<?php

/*
 * @file islandora.module
 * defines paths (drupal menu items) as entry points and acts as a hub for dispatching tasks to other modules.
 * 
 * 
 * This file is part of Islandora.
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with the program.  If not, see <http ://www.gnu.org/licenses/>.
 */


define('FEDORA_VIEW', 'view fedora repository');
define('FEDORA_METADATA_EDIT', 'edit fedora metadata');
define('FEDORA_ADD_DS', 'add fedora datastreams');
define('FEDORA_INGEST', 'ingest fedora objects');
define('FEDORA_PURGE', 'delete fedora objects and datastreams');
define('FEDORA_MODIFY_STATE', 'modify fedora state');
define('ISLANDORA_VIEW_HOOK', 'islandora_view_object');
define('ISLANDORA_EDIT_HOOK', 'islandora_edit_object');

/**
 * Implementation of hook_menu. 
 * we need some standard entry points so we can have consistent urls for different Object actions
 */
function islandora_menu() {
  $items = array();

  $items['admin/islandora'] = array(
    'title' => 'Islandora Configuration',
    'description' => "Configure Islandora's interaction with Fedora",
    'access arguments' => array('administer site configuration'),
    'type' => MENU_NORMAL_ITEM,
  );
  $items['admin/islandora/configure'] = array(
    'title' => 'Islandora Configuration',
    'description' => 'Enter the Islandora collection information here.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('islandora_repository_admin'),
    'file' => 'admin/islandora.admin.inc',
    'access arguments' => array('administer site configuration'),
    'type' => MENU_NORMAL_ITEM,
    'weight' => 0,
  );

  $items['admin/islandora/solution_packs'] = array(
    'title' => 'Solution Packs',
    'description' => 'Install content models and collections required by installed solution packs.',
    'page callback' => 'islandora_solution_packs_page',
    'access arguments' => array(FEDORA_ADD_DS),
    'file' => 'admin/islandora.solutionpacks.inc',
    'type' => MENU_NORMAL_ITEM,
  );

  $items['islandoracm.xsd'] = array(
    'title' => 'Islandora Content Model XML Schema Definition',
    'page callback' => 'islandora_display_schema',
    'page arguments' => array('islandoracm.xsd'),
    'type' => MENU_CALLBACK,
    'access arguments' => array(FEDORA_VIEW),
  );

  $items['collection_policy.xsd'] = array(
    'title' => 'Islandora Content Model XML Schema Definition',
    'page callback' => 'islandora_display_schema',
    'page arguments' => array('collection_policy.xsd'),
    'type' => MENU_CALLBACK,
    'access arguments' => array(FEDORA_VIEW),
  );

  $items['islandora/ingest/%'] = array(
    'title' => 'Ingest object',
    'page callback' => 'islandora_ingest_callback',
    'page arguments' => array(2),
    'file' => 'includes/ingest-menu.inc',
    'type' => MENU_CALLBACK,
    'access arguments' => array(FEDORA_INGEST),
  );

  $items['islandora'] = array(
    'title' => 'Islandora Repository',
    'page callback' => 'islandora_view_default_object',
    'type' => MENU_NORMAL_ITEM,
    'access arguments' => array(FEDORA_VIEW),
  );

  $items['islandora/object/%'] = array(
    'title' => 'Repository',
    'page callback' => 'islandora_view_object',
    'page arguments' => array(2),
    'type' => MENU_NORMAL_ITEM,
    'access arguments' => array(FEDORA_VIEW),
  );


  $items['islandora/object/%/add'] = array(
    'title' => 'Add to an object',
    'file' => 'includes/add-menu.inc',
    'page callback' => 'islandora_add_callback',
    'page arguments' => array(2),
    'type' => MENU_NORMAL_ITEM,
    'access arguments' => array(FEDORA_ADD_DS)
  );

  $items['islandora/object/%/view'] = array(
    'title' => 'View',
    'page callback' => 'islandora_view_object',
    'page arguments' => array(2),
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'access arguments' => array(FEDORA_VIEW),
  );

