<?php

/**
 * @file
 * Rules scheduler module.
 */

define('RULES_SCHEDULER_PATH', 'admin/config/workflow/rules/schedule');

/**
 * Implements hook_cron().
 */
function rules_scheduler_cron() {
  // Limit adding tasks to 1000 per cron run.
  $result = db_select('rules_scheduler', 'r', array('fetch' => PDO::FETCH_ASSOC))
    ->fields('r')
    ->condition('date', time(), '<=')
    ->range(0, 1000)
    ->execute();

  $queue = DrupalQueue::get('rules_scheduler_tasks');
  foreach ($result as $task) {
    // Add the task to the queue and remove the entry afterwards.
    if ($queue->createItem($task)) {
      db_delete('rules_scheduler')
        ->condition('tid', $task['tid'])
        ->execute();
      $task_created = TRUE;
    }
  }

  if (!empty($task_created)) {
    // hook_exit() is not invoked for cron runs, so register it as shutdown
    // callback for logging the rules log to the watchdog.
    drupal_register_shutdown_function('rules_exit');
    // Clear the log before running tasks via the queue to avoid logging
    // unrelated logs from previous cron-operations.
    RulesLog::logger()->clear();
  }
}

/**
 * Implements hook_cron_queue_info().
 */
function rules_scheduler_cron_queue_info() {
  $queues['rules_scheduler_tasks'] = array(
    'worker callback' => 'rules_scheduler_run_task',
    'time' => 15,
  );
  return $queues;
}

/**
 * Queue worker callback for running a single task.
 */
function rules_scheduler_run_task(array $task) {
  if ($component = rules_get_cache('comp_' . $task['config'])) {
    $replacements = array('%label' => $component->label(), '%plugin' => $component->plugin());
    $replacements['%identifier'] = $task['identifier'] ? $task['identifier'] : t('without identifier');
    rules_log('Scheduled evaluation of %plugin %label, task %identifier.', $replacements, RulesLog::INFO, $component, TRUE);
    $state = unserialize($task['state']);
    $state->restoreBlocks();
    // Finally evaluate the component with the given state.
    $component->evaluate($state);
    rules_log('Finished evaluation of %plugin %label, task %identifier.', $replacements, RulesLog::INFO, $component, FALSE);
    $state->cleanUp();
  }
}

/**
 * Implements hook_rules_ui_menu_alter().
 *
 * Adds a menu item for the 'schedule' operation.
 */
function rules_scheduler_rules_ui_menu_alter(&$items, $base_path, $base_count) {
  $items[$base_path . '/manage/%rules_config/schedule'] = array(
    'title callback' => 'rules_get_title',
    'title arguments' => array('Schedule !plugin "!label"', $base_count + 1),
    'page callback' => 'drupal_get_form',
    'page arguments' => array('rules_scheduler_schedule_form', $base_count + 1, $base_path),
    'access callback' => 'rules_config_access',
    'access arguments' => array('update', $base_count + 1),
    'file' => 'rules_scheduler.admin.inc',
    'file path' => drupal_get_path('module', 'rules_scheduler'),
  );
}

/**
 * Implements hook_menu().
 */
function rules_scheduler_menu() {
  $items = array();
  $items[RULES_SCHEDULER_PATH] = array(
    'title' => 'Schedule',
    'type' => MENU_LOCAL_TASK,
    'page callback' => 'rules_scheduler_schedule_page',
    'access arguments' => array('administer rules'),
    'file' => 'rules_scheduler.admin.inc',
  );
  $items[RULES_SCHEDULER_PATH .'/%rules_scheduler_task/delete'] = array(
    'title' => 'Delete a scheduled task',
    'type' => MENU_CALLBACK,
    'page callback' => 'drupal_get_form',
    'page arguments' => array('rules_scheduler_delete_task', 5),
    'access arguments' => array('administer rules'),
    'file' => 'rules_scheduler.admin.inc',
  );
  return $items;
}

/**
 * Load a task by a given task ID.
 */
function rules_scheduler_task_load($tid) {
  $result = db_select('rules_scheduler', 'r')
    ->fields('r')
    ->condition('tid', (int) $tid)
    ->execute();
  return $result->fetchAssoc();
}

/**
 * Delete a task by a given task ID.
 */
function rules_scheduler_task_delete($tid) {
  db_delete('rules_scheduler')
    ->condition('tid', $tid)
    ->execute();
}

/**
 * Schedule a task to be executed later on.
 *
 * @param $task
 *   An array representing the task with the following keys:
 *   - config: The machine readable name of the to be scheduled component.
 *   - date: Timestamp when the component should be executed.
 *   - state: An rules evaluation state to use for scheduling.
 *   - identifier: User provided string to identify the task per scheduled
 *   configuration.
 */
function rules_scheduler_schedule_task($task) {
  if (!empty($task['identifier'])) {
    // If there is a task with the same identifier and component, we replace it.
    db_delete('rules_scheduler')
      ->condition('config', $task['config'])
      ->condition('identifier', $task['identifier'])
      ->execute();
  }
  drupal_write_record('rules_scheduler', $task);
}

/**
 * Implements hook_rules_config_delete().
 */
function rules_scheduler_rules_config_delete($rules_config) {
  // Delete all tasks scheduled for this config.
  db_delete('rules_scheduler')
    ->condition('config', $rules_config->name)
    ->execute();
}

/**
 * Implements hook_views_api().
 */
function rules_scheduler_views_api() {
  return array(
    'api' => '3.0-alpha1',
    'path' => drupal_get_path('module', 'rules_scheduler') .'/includes',
  );
}