<?php

/**
 * @file
 * The Flag module.
 */

define('FLAG_API_VERSION', 3);

define('FLAG_ADMIN_PATH', 'admin/structure/flags');
define('FLAG_ADMIN_PATH_START', 3);

/**
 * Implements hook_entity_info().
 */
function flag_entity_info() {
  $return = array(
    'flagging' => array(
      'label' => t('Flagging'),
      'controller class' => 'FlaggingController',
      'base table' => 'flagging',
      'fieldable' => TRUE,
      'entity keys' => array(
        'id' => 'flagging_id',
        'bundle' => 'flag_name',
      ),
      // The following tells Field UI how to extract the bundle name from a
      // $flag object when we're visiting ?q=admin/.../manage/%flag/fields.
      'bundle keys' => array(
        'bundle' => 'name',
      ),
      'bundles' => array(),
      // The following tells EntityAPI how to save flaggings, thus allowing use
      // of Entity metadata wrappers (if present).
      'save callback' => 'flagging_save',
      'creation callback' => 'flagging_create',
    ),
  );

  // Add bundle info but bypass flag_get_flags() as we cannot use it here, as
  // it calls entity_get_info().
  $result = db_query("SELECT name, title FROM {flag}");
  $flag_names = $result->fetchAllKeyed();
  foreach ($flag_names as $flag_name => $flag_title) {
    $return['flagging']['bundles'][$flag_name] = array(
      'label' => $flag_title,
      'admin' => array(
        'path' => FLAG_ADMIN_PATH . '/manage/%flag',
        'real path' => FLAG_ADMIN_PATH . '/manage/' . $flag_name,
        'bundle argument' => FLAG_ADMIN_PATH_START + 1,
        'access arguments' => array('administer flags'),
      ),
    );
  }

  return $return;
}

/**
 * Loads a flagging entity.
 *
 * @param $flagging_id
 *   The 'flagging_id' database serial column.
 * @param $reset
 *   Whether to reset the DrupalDefaultEntityController cache.
 *
 * @return
 *   The entity object, or FALSE if it can't be found.
 */
function flagging_load($flagging_id, $reset = FALSE) {
  // The flag machine name is loaded in by FlaggingController::buildQuery().
  $result = entity_load('flagging', array($flagging_id), array(), $reset);
  return reset($result);
}

/**
 * Entity API creation callback.
 *
 * Creates an unsaved flagging object for use with $flag->flag().
 *
 * @param $values
 *   An array of values as described by the entity's property info. Only
 *   'flag_name' or 'fid' must be specified, since $flag->flag() does the rest.
 *
 * @return
 *   An unsaved flagging object containing the property values.
 */
function flagging_create($values = array()) {
  $flagging = (object) array();

  if (!isset($values['flag_name'])) {
    if (isset($values['fid'])) {
      // Add flag_name, determined from fid.
      $flag = flag_get_flag(NULL, $values['fid']);
      $values['flag_name'] = $flag->name;
    }
  }

  // Apply the given values.
  foreach ($values as $key => $value) {
    $flagging->$key = $value;
  }

  return $flagging;
}

/**
 * Saves a flagging entity.
 *
 * For a new flagging, throws an exception is the flag action is not allowed for
 * the given combination of flag, entity, and user.
 *
 * @param $flagging
 *   The flagging entity. This may have either flag_name or the flag fid set,
 *   and may also omit the uid property to use the current user.
 *
 * @throws Exception
 */
function flagging_save($flagging) {
  // Get the flag, either way.
  if (isset($flagging->flag_name)) {
    $flag = flag_get_flag($flagging->flag_name);
  }
  else {
    $flag = flag_get_flag(NULL, $flagging->fid);
  }

  if (!$flag) {
    throw new Exception('Flag not found for flagging entity.');
  }

  // Fill in properties that may be omitted.
  $flagging->fid = $flag->fid;
  $flagging->flag_name = $flag->name;

  if (!empty($flagging->uid)) {
    $account = user_load($flagging->uid);
  }
  else {
    $account = NULL;
  }

  $result = $flag->flag('flag', $flagging->entity_id, $account, FALSE, $flagging);

  if (!$result) {
    throw new Exception('Flag action not allowed for given flagging entity properties.');
  }
}

// @todo: Implement flagging_view(). Not extremely useful. I already have it.

// @todo: When renaming a flag: Call field_attach_rename_bundle().

// @todo: When creating a flag: Call field_attach_create_bundle().

// @todo: When deleting a flag: Call field_attach_delete_bundle().

// @tood: Discuss: Should flag deleting call flag_reset_flag()? No.

// @todo: flag_reset_flag():
// - it should delete the flaggings.
// - (it has other issues; see http://drupal.org/node/894992.)
// - (is problematic: it might not be possible to delete all data in a single
//   page request.)

// @todo: Discuss: Note that almost all functions/identifiers dealing with
// flaggings *aren't* prefixed by "flag_". For example:
// - The menu argument is %flagging, not %flag_flagging.
// - The entity type is "flagging", not "flag_flagging".
// On the one hand this succinct version is readable and nice. On the other
// hand, it isn't very "correct".

/**
 * Implements hook_entity_query_alter().
 *
 * Replaces bundle condition in EntityFieldQuery on flagging entities
 * with query condition on [name] field in [flag] table.
 *
 * @see flag_query_flagging_flag_names_alter()
 */
function flag_entity_query_alter(EntityFieldQuery $query) {
  $conditions = &$query->entityConditions;

  // Alter only flagging queries with bundle conditions.
  if (isset($conditions['entity_type']) && $conditions['entity_type']['value'] == 'flagging' && isset($conditions['bundle'])) {
    // Add tag to alter query.
    $query->addTag('flagging_flag_names');
    // Make value and operator of the bundle condition accessible
    // in hook_query_TAG_alter.
    $query->addMetaData('flag_name_value', $conditions['bundle']['value']);
    $query->addMetaData('flag_name_operator', $conditions['bundle']['operator']);
    unset($conditions['bundle']);
  }
}

/**
 * Implements hook_query_TAG_alter() for flagging_flag_names tag.
 *
 * @see flag_entity_query_alter()
 */
function flag_query_flagging_flag_names_alter(QueryAlterableInterface $query) {
  // Get value and operator for bundle condition from meta data.
  $value = $query->getMetaData('flag_name_value');
  $operator = $query->getMetaData('flag_name_operator');
  // Join [flag] and [flagging] tables by [fid] and
  // apply bundle condition on [flag].[name] field.
  $query->join('flag', 'f', 'flagging.fid = f.fid');
  $query->condition('f.name', $value, $operator);
}

/**
 * Implements hook_menu().
 */
function flag_menu() {
  $items[FLAG_ADMIN_PATH] = array(
    'title' => 'Flags',
    'page callback' => 'flag_admin_page',
    'access callback' => 'user_access',
    'access arguments' => array('administer flags'),
    'description' => 'Configure flags for marking content with arbitrary information (such as <em>offensive</em> or <em>bookmarked</em>).',
    'file' => 'includes/flag.admin.inc',
    'type' => MENU_NORMAL_ITEM,
  );
  $items[FLAG_ADMIN_PATH . '/list'] = array(
    'title' => 'List',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  );
  $items[FLAG_ADMIN_PATH . '/add'] = array(
    'title' => 'Add flag',
    'page callback' => 'flag_add_page',
    'access callback' => 'user_access',
    'access arguments' => array('administer flags'),
    'file' => 'includes/flag.admin.inc',
    'type' => MENU_LOCAL_ACTION,
    'weight' => 1,
  );
  $items[FLAG_ADMIN_PATH . '/import'] = array(
    'title' => 'Import',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('flag_import_form'),
    'access arguments' => array('use flag import'),
    'file' => 'includes/flag.export.inc',
    'type' => MENU_LOCAL_TASK,
    'weight' => 2,
  );
  $items[FLAG_ADMIN_PATH . '/export'] = array(
    'title' => 'Export',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('flag_export_form'),
    'access arguments' => array('administer flags'),
    'file' => 'includes/flag.export.inc',
    'type' => MENU_LOCAL_TASK,
    'weight' => 3,
  );

  $items[FLAG_ADMIN_PATH . '/manage/%flag'] = array(
    // Allow for disabled flags.
    'load arguments' => array(TRUE),
    'page callback' => 'drupal_get_form',
    'page arguments' => array('flag_form', FLAG_ADMIN_PATH_START + 1),
    'access callback' => 'user_access',
    'access arguments' => array('administer flags'),
    'file' => 'includes/flag.admin.inc',
    'type' => MENU_CALLBACK,
    // Make the flag title the default title for descendant menu items.
    'title callback' => '_flag_menu_title',
    'title arguments' => array(FLAG_ADMIN_PATH_START + 1),
  );
  $items[FLAG_ADMIN_PATH . '/manage/%flag/edit'] = array(
    // Allow for disabled flags.
    'load arguments' => array(TRUE),
    'title' => 'Edit flag',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  );
  $items[FLAG_ADMIN_PATH . '/manage/%flag/export'] = array(
    'title' => 'Export',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('flag_export_form', FLAG_ADMIN_PATH_START + 1),
    'access arguments' => array('administer flags'),
    'file' => 'includes/flag.export.inc',
    'type' => MENU_LOCAL_TASK,
    'weight' => 20,
  );
  $items[FLAG_ADMIN_PATH . '/manage/%flag/delete'] = array(
    'title' => 'Delete flag',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('flag_delete_confirm', FLAG_ADMIN_PATH_START + 1),
    'access callback' => 'user_access',
    'access arguments' => array('administer flags'),
    'file' => 'includes/flag.admin.inc',
    'type' => MENU_CALLBACK,
  );
  $items[FLAG_ADMIN_PATH . '/manage/%flag/update'] = array(
    // Allow for disabled flags.
    'load arguments' => array(TRUE),
    'title' => 'Update',
    'page callback' => 'flag_update_page',
    'page arguments' => array(FLAG_ADMIN_PATH_START + 1),
    'access arguments' => array('administer flags'),
    'file' => 'includes/flag.export.inc',
    'type' => MENU_CALLBACK,
  );

  $items['flag/%/%flag/%'] = array(
    'title' => 'Flag',
    'page callback' => 'flag_page',
    'page arguments' => array(1, 2, 3),
    'access callback' => 'user_access',
    'access arguments' => array('access content'),
    'file' => 'includes/flag.pages.inc',
    'type' => MENU_CALLBACK,
  );
  $items['flag/confirm/%/%flag/%'] = array(
    'title' => 'Flag confirm',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('flag_confirm', 2, 3, 4),
    'access callback' => 'user_access',
    'access arguments' => array('access content'),
    'file' => 'includes/flag.pages.inc',
    'type' => MENU_CALLBACK,
  );

  return $items;
}

/**
 * Implements hook_admin_menu_map().
 */
function flag_admin_menu_map() {
  if (!user_access('administer flags')) {
    return;
  }