  $items['islandora/object/%/edit'] = array(
    'title' => 'Edit',
    'page callback' => 'islandora_edit_object',
    'page arguments' => array(2),
    'type' => MENU_LOCAL_TASK,
    'access arguments' => array(FEDORA_MODIFY_STATE),
  );

  $items['islandora/object/%/delete'] = array(
    'title' => 'Purge object',
    'page callback' => 'islandora_purge_object',
    'page arguments' => array(2),
    'type' => MENU_CALLBACK,
    'access arguments' => array(FEDORA_PURGE),
  );

  $items['islandora/object/%/datastream/%'] = array(
    'title' => 'View datastream',
    'page callback' => 'islandora_datastream_as_attachment',
    'page arguments' => array(2, 4),
    'type' => MENU_CALLBACK,
    'file' => 'utils/datastream.inc',
    'access arguments' => array(FEDORA_VIEW),
  );

  $items['islandora/object/%/datastream/%/view'] = array(
    'title' => 'View datastream',
    'page callback' => 'islandora_datastream_as_attachment',
    'page arguments' => array(2, 4),
    'type' => MENU_CALLBACK,
    'file' => 'utils/datastream.inc',
    'access arguments' => array(FEDORA_VIEW),
  );

  $items['islandora/object/%/datastream/%/download'] = array(
    'title' => 'Download datastream',
    'page callback' => 'islandora_datastream_as_attachment',
    'page arguments' => array(2, 4),
    'type' => MENU_CALLBACK,
    'file' => 'utils/datastream.inc',
    'access arguments' => array(FEDORA_VIEW),
  );

  $items['islandora/object/%/datastream/%/edit'] = array(
    'title' => 'Edit datastream',
    'page callback' => 'islandora_edit_datastream',
    'page arguments' => array(2, 4),
    'type' => MENU_CALLBACK,
    'access arguments' => array(FEDORA_METADATA_EDIT),
  );

  $items['islandora/object/%/datastream/%/delete'] = array(
    'title' => 'Purge data stream',
    'page callback' => 'islandora_purge_datastream',
    'page arguments' => array(2, 4),
    'type' => MENU_CALLBACK,
    'access arguments' => array(FEDORA_PURGE),
  );

  return $items;
}

/**
 * determines whether we can see the object or not
 * checks PID namespace permissions, and user permissions
 * @global object $user
 * @param string $op
 * @param string $pid
 *
 *  @return boolean 
 */
function islandora_node_access($op, $pid = NULL, $as_user = NULL) {
  //$returnValue = FALSE;

  if ($pid == NULL) {
    $pid = variable_get('fedora_repository_pid', 'islandora:root');
  }

  $isRestricted = variable_get('fedora_namespace_restriction_enforced', TRUE);
  $namespace_access = NULL;
  if (!$isRestricted) {
    $namespace_access = TRUE;
  }
  else {
    $pid_namespace = substr($pid, 0, strpos($pid, ':') + 1); //Get the namespace (with colon)
    $allowed_namespaces = explode(" ", variable_get('fedora_pids_allowed', 'default: demo: changeme: islandora: ilives: islandora-book: books: newspapers: '));

