests.
    if($randomNumber == 25) {
      $this->clear_expired_transients();
    }
  }

  /**
   * Clear the dead expired transients from cache
   *
   * @since    1.0.0
   */
  public function clear_expired_transients() {
    global $wpdb;
    $table_prefix = $wpdb->prefix;
    $transients_prefix  = esc_sql( "_transient_timeout_aalb%" );
    $sql = $wpdb -> prepare (
      '
        SELECT option_name
        FROM ' . $table_prefix . 'options
        WHERE option_name LIKE %s
      ',
      $transients_prefix
    );
    $transients = $wpdb -> get_col( $sql );
    foreach( $transients as $transient ) {
      // Strip away the WordPress prefix in order to arrive at the transient key.
      $key = str_replace( '_transient_timeout_', '', $transient );
      delete_transient($key);
    }
    wp_cache_flush();
  }

  /**
   * Displays error messages in preview mode only
   *
   * @since    1.0.0
   * @param    string    $error_message    Error message to be displayed
   */
  public function show_error_in_preview($error_message) {
    if (is_preview()) {
      //If it's preview mode
      echo "<br><font color='red'><b>" . $error_message . "</b></font>";
    }
  }

  /**
   * Returns the Store IDs Array.
   * Returns AALB_DEFAULT_STORE_ID_NAME if the nothing is specified.
   *
   * @since    1.0.0
   */
  public function get_store_ids_array(){
    return explode("\r\n", strlen(get_option(AALB_STORE_ID_NAMES))?get_option(AALB_STORE_ID_NAMES):AALB_DEFAULT_STORE_ID_NAME);
  }

  /**
   * Fetches the Wordpress version number
   *
   * @since    1.0.0
   * @return string Version number of Wordpress
   */
  function get_wordpress_version() {
    global $wp_version;
    return $wp_version;
  }

  /**
   * Fetches the Uploads Directory where custom templates are stored.
   * If the dir doesn't exists, it is created and returned.
   *
   * @since    1.3
   * @return   Full directory path of the template uploads directory
   */
  public function get_template_upload_directory() {
    global $wp_filesystem;
    $this->aalb_initialize_wp_filesystem_api();
    $aalb_template_upload_dir = $this->get_template_upload_directory_name($wp_filesystem);
    if ( ! $wp_filesystem->is_dir($aalb_template_upload_dir) ) {
      if(! $this->create_template_upload_dir($aalb_template_upload_dir)) {
        return false;
      }
    }
    return $aalb_template_upload_dir;
  }

  /**
   * Creates the Uploads Directory where custom templates are stored
   *
   * @since    1.3
   * @return   TRUE on successful creation of the dir; FALSE otherwise
   */
  public function create_template_upload_dir($aalb_template_upload_dir) {
    global $wp_filesystem;
    if(!wp_mkdir_p($aalb_template_upload_dir)) {
        error_log("Error Creating Dir . " . $aalb_template_upload_dir . ". Please set the folder permissions correctly.");
        return false;
      }
    return true;
  }

  /**
   * Gets the template uploads dir name.
   *
   * @since    1.3
   * @return   full path of the template uploads directory
   */
  public function get_template_upload_directory_name() {
    global $wp_filesystem;
    $upload_dir = wp_upload_dir();
    return $wp_filesystem->find_folder( $upload_dir['basedir'] ) . 'amazon-associates-link-builder/template/';
  }

  /**
   * Loads necessary files and initializes WP Filesystem API
   *
   * @since    1.3
   */
  public function aalb_initialize_wp_filesystem_api() {
    require_once( ABSPATH . 'wp-admin/includes/file.php' );
    WP_Filesystem();
  }

  /**
   * Gets the extension of the file
   *
   * @since     1.0
   * @param     string    $file_name    Name of the file
   * @return    string                  Extension of the file
   */
  public function aalb_get_file_extension($file_name) {
    return substr(strrchr($file_name,'.'),1);
  }

  /**
   * Gets the name of the file without the extension
   *
   * @since     1.0
   * @param     string    $file_name    Name of the file
   * @return    string                  Name of the file without the extension
   */
  function aalb_get_file_name($file_name) {
    return substr($file_name, 0, strlen($file_name) - strlen(strrchr($file_name,'.')));
  }

  /**
   * Reads both the templates/ and the uploads/ directory and updates the template list.
   * Helper to replicate the current status of the default and custom templates
   *
   * @since    1.3
   */
  public function refresh_template_list() {
    global $wp_filesystem;
    $this->aalb_initialize_wp_filesystem_api();

    $aalb_templates = array();
    $upload_dir = $this->get_template_upload_directory();

    //Read and update templates from the plugin's template/ directory (Default Templates)
    if ($handle = opendir(AALB_TEMPLATE_DIR)) {
      while (false !== ($entry = readdir($handle))) {
        $file_name = $this->aalb_get_file_name($entry);
        $file_extension = $this->aalb_get_file_extension($entry);
        if ($file_extension == "css" and file_exists(AALB_TEMPLATE_DIR . $file_name . '.mustache')) {
          $aalb_templates[] = $file_name;
        }
      }
      closedir($handle);
    }

    //Read and update templates from the uploads/ directory (Custom Templates)
    if ($handle = opendir($upload_dir)) {
      while (false !== ($entry = readdir($handle))) {
        $file_name = $this->aalb_get_file_name($entry);
        $file_extension = $this->aalb_get_file_extension($entry);
        if ($file_extension == "css" and file_exists($upload_dir . $file_name . '.mustache')) {
          $aalb_templates[] = $file_name;
        }
      }
    }
    update_option(AALB_TEMPLATE_NAMES, $aalb_templates);
  }
}
?>