  $map = array();
  $map[FLAG_ADMIN_PATH . '/manage/%flag'] = array(
    'parent' => FLAG_ADMIN_PATH,
    'arguments' => array(
      array(
        '%flag' => array_keys(flag_get_flags()),
      ),
    ),
  );

  if (module_exists('field_ui')) {
    foreach (entity_get_info() as $obj_type => $info) {
      if ($obj_type == 'flagging') {
        foreach ($info['bundles'] as $bundle_name => $bundle_info) {
          if (isset($bundle_info['admin'])) {
            $fields = array();

            foreach (field_info_instances($obj_type, $bundle_name) as $field) {
              $fields[] = $field['field_name'];
            }

            $arguments = array(
              '%flag' => array($bundle_name),
              '%field_ui_menu' => $fields,
            );

            $path = $bundle_info['admin']['path'];
            $map["$path/fields/%field_ui_menu"]['parent'] = "$path/fields";
            $map["$path/fields/%field_ui_menu"]['arguments'][] = $arguments;
          }
        }
      }
    }
  }

  return $map;
}

/**
 * Menu loader for '%flag' arguments.
 *
 * @param $flag_name
 *   The machine name of the flag.
 * @param $include_disabled
 *   (optional) Whether to return a disabled flag too. Normally only enabled
 *   flags are returned. Some menu items operate on disabled flags and in this
 *   case you need to turn on this switch by doing:
 *   @code
 *   'load arguments' => array(TRUE)
 *   @endcode
 *   in your hook_menu().
 *
 * @return
 *   Either the flag object, or FALSE if none was found.
 */
function flag_load($flag_name, $include_disabled = FALSE) {
  if (($flag = flag_get_flag($flag_name))) {
    return $flag;
  }
  else {
    // No enabled flag was found. Search among the disabled ones.
    if ($include_disabled) {
      $default_flags = flag_get_default_flags(TRUE);
      if (isset($default_flags[$flag_name])) {
        return $default_flags[$flag_name];
      }
    }
  }
  // A menu loader has to return FALSE (not NULL) when no object is found.
  return FALSE;
}

/**
 * Menu title callback.
 */
function _flag_menu_title($flag) {
  // The following conditional it to handle a D7 bug (@todo: link).
  return $flag ? $flag->get_title() : '';
}

/**
 * Implements hook_help().
 */
function flag_help($path, $arg) {
  switch ($path) {
    case FLAG_ADMIN_PATH:
      $output = '<p>' . t('This page lists all the <em>flags</em> that are currently defined on this system.') . '</p>';
      return $output;

    case FLAG_ADMIN_PATH . '/add':
      $output = '<p>' . t('Select the type of flag to create. An individual flag can only affect one type of object. This cannot be changed once the flag is created.') . '</p>';
      return $output;

    case FLAG_ADMIN_PATH . '/manage/%/fields':
      // Get the existing link types that provide a flagging form.
      $link_types = flag_get_link_types();
      $form_link_types = array();
      foreach (flag_get_link_types() as $link_type) {
        if ($link_type['provides form']) {
          $form_link_types[] = '<em>' . $link_type['title'] . '</em>';
        }
      }

      // Get the flag for which we're managing fields.
      $flag = menu_get_object('flag', FLAG_ADMIN_PATH_START + 1);

      // Common text.
      $output  = '<p>' . t('Flags can have fields added to them. For example, a "Spam" flag could have a <em>Reason</em> field where a user could type in why he believes the item flagged is spam. A "Bookmarks" flag could have a <em>Folder</em> field into which a user could arrange her bookmarks.') . '</p>';
      $output .= '<p>' . t('On this page you can add fields to flags, delete them, and otherwise manage them.') . '</p>';

      // Three cases:
      if ($flag->link_type == 'form') {
        // Case 1: the current link type is the flagging form. Don't tell the
        // user anything extra, all is fine.
      }
      elseif ($link_types[$flag->link_type]['provides form']) {
        // Case 2: the current link type shows the form for creation of the
        // flagging, but it not the flagging form. Tell the user they can't edit
        // existing flagging fields.
        $output .= t("Field values may be edited when flaggings are created because this flag's link type shows a form for the flagging. However, to edit field values on existing flaggings, you will need to set your flag to use the <em>Flagging form</em> link type. This is provided by the <em><a href='!flagging-form-url'>Flagging Form</a></em> module.", array(
          '!flagging-form-url' => 'http://drupal.org/project/flagging_form',
        ));
        if (!module_exists('flagging_form')) {
          $output .= ' <span class="warning">'
            . t("You do not currently have this module enabled.")
            . '</span>';
        }
        $output .= '</p>';
      }
      else {
        // Case 3: the current link type does not allow access to the flagging
        // form. Tell the user they should change it.
        $output .= '<p class="warning">' . t("To allow users to enter values for fields you will need to <a href='!form-link-type-url'>set your flag</a> to use one of the following link types which allow users to access the flagging form: !link-types-list. (In case a form isn't used, the fields are assigned their default values.)", array(
          '!form-link-type-url' => url('admin/structure/flags/manage/' . $flag->name, array('fragment' => 'edit-link-type')),
          // The list of labels from link types. These are all defined in code
          // in hook_flag_link_type_info() and therefore safe to output raw.
          '!link-types-list' => implode(', ', $form_link_types),
        )) . '</p>';
        $output .= '<p>' . t("Additionally, to edit field values on existing flaggings, you will need to set your flag to use the Flagging form link type. This is provided by the <em><a href='!flagging-form-url'>Flagging Form</a></em> module.", array(
          '!flagging-form-url' => 'http://drupal.org/project/flagging_form',
        ));
        if (!module_exists('flagging_form')) {
          $output .= ' <span class="warning">'
            . t("You do not currently have this module enabled.")
            . '</span>';
        }
        $output .= '</p>';
      }

      return $output;
  }
}

/**
 * Implements hook_init().
 */
function flag_init() {
  module_load_include('inc', 'flag', 'includes/flag.actions');
}

/**
 * Implements hook_hook_info().
 */
function flag_hook_info() {
  $hooks['flag_type_info'] = array(
    'group' => 'flag',
  );
  $hooks['flag_type_info_alter'] = array(
    'group' => 'flag',
  );
  $hooks['flag_link_type_info'] = array(
    'group' => 'flag',
  );
  $hooks['flag_link_type_info_alter'] = array(
    'group' => 'flag',
  );
  return $hooks;
}

/**
 * Get a flag type definition.
 *
 * @param $entity_type
 *   (optional) The entity type to get the definition for, or NULL to return
 *   all flag types.
 *
 * @return
 *   The flag type definition array.
 *
 * @see hook_flag_type_info()
 */
function flag_fetch_definition($entity_type = NULL) {
  $definitions = &drupal_static(__FUNCTION__);
  if (!isset($definitions)) {
    if ($cache = cache_get('flag_type_info')) {
      $definitions = $cache->data;
    }
    else {
      $definitions = module_invoke_all('flag_type_info');
      drupal_alter('flag_type_info', $definitions);

      cache_set('flag_type_info', $definitions);
    }
  }

  if (isset($entity_type)) {
    if (isset($definitions[$entity_type])) {
      return $definitions[$entity_type];
    }
  }
  else {
    return $definitions;
  }
}

/**
 * Returns all flag types defined on the system.
 *
 * @return
 *   An array of flag type names.
 */
function flag_get_types() {
  $types = &drupal_static(__FUNCTION__);
  if (!isset($types)) {
    $types = array_keys(flag_fetch_definition());
  }
  return $types;
}

/**
 * Instantiates a new flag handler.
 *
 * A flag handler is more commonly know as "a flag". A factory method usually
 * populates this empty flag with settings loaded from the database.
 *
 * @param $entity_type
 *  The entity type to create a flag handler for. This may be FALSE if the
 *  entity type property could not be found in the flag configuration data.
 *
 * @return
 *  A flag handler object. This may be the special class flag_broken is there is
 *  a problem with the flag.
 */
function flag_create_handler($entity_type) {
  $definition = flag_fetch_definition($entity_type);
  if (isset($definition) && class_exists($definition['handler'])) {
    $handler = new $definition['handler']();
  }
  else {
    $handler = new flag_broken();
  }
  $handler->entity_type = $entity_type;
  $handler->construct();
  return $handler;
}

/**
 * Implements hook_permission().
 */
function flag_permission() {
  $permissions = array(
    'administer flags' => array(
      'title' => t('Administer flags'),
      'description' => t('Create and edit site-wide flags.'),
    ),
    'use flag import' => array(
      'title' => t('Use flag importer'),
      'description' => t('Access the flag import functionality.'),
      'restrict access' => TRUE,
    ),
  );

  // Reset static cache to ensure all flag permissions are available.
  drupal_static_reset('flag_get_flags');
  $flags = flag_get_flags();
  // Provide flag and unflag permissions for each flag.
  foreach ($flags as $flag_name => $flag) {
    $permissions += $flag->get_permissions();
  }

  return $permissions;
}

/**
 * Implements hook_form_FORM_ID_alter(): user_admin_permissions.
 *
 * Disable permission on the permissions form that don't make sense for
 * anonymous users when Session API module is not enabled.
 */
function flag_form_user_admin_permissions_alter(&$form, &$form_state, $form_id) {
  if (!module_exists('session_api')) {
    $flags = flag_get_flags();
    // Disable flag and unflag permission checkboxes for anonymous users.
    foreach ($flags as $flag_name => $flag) {
      $form['checkboxes'][DRUPAL_ANONYMOUS_RID]["flag $flag_name"]['#disabled'] = TRUE;
      $form['checkboxes'][DRUPAL_ANONYMOUS_RID]["unflag $flag_name"]['#disabled'] = TRUE;
    }
  }
}

/**
 * Implements hook_flag_link().
 */
function flag_flag_link($flag, $action, $entity_id) {
  $token = flag_get_token($entity_id);
  return array(
    'href' => 'flag/' . ($flag->link_type == 'confirm' ? 'confirm/' : '') . "$action/$flag->name/$entity_id",
    'query' => drupal_get_destination() + ($flag->link_type == 'confirm' ? array() : array('token' => $token)),
  );
}

/**
 * Implements hook_field_extra_fields().
 */
function flag_field_extra_fields() {
  $extra = array();

  $flags = flag_get_flags();
  foreach ($flags as $name => $flag) {
    // Skip flags that aren't on entities.
    if (!($flag instanceof flag_entity)) {
      continue;
    }