    $namespace_access = in_array($pid_namespace, $allowed_namespaces);
  }

  return ($namespace_access && user_access($op, $as_user));
}

/**
 * Gives the option of deleting or purging and object.
 * 
 * The default behaviour is to purge the object to reduce maintenance.
 * If a solution pack wants to change this behaviour and have the object set to deleted then
 * it can respond to the 'islandora_pre_purge_object' hook with an array containing the pair 
 * 'delete' => TRUE. 
 * Once the object has been deleted/purged then a second call lets the solution packs know that
 * the object has been dealt with. In this call the object id and content models are sent out so
 * that the solution packs can act on this news. There is no guarantee that the object still exists
 * and so the object object isn't sent.
 * 
 * @param string $object_id
 *   ID of the object
 * @return type 
 */
function islandora_purge_object($object_id) {
  module_load_include('inc', 'islandora', 'RestConnection');
  global $user;
  if (!isset($object_id)) {
    drupal_set_message(t('Cannot remove object, object id not set'));
    return;
  }
  try {
    $restConnection = new RestConnection($user);
    $fedora_object = new FedoraObject($object_id, $restConnection->repository);
  } catch (Exception $e) {
    drupal_set_message(t('Error getting Islandora object %s %e', array('%s' => $object_id, '%e' => $e)), 'error');
    return "";
  }
  if (!isset($fedora_object)) {
    drupal_set_message(t('Could not remove object, object not found'));
    return;
  }
  $content_models = $fedora_object->models;
  $arr = module_invoke_all('islandora_pre_purge_object', $fedora_object); //notify modules of pending deletion
  if (isset($arr['delete']) && $arr['delete']) {
    try {
      $fedora_object->delete();
    } catch (Exception $e) {
      drupal_set_message(t('Error deleting Islandora object %s %e', array('%s' => $object_id, '%e' => $e)), 'error');
      return "";
    }
  }
  else {
    try {
      $restConnection->repository->purgeObject($object_id);
    } catch (Exception $e) {
      drupal_set_message(t('Error purging Islandora object %s %e', array('%s' => $object_id, '%e' => $e)), 'error');
      return "";
    }
  }
  module_invoke_all('islandora_post_purge_object', $object_id, $content_models);  //notify modules post deletion
  drupal_goto('islandora');
}

/**
 * returns an array listing object types provided by sub modules
 * @return array 
 */
function islandora_get_types() {
  return module_invoke_all('islandora_get_types');
}

/**
 * a function to call other modules edit page.  If there are not any modules
 * that handle this function this module will build a default page.
 * @global object $user
 * @param string $object_id
 * @return string 
 */
function islandora_edit_object($object_id) {
  module_load_include('inc', 'islandora', 'RestConnection');
  global $user;
  try {
    $restConnection = new RestConnection($user);
    $fedora_object = new FedoraObject($object_id, $restConnection->repository);
  } catch (Exception $e) {
    drupal_set_message(t('Error getting Islandora object %s', array('%s' => $object_id)), 'error');
    return"";
  }
  drupal_alter('islandora_edit_object', $fedora_object);
  $arr = module_invoke_all('islandora_edit_object', $fedora_object);
  $output = "";
  foreach ($arr as $key => $value) {
    $output .= $key . '<br />' . $value; //if we have multiple modules handle one cmodel we need to iterate over multiple
  }
  //we could do another module invoke all here to build the edit tab with a default implemented in this module?
  return $output;
}

/**
 * builds a default page for the edit tab
 * @param object $fedora_object 
 *   A tuque Fedora Object
 */
function islandora_islandora_edit_object($fedora_object) {
  $supported_models = islandora_get_types();
  $output = "";
  foreach ($fedora_object->models as $model) {
    if (isset($supported_models[$model][ISLANDORA_EDIT_HOOK]) && $supported_models[$model][ISLANDORA_EDIT_HOOK] == TRUE) {//another module is handling the view
      return;
    }
  }
  $output = theme('islandora_default_edit', array('islandora_object' => $fedora_object));
  return array('Default Edit output' => $output);
}

