<?php

/**
 * @file
 * Locks media objects from being deleted by adding an file_usage entry
 * https://drupal.org/node/1239056
 * drupal deletes files which aren't used anymore
 */

// Modules have no id, but file_usage want's one.
define("FILE_LOCK_ID", 0);

/**
 * Implements hook_help().
 */
function file_lock_help($path, $arg) {
  switch ($path) {
    case 'admin/help#file_lock':
      $output = '<p>' . t("This module provides a way to lock files on your website. Locked files won't get deleted if they aren't used anymore.") . '</p>';
      return $output;
  }
}

/**
 * Implements hook_menu().
 */
function file_lock_menu() {
  $items['admin/config/media/lock'] = array(
    'title' => 'File Lock',
    'description' => 'Configure the file lock settings.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('file_lock_admin_config'),
    'access arguments' => array('administer files'),
    'file' => 'file_lock.admin.inc',
  );

  return $items;

}

/**
 * Implements hook_file_insert().
 */
function file_lock_file_insert($file) {
  $config_hook = variable_get("file_lock_hook", 'none');
  if ($config_hook == 'insert' || $config_hook == 'all') {
    file_lock_act_on($file);
  }
}

/**
 * Implements hook_file_update().
 */
function file_lock_file_update($file) {
  $config_hook = variable_get("file_lock_hook", 'none');
  if ($config_hook == 'update' || $config_hook == 'all') {
    file_lock_act_on($file);
  }
}


/**
 * Implements hook_file_operations_info().
 */
function file_lock_file_operations_info() {
  $operations = array(
    'file_lock' => array(
      'label' => t('Lock selected files'),
      'callback' => 'file_lock_lock_files',
      'confirm' => FALSE,
    ),
    'file_unlock' => array(
      'label' => t('Unlock selected files'),
      'callback' => 'file_lock_unlock_files',
      'confirm' => FALSE,
    ),
  );
  return $operations;
}

/**
 * set lock for $file if it matches the given $lock_mode
 *
 * @param file $file
 *   the file to lock
 * @param string $lock_mode
 *   the mode to check the file for
 */
function file_lock_act_on($file, $lock_mode = NULL) {
  // Do not lock temporary files.
  if (empty($file->status)) {
    return;
  }

  if ($lock_mode == NULL) {
    $lock_mode = variable_get('file_lock_mode', 'none');
  }

  switch ($lock_mode) {

    case 'all':
      file_lock_add_lock($file);
      break;

    case 'pattern':
      $pattern = variable_get('file_lock_pattern', '*');
      if (fnmatch($pattern, $file->filename)) {
        file_lock_add_lock($file);
      }
      break;

    case 'regex':
      $pattern = variable_get('file_lock_regex', '/.*/');
      if (preg_match($pattern, $file->filename)) {
        file_lock_add_lock($file);
      }
      break;

  }
}


/**
 * Add lock for multiple files
 *
 * @param array $files
 *   array of files, indexed by fid.
 */
function file_lock_lock_files($files) {
  foreach ($files as $fid => $f) {
    // Do not lock temporary files.
    if (($file = file_load($fid)) && !empty($file->status)) {
      file_lock_add_lock($file);
    }
    else {
      unset($files[$fid]);
    }
  }
  drupal_set_message(t('Locked @count files.', array('@count' => count($files))));
}

/**
 * Remove lock for multiple files
 *
 * @param array $files
 *   array of files, indexed by fid.
 */
function file_lock_unlock_files($files) {
  foreach ($files as $fid => $f) {
    $file = new stdClass();
    $file->fid = $fid;

    file_lock_remove_lock($file);
  }
  drupal_set_message(t('Unlocked @count files.', array('@count' => count($files))));
}

/**
 * Add lock for the $file
 * This is done by adding an entry to the file_usage table.
 *
 * @param file $file
 *   file object (with at least 'fid' set)
 */
function file_lock_add_lock($file) {
  if (!file_lock_is_locked($file)) {
    // Only add one lock for every file.
    file_usage_add($file, 'file_lock', 'module', FILE_LOCK_ID);
  }
}

/**
 * Remove lock for the $file
 *
 * @param file $file
 *   file object (with at least 'fid' set)
 */
function file_lock_remove_lock($file) {
  file_usage_delete($file, 'file_lock', 'FILE_LOCK_ID');
}

/**
 * Check if a file has already an entry in file_usage for file_lock
 *
 * @param file $file
 *   the file to check
 *
 * @return bool
 *   TRUE if file is locked
 *   FALSE if file is not locked
 */
function file_lock_is_locked($file) {
  $file_usage_list = file_usage_list($file);
  return isset($file_usage_list['file_lock']);
}