    $applicable_bundles = $flag->types;
    // If the list of bundles is empty, it indicates all bundles apply.
    if (empty($applicable_bundles)) {
      $entity_info = entity_get_info($flag->entity_type);
      $applicable_bundles = array_keys($entity_info['bundles']);
    }

    foreach ($applicable_bundles as $bundle_name) {
      if ($flag->show_on_form) {
        $extra[$flag->entity_type][$bundle_name]['form']['flag'] = array(
          'label' => t('Flags'),
          'description' => t('Checkboxes for toggling flags'),
          'weight' => 10,
        );
      }

      if ($flag->show_as_field) {
        $extra[$flag->entity_type][$bundle_name]['display']['flag_' . $name] = array(
          // It would be nicer to use % as the placeholder, but the label is
          // run through check_plain() by field_ui_display_overview_form()
          // (arguably incorrectly; see http://drupal.org/node/1991292).
          'label' => t('Flag: @title', array(
            '@title' => $flag->title,
          )),
          'description' => t('Individual flag link'),
          'weight' => 10,
        );
      }
    }
  }

  return $extra;
}

/**
 * Implements hook_form_FORM_ID_alter(): node_type_form.
 */
function flag_form_node_type_form_alter(&$form, &$form_state, $form_id) {
  global $user;
  $flags = flag_get_flags('node', $form['#node_type']->type, $user);
  foreach ($flags as $flag) {
    if ($flag->show_on_form) {
      // To be able to process node tokens in flag labels, we create a fake
      // node and store it in the flag's cache for replace_tokens() to find,
      // with a fake ID.
      $flag->remember_entity('fake', (object) array(
        'nid' => NULL,
        'type' => $form['#node_type']->type,
        'title' => '',
      ));
      $var = 'flag_' . $flag->name . '_default';
      $form['workflow']['flag'][$var] = array(
        '#type' => 'checkbox',
        '#title' => $flag->get_label('flag_short', 'fake'),
        '#default_value' => variable_get($var . '_' . $form['#node_type']->type, 0),
        '#return_value' => 1,
      );
    }
  }

  if (isset($form['workflow']['flag'])) {
    $form['workflow']['flag'] += array(
      '#type' => 'item',
      '#title' => t('Default flags'),
      '#description' => t('Above are the <a href="@flag-url">flags</a> you elected to show on the node editing form. You may specify their initial state here.', array('@flag-url' => url(FLAG_ADMIN_PATH))),
      // Make the spacing a bit more compact:
      '#prefix' => '<div class="form-checkboxes">',
      '#suffix' => '</div>',
    );
  }
}

/**
 * Implements hook_field_attach_form().
 *
 * Handles the 'show_on_form' flag option.
 *
 * Warning: will not work on entity types that are not fieldable, as this relies
 * on a field module hook.
 *
 * @see flag_field_attach_submit()
 */
function flag_field_attach_form($entity_type, $entity, &$form, &$form_state, $langcode) {
  list($id) = entity_extract_ids($entity_type, $entity);
  // Some modules are being stupid here. Commerce!
  if (empty($id)) {
    $id = NULL;
  }

  // Keep track of whether the entity is new or not, as we're about to fiddle
  // with the entity id for the flag's entity cache.
  $is_existing_entity = !empty($id);

  // Get all possible flags for this entity type.
  $flags = flag_get_flags($entity_type);

  // Filter out flags which need to be included on the node form.
  $flags_in_form = 0;
  $flags_visible = 0;
  foreach ($flags as $flag) {
    if (!$flag->show_on_form) {
      continue;
    }

    // Get the flag status.
    if ($is_existing_entity) {
      $flag_status = $flag->is_flagged($id);
    }
    else {
      // We don't have per-bundle defaults on general entities yet: default
      // status is just unflagged.
      $flag_status = FALSE;
      // Apply the per-bundle defaults for nodes.
      if ($entity_type == 'node') {
        $node_type = $entity->type;
        $flag_status = variable_get('flag_' . $flag->name . '_default_' . $node_type, 0);
      }

      // For a new, unsaved entity, make a dummy entity ID so that the flag
      // handler can remember the entity. This allows access to the flag to be
      // correctly handled in node and comment preview.
      $id = 'new';
      $flag->remember_entity($id, $entity);
    }

    // If the flag is not global and the user doesn't have access, skip it.
    // Global flags have their value set even if the user doesn't have access
    // to it, similar to the way "published" and "promote" keep the default
    // values even if the user doesn't have "administer nodes" permission.
    // Furthermore, a global flag is set to its default value on new nodes
    // even if the user creating the node doesn't have access to the flag.
    global $user;
    $access = $flag->access($id, $flag_status ? 'unflag' : 'flag');
    if (!$access && !$flag->global) {
      continue;
    }

    $form['flag'][$flag->name] = array(
      '#type' => 'checkbox',
      '#title' => $flag->get_label('flag_short', $id),
      '#description' => $flag->get_label('flag_long', $id),
      '#default_value' => $flag_status,
      '#return_value' => 1,
      // Used by our drupalSetSummary() on vertical tabs.
      '#attributes' => array('title' => $flag->get_title()),
    );

    // If the user does not have access to the flag, set as a value.
    if (!$access) {
      $form['flag'][$flag->name]['#type'] = 'value';
      $form['flag'][$flag->name]['#value'] = $flag_status;
    }
    else {
      $flags_visible++;
    }
    $flags_in_form++;
  }

  if ($flags_in_form) {
    $form['flag'] += array(
      '#weight' => 1,
      '#tree' => TRUE,
    );
  }
  if ($flags_visible) {
    $form['flag'] += array(
      '#type' => 'fieldset',
      '#title' => t('Flags'),
      '#collapsible' => TRUE,
    );

    if ($entity_type == 'node') {
      // Turn the fieldset into a vertical tab.
      $form['flag'] += array(
        '#group' => 'additional_settings',
        '#attributes' => array('class' => array('flag-fieldset')),
        '#attached' => array(
          'js' => array(
            'vertical-tabs' => drupal_get_path('module', 'flag') . '/theme/flag-admin.js',
          ),
        ),
      );
    }
  }
}

/**
 * Implements hook_field_attach_submit().
 *
 * @see flag_field_attach_form()
 */
function flag_field_attach_submit($entity_type, $entity, $form, &$form_state) {
  // This is invoked for each flag_field_attach_form(), but possibly more than
  // once for a particular form in the case that a form is showing multiple
  // entities (field collection, inline entity form). Hence we can't simply
  // assume our submitted form values are in $form_state['values']['flag'].
  if (isset($form['flag'])) {
    $parents = $form['flag']['#parents'];
    $flag_values = drupal_array_get_nested_value($form_state['values'], $parents);

    // Put the form values in the entity so flag_field_attach_save() can find
    // them. We can't call flag() here as new entities have no id yet.
    $entity->flag = $flag_values;
  }
}

/**
 * Implements hook_field_attach_insert().
 */
function flag_field_attach_insert($entity_type, $entity) {
  if (isset($entity->flag)) {
    flag_field_attach_save($entity_type, $entity);
  }
}

/**
 * Implements hook_field_attach_update().
 */
function flag_field_attach_update($entity_type, $entity) {
  if (isset($entity->flag)) {
    flag_field_attach_save($entity_type, $entity);
  }
}

/**
 * Shared saving routine between flag_field_attach_insert/update().
 *
 * @see flag_field_attach_form()
 */
function flag_field_attach_save($entity_type, $entity) {
  list($id) = entity_extract_ids($entity_type, $entity);
  // Get the flag values we stashed in the entity in flag_field_attach_submit().
  foreach ($entity->flag as $flag_name => $state) {
    flag($state ? 'flag' : 'unflag', $flag_name, $id);
  }
}

/*
 * Implements hook_contextual_links_view_alter().
 */
function flag_contextual_links_view_alter(&$element, $items) {
  if (isset($element['#element']['#entity_type'])) {
    $entity_type = $element['#element']['#entity_type'];

    // Get the entity out of the element. This requires a bit of legwork.
    if (isset($element['#element']['#entity'])) {
      // EntityAPI entities will all have the entity in the same place.
      $entity = $element['#element']['#entity'];
    }
    elseif (isset($element['#element']['#' . $entity_type])) {
      // Node module at least puts it here.
      $entity = $element['#element']['#' . $entity_type];
    }
    else {
      // Give up.
      return;
    }

    // Get all possible flags for this entity type.
    $flags = flag_get_flags($entity_type);

    foreach ($flags as $name => $flag) {
      if (!$flag->show_contextual_link) {
        continue;
      }

      list($entity_id) = entity_extract_ids($entity_type, $entity);
      if (!$flag->access($entity_id) && (!$flag->is_flagged($entity_id) || !$flag->access($entity_id, 'flag'))) {
        // User has no permission to use this flag or flag does not apply to
        // this object. The link is not skipped if the user has "flag" access
        // but not "unflag" access (this way the unflag denied message is
        // shown).
        continue;
      }

      $element['#links']['flag-' . $name] = array(
        'title' => $flag->theme($flag->is_flagged($entity_id) ? 'unflag' : 'flag', $entity_id),
        'html' => TRUE,
      );
    }
  }
}

/**
 * Implements hook_entity_view().
 *
 * Handles the 'show_in_links' and 'show_as_field' flag options.
 *
 * Note this is broken for taxonomy terms for version of Drupal core < 7.17.
 */
function flag_entity_view($entity, $type, $view_mode, $langcode) {
  // Get all possible flags for this entity type.
  $flags = flag_get_flags($type);
  foreach ($flags as $flag) {
    // Check if the flag outputs on entity view.
    if (!($flag->show_as_field || $flag->shows_in_entity_links($view_mode))) {
      // Flag is not configured to output on entity view, so skip it to save on
      // calls to access checks.
      continue;
    }

    $entity_id = $flag->get_entity_id($entity);
    // For a new, unsaved entity, make a dummy entity ID so that the flag
    // handler can remember the entity. This allows access to the flag to be
    // correctly handled in node and comment preview.
    if (is_null($entity_id)) {
      $entity_id = 'new';
    }
    $flag->remember_entity($entity_id, $entity);

    if (!$flag->access($entity_id) && (!$flag->is_flagged($entity_id) || !$flag->access($entity_id, 'flag'))) {
      // User has no permission to use this flag or flag does not apply to this
      // entity. The link is not skipped if the user has "flag" access but
      // not "unflag" access (this way the unflag denied message is shown).
      continue;
    }

    // We're good to go. Output the flag in the appropriate manner(s).