/**
 * Gives the option of purging or deleting a datastream.
 * 
 * The default behaviour is to purge the datastream but this can be overridden using the 
 * 'islandora_pre_purge_datastream' hook. The returned array can include a 'block' => TRUE 
 * pair which will prevent the datastream from being deleted if it particularly needed for 
 * a certain function. Returning 'delete' => TRUE will cause the datastream to be put into 
 * a deleted state.
 * 
 * @param string $object_id
 *   ID of the object
 * @param string $datastream_id
 *   ID of the datastream
 *   
 */
function islandora_purge_datastream($object_id, $datastream_id) {
  module_load_include('inc', 'islandora', 'RestConnection');
  global $user;
  if (!isset($datastream_id)) {
    drupal_set_message(t('Cannot remove datastream, datastream id not set'));
    return;
  }
  try {
    $restConnection = new RestConnection($user);
    $fedora_object = new FedoraObject($object_id, $restConnection->repository);
  } catch (Exception $e) {
    drupal_set_message(t('Error getting Islandora object %s %e', array('%s' => $object_id, '%e' => $e)), 'error');
    return "";
  }
  if (!isset($fedora_object)) {
    drupal_set_message(t('Could not remove object, object not found'));
    return;
  }
  if (!isset($fedora_object)) {
    drupal_set_message(t('Could not remove object, object not found'));
    return;
  }
  $arr = module_invoke_all('islandora_pre_purge_datastream', $fedora_object, $datastream_id); //notify modules of pending deletion so we can update rels etc
  if (isset($arr['block']) && $arr['block']) {
    drupal_set_message(t('Purging of the %d datastream was blocked', array('%d' => $datastream_id)), 'warning');
    return;
  }
  if (isset($arr['delete']) && $arr['delete']) {
    try {
      $datastream = new FedoraDatastream($datastream_id, $fedora_object, $restConnection->repository);
      $datastream->state = 'D';
    } catch (Exception $e) {
      drupal_set_message(t('Error deleting %s datastream from Islandora object %o %e', array('%s' => $datastream_id, '%o' => $object_id, '%e' => $e)), 'error');
      return;
    }
  }
  else {
    try {
      $fedora_object->purgeDatastream($datastream_id);
    } catch (Exception $e) {
      drupal_set_message(t('Error purging %s datastream from Islandora object %o %e', array('%s' => $datastream_id, '%o' => $object_id, '%e' => $e)), 'error');
      return;
    }
  }
  module_invoke_all('islandora_post_purge_datastream', $fedora_object, $datastream_id);  //notify modules post deletion
  drupal_set_message(t('%d datastream sucessfully purged from Islandora object %o', array('%d' => $datastream_id, '%o' => $object_id)));
  drupal_goto('islandora/object/' . $object_id);
}

function islandora_view_default_object() {
  $pid = variable_get('islandora_repository_pid', 'islandora:root');
  return islandora_view_object($pid);
}

/**
 * The view entry point.  modules should implement hook_islandora_view_object for the Fedora Content models that
 * their modules want to provide a view for.
 * @global object $user
 * @param string $object_id
 * 
 * @return string 
 */
function islandora_view_object($object_id) {
  //return $object_id;
  if (!isset($object_id)) {
    drupal_set_message(t('Cannot view object, object id not set'));
    return;
  }

  $page_number = (empty($_GET['page'])) ? '1' : $_GET['page'];
  $page_size = (empty($_GET['pagesize'])) ? '10' : $_GET['pagesize'];
  module_load_include('inc', 'islandora', 'RestConnection');
  global $user;
  try {
    $restConnection = new RestConnection($user);
    $fedora_object = new FedoraObject($object_id, $restConnection->repository);
  } catch (Exception $e) {
    drupal_set_message(t('Error getting Islandora object %s', array('%s' => $object_id)), 'error');
    return"";
  }
  drupal_alter('islandora_view_object', $fedora_object); //modify object if required before it is passed along
  $arr = module_invoke_all('islandora_view_object', $fedora_object, $user, $page_number, $page_size); //allow submodules to decide how to handle content base on object type
  if (empty($arr)) {
    //TODO: make sure we iterate over the array as they will be more then one cmodel per object
    drupal_set_message(t('there was an error loading the view for islandora object %s', array('%s' => $object_id)), 'error');
    return "";
  }
  //module_invoke_all(islandora_display($arr)),
  $output = "";
  foreach ($arr as $key => $value) {
    $output .= $key . '<br />' . $value; //if we have multiple modules handle one cmodel we need to iterate over multiple
  }
  //we could do another module invoke all here to build the edit tab with a default implemented in this module?
  return $output; //just an example as we could have more then one array element
}

/**
 * the default view hook.  If there are no modules registered to handle this objects cmodels or there are 
 * not any cmodels specified this will create a default display.
 * @param string $object_id
 * @return string 
 */
function islandora_islandora_view_object($object) {
  $supported_models = islandora_get_types();
  $output = "";
    foreach ($object->models as $model) {
      if (isset($supported_models[$model][ISLANDORA_VIEW_HOOK]) && $supported_models[$model][ISLANDORA_VIEW_HOOK] == TRUE) {//another module is handling the view
        return;
      }
    }
  $output = theme('islandora_default', array('islandora_object' => $object));
  return array('Default Output' => $output);
  }

