<?php
// $Id: notifications.module,v 1.6 2008-02-14 16:54:32 jareyero Exp $

/**
 * @file
 * Notifications module
 *
 * This is the base module of the notifications framework. It handles event processing, queueing,
 * message composition and sending.
 * 
 * Different subscriptions types are provided by plug-in modules implementing hook_notifications()
 * Most of the UI is implemented in notifications_ui module
 * The messaging framework is used for message delivery
 * Token module is used for token replacement in messages 
 * 
 * This is based on the previous subscriptions module
 * 
 * Development Seed, http://www.developmentseed.org, 2007 
 *
 */

/**
 * Implementation of hook_menu().
 */
function notifications_menu($may_cache) {
  global $user;  // we need the user to to build some urls

  if ($may_cache) {
    // Administration
    $items[] = array('path' => 'admin/notifications',
      'title' => t('Notifications'),
      'description' => t('Configure and manage notifications modules.'),
      'callback' => 'notifications_admin_overview_page',
      'access' => user_access('administer notifications'),
    );
    $items[] = array('path' => 'admin/notifications/status',
      'title' => t('Status'),
      'description' => t('Manage users notifications.'),
      'callback' => 'notifications_admin_status_page',
      'access' => user_access('administer notifications'),
    );
    $items[] = array('path' => 'admin/notifications/status/overview',
      'title' => t('Overview'),
      'description' => t('Subscriptions overview.'),
      'type' => MENU_DEFAULT_LOCAL_TASK,
      'weight' => -10,
    );
    $items[] = array('path' => 'admin/notifications/status/queue', 
      'title' => t('Queue'),
      'description' => t('Subscriptions queue.'),
      'callback' => 'notifications_admin_queue',
      'type' => MENU_LOCAL_TASK
    );
    
    // Site settings
    $items[] = array(
      'path' => 'admin/notifications/settings',
      'title' => t('Settings'),
      'description' => t('Site settings for user notifications.'),
      'callback' => 'drupal_get_form',
      'callback arguments' => 'notifications_settings_form',
      'access' => user_access('administer site configuration'),
    );
    $items[] = array(
      'path' => 'admin/notifications/settings/general',
      'title' => t('General'),
      'weight' => -10,
      'type' => MENU_DEFAULT_LOCAL_TASK,
    );
    // Subscribe links. For this items access will be checked later in the page
    $items[] = array(
      'path' => 'notifications/subscribe',
      'type' => MENU_CALLBACK,
      'callback' => 'notifications_page_subscribe',
      'access' => $user->uid,
    );
    // Unsubscribe links This page will need to work with anonymous users
    $items[] = array(
      'path' => 'notifications/unsubscribe',
      'type' => MENU_CALLBACK,
      'callback' => 'notifications_page_unsubscribe',
      'access' => TRUE,
    );
  }
  else {
    if (arg(0) == 'notifications' || arg(1) == 'notifications' || arg(2) == 'notifications') {
      include_once drupal_get_path('module', 'notifications') .'/notifications.admin.inc';
    }
    
    if ($user->uid && arg(0) == 'user' && is_numeric(arg(1)) && ($user->uid == arg(1) && user_access('maintain own subscriptions') || user_access('administer notifications'))) {
      $account = ($user->uid == arg(1)) ? $user : user_load(array('uid' => arg(1)));
      $items[] = array(
          'path' => 'user/'. $account->uid .'/notifications',
          'type' => MENU_LOCAL_TASK,
          'title' => t('Notifications'),
          'callback' => 'notifications_page_user_overview',
          'callback arguments' => array($account)
      );
      $items[] = array(
          'path' => 'user/'. $account->uid .'/notifications/overview',
          'type' => MENU_DEFAULT_LOCAL_TASK,
          'title' => t('Overview'),
          'weight' => -10,
      );
    }
  }
  return $items;
}

/**
 * Implementation of hook_perms()
 * 
 */
function notifications_perm() {
  return array_merge(array('administer notifications', 'maintain own subscriptions'));
}