    // The old-style entity links output.
    if ($flag->shows_in_entity_links($view_mode)) {
      // The flag links are actually fully rendered theme functions.
      // The HTML attribute is set to TRUE to allow whatever the themer desires.
      $links['flag-' . $flag->name] = array(
        'title' => $flag->theme($flag->is_flagged($entity_id) ? 'unflag' : 'flag', $entity_id),
        'html' => TRUE,
      );
    }

    // The pseudofield output.
    if ($flag->show_as_field) {
      $entity->content['flag_' . $flag->name] = array(
        '#markup' => $flag->theme($flag->is_flagged($entity_id) ? 'unflag' : 'flag', $entity_id, array('needs_wrapping_element' => TRUE)),
      );
    }
  }

  // If any links were made, add them to the entity's links array.
  if (isset($links)) {
    $entity->content['links']['flag'] = array(
      '#theme' => 'links',
      '#links' => $links,
      '#attributes' => array('class' => array('links', 'inline')),
    );
  }
}

/**
 * Implements hook_node_insert().
 */
function flag_node_insert($node) {
  flag_node_save($node);
}

/**
 * Implements hook_node_update().
 */
function flag_node_update($node) {
  flag_node_save($node);
}

/**
 * Shared saving routine between flag_node_insert() and flag_node_update().
 */
function flag_node_save($node) {
  // Response to the flag checkboxes added to the form in flag_form_alter().
  $remembered = FALSE;
  if (isset($node->flag)) {
    foreach ($node->flag as $name => $state) {
      $flag = flag_get_flag($name);
      // Flagging may trigger actions. We want actions to get the current
      // node, not a stale database-loaded one:
      if (!$remembered) {
        $flag->remember_entity($node->nid, $node);
        // Actions may modify a node, and we don't want to overwrite this
        // modification:
        $remembered = TRUE;
      }

      $action = $state ? 'flag' : 'unflag';
      // Pass TRUE for $skip_permission_check so that flags that have been
      // passed through as hidden form values are saved.
      $flag->flag($action, $node->nid, NULL, TRUE);
    }
  }
}

/**
 * Implements hook_entity_delete().
 */
function flag_entity_delete($entity, $type) {
  // Node and user flags handle things through the entity type delete hooks.
  // @todo: make this configurable in the flag type definition?
  if ($type == 'node' || $type == 'user') {
    return;
  }

  list($id) = entity_extract_ids($type, $entity);
  _flag_entity_delete($type, $id);
}

/**
 * Implements hook_node_delete().
 */
function flag_node_delete($node) {
  foreach (flag_get_flags('node') as $flag) {
    // If the flag is being tracked by translation set and the node is part
    // of a translation set, don't delete the flagging record.
    // Instead, data will be updated in hook_node_translation_change(), below.
    if (!$flag->i18n || empty($node->tnid)) {
      _flag_entity_delete('node', $node->nid, $flag->fid);
    }
  }
}

/**
 * Implements hook_node_translation_change().
 *
 * (Hook provided by translation_helpers module.)
 */
function flag_node_translation_change($node) {
  if (isset($node->translation_change)) {
    // If there is only one node remaining, track by nid rather than tnid.
    // Otherwise, use the new tnid.
    $entity_id = $node->translation_change['new_tnid'] == 0 ? $node->translation_change['remaining_nid'] : $node->translation_change['new_tnid'];
    foreach (flag_get_flags('node') as $flag) {
      if ($flag->i18n) {
        db_update('flagging')->fields(array('entity_id' => $entity_id))
          ->condition('fid', $flag->fid)
          ->condition('entity_id', $node->translation_change['old_tnid'])
          ->execute();
        db_update('flag_counts')->fields(array('entity_id' => $entity_id))
          ->condition('fid', $flag->fid)
          ->condition('entity_id', $node->translation_change['old_tnid'])
          ->execute();
      }
    }
  }
}

/**
 * Deletes flagging records for the entity.
 *
 * @param $entity_type
 *   The type of the entity being deleted; e.g. 'node' or 'comment'.
 * @param $entity_id
 *   The ID of the entity being deleted.
 * @param $fid
 *   The flag id
 */
function _flag_entity_delete($entity_type, $entity_id, $fid = NULL) {
  $query_content = db_delete('flagging')
    ->condition('entity_type', $entity_type)
    ->condition('entity_id', $entity_id);
  $query_counts = db_delete('flag_counts')
    ->condition('entity_type', $entity_type)
    ->condition('entity_id', $entity_id);
  if (isset($fid)) {
    $query_content->condition('fid', $fid);
    $query_counts->condition('fid', $fid);
  }
  $query_content->execute();
  $query_counts->execute();
}

/**
 * Implements hook_user_login().
 */
function flag_user_login(&$edit, &$account) {
  // Migrate anonymous flags to this user's account.
  if (module_exists('session_api') && ($sid = flag_get_sid(0))) {
    // Get a list of flagging IDs that will be moved over.
    $duplicate_flaggings = array();
    $flaggings = db_select('flagging', 'fc')
      ->fields('fc', array('flagging_id', 'fid', 'entity_id'))
      ->condition('uid', 0)
      ->condition('sid', $sid)
      ->execute()
      ->fetchAllAssoc('flagging_id', PDO::FETCH_ASSOC);

    // Convert anonymous flaggings to their authenticated account.
    foreach ($flaggings as $flagging_id => $flagging) {
      // Each update is wrapped in a try block to prevent unique key errors.
      // Any duplicate object that was flagged as anonoymous is deleted in the
      // subsequent db_delete() call.
      try {
        db_update('flagging')
          ->fields(array(
            'uid' => $account->uid,
            'sid' => 0,
          ))
          ->condition('flagging_id', $flagging_id)
          ->execute();
      }
      catch (Exception $e) {
        $duplicate_flaggings[$flagging_id] = $flagging;
      }
    }

    // Delete any remaining flags this user had as an anonymous user. We use the
    // proper unflag action here to make sure the count gets decremented again
    // and so that other modules can clean up their tables if needed.
    $anonymous_user = drupal_anonymous_user();
    foreach ($duplicate_flaggings as $flagging_id => $flagging) {
      $flag = flag_get_flag(NULL, $flagging['fid']);
      $flag->flag('unflag', $flagging['entity_id'], $anonymous_user, TRUE);
    }

    // Clean up anonymous cookies.
    FlagCookieStorage::drop();
  }
}

/**
 * Implements hook_user_cancel().
 */
function flag_user_cancel($edit, $account, $method) {
  flag_user_account_removal($account);
}

/**
 * Implements hook_user_delete().
 */
function flag_user_delete($account) {
  flag_user_account_removal($account);
}

/**
 * Shared helper for user account cancellation or deletion.
 */
function flag_user_account_removal($account) {
  // Remove flags by this user.
  $query = db_select('flagging', 'fc');
  $query->leftJoin('flag_counts', 'c', 'fc.entity_id = c.entity_id AND fc.entity_type = c.entity_type AND fc.fid = c.fid');
  $result = $query
    ->fields('fc', array('fid', 'entity_id'))
    ->fields('c', array('count'))
    ->condition('fc.uid', $account->uid)
    ->execute();

  foreach ($result as $flag_data) {
    // Only decrement the flag count table if it's greater than 1.
    if ($flag_data->count > 0) {
      $flag_data->count--;
      db_update('flag_counts')
        ->fields(array(
          'count' => $flag_data->count,
        ))
        ->condition('fid', $flag_data->fid)
        ->condition('entity_id', $flag_data->entity_id)
        ->execute();
    }
    elseif ($flag_data->count == 0) {
      db_delete('flag_counts')
        ->condition('fid', $flag_data->fid)
        ->condition('entity_id', $flag_data->entity_id)
        ->execute();
    }
  }
  db_delete('flagging')
    ->condition('uid', $account->uid)
    ->execute();

  // Remove flags that have been done to this user.
  _flag_entity_delete('user', $account->uid);
}

/**
 * Implements hook_user_view().
 */
function flag_user_view($account, $view_mode) {
  $flags = flag_get_flags('user');
  $flag_items = array();
  foreach ($flags as $flag) {
    if (!$flag->access($account->uid)) {
      // User has no permission to use this flag.
      continue;
    }
    if (!$flag->show_on_profile) {
      // Flag not set to appear on profile.
      continue;
    }
    $flag_items[$flag->name] = array(
      '#type' => 'user_profile_item',
      '#title' => $flag->get_title($account->uid),
      '#markup' => $flag->theme($flag->is_flagged($account->uid) ? 'unflag' : 'flag', $account->uid),
      '#attributes' => array('class' => array('flag-profile-' . $flag->name)),
    );
  }
  if (!empty($flag_items)) {
    $account->content['flags'] = $flag_items;
    $account->content['flags'] += array(
      '#type' => 'user_profile_category',
      '#title' => t('Actions'),
      '#attributes' => array('class' => array('flag-profile')),
    );
  }
}

/**
 * Implements hook_session_api_cleanup().
 *
 * Clear out anonymous user flaggings during Session API cleanup.
 */
function flag_session_api_cleanup($arg = 'run') {
  // Session API 1.1 version:
  if ($arg == 'run') {
    $query = db_select('flagging', 'fc');
    $query->leftJoin('session_api', 's', 'fc.sid = s.sid');
    $result = $query
      ->fields('fc', array('sid'))
      ->condition('fc.sid', 0, '<>')
      ->isNull('s.sid')
      ->execute();
    foreach ($result as $row) {
      db_delete('flagging')
        ->condition('sid', $row->sid)
        ->execute();
    }
  }
  // Session API 1.2+ version.
  elseif (is_array($arg)) {
    $outdated_sids = $arg;
    db_delete('flagging')->condition('sid', $outdated_sids, 'IN')->execute();
  }
}

/**
 * Implements hook_field_attach_delete_bundle().
 *
 * Delete any flags' applicability to the deleted bundle.
 */
function flag_field_attach_delete_bundle($entity_type, $bundle, $instances) {
  // This query can't use db_delete() because that doesn't support a
  // subquery: see http://drupal.org/node/1267508.
  db_query("DELETE FROM {flag_types} WHERE type = :bundle AND fid IN (SELECT fid FROM {flag} WHERE entity_type = :entity_type)", array(
    ':bundle' => $bundle,
    ':entity_type' => $entity_type,
  ));
}

/**
 * Flags or unflags an item.
 *
 * @param $action
 *   Either 'flag' or 'unflag'.
 * @param $flag_name
 *   The name of the flag to use.
 * @param $entity_id
 *   The ID of the item to flag or unflag.
 * @param $account
 *   (optional) The user on whose behalf to flag. Omit for the current user.
 * @param permissions_check
 *   (optional) A boolean indicating whether to skip permissions.
 *
 * @return
 *   FALSE if some error occured (e.g., user has no permission, flag isn't
 *   applicable to the item, etc.), TRUE otherwise.
 */
function flag($action, $flag_name, $entity_id, $account = NULL, $permissions_check = FALSE) {
  if (!($flag = flag_get_flag($flag_name))) {
    // Flag does not exist.
    return FALSE;
  }
  return $flag->flag($action, $entity_id, $account, $permissions_check);
}