/**
 * Theme registry function
 * @return array
 */
function islandora_theme() {
  return array(
    'islandora_default' => array(
      'template' => 'islandora-object',
      'variables' => array('islandora_object' => NULL),
    ),
    'islandora_default_edit' => array(
      'template' => 'islandora-object-edit',
      'variables' => array('islandora_object' => NULL),
    ),
  );
}

/**
 * drupal hook_permissions function
 * @return array
 */
function islandora_permission() {
  return array(
    FEDORA_VIEW => array(
      'title' => t('View Fedora Repository objects and datastreams'),
      'description' => t('Users with this permission will be allowed to view Fedora objects and datastreams.  Unless Fedora XACML security policies limits this functionality to certain objects.')
    ),
    FEDORA_ADD_DS => array(
      'title' => t('Add Fedora streams to Fedora objects'),
      'description' => t('Users with this permission will be allowed to add datastreams to Fedora objects.  Unless Fedora XACML security policies limits this functionality to certain objects.')
    ),
    FEDORA_METADATA_EDIT => array(
      'title' => t('Edit Fedora Metadata'),
      'description' => t('Users with this permission will be allowed to edit Fedora Metadata streams')
    ),
    FEDORA_INGEST => array(
      'title' => t('Create new Fedora objects'),
      'description' => t('Users with this permission will be allowed to create new objects in the Fedora repository')
    ),
    FEDORA_PURGE => array(
      'title' => t('Permanently remove objects from the Fedora repository'),
      'description' => t('Users with this permission will be allowed to Permantly remove objects from the Fedora repository.')
    ),
    FEDORA_MODIFY_STATE => array(
      'title' => t('Change a Fedora objects state'),
      'description' => t('Users with this permission will be allowed to change a Fedora objects state.')
    ),
  );
}

/**
 * 
 * @param string $object_id
 * @return type 
 */
function islandora_add_datastream($object_id) {
  if (!isset($object_id)) {
    drupal_set_message(t('Cannot add datastream to object, object id not set'));
    return;
  }
  //send message to synapse
  $object = new IslandoraObject($object_id);

  if (!isset($object)) {
    drupal_set_message(t('Could not remove object, object not found'));
    return;
  }
  module_invoke_all('islandora_add_datastream', $object); //allow submodules to handle add datastream based on object type
}

function islandora_preprocess_islandora_default(&$variables) {
  $islandora_object = $variables['islandora_object'];
  module_load_include('inc', 'islandora', 'utils/islandora_dublin_core');
  try {
    $dc = $islandora_object['DC']->content;
    //$dc_xml = simplexml_load_string($dc);
    $dc_object = Dublin_Core::import_from_xml_string($dc);
  } catch (Exception $e) {
    drupal_set_message(t('Error retrieving object %s %t', array('%s' => $islandora_object->id, '%t' => $e->getMessage())), 'error');
  }
  $variables['islandora_dublin_core'] = $dc_object;
  $variables['islandora_object_label'] = $islandora_object->label;
  global $base_url;
  if (isset($islandora_object['TN'])) {
    $variables['islandora_thumbnail_url'] = $base_url . '/islandora/object/' . $islandora_object->id . '/datastream/TN/view';
  }
}

function islandora_preprocess_islandora_default_edit(&$variables) {
  $islandora_object = $variables['islandora_object'];
  global $base_url;
  $datastreams = array();
  $variables['islandora_editmetadata_url'] = $base_url . '/islandora/edit_form/' . $islandora_object->id;
  foreach ($islandora_object as $ds) {
    $datastreams['download_url'] = $base_url . '/islandora/object/' . $islandora_object->id . '/datastream/' . $ds->id .'/download';
    $datastreams['view_url'] = $base_url . '/islandora/object/' . $islandora_object->id . '/datastream/' . $ds->id .'/view';
    $datastreams['delete_url'] = $base_url . '/islandora/object/' . $islandora_object->id . '/datastream/' . $ds->id .'/delete';
    $datastreams['label'] = $ds->label;
    $variables['islandora_datastreams'][$ds->id] = $datastreams;    
  }
}