/**
 * Implementation of hook_user().
 */
function notifications_user($type, $edit, &$user, $category = NULL) {
  switch ($type) {
    case 'form':
      if ((user_access('maintain own subscriptions') || user_access("admin users subscriptions")  )&& $category == 'account') {
        $form['notifications'] = array(
          '#type'        => 'fieldset',
          '#title'       => t('Notifications settings'),
          '#weight'      => 5,
          '#collapsible' => TRUE,
        );
        $form['notifications']['notifications_send_method'] = array(
          '#type' => 'select',
          '#title' => t('Default send method'),
          '#options' => _notifications_send_methods($user),
          '#default_value' => notifications_user_setting('send_method', $user),
        );
        $form['notifications']['notifications_send_interval'] = array(
          '#type' => 'select',
          '#title' => t('Default send interval'),
          '#options' => _notifications_send_intervals(),
          '#default_value' => notifications_user_setting('send_interval', $user),
        );      
        /*
        $form['notifications']['notifications_teaser'] = array(
          '#type'          => 'checkbox',
          '#title'         => t('Include teaser'),
          '#default_value' => isset($edit['notifications_teaser']) ? $edit['notifications_teaser'] : variable_get('notifications_teaser', 0),
          '#description'   => t('Checking this box adds an excerpt of the post to the subscription email.'),
        );
        */
        return $form;
      }
      break;
  }
}

/**
 * Gets a user setting, defaults to default system setting for each
 * 
 * @param $name
 *   Setting name
 * @param $account
 *   Optional user account, will default to current user
 * @param $default
 *   Optional default to return if this is not set
 */
function notifications_user_setting($name, $account = NULL, $default = NULL) {
  global $user;
  $account = $account ? $account : $user;
  $field = 'notifications_'.$name;
  if (isset($account->$field)) {
    return $account->$field;
  } else {
    return variable_get('notifications_default_'.$name, $default);
  }
}

/**
 * Process subscriptions events
 */
function notifications_event($event){
  global $user;
  // Fill in event with default values
  $event += array(
    'uid' => $user->uid,
    'load_args' => '',
    'created' => time(),
    'module' => 'notifications', // Module that triggered the event
    'type' => '', // Object/event type
    'action' => '', // Action that happened to the object
    'params' => array(), // Object parameters
  );
  $event = (object)$event;
  // Notify other modules we are about to trigger some subscriptions event
  // Modules can do cleanup operations or modify event properties
  notifications_module_invoke('event trigger', $event);
  // Store event
  notifications_event_save($event);
  // Queue subscriptions
  notifications_queue($event);
}

/**
 * Queue events for notifications
 *
 * @param $event
 *   Event array.
 */
function notifications_queue($event) {
  
  // Build query fields for this event type
  $query_args = notifications_module_info('query', 'event', $event->type, $event);
  $query['args'] = array($event->eid, $event->created, $event->type);
  foreach ($query_args as $query_params) {
    $query = notifications_query_build($query_params, $query);
  }
  
  // We throw in all the conditions and check the number of matching conditions
  // that must be equal to the subscription conditions number
  $sql = 'INSERT INTO {notifications_queue} (uid, sid, module, eid, send_interval, send_method, cron, created, conditions) '.
    'SELECT DISTINCT s.uid, s.sid, s.module, %d, s.send_interval, s.send_method, s.cron, %d, s.conditions '.
    'FROM {notifications} s INNER JOIN {notifications_fields} f ON s.sid = f.sid '.
    implode (' ', $query['join']).
    " WHERE s.status = 1 AND s.event_type = '%s' AND ((".implode(') OR (', $query['where']).'))'.
    ' GROUP BY s.uid, s.sid, s.module, s.conditions '. // May need more grouping here
    ' HAVING s.conditions = count(f.sid)';
  db_query($sql, $query['args']);

  // Modules can do cleanup operations or modify the queue
  notifications_module_invoke('event queued', $event);
  
  // Optional immediate sending.
  if (variable_get('notifications_send_immediate', 0)) {
    require_once drupal_get_path('module', 'notifications') .'/notifications.cron.inc';
    notifications_process_rows(array('cron' => 1, 'eid' => $event->eid, 'send_interval' => 0));
  }
}