/**
 * Implements hook_flag_flag().
 */
function flag_flag_flag($flag, $entity_id, $account, $flagging) {
  if (module_exists('trigger')) {
    flag_flag_trigger('flag', $flag, $entity_id, $account, $flagging);
  }
}

/**
 * Implements hook_flag_unflag().
 */
function flag_flag_unflag($flag, $entity_id, $account, $flagging) {
  if (module_exists('trigger')) {
    flag_flag_trigger('unflag', $flag, $entity_id, $account, $flagging);
  }
}

/**
 * Trigger actions if any are available. Helper for hook_flag_(un)flag().
 *
 * @param $op
 *  The operation being performed: one of 'flag' or 'unflag'.
 * @param $flag
 *  The flag object.
 * @param $entity_id
 *  The id of the entity the flag is on.
 * @param $account
 *  The user account performing the action.
 * @param $flagging_id
 *  The flagging entity.
 */
function flag_flag_trigger($action, $flag, $entity_id, $account, $flagging) {
  $context['hook'] = 'flag';
  $context['account'] = $account;
  $context['flag'] = $flag;
  $context['op'] = $action;
  // We add to the $context all the objects we know about:
  $context = array_merge($flag->get_relevant_action_objects($entity_id), $context);
  // The primary object the actions work on.
  $object = $flag->fetch_entity($entity_id);

  // Generic "all flags" actions.
  foreach (trigger_get_assigned_actions('flag_' . $action) as $aid => $action_info) {
    // The 'if ($aid)' is a safeguard against
    // http://drupal.org/node/271460#comment-886564
    if ($aid) {
      actions_do($aid, $object, $context);
    }
  }
  // Actions specifically for this flag.
  foreach (trigger_get_assigned_actions('flag_' . $action . '_' . $flag->name) as $aid => $action_info) {
    if ($aid) {
      actions_do($aid, $object, $context);
    }
  }
}

/**
 * Implements hook_flag_access().
 */
function flag_flag_access($flag, $entity_id, $action, $account) {
  // Do nothing if there is no restriction by authorship.
  if (empty($flag->access_author)) {
    return;
  }

  // Restrict access by authorship. It's important that TRUE is never returned
  // here, otherwise we'd grant permission even if other modules denied access.
  if ($flag->entity_type == 'node') {
    // For non-existent nodes (such as on the node add form), assume that the
    // current user is creating the content.
    if (empty($entity_id) || !($node = $flag->fetch_entity($entity_id))) {
      return $flag->access_author == 'others' ? FALSE : NULL;
    }

    if ($flag->access_author == 'own' && $node->uid != $account->uid) {
      return FALSE;
    }
    elseif ($flag->access_author == 'others' && $node->uid == $account->uid) {
      return FALSE;
    }
  }

  // Restrict access by comment authorship.
  if ($flag->entity_type == 'comment') {
    // For non-existent comments (such as on the comment add form), assume that
    // the current user is creating the content.
    if (empty($entity_id) || !($comment = $flag->fetch_entity($entity_id))) {
      return $flag->access_author == 'comment_others' ? FALSE : NULL;
    }

    $node = node_load($comment->nid);
    if ($flag->access_author == 'node_own' && $node->uid != $account->uid) {
      return FALSE;
    }
    elseif ($flag->access_author == 'node_others' && $node->uid == $account->uid) {
      return FALSE;
    }
    elseif ($flag->access_author == 'comment_own' && $comment->uid != $account->uid) {
      return FALSE;
    }
    elseif ($flag->access_author == 'comment_others' && $comment->uid == $account->uid) {
      return FALSE;
    }
  }
}

/**
 * Implements hook_flag_access_multiple().
 */
function flag_flag_access_multiple($flag, $entity_ids, $account) {
  $access = array();

  // Do nothing if there is no restriction by authorship.
  if (empty($flag->access_author)) {
    return $access;
  }

  if ($flag->entity_type == 'node') {
    // Restrict access by authorship. This is similar to flag_flag_access()
    // above, but returns an array of 'nid' => $access values. Similarly, we
    // should never return TRUE in any of these access values, only FALSE if we
    // want to deny access, or use the current access value provided by Flag.
    $result = db_select('node', 'n')
      ->fields('n', array('nid', 'uid'))
      ->condition('nid', array_keys($entity_ids), 'IN')
      ->condition('type', $flag->types, 'IN')
      ->execute();
    foreach ($result as $row) {
      if ($flag->access_author == 'own') {
        $access[$row->nid] = $row->uid != $account->uid ? FALSE : NULL;
      }
      elseif ($flag->access_author == 'others') {
        $access[$row->nid] = $row->uid == $account->uid ? FALSE : NULL;
      }
    }
  }

  if ($flag->entity_type == 'comment') {
    // Restrict access by comment ownership.
    $query = db_select('comment', 'c');
    $query->leftJoin('node', 'n', 'c.nid = n.nid');
    $query
      ->fields('c', array('cid', 'nid', 'uid'))
      ->condition('c.cid', $entity_ids, 'IN');
    $query->addField('c', 'uid', 'comment_uid');
    $result = $query->execute();

    foreach ($result as $row) {
      if ($flag->access_author == 'node_own') {
        $access[$row->cid] = $row->node_uid != $account->uid ? FALSE : NULL;
      }
      elseif ($flag->access_author == 'node_others') {
        $access[$row->cid] = $row->node_uid == $account->uid ? FALSE : NULL;
      }
      elseif ($flag->access_author == 'comment_own') {
        $access[$row->cid] = $row->comment_uid != $account->uid ? FALSE : NULL;
      }
      elseif ($flag->access_author == 'comment_others') {
        $access[$row->cid] = $row->comment_uid == $account->uid ? FALSE : NULL;
      }
    }
  }

  // Always return an array (even if empty) of accesses.
  return $access;
}

/**
 * Implements hook_theme().
 */
function flag_theme() {
  $path = drupal_get_path('module', 'flag') . '/theme';

  return array(
    'flag' => array(
      'variables' => array(
        'flag' => NULL,
        'action' => NULL,
        'entity_id' => NULL,
        'after_flagging' => FALSE,
        'needs_wrapping_element' => FALSE,
        'errors' => array(),
      ),
      'template' => 'flag',
      'pattern' => 'flag__',
      'path' => $path,
    ),
    'flag_tokens_browser' => array(
      'variables' => array(
        'types' => array('all'),
        'global_types' => TRUE,
      ),
      'file' => 'flag.tokens.inc',
    ),
    'flag_admin_listing' => array(
      'render element' => 'form',
      'file' => 'includes/flag.admin.inc',
    ),
    'flag_admin_listing_disabled' => array(
      'variables' => array(
        'flags' => NULL,
        'default_flags' => NULL,
      ),
      'file' => 'includes/flag.admin.inc',
    ),
    'flag_admin_page' => array(
      'variables' => array(
        'flags' => NULL,
        'default_flags' => NULL,
        'flag_admin_listing' => NULL,
      ),
      'file' => 'includes/flag.admin.inc',
    ),
    'flag_form_roles' => array(
      'render element' => 'element',
      'file' => 'includes/flag.admin.inc',
    ),
  );
}

/**
 * A preprocess function for our theme('flag'). It generates the
 * variables needed there.
 *
 * The $variables array initially contains the following arguments:
 * - $flag
 * - $action
 * - $entity_id
 * - $after_flagging
 * - $errors
 * - $needs_wrapping_element
 *
 * See 'flag.tpl.php' for their documentation.
 */
function template_preprocess_flag(&$variables) {
  global $user;
  $initialized = &drupal_static(__FUNCTION__, array());

  // Some typing shotcuts:
  $flag =& $variables['flag'];
  $action = $variables['action'];
  $entity_id = $variables['entity_id'];
  $errors = implode('<br />', $variables['errors']);
  $flag_css_name = str_replace('_', '-', $flag->name);

  // Generate the link URL.
  $link_type = $flag->get_link_type();
  $link = module_invoke($link_type['module'], 'flag_link', $flag, $action, $entity_id);
  if (isset($link['title']) && empty($link['html'])) {
    $link['title'] = check_plain($link['title']);
  }

  // Replace the link with the access denied text if unable to flag.
  if ($action == 'unflag' && !$flag->access($entity_id, 'unflag')) {
    $link['title'] = $flag->get_label('unflag_denied_text', $entity_id);
    unset($link['href']);
  }

  // Anonymous users always need the JavaScript to maintain their flag state.
  if ($user->uid == 0) {
    $link_type['uses standard js'] = TRUE;
  }

  // Load the JavaScript/CSS, if the link type requires it.
  if (!isset($initialized[$link_type['name']])) {
    if ($link_type['uses standard css']) {
      drupal_add_css(drupal_get_path('module', 'flag') . '/theme/flag.css');
    }
    if ($link_type['uses standard js']) {
      drupal_add_js(drupal_get_path('module', 'flag') . '/theme/flag.js');
    }
    $initialized[$link_type['name']] = TRUE;
  }

  $variables['link'] = $link;
  $variables['link_href'] = isset($link['href']) ? check_url(url($link['href'], $link)) : FALSE;
  $variables['link_text'] = isset($link['title']) ? $link['title'] : $flag->get_label($action . '_short', $entity_id);
  $variables['link_title'] = isset($link['attributes']['title']) ? check_plain($link['attributes']['title']) : check_plain(strip_tags($flag->get_label($action . '_long', $entity_id)));
  $variables['status'] = ($action == 'flag' ? 'unflagged' : 'flagged');
  $variables['flag_name_css'] = $flag_css_name;

  $variables['flag_wrapper_classes_array'] = array();
  $variables['flag_wrapper_classes_array'][] = 'flag-wrapper';
  $variables['flag_wrapper_classes_array'][] = 'flag-' . $flag_css_name;
  $variables['flag_wrapper_classes_array'][] = 'flag-' . $flag_css_name . '-' . $entity_id;

