<?php

/**
 * @file
 * Defines module hooks and logic.
 */

/**
 * Implements hook_menu().
 */
function guideme_menu() {
  return array(
    'guideme/mark-done/%' => array(
      'page callback' => 'guideme_ajax_mark_done',
      'page arguments' => array(2),
      'access callback' => 'guideme_access',
      'access arguments' => array(2),
      'type' => MENU_CALLBACK,
    ),
  );
}

/**
 * Implements hook_hook_info().
 */
function guideme_hook_info() {
  return array(
    'guideme_path' => array('group' => 'guideme'),
    'guideme_path_alter' => array('group' => 'guideme'),
  );
}

/**
 * Implements hook_permission().
 */
function guideme_permission() {
  $guide_paths = guideme_get_guide_paths();
  if (!empty($guide_paths)) {
    $permission = array();
    foreach ($guide_paths as $key => $value) {
      $permission["use $key guided path"] = array(
        'title' => t("Use the %path guided path", array('%path' => $key)),
        'description' => t("Allow a user to follow the %path guided step by step instructional path.", array('%path' => $key)),
      );
    }
    return $permission;
  }
}

/**
 * Implements hook_init().
 */
function guideme_init() {
  global $user;

  $map = guideme_get_map();
  $url = drupal_is_front_page() ? '<front>' : current_path();
  $guide_path_id = guidemap_fetch_appropriate_guide_path($map, $url);

  if (!empty($guide_path_id)) {
    if (user_access("use $guide_path_id guided path") && !guideme_has_user_completed_guide_path($user->uid, $guide_path_id)) {
      guideme_initialize_guide_path($guide_path_id, $url);
    }
  }
}

/**
 * Access callback: check if user has access to guide path.
 *
 * @param string $guide_path_id
 *
 * @return bool
 */
function guideme_access($guide_path_id) {
  return user_access("use $guide_path_id guided path");
}

/**
 * Page callback: AJAX, mark guide path as done.
 *
 * @param string $guide_path_id
 */
function guideme_ajax_mark_done($guide_path_id) {
  global $user;
  if ($_POST['token'] === $_SESSION['guideme']['token']) {
    guideme_user_completed_guide_path($user->uid, $guide_path_id);
    return '';
  }
  else {
    drupal_access_denied();
  }
}

/**
 * Helper function to get the registered guide paths.
 * Uses both static and persistent caching.
 *
 * @return array
 */
function guideme_get_guide_paths() {
  $guide_paths = &drupal_static(__FUNCTION__);
  
  if (!isset($guide_paths)) {
    $cache = cache_get('guideme:guide_paths');
    if ($cache) {
      $guide_paths = $cache->data;
    }
    else {
      $guide_paths = module_invoke_all('guideme_path');
      drupal_alter('guideme_path', $guide_paths);
      $guide_paths = guideme_add_defaults($guide_paths);

      cache_set('guideme:guide_paths', $guide_paths, 'cache', CACHE_TEMPORARY);
    }
  }
  
  return $guide_paths;
}

/**
 * Helper function to get a single guide path.
 *
 * @param string $guide_path_id
 *
 * @return array|null
 */
function guideme_get_guide_path($guide_path_id) {
  $guide_paths = guideme_get_guide_paths();
  return !empty($guide_paths[$guide_path_id]) ? $guide_paths[$guide_path_id] : NULL;
}

/**
 * Helper function to get the registered paths map.
 * Uses both static and persistent caching.
 *
 * @return array
 */
function guideme_get_map() {
  $map = &drupal_static(__FUNCTION__);
  
  if (!isset($map)) {
    $cache = cache_get('guideme:map');
    if ($cache) {
      $map = $cache->data;
    }
    else {
      $guide_paths = guideme_get_guide_paths();
      $map = guideme_map_guide_paths($guide_paths);
      cache_set('guideme:map', $map, 'cache', CACHE_TEMPORARY);
    }
  }
  
  return $map;
}

/**
 * Extract URI mapping from the registered paths for quick retreival and
 * to easily initiate a guide path.
 *
 * @param array $guide_paths
 *
 * @return array
 */
function guideme_map_guide_paths($guide_paths) {
  $map = array();

  // First, sort by weight.
  uasort($guide_paths, 'drupal_sort_weight');

  // Extract the URIs.
  foreach ($guide_paths as $key => $info) {
    $map[$key] = array_keys($info['steps']);
  }

  return $map;
}

/**
 * Set default values on guide paths that left out optional parameters,
 * like weight.
 *
 * @param array $guide_paths
 *
 * @return array
 */
function guideme_add_defaults($guide_paths) {
  foreach ($guide_paths as $key => $info) {
    if (!isset($info['weight'])) {
      $guide_paths[$key]['weight'] = 0;
    }
  }
  return $guide_paths;
}

/**
 * Check if the current path is registered for a guided path.
 *
 * @param array $map
 * @param string $current_path
 *
 * @return string|null
 */
function guidemap_fetch_appropriate_guide_path($map, $current_path) {
  foreach ($map as $key => $paths) {
    if (in_array($current_path, $paths)) {
      return $key;
    }
  }
}

/**
 * Check if user has completed the path.
 *
 * @param int $uid
 * @param string $guide_path
 *
 * @return bool
 */
function guideme_has_user_completed_guide_path($uid, $guide_path) {
  $result = db_select('guideme_user_completion', 'gc')
    ->fields('gc', array('uid'))
    ->condition('gc.uid', $uid)
    ->condition('gc.guide_path', $guide_path)
    ->execute();

  if (!empty($result)) {
    return !!$result->fetchField();
  }
  else {
    return FALSE;
  }
}

/**
 * Set user has completed the path.
 *
 * @param int $uid
 * @param string $guide_path
 */
function guideme_user_completed_guide_path($uid, $guide_path) {
  db_merge('guideme_user_completion')
    ->key(array('uid' => $uid, 'guide_path' => $guide_path))
    ->fields(array('uid' => $uid, 'guide_path' => $guide_path))
    ->execute();
}

/**
 * Initialize the guide path.
 *
 * @param string $guide_path
 * @param string $url
 */
function guideme_initialize_guide_path($guide_path_id, $url) {
  $guide_path = guideme_get_guide_path($guide_path_id);
  $page_steps = $guide_path['steps'][$url];

  $token = uniqid(TRUE);
  $_SESSION['guideme']['token'] = $token;

  guideme_add_assets();
  drupal_add_js(array('guideMe' => array(
    'id' => $guide_path_id,
    'steps' => $page_steps,
    'token' => $token,
  )), 'setting');
}

/**
 * Helper function to add all Guideme assets.
 */
function guideme_add_assets() {
  static $added = FALSE;
  if (!$added) {
    $path = drupal_get_path('module', 'guideme');
    drupal_add_js("$path/js/vendor/joyride/jquery.joyride-2.1.js");
    drupal_add_js("$path/js/guideme.js");
    drupal_add_css("$path/css/vendor/joyride/joyride-2.1.css");
    $added = TRUE;
  }
}