/**
 * Query builder for subscriptions
 * 
 * @param $params
 *   Array of query conditions
 */
function notifications_query_build($params, $base = array()) {
  $query = $base + array('select' => array(), 'join' => array(), 'where' => array(), 'args' => array());
  foreach ($params as $name => $elements) {
      if ($name == 'fields') {
        foreach ($elements as $field => $value ) {
          $query['where'][] = "f.field = '%s' AND f.value = '%s'";
          $query['args'][] = $field;
          $query['args'][] = $value;
        }
      } elseif (is_array($elements)) {
        $query[$name] = array_merge($query[$name], $elements);
      } else {
        $query[$name][] = $elements;
      }
  }
  return $query;
}

/**
 * Stores new events
 * 
 * @param $event
 *   Event object
 * @ TODO: Avoid to and from array conversion
 */
function notifications_event_save(&$event) {
  $event = (array)$event;
  $event['eid'] = db_next_id('{notifications_event}_eid');
  db_query ("INSERT INTO {notifications_event} (eid, module, type, action, uid, created, params) VALUES (%d, '%s', '%s', '%s', %d, %d, '%s')",
    $event['eid'], $event['module'], $event['type'], $event['action'], $event['uid'],  $event['created'], serialize($event['params']));
  $event = (object)$event;
}

/**
 * Get subscription for a given user
 * 
 * @param $uid
 *   User id
 * @param $event_type
 *   Event type
 * @param $oid
 *   Object id for caching. I.e. for a node it will be nid
 * @param $object
 *   Object to check subscriptions to. I.e. $node
 * 
 * @return
 *   Array of subscriptions for this user and object indexed by sid 
 */
function notifications_user_get_subscriptions($uid, $event_type, $oid, $object = NULL, $refresh = FALSE) {
  static $subscriptions;

  if ($refresh || !isset($subscriptions[$uid][$event_type][$oid])){
    $subscriptions[$uid][$event_type][$oid] = array();
    $query_args = notifications_module_info('query', 'user', $event_type, $object);
    // Base query
    $query = array(
      'args' => array($uid, $event_type),
    );
    foreach ($query_args as $query_params) {
      $query = notifications_query_build($query_params, $query);
    }

    $sql = 'SELECT s.*, f.* FROM {notifications} s INNER JOIN {notifications_fields} f ON s.sid = f.sid '.
      implode(' ', $query['join']). 
      " WHERE s.uid = %d AND event_type = '%s' AND ((".implode(') OR (', $query['where']).'))';
    $result = db_query($sql, $query['args']);
    while ($sub = db_fetch_object($result)) {
      if (!isset($subscriptions[$uid][$event_type][$oid][$sub->sid])) {
        $subscriptions[$uid][$event_type][$oid][$sub->sid] = $sub;
      }
      $subscriptions[$uid][$event_type][$oid][$sub->sid]->fields[$sub->field] = $sub->value;
    }
  }