  $variables['flag_classes_array'] = array();
  $variables['flag_classes_array'][] = 'flag';
  if (isset($link['href'])) {
    $variables['flag_classes_array'][] = $variables['action'] . '-action';
    $variables['flag_classes_array'][] = 'flag-link-' . $flag->link_type;
  }
  else {
    $variables['flag_classes_array'][] = $variables['action'] . '-disabled';
  }
  if (isset($link['attributes']['class'])) {
    $link['attributes']['class'] = is_string($link['attributes']['class']) ? array_filter(explode(' ', $link['attributes']['class'])) : $link['attributes']['class'];
    $variables['flag_classes_array'] = array_merge($variables['flag_classes_array'], $link['attributes']['class']);
  }
  $variables['message_classes_array'] = array();
  if ($variables['after_flagging']) {
    $variables['message_classes_array'][] = 'flag-message';
    if ($errors) {
      $variables['message_classes_array'][] = 'flag-failure-message';
      $variables['message_text'] = $errors;
    }
    else {
      $inverse_action = ($action == 'flag' ? 'unflag' : 'flag');
      $variables['message_classes_array'][] = 'flag-success-message';
      $variables['message_classes_array'][] = 'flag-' . $variables['status'] . '-message';
      $variables['message_text'] = $flag->get_label($inverse_action . '_message', $entity_id);
      $variables['flag_classes_array'][] = $variables['status'];
      // By default we make our JS code remove, after a few seconds, only
      // success messages.
      $variables['message_classes_array'][] = 'flag-auto-remove';
    }
  }
  else {
    $variables['message_text'] = '';
  }
}

/**
 * Theme processor for flag.tpl.php.
 *
 * @param array &$variables
 *  An array of variables for the template. See 'flag.tpl.php' for their
 *  documentation.
 */
function template_process_flag(&$variables) {
  // Convert class arrays to strings.
  $variables['flag_wrapper_classes'] = implode(' ', $variables['flag_wrapper_classes_array']);
  $variables['flag_classes'] = implode(' ', $variables['flag_classes_array']);
  $variables['message_classes'] = implode(' ', $variables['message_classes_array']);
}

/**
 * Return an array of flag names keyed by fid.
 */
function _flag_get_flag_names() {
  $flags = flag_get_flags();
  $flag_names = array();
  foreach ($flags as $flag) {
    $flag_names[$flag->fid] = $flag->name;
  }
  return $flag_names;
}

/**
 * Return an array of flag link types suitable for a select list or radios.
 */
function _flag_link_type_options() {
  $options = array();
  $types = flag_get_link_types();
  foreach ($types as $type_name => $type) {
    $options[$type_name] = $type['title'];
  }
  return $options;
}

/**
 * Return an array of flag link type descriptions.
 */
function _flag_link_type_descriptions() {
  $options = array();
  $types = flag_get_link_types();
  foreach ($types as $type_name => $type) {
    $options[$type_name] = $type['description'];
  }
  return $options;
}

// ---------------------------------------------------------------------------
// Non-Views public API

/**
 * Get the count of flags for a particular entity type.
 *
 * When called during a flagging or unflagging (such as from a hook
 * implementation or from Rules), the flagging or unflagging that is in the
 * process of being performed:
 *  - will be included during a flagging operation
 *  - will STILL be included during an unflagging operation. That is, the count
 *    will not yet have been decreased.
 * This is because this queries the {flagging} table, which only has its record
 * deleted at the very end of the unflagging process.
 *
 * @param $flag
 *   The flag.
 * @param $entity_type
 *   The entity type. For example, 'node'.
 *
 * @return
 *   The flag count with the flag name and entity type as the array key.
 */
function flag_get_entity_flag_counts($flag, $entity_type) {
  $counts = &drupal_static(__FUNCTION__);

  // We check to see if the flag count is already in the cache,
  // if it's not, run the query.
  if (!isset($counts[$flag->name][$entity_type])) {
    $counts[$flag->name][$entity_type] = array();
    $result = db_select('flagging', 'f')
      ->fields('f', array('fid'))
      ->condition('fid', $flag->fid)
      ->condition('entity_type', $entity_type)
      ->countQuery()
      ->execute()
      ->fetchField();
    $counts[$flag->name][$entity_type] = $result;
  }

  return $counts[$flag->name][$entity_type];
}

/**
 * Get the user's flag count.
 *
 * When called during a flagging or unflagging (such as from a hook
 * implementation or from Rules), the flagging or unflagging that is in the
 * process of being performed:
 *  - will be included during a flagging operation
 *  - will STILL be included during an unflagging operation. That is, the count
 *    will not yet have been decreased.
 * This is because this queries the {flagging} table, which only has its record
 * deleted at the very end of the unflagging process.
 *
 * @param $flag
 *   The flag.
 * @param $user
 *   The user object.
 *
 * @return
 *   The flag count with the flag name and the uid as the array key.
 */
function flag_get_user_flag_counts($flag, $user) {
  $counts = &drupal_static(__FUNCTION__);

  // We check to see if the flag count is already in the cache,
  // if it's not, run the query.
  if (!isset($counts[$flag->name][$user->uid])) {
    $counts[$flag->name][$user->uid] = array();
    $result = db_select('flagging', 'f')
      ->fields('f', array('fid'))
      ->condition('fid', $flag->fid)
      ->condition('uid', $user->uid)
      ->countQuery()
      ->execute()
      ->fetchField();
    $counts[$flag->name][$user->uid] = $result;
  }

  return $counts[$flag->name][$user->uid];
}

/**
 * Get flag counts for all flags on a node.
 *
 * When called during a flagging or unflagging (such as from a hook
 * implementation or from Rules), the count this returns takes into account the
 * the flagging or unflagging that is in the process of being performed.
 *
 * @param $entity_type
 *   The entity type (usually 'node').
 * @param $entity_id
 *   The entity ID (usually the node ID).
 *
 * @return
 *   The flag count with the entity type and id as array keys.
 */
function flag_get_counts($entity_type, $entity_id) {
  $counts = &drupal_static(__FUNCTION__);

  if (!isset($counts[$entity_type][$entity_id])) {
    $counts[$entity_type][$entity_id] = array();
    $query = db_select('flag', 'f');
    $query->leftJoin('flag_counts', 'fc', 'f.fid = fc.fid');
    $result = $query
      ->fields('f', array('name'))
      ->fields('fc', array('count'))
      ->condition('fc.entity_type', $entity_type)
      ->condition('fc.entity_id', $entity_id)
      ->execute();
    foreach ($result as $row) {
      $counts[$entity_type][$entity_id][$row->name] = $row->count;
    }
  }

  return $counts[$entity_type][$entity_id];
}

/**
 * Get the total count of items flagged within a flag.
 *
 * When called during a flagging or unflagging (such as from a hook
 * implementation or from Rules), the count this returns takes into account the
 * the flagging or unflagging that is in the process of being performed.
 *
 * @param $flag_name
 *   The flag name for which to retrieve a flag count.
 * @param $reset
 *   (optional) Reset the internal cache and execute the SQL query another time.
 */
function flag_get_flag_counts($flag_name, $reset = FALSE) {
  $counts = &drupal_static(__FUNCTION__);

  if ($reset) {
    $counts = array();
  }
  if (!isset($counts[$flag_name])) {
    $flag = flag_get_flag($flag_name);
    $counts[$flag_name] = db_select('flag_counts', 'fc')
      ->fields('fc', array('fid'))
      ->condition('fid', $flag->fid)
      ->countQuery()
      ->execute()
      ->fetchField();
  }

  return $counts[$flag_name];
}

/**
 * Load a single flag either by name or by flag ID.
 *
 * @param $name
 *  (optional) The flag name.
 * @param $fid
 *  (optional) The the flag id.
 *
 * @return
 *  The flag object, or FALSE if no matching flag was found.
 */
function flag_get_flag($name = NULL, $fid = NULL) {
  $flags = flag_get_flags();
  if (isset($name)) {
    if (isset($flags[$name])) {
      return $flags[$name];
    }
  }
  elseif (isset($fid)) {
    foreach ($flags as $flag) {
      if ($flag->fid == $fid) {
        return $flag;
      }
    }
  }
  return FALSE;
}

/**
 * List all flags available.
 *
 * If node type or account are entered, a list of all possible flags will be
 * returned.
 *
 * @param $entity_type
 *   (optional) The type of entity for which to load the flags. Usually 'node'.
 * @param $content_subtype
 *   (optional) The node type for which to load the flags.
 * @param $account
 *   (optional) The user accont to filter available flags. If not set, all
 *   flags for will this node will be returned.
 *
 * @return
 *   An array of the structure [fid] = flag_object.
 */
function flag_get_flags($entity_type = NULL, $content_subtype = NULL, $account = NULL) {
  $flags = &drupal_static(__FUNCTION__);

  // Retrieve a list of all flags, regardless of the parameters.
  if (!isset($flags)) {
    $flags = array();

    // Database flags.
    $query = db_select('flag', 'f');
    $query->leftJoin('flag_types', 'fn', 'fn.fid = f.fid');
    $result = $query
      ->fields('f', array(
        'fid',
        'entity_type',
        'name',
        'title',
        'global',
        'options',
      ))
      ->fields('fn', array('type'))
      ->execute();
    foreach ($result as $row) {
      if (!isset($flags[$row->name])) {
        $flags[$row->name] = flag_flag::factory_by_row($row);
      }
      else {
        $flags[$row->name]->types[] = $row->type;
      }
    }

    // Add code-based flags provided by modules.
    $default_flags = flag_get_default_flags();
    foreach ($default_flags as $name => $default_flag) {
      // Insert new enabled flags into the database to give them an FID.
      if ($default_flag->status && !isset($flags[$name])) {
        $default_flag->save();
        $flags[$name] = $default_flag;
      }

      if (isset($flags[$name])) {
        // Ensure overridden flags are associated with their parent module.
        $flags[$name]->module = $default_flag->module;

        // Update the flag with any properties that are "locked" by the code
        // version.
        if (isset($default_flag->locked)) {
          $flags[$name]->locked = $default_flag->locked;
          foreach ($default_flag->locked as $property) {
            $flags[$name]->$property = $default_flag->$property;
          }
        }
      }
    }

    // Sort the list of flags by weight.
    uasort($flags, '_flag_compare_weight');

    foreach ($flags as $flag) {
      // Allow modules implementing hook_flag_alter(&$flag) to modify each flag.
      drupal_alter('flag', $flag);
    }
  }

  // Make a variable copy to filter types and account.
  $filtered_flags = $flags;

  // Filter out flags based on type and subtype.
  if (isset($entity_type) || isset($content_subtype)) {
    foreach ($filtered_flags as $name => $flag) {
      if (!$flag->access_entity_enabled($entity_type, $content_subtype)) {
        unset($filtered_flags[$name]);
      }
    }
  }

  // Filter out flags based on account permissions.
  if (isset($account) && $account->uid != 1) {
    foreach ($filtered_flags as $name => $flag) {
      // We test against the 'flag' action, which is the minimum permission to
      // use a flag.
      if (!$flag->user_access('flag', $account)) {
        unset($filtered_flags[$name]);
      }
    }
  }

  return $filtered_flags;
}

/**
 * Comparison function for uasort().
 */
function _flag_compare_weight($flag1, $flag2) {
  if ($flag1->weight == $flag2->weight) {
    return 0;
  }
  return $flag1->weight < $flag2->weight ? -1 : 1;
}

/**
 * Retrieve a list of flags defined by modules.
 *
 * @param $include_disabled
 *   (optional) Unless specified, only enabled flags will be returned.
 *
 * @return
 *   An array of flag prototypes, not usable for flagging. Use flag_get_flags()
 *   if needing to perform a flagging with any enabled flag.
 */
function flag_get_default_flags($include_disabled = FALSE) {
  $default_flags = array();
  $flag_status = variable_get('flag_default_flag_status', array());

  $default_flags_info = array();
  foreach (module_implements('flag_default_flags') as $module) {
    $function = $module . '_flag_default_flags';
    foreach ($function() as $flag_name => $flag_info) {
      // Backward compatibility: old exported default flags have their names
      // in $flag_info instead, so we use the + operator to not overwrite it.
      $default_flags_info[$flag_name] = $flag_info + array(
        'name' => $flag_name,
        'module' => $module,
      );
    }
  }

  // Allow modules to alter definitions using hook_flag_default_flags_alter().
  drupal_alter('flag_default_flags', $default_flags_info);

  foreach ($default_flags_info as $flag_info) {
    $flag = flag_flag::factory_by_array($flag_info);

    // Disable flags that are not at the current API version.
    if (!$flag->is_compatible()) {
      $flag->status = FALSE;
    }

    // Add flags that have been enabled.
    if ((!isset($flag_status[$flag->name]) && (!isset($flag->status) || $flag->status)) || !empty($flag_status[$flag->name])) {
      $flag->status = TRUE;
      $default_flags[$flag->name] = $flag;
    }
    // Add flags that have been disabled.
    elseif ($include_disabled) {
      $flag->status = FALSE;
      $default_flags[$flag->name] = $flag;
    }
  }

  return $default_flags;
}

/**
 * Get all flagged entities in a flag.
 *
 * @param $flag_name
 *   The flag name for which to retrieve flagged entites.
 *
 * @return
 *   An array of flagging data, keyed by the flagging ID.
 */
function flag_get_flag_flagging_data($flag_name) {
  $return = array();
  $flag = flag_get_flag($flag_name);
  $result = db_select('flagging', 'fc')
    ->fields('fc')
    ->condition('fid', $flag->fid)
    ->execute();
  return $result->fetchAllAssoc('flagging_id');
}

/**
 * Find what a user has flagged, either a single entity or on the entire site.
 *
 * When called during a flagging or unflagging (such as from a hook
 * implementation or from Rules), the flagging or unflagging that is in the
 * process of being performed:
 *  - will be included during a flagging operation
 *  - will STILL be included during an unflagging operation. That is, the count
 *    will not yet have been decreased.
 * This is because this queries the {flagging} table, which only has its record
 * deleted at the very end of the unflagging process.
 *
 * @param $entity_type
 *   The type of entity that will be retrieved. Usually 'node'.
 * @param $entity_id
 *   (optional) The entity ID to check for flagging. If none given, all
 *   entities flagged by this user will be returned.
 * @param $uid
 *   (optional) The user ID whose flags we're checking. If none given, the
 *   current user will be used.
 * @param $sid
 *   (optional) The user SID (provided by Session API) whose flags we're
 *   checking. If none given, the current user will be used. The SID is 0 for
 *   logged in users.
 *
 * @return
 *   If returning a single item's flags (that is, when $entity_id isn't NULL),
 *   an array of the structure
 *   [flag_name] => (
 *     flagging_id => [flagging_id],
 *     uid => [uid],
 *     entity_id => [entity_id],
 *     timestamp => [timestamp],
 *     ...)
 *
 *   If returning all items' flags, an array of arrays for each flag:
 *   [flag_name] => [entity_id] => Object from above.
 */
function flag_get_user_flags($entity_type, $entity_id = NULL, $uid = NULL, $sid = NULL) {
  $flagged_content = &drupal_static(__FUNCTION__);

  $uid = !isset($uid) ? $GLOBALS['user']->uid : $uid;
  $sid = !isset($sid) ? flag_get_sid($uid) : $sid;

  if (isset($entity_id)) {
    if (!isset($flagged_content[$uid][$sid][$entity_type][$entity_id])) {
      $flag_names = _flag_get_flag_names();
      $flagged_content[$uid][$sid][$entity_type][$entity_id] = array();
      $result = db_select('flagging', 'fc')
        ->fields('fc')
        ->condition('entity_type', $entity_type)
        ->condition('entity_id', $entity_id)
        ->condition(db_or()
          ->condition('uid', $uid)
          ->condition('uid', 0)
        )
        ->condition('sid', $sid)
        ->execute();

      foreach ($result as $flagging_data) {
        $flagged_content[$uid][$sid][$entity_type][$entity_id][$flag_names[$flagging_data->fid]] = $flagging_data;
      }
    }
    return $flagged_content[$uid][$sid][$entity_type][$entity_id];
  }

  else {
    if (!isset($flagged_content[$uid][$sid][$entity_type]['all'])) {
      $flag_names = _flag_get_flag_names();
      $flagged_content[$uid][$sid][$entity_type]['all'] = array();
      $result = db_select('flagging', 'fc')
        ->fields('fc')
        ->condition('entity_type', $entity_type)
        ->condition(db_or()
          ->condition('uid', $uid)
          ->condition('uid', 0)
        )
        ->condition('sid', $sid)
        ->execute();
      foreach ($result as $flagging_data) {
        $flagged_content[$uid][$sid][$entity_type]['all'][$flag_names[$flagging_data->fid]][$flagging_data->entity_id] = $flagging_data;
      }
    }
    return $flagged_content[$uid][$sid][$entity_type]['all'];
  }

}

/**
 * Return a list of users who have flagged an entity.
 *
 * When called during a flagging or unflagging (such as from a hook
 * implementation or from Rules), the flagging or unflagging that is in the
 * process of being performed:
 *  - will be included during a flagging operation
 *  - will STILL be included during an unflagging operation. That is, the count
 *    will not yet have been decreased.
 * This is because this queries the {flagging} table, which only has its record
 * deleted at the very end of the unflagging process.
 *
 * @param $entity_type
 *   The type of entity that will be retrieved. Usually 'node'.
 * @param $entity_id
 *   The entity ID to check for flagging.
 * @param $flag_name
 *   (optional) The name of a flag if wanting a list specific to a single flag.
 *
 * @return
 *   A nested array of flagging records (i.e. rows from the {flagging} table,
 *   rather than complete Flagging entities). The structure depends on the
 *   presence of the $flag_name parameter:
 *    - if $flag_name is omitted, the array is keyed first by the user ID of
 *      the users that flagged the entity, then by flag name. Each value is
 *      then the flagging record.
 *    - if $flag_name is given, the array is keyed only by user ID. Each value
 *      is the flagging record.
 *   If no flags were found an empty array is returned.
 */
function flag_get_entity_flags($entity_type, $entity_id, $flag_name = NULL) {
  $entity_flags = &drupal_static(__FUNCTION__, array());

  if (!isset($entity_flags[$entity_type][$entity_id])) {
    $flag_names = _flag_get_flag_names();
    $result = db_select('flagging', 'fc')
      ->fields('fc')
      ->condition('entity_type', $entity_type)
      ->condition('entity_id', $entity_id)
      ->orderBy('timestamp', 'DESC')
      ->execute();
    $entity_flags[$entity_type][$entity_id] = array();
    foreach ($result as $flagging_data) {
      // Build a list of flaggings for all flags by user.
      $entity_flags[$entity_type][$entity_id]['users'][$flagging_data->uid][$flag_names[$flagging_data->fid]] = $flagging_data;
      // Build a list of flaggings for each individual flag.
      $entity_flags[$entity_type][$entity_id]['flags'][$flag_names[$flagging_data->fid]][$flagging_data->uid] = $flagging_data;
    }
  }
  if (empty($entity_flags[$entity_type][$entity_id])) {
    return array();
  }
  if (isset($flag_name)) {
    if (isset($entity_flags[$entity_type][$entity_id]['flags'][$flag_name])) {
      return $entity_flags[$entity_type][$entity_id]['flags'][$flag_name];
    }
    return array();
  }
  return $entity_flags[$entity_type][$entity_id]['users'];
}

/**
 * A utility function for outputting a flag link.
 *
 * You should call this function from your template when you want to put the
 * link on the page yourself. For example, you could call this function from
 * your theme preprocessor for node.tpl.php:
 * @code
 * $variables['my_flag_link'] = flag_create_link('bookmarks', $node->nid);
 * @endcode
 *
 * @param $flag_name
 *   The "machine readable" name of the flag; e.g. 'bookmarks'.
 * @param $entity_id
 *   The entity ID to check for flagging, for example a node ID.
 * @param $variables
 *  An array of further variables to pass to theme('flag'). For the full list
 *  of parameters, see flag.tpl.php. Of particular interest:
 *  - after_flagging: Set to TRUE if this flag link is being displayed as the
 *    result of a flagging action.
 *  - errors: An array of error messages.
 *
 * @return
 *   The HTML for the themed flag link.
 */
function flag_create_link($flag_name, $entity_id, $variables = array()) {
  $flag = flag_get_flag($flag_name);
  if (!$flag) {
    // Flag does not exist.
    return;
  }
  if (!$flag->access($entity_id) && (!$flag->is_flagged($entity_id) || !$flag->access($entity_id, 'flag'))) {
    // User has no permission to use this flag.
    return;
  }
  return $flag->theme($flag->is_flagged($entity_id) ? 'unflag' : 'flag', $entity_id, $variables);
}

/**
 * Trim a flag to a certain size.
 *
 * @param $fid
 *   The flag object.
 * @param $account
 *   The user object on behalf the trimming will occur.
 * @param $cutoff_size
 *   The number of flaggings allowed. Any flaggings beyond that will be trimmed.
 * @param $trim_newest
 *   An optional boolean indicating whether to trim the newest flags.
 * @param $permissions_check
 *   (optional) A boolean indicating whether to skip permissions.
 *   This will trim the flag if $permissions_check is TRUE even if the user
 *   doesn't have the permission to flag/unflag.
 */
function flag_trim_flag($flag, $account, $cutoff_size, $trim_newest, $permissions_check = FALSE) {
  $query = db_select('flagging', 'fc')
    ->fields('fc')
    ->condition('fid', $flag->fid)
    ->condition(db_or()->condition('uid', $account->uid)->condition('uid', 0))
    // Account for session ID (in the case of anonymous users).
    ->condition('sid', flag_get_sid($account->uid));
  // If $trim_newest is TRUE, then, we should order by 'ASC' as we should trim
  // the newest flags.
  if ($trim_newest) {
    $query->orderBy('timestamp', 'ASC');
  }
  else {
    $query->orderBy('timestamp', 'DESC');
  }