  return $subscriptions[$uid][$event_type][$oid];
}

/**
 * Update or create subscription
 * 
 * This function checks for duplicated subscriptions before saving.
 * If a similar subscription is found it will be updated.
 * If no subscription is found and it is new, the sid will be added into the object.
 * 
 * @param $subscription
 *   Subscription object or array
 */
function notifications_save_subscription(&$subscription) {
  global $user;
  $subscription = (object)$subscription;
  $subscription->conditions = count($subscription->fields);
  $account = $subscription->uid ? user_load(array('uid' => $subscription->uid)) : $user;
  // Default values for fields: send_interval, send_method, etc...
  foreach (_notifications_subscription_defaults($account) as $field => $value) {
    if (!isset($subscription->$field)) {
      $subscription->$field = $value;
    }
  }
  // If the send method is a pull method, do not mark for cron processing
  // We make the decission here to allow some flexibility in the future
  // like allowing mixed pull/push for the same sending method in the future 
  if (messaging_method_info('type', $subscriptions->send_method, 0) & MESSAGING_TYPE_PULL) {
    $subscription->cron = 0;
  } else {
    $subscription->cron = 1;
  }
  if ($subscription->sid) {
    $op = 'update';
    db_query("UPDATE {notifications} SET uid = %d, type = '%s', event_type = '%s', conditions = %d, send_interval = '%d', send_method = '%s', cron = %d, module = '%s', status = %d WHERE sid = %d", $subscription->uid, $subscription->type, $subscription->event_type, $subscription->conditions, $subscription->send_interval, $subscription->send_method, $subscription->cron, $subscription->module, $subscription->status, $subscription->sid);
    db_query("DELETE FROM {notifications_fields} WHERE sid = %d", $subscription->sid);
  } elseif ($duplicate = notifications_get_subscriptions(array('uid' => $subscription->uid, 'type' => $subscription->type, 'event_type' => $subscription->event_type, 'module' => $subscription->module), $subscription->fields)) {
    // We've found duplicates, resolve conflict updating first, deleting the rest
    $update = array_shift($duplicate);
    $update->send_interval = $subscription->send_interval;
    $uddate->send_method = $subscription->send_method;
    $subscription = $update;
    drupal_set_message(t('A duplicated subscription has been found and updated'));
    // If there are more, delete, keep the table clean
    while (array_shift($duplicate)) {
      notifications_delete_subscription($duplicate->sid);
    }
    return notifications_save_subscription($subscription);    
  } else {
    $op = 'insert';
    $subscription->sid = db_next_id('{notifications}_sid');
    db_query("INSERT INTO {notifications} (sid, uid, type, event_type, conditions, send_interval, send_method, cron, module, status) VALUES(%d, %d, '%s', '%s', %d, %d, '%s', %d, '%s', %d)", $subscription->sid, $subscription->uid, $subscription->type, $subscription->event_type, $subscription->conditions, $subscription->send_interval, $subscription->send_method, $subscription->cron, $subscription->module, $subscription->status);
  }
  foreach ($subscription->fields as $name => $value) {
    db_query("INSERT INTO {notifications_fields} (sid, field, value) VALUES(%d, '%s', '%s')", $subscription->sid, $name, $value);
  }
  notifications_module_invoke($op, $subscription);
}

/**
 * Get an individual subscription.
 *
 * @param $subs
 *   Either a subscription object or a subscription id (sid).
 * @param $refresh
 *   Force cache refresh
 * @return
 *   Subscriptions object.
 */
function notifications_load_subscription($subs, $refresh = FALSE) {
  static $cache = array();
  if (is_object($subs)) {
    $sid = $subs->sid;
    $subscription = $subs;
  } else {
    $sid = $subs;
  }
  if ($refresh || !array_key_exists($sid, $cache)) {
    if (!isset($subscription)) {
      $subscription = db_fetch_object(db_query("SELECT * FROM {notifications} WHERE sid = %d", $sid));
    }
    if ($subscription) {
      $subscription->fields = array();
      $result = db_query("SELECT * FROM {notifications_fields} WHERE sid = %d", $sid);
      while ($condition = db_fetch_object($result)) {
        $subscription->fields[$condition->field] = $condition->value;
      }
    }
    $cache[$sid] = $subscription;
  }
  return $cache[$sid];
}

/**
 * Delete subscription and clean up related data.
 * 
 * It also removes pending notifications related to that subscription 
 * 
 * @param $sid
 *   Id of subscriptin to delete
 */
function notifications_delete_subscription($sid) {
  foreach (array('notifications', 'notifications_fields', 'notifications_queue') as $table) {
    db_query("DELETE FROM {$table} WHERE sid = %d", $sid);
  }
}

/**
 * Delete multiple subscriptions and clean up related data.
 * 
 * It also removes pending notifications related to that subscription 
 * 
 * @param $conditions
 *   Array of multiple conditions to delete subscriptions
 */
function notifications_delete_subscriptions($conditions) {
  foreach ($conditions as $field => $value) {
    $where[] =  "$field = '%s'";
  }
  foreach (array('notifications_fields', 'notifications_queue') as $table) {
    db_query("DELETE FROM {$table} WHERE sid IN (SELECT sid FROM {notifications} WHERE ". implode(' AND ', $where) . ")", $conditions);
  }
  db_query("DELETE FROM {notifications} WHERE ". implode(' AND ', $where), $conditions);
}

/**
 * Get subscriptions that fit a set of conditions.
 *
 * @param $params
 *   Array of parameters for the query
 * @param $conditions
 *   Optional array of condition fields
 * @param $limit
 *   Whether to limit the result to subscriptions with exatly that condition fields
 * @param $key
 *   Optional key field to use as the array index. Will default to sid 
 * 
 * @return
 *   Array of subscriptions indexed by uid, module, field, value, author
 */
function notifications_get_subscriptions($params, $conditions = array(), $limit = TRUE, $key = 'sid') {
  // Build query
  $join = $where = array();
  if ($conditions) {
    if ($limit) {
      $params += array('conditions' => count($conditions));
    }
    $index = 0;
    foreach ($conditions as $name => $value) {
      $alias = "f$index";
      $join[] = "INNER JOIN {notifications_fields} $alias ON s.sid = $alias.sid ";
      $params["$alias.field"] = $name;
      if (!is_null($value)) {
        $params["$alias.value"] = $value;
      }
      $index++;
    }
  }  
  foreach ($params as $field => $value) {
    $name = strstr($field, '.') ? $field : 's.'.$field;
    $where[] = is_numeric($value) ? $name.' = %d' : "$name = '%s'";
  }
  
  $sql = 'SELECT * FROM {notifications} s '. implode(' ', $join) .
  $sql .= ' WHERE '.implode(' AND ', $where);
  
  $result = db_query($sql, $params);
  $subscriptions = array();
  while ($s = db_fetch_object($result)) {
    $subscriptions[$s->$key] = notifications_load_subscription($s);
  }
  return $subscriptions;
}

/**
 * Get info about subscription types
 *
 * @param $type
 *   String, the subscriptions type OPTIONAL
 * @param $field
 *   String, a specific field to retrieve info from OPTIONAL
 *
 * @return
 *   Information for a given field and type
 *   or information for a given field for all types
 */
function notifications_subscription_types($type = NULL, $field = NULL) {
  static $types;
  if (!isset($types)) {
    $types = notifications_module_info('subscription types');
  }
  
  if ($field && $type) {
    return isset($types[$type][$field]) ? $types[$type][$field] : NULL;
  }
  elseif ($field) {
    $return = array();
    foreach ($types as $id => $info) {
      $return[$id] = $info[$field];
    }
    return $return;
  }
  elseif ($type) {
    return isset($types[$type]) ? $types[$type] : array();
  }
  else {
    return $types;
  }
}

/**
 * Invokes hook_notifications() with a single parameter or more but not needing
 * an object to be passed as reference.
 */
function notifications_module_info($op, $arg0 = NULL, $arg1 = NULL, $arg2 = NULL) {
  $object = NULL;
  return notifications_module_invoke($op, $arg0, $arg1, $arg2);
}

/**
 * Invokes hook_notifications() in every module.
 *
 * We cannot use module_invoke() for this, because the arguments need to
 * be passed by reference.
 */
function notifications_module_invoke($op, &$arg0, $arg1 = NULL, $arg2 = NULL) {
  $result = array();
  foreach (module_implements('notifications') as $module) {
    $function = $module .'_notifications';
    if ($return = $function($op, $arg0, $arg1, $arg2)) {
      $result = array_merge($result, $return);
    }
  }
  return $result;
}