  // Execute the query.
  $result = $query->execute();

  $i = 1;
  foreach ($result as $row) {
    if ($i++ > $cutoff_size) {
      flag('unflag', $flag->name, $row->entity_id, $account, $permissions_check);
    }
  }
}

/**
 * Remove all flagged entities from a flag.
 *
 * @param $flag
 *   The flag object.
 * @param $entity_id
 *   (optional) The entity ID on which all flaggings will be removed. If left
 *   empty, this will remove all of this flag's entities.
 */
function flag_reset_flag($flag, $entity_id = NULL) {
  $query = db_select('flagging', 'fc')
    ->fields('fc')
    ->condition('fid', $flag->fid);

  if ($entity_id) {
    $query->condition('entity_id', $entity_id);
  }

  $result = $query->execute()->fetchAllAssoc('flagging_id', PDO::FETCH_ASSOC);
  $rows = array();
  foreach ($result as $row) {
    $rows[] = $row;
  }
  module_invoke_all('flag_reset', $flag, $entity_id, $rows);

  $query = db_delete('flagging')->condition('fid', $flag->fid);
  // Update the flag_counts table.
  $count_query = db_delete('flag_counts')->condition('fid', $flag->fid);
  if ($entity_id) {
    $query->condition('entity_id', $entity_id);
    $count_query->condition('entity_id', $entity_id);
  }
  $count_query->execute();
  return $query->execute();
}

/**
 * Return an array of link types provided by modules.
 *
 * @return
 *  An array of link types as defined by hook_flag_link_type_info(). These are
 *  keyed by the type name, and each value is an array of properties. In
 *  addition to those defined in hook_flag_link_type_info(), the following
 *  properties are set:
 *  - 'module': The providing module.
 *  - 'name': The machine name of the type.
 *
 * @see hook_flag_link_type_info()
 * @see hook_flag_link_type_info_alter()
 */
function flag_get_link_types() {
  $link_types = &drupal_static(__FUNCTION__);

  if (!isset($link_types)) {
    if ($cache = cache_get('flag_link_type_info')) {
      $link_types = $cache->data;
    }
    // In some rare edge cases cache_get() can return an empty result. If it
    // does, we make sure to fetch the link types again.
    if (empty($link_types)) {
      $link_types = array();
      foreach (module_implements('flag_link_type_info') as $module) {
        $module_types = module_invoke($module, 'flag_link_type_info');
        foreach ($module_types as $type_name => $info) {
          $link_types[$type_name] = $info + array(
            'module' => $module,
            'name' => $type_name,
            'title' => '',
            'description' => '',
            'options' => array(),
            'uses standard js' => TRUE,
            'uses standard css' => TRUE,
            'provides form' => FALSE,
          );
        }
      }
      drupal_alter('flag_link_type_info', $link_types);

      cache_set('flag_link_type_info', $link_types);
    }
  }

  return $link_types;
}

/**
 * Get a private token used to protect links from spoofing - CSRF.
 */
function flag_get_token($entity_id) {
  // Anonymous users get a less secure token, since it must be the same for all
  // anonymous users on the entire site to work with page caching.
  return ($GLOBALS['user']->uid) ? drupal_get_token($entity_id) : md5(drupal_get_private_key() . $entity_id);
}

/**
 * Check to see if a token value matches the specified node.
 */
function flag_check_token($token, $entity_id) {
  return flag_get_token($entity_id) == $token;
}

/**
 * Set the Session ID for a user. Utilizes the Session API module.
 *
 * Creates a Session ID for an anonymous user and returns it. It will always
 * return 0 for registered users.
 *
 * @param int $uid
 *   (optional) The user ID to create a session ID for. Defaults to the
 *   current user.
 * @param bool $create
 *   (optional) Determines whether a session should be created if it doesn't
 *   exist yet. Defaults to TRUE.
 *
 * @return
 *   The session ID, if a session was created. If not, the return value is 0.
 *
 * @see flag_get_sid()
 */
function flag_set_sid($uid = NULL, $create = TRUE) {
  $sids = &drupal_static(__FUNCTION__, array());

  if (!isset($uid)) {
    $uid = $GLOBALS['user']->uid;
  }

  // Set the sid if none has been set yet. If the caller specified to create an
  // sid and we have an invalid one (-1), create it.
  if (!isset($sids[$uid]) || ($sids[$uid] == -1 && $create)) {
    if (module_exists('session_api') && session_api_available() && $uid == 0) {
      // This returns one of the following:
      // - -1. This indicates that no session exists and none was created.
      // - A positive integer with the Session ID when it does exist.
      $sids[$uid] = session_api_get_sid($create);
    }
    else {
      $sids[$uid] = 0;
    }
  }

  // Keep the -1 case internal and let the outside world only distinguish two
  // cases: (1) there is an SID; (2) there is no SID (-> 0).
  return $sids[$uid] == -1 ? 0 : $sids[$uid];
}

/**
 * Get the Session ID for a user. Utilizes the Session API module.
 *
 * Gets the Session ID for an anonymous user. It will always return 0 for
 * registered users.
 *
 * @param int $uid
 *   (optional) The user ID to return the session ID for. Defaults to the
 *   current user.
 * @param bool $create
 *   (optional) Determines whether a session should be created if it doesn't
 *   exist yet. Defaults to FALSE.
 *
 * @return
 *   The session ID, if the session exists. If not, the return value is 0.
 *
 * @see flag_set_sid()
 */
function flag_get_sid($uid = NULL, $create = FALSE) {
  return flag_set_sid($uid, $create);
}

// ---------------------------------------------------------------------------
// Drupal Core operations

/**
 * Implements hook_node_operations().
 *
 * Add additional options on the admin/build/node page.
 */
function flag_node_operations() {
  global $user;

  $flags = flag_get_flags('node', NULL, $user);
  $operations = array();

  foreach ($flags as $flag) {
    $operations['flag_' . $flag->name] = array(
      'label' => $flag->get_label('flag_short'),
      'callback' => 'flag_nodes',
      'callback arguments' => array('flag', $flag->name),
      'behavior' => array(),
    );
    $operations['unflag_' . $flag->name] = array(
      'label' => $flag->get_label('unflag_short'),
      'callback' => 'flag_nodes',
      'callback arguments' => array('unflag', $flag->name),
      'behavior' => array(),
    );
  }
  return $operations;
}

/**
 * Callback function for hook_node_operations().
 */
function flag_nodes($nodes, $action, $flag_name) {
  $performed = FALSE;
  foreach ($nodes as $nid) {
    $performed |= flag($action, $flag_name, $nid);
  }
  if ($performed) {
    drupal_set_message(t('The update has been performed.'));
  }
}

/**
 * Implements hook_user_operations().
 */
function flag_user_operations() {
  global $user;

  $flags = flag_get_flags('user', NULL, $user);
  $operations = array();

  foreach ($flags as $flag) {
    $operations['flag_' . $flag->name] = array(
      'label' => $flag->get_label('flag_short'),
      'callback' => 'flag_users',
      'callback arguments' => array('flag', $flag->name),
    );
    $operations['unflag_' . $flag->name] = array(
      'label' => $flag->get_label('unflag_short'),
      'callback' => 'flag_users',
      'callback arguments' => array('unflag', $flag->name),
    );
  }
  return $operations;
}
/**
 * Callback function for hook_user_operations().
 */
function flag_users($users, $action, $flag_name) {
  foreach ($users as $uid) {
    flag($action, $flag_name, $uid);
  }
}

// ---------------------------------------------------------------------------
// Contrib integration hooks

/**
 * Implements hook_views_api().
 */
function flag_views_api() {
  return array(
    'api' => 3.0,
    'path' => drupal_get_path('module', 'flag') . '/includes/views',
  );
}

/**
 * Implements hook_features_api().
 */
function flag_features_api() {
  return array(
    'flag' => array(
      'name' => t('Flag'),
      'feature_source' => TRUE,
      'default_hook' => 'flag_default_flags',
      'file' => drupal_get_path('module', 'flag') . '/includes/flag.features.inc',
    ),
  );
}

/**
 * Implements hook_ctools_plugin_directory().
 */
function flag_ctools_plugin_directory($module, $plugin) {
  if ($module == 'ctools' && !empty($plugin)) {
    return "plugins/$plugin";
  }
}

// ---------------------------------------------------------------------------
// Entity Metadata callbacks

/**
 * Getter callback that returns whether the given entity is flagged.
 */
function flag_properties_get_flagging_boolean($entity, array $options, $name, $entity_type, $property_info) {
  list($entity_id,) = entity_extract_ids($entity_type, $entity);

  $flagging_data = flag_get_user_flags($entity_type, $entity_id);
  return isset($flagging_data[$property_info['flag_name']]);
}

/**
 * Getter callback that returns entities the given user flagged.
 */
function flag_properties_get_flagged_entities($entity, array $options, $name, $entity_type, $property_info) {
  // Need the entity type the flag applies to.
  $flag_entity_type = $property_info['flag_entity_type'];

  $flagging_data = flag_get_user_flags($flag_entity_type, NULL, $entity->uid);

  $flag_name = $property_info['flag_name'];
  if (isset($flagging_data[$flag_name])) {
    return array_keys($flagging_data[$flag_name]);
  }
  return array();
}

/**
 * Getter callback that returns users who flagged the given entity.
 */
function flag_properties_get_flagging_users($entity, array $options, $name, $entity_type, $property_info) {
  list($entity_id,) = entity_extract_ids($entity_type, $entity);

  $flagging_data = flag_get_entity_flags($entity_type, $entity_id, $property_info['flag_name']);

  return array_keys($flagging_data);
}

/**
 * Getter callback that returns the SID of the user that is being retrieved.
 *
 * Callback for hook_entity_property_info_alter().
 *
 * @param stdobj $entity
 *  The entity object representing a user for which we are getting inforamtion for.
 *
 * @param array $options
 *  Options reguarding the nature of the entity. Language, etc.
 *
 * @param string $name
 *  The name of the property we are running this callback for.
 *
 * @param string $entity_type
 *  The type that the stdobj $entity is supposed to be.
 *
 * @param $property_info
 *  The ifnromatin that represents the property we are providing a result for.
 *
 * @return an integer representing the user's sid field from the session_api table
 *
 * @ingroup callbacks
 */
function flag_properties_get_user_sid($entity, array $options, $name, $entity_type, $property_info) {
  $sid = flag_get_sid($entity->uid, FALSE);
  return $sid;
}