/**
 * Implementation of hook_messaging()
 */
function notifications_messaging($op, $arg1 = NULL, $arg2 = NULL, $arg3 = NULL, $arg4 = NULL) {
  switch ($op) {
    case 'message groups':
      // Generic notifications event
      $info['notifications-event'] = array(
        'module' => 'notifications',
        'name' => t('Notifications event'),
      );
      $info['notifications-digest'] = array(
        'module' => 'notifications',
        'name' => t('Notifications digest'),
      );
      return $info;
    case 'message keys':      
      $type = $arg1;
      switch ($type) {
        case 'notifications-event':
          // Event notifications
          return array(
            'subject' => t('Subject for event notifications'),
            'header' => t('Body header for event notifications'),
            'main' => t('Body for event notifications'),
            'footer' => t('Body footer for event notifications'),
          );
        case 'notifications-digest':
          return array(
            'subject' => t('Subject for digested notifications'),
            'header' =>  t('Header for digested notifications'),
            'main' => t('Line for digested events'),
            'footer' => t('Footer for digested notifications'),
          );
      }
      break;
    case 'messages':
      $type = $arg1;
      // Event notifications
      if ($type == 'notifications-event') {
        return array(
          'subject' => t('Event notification for [user] from [site-name]'),
          'header' => t("Greetings [user],"),
          'main' => t("A item to which you are subscribed has been updated"),
          'footer' => array(
              t('This is an automatic message from [site-name]'),
              t('To manage your subscriptions, browse to [subscriptions-manage]'),
              t('You can unsubscribe at [unsubscribe-url]'),
          ),
        );
      }
      // Digested messages
      if ($type == 'notifications-digest') {
        return array(
          'subject' => t('[site-name] subscription update for [user]'),
          'header' => t("Greetings, [user].\n\nThese are your messages"),
          'main' => t("A [type] has been updated: [title]\n\n[event_list]"),
          'footer' => array(
            t('This is an automatic message from [site-name])'),
            t('To manage your subscriptions, browse to [subscriptions-manage]'),
          ),        
        );
      }
      break;
    case 'tokens':
      $type = explode('-', $arg1);
      $tokens = array();
      // These are the token groups that will be used for this module's messages
      if ($type[0] == 'notifications' ) {
        $tokens = array('global', 'subscription', 'user');
        if($type[1] == 'event') {
          $tokens[] = 'event';
        }
      }
      return $tokens;
    case 'pull':
      require_once drupal_get_path('module', 'notifications') .'/notifications.cron.inc';
      return notifications_process_pull($arg1, $arg2, $arg3, $arg4);      
  }
}

/**
 * Implementation of hook_token_values()
 * 
 * @ TODO: Work out event tokens
 */
function notifications_token_values($type, $object = NULL, $options = array()) {
  switch ($type) {
    case 'subscription':
      $values = array();
      if ($subscription = $object) {
        $link = notifications_get_link('unsubscribe', array('sid' => $subscription->sid, 'signed' => TRUE, 'destination' => FALSE));
        $values['unsubscribe-url'] = url($link['href'], $link['query'], NULL, TRUE);      
      }
      return $values;
    case 'user':
      if ($account = $object) {
        return array(
          'subscriptions-manage' => $account->uid ? url("user/$account->uid/notifications", NULL, NULL, TRUE) : '',
        );
      }
  }
}

/**
 * Implementation of hook_token_list(). Documents the individual
 * tokens handled by the module.
 */
function notifications_token_list($type = 'all') {
  $tokens = array();
  if ($type == 'user' || $type == 'all') {
    $tokens['user']['subscriptions-manage']    = t('The url for the current user to manage subscriptions.');
  }
  if ($type == 'subscription' || $type == 'all') {
    $tokens['subscription']['unsubscribe-url']      = t('The url for disabling a specific subscription.');
  }
  if ($type == 'event' || $type == 'all') {
    $tokens['event']['event-list'] = t('List of events for message digests');
    $tokens['event']['event-detail'] = t('Detailed information for event');
  }
  return $tokens;
}

/**
 * Get event types
 */
function notifications_event_types($type = NULL, $action = NULL) {
  static $info;
  if (!$info) {
    $types = notifications_module_info('event types');
    foreach ($types as $type_info) {
      $info[$type_info['type']][$type_info['action']] = $type_info;
    }
    
  }
  if ($action) {
    return isset($info[$type][$action]) ? $info[$type][$action] : array();
  } elseif ($type) {
    return isset($info[$type]) ? $info[$type] : array();
  } else {
    return $info;
  }
}

/**
 * Implementation of hook_cron()
 */
function notifications_cron() {
  include_once drupal_get_path('module', 'notifications') .'/notifications.cron.inc';
  notifications_process_run();
}

/**
 * Return url for subscriptions
 */
function notifications_get_link($type, $params) {
  global $user;
  $params += array(
    'uid' => $user->uid,
    'confirm' => TRUE,
    'signed' => FALSE,
    'destination' => $_GET['q'],
  );
  switch ($type) {
    case 'subscribe':
      $elements = array(
        'subscribe',
        $params['uid'],
        $params['type'],
        implode(',', array_keys($params['fields'])),
        implode(',', $params['fields'])
      );
      break;
    case 'unsubscribe':
      $elements = array(
        'unsubscribe',
        $params['sid']        
      );
      break;
  }
  // Build query string
  $query = array();
  if ($params['destination']) {
    $query[] = 'destination='.$params['destination'];
  }
  if ($params['confirm']) {
    $query[] = 'confirm=1';
  }
  if ($params['signed']) {
    $query[] = 'signature='._notifications_signature($elements);
  }
  return array(
    'href' => 'notifications/'.implode('/', $elements),
    'query' => implode('&', $query),
  );
}

/**
 * Check access to objects
 * 
 * This will check permissions for subscriptions and events before subscribing
 * and before getting updates.
 * 
 * @param $type
 *   Type of object to check for access. Possible values:
 *   - 'event', will check access to event objects
 *   - 'subscription', will check access to subscribed objects
 */
function notifications_user_allowed($type, $account, $object = NULL) {

  // Invoke notifications hook and check for a FALSE return value
  
  $permissions = notifications_module_info('access', $type, $account, $object);

  if ($permissions) {
    return !in_array(FALSE, $permissions);
  } else {
    // If no module has anthing to say about access I guess it will be true
    return TRUE;
  }
}

/**
 * Implementation of notifications_hook()
 * 
 * Check access permissions to subscriptions
 */
function notifications_notifications($op, &$arg0, $arg1 = NULL, $arg2 = NULL) {
  switch ($op) {
    case 'access':
      if ($arg0 == 'subscription') {
        $account = $arg1;
        $subscription = $arg2;
        // First we check valid subscription type
        $access = FALSE;
        if ($subscription->type && ($info = notifications_subscription_types($subscription->type))) {
          // To allow mixed subscription types to work we dont have a fixed field list
          // Then check specific access to this type. Each type must have a permission
          if (!empty($info['access callback'])) {
            $access = call_user_func($info['access callback'], $account, $subscription);
          } elseif (!empty($info['access']) && user_access($info['access'], $account)|| user_access('administer notifications', $account)) {
           // Check matching fields
            if (!array_diff($info['fields'], array_keys($subscription->fields))) {
              $access = TRUE;
            }
          }
        }
        return array($access);
      }
  }
}

/**
 * List of send intervals
 */
function _notifications_send_intervals() {
  return variable_get('notifications_send_intervals',
    array(
      -1 => t('Never'),
      0 => t('As soon as possible'),
      900 => t('Every 15 minutes'),
      3600 => t('Hourly'),
      10800 => t('Every three hours'),
      86400 => t('Daily'),
    )
  );
}

/**
 * List of send methods
 */
function _notifications_send_methods($account = NULL) {
  return variable_get('notifications_send_methods', messaging_method_list($account));
}

/**
 * Signature for url parameters
 */
function _notifications_signature($params) {
  return md5('notifications:'.drupal_get_private_key().':'.implode(':', $params));
}

/**
 * Default values for subscription
 */
function _notifications_subscription_defaults($account = NULL) {
  return array(
    'send_interval' => notifications_user_setting('send_interval', $account, 0),
    'send_method' => notifications_user_setting('send_method', $account, ''),
    'module' => 'notifications',
    'status' => 1,
  ); 
}

/**
 * Implementation of hook_simpletest().
 */
function notifications_simpletest() {
  $dir = drupal_get_path('module', 'notifications'). DIRECTORY_SEPARATOR . 'tests';
  $tests = file_scan_directory($dir, '\.test');
  return array_keys($tests);
}