lr_publish.module

<?php

/**
 * @file
 * A module to publish drupal node metadata to a Learning Registry node.
 *
 * This module takes the specified node content and publishes it to a
 * Learning Registry node.
 */


/**
 * Display help and module information.
 *
 * @param string $path
 *   A string that specifies which path of the site we're displaying help.
 * @param string $arg
 *   An array that holds that current path as would be returned from arg().
 *
 * @return string $help
 *   A string that contains the help text for the specified path.
 */
function lr_publish_help($path, $arg) {
  $output = '';
  switch ($path) {
    case "admin/help#lr_publish":
      $output = '<p>' .
        t("Pushes Drupal node data to the specified Learning Registry node.") .
        '<p>';
      break;
  }
  return $output;
} // function lr_publish_help


/**
 * Valid permissions for this module
 *
 * @return array
 *   An array of valid permissions for the lr_publish module.
 */
function lr_publish_perm() {
  return array('administer lr_publish_perm');
} // function lr_publish_perm


/**
 * Implementation of hook_menu().
 */
function lr_publish_menu() {
  $items['admin/settings/lr_publish'] = array(
    'title' => t('LR publish settings'),
    'description' => t('Publish selected node metadata to a Learning Registry node.'),
    'page callback' => 'drupal_get_form',
    'page arguments' => array('lr_publish_admin_settings'),
    'access arguments' => array('access administration pages'),
    'type' => MENU_NORMAL_ITEM,
    'file' => 'lr_publish.admin.inc',
  );

  return $items;
}


/**
 * Implementation of hook_nodeapi()
 */
function lr_publish_nodeapi(&$node, $op) {
  $nodes_to_publish = variable_get('lr_publish_node_types', array());
  if (in_array($node->type, $nodes_to_publish) &&
    $node->nid);
  switch($op) {
    case 'insert':
      if ($node->status == 1) {
        _lr_publish_publish($node);
      }
      break;
    // case 'update':
    //   if ($node->status == 0) {
    //     _lr_publish_set_deleted($node);
    //   }
    //   else if ($node->status == 1) {
    //     _lr_publish_update($node);
    //   }
    //   break;
    // case 'delete':
    //   _lr_publish_set_deleted($node);
    //   break;
  }
}


/**
 * Publish node metadata to specified Learning Registry node.
 *
 * @param object &$node
 *   A reference to the node object. We have to be very careful to not set
 *   anything, only read from the node object reference since the node
 *   reference allows us to edit the node content.
 */
function _lr_publish_publish(&$node) {
  $content_info = _lr_get_content_info(&$node);
  $resource_data = _lr_def_resource_data($content_info);
  $empty_submission = _lr_build_envelope();
  //watchdog('lr_publish', json_encode($empty_submission));
  $prepared_submission =
    _lr_add_resource_data_to_submission($empty_submission, $resource_data);
  $resource_post_payload = json_encode($prepared_submission);
  //watchdog('lr_publish', $resource_post_payload, array(), WATCHDOG_DEBUG);

  _lr_send_to_registry($node->nid, $resource_post_payload);
}


/**
 * Sets the deleted status for a deleted Drupal node in the LR node.
 *
 * @param object &$node
 *   A reference to the node object. We have to be very careful to not set
 *   anything, only read from the node object reference since the node
 *   reference allows us to edit the node content.
 */
function _lr_publish_set_deleted(&$node) {
  return;
}


/**
 * Update the info published to the node.
 *
 * @param object &$node
 *   A reference to the node object. We have to be very careful to not set
 *   anything, only read from the node object reference since the node
 *   reference allows us to edit the node content.
 */
function _lr_publish_update(&$node) {
  return;
}


/**
 * Return info we submit about nodes to the LR.
 *
 * @param object &$node
 *   A reference to the node object. We have to be very careful to not set
 *   anything, only read from the node object reference since the node
 *   reference allows us to edit the node content.
 */
function _lr_get_content_info(&$node) {
  $content_info = array();
  $content_info['resource_locator'] = _lr_get_node_url($node->nid);
  // TODO: correctly specify resource data type
  // resource_data_type is currently hardcoded, will be fixed in a later version
  $content_info['resource_data_type'] = 'metadata';
  $content_info['submitter'] = variable_get('lr_publish_submitter', NULL);
  // currently set curator and submitter the same, once we get a better sense
  // of what each field means, this will change
  $content_info['curator'] = $content_info['submitter'];
  // TODO: correctly set active value, currently hardcoded to TRUE
  $content_info['active' ] = TRUE;
  $content_info['payload_schema'] = "DC 1.1";

  // define the node fields we send.
  // TODO: actually send a useful subset of fields
  $resource_data->title = $node->title;
  $resource_data->creation_timestamp = $node->created;
  $resource_data->modification_timestamp = $node->changed;

  $content_info['resource_data'] = $resource_data;

  return $content_info;
}


/**
 * Return the absolute URL to a node.
 *
 * @param int $nid
 *   The numerical node id.
 *
 * @return string $node_url
 *   The absolute URL to the node.
 */
function _lr_get_node_url($nid) {
  $url = $GLOBALS['base_url'] . $GLOBALS['base_path'] . "node/" . $nid;
  return $url;
}

/**
 * Make the curl calls to send to the LR node.
 *
 * All the specified nodeapi operations ($ops) call this function to actually send the data.
 *
 * @param string $nid
 *    A string containing the node ID for submission into the registry.
 * @param string $json
 *    A string containing the json object that will be sent to the registry node.
 * @param int $service_num
 *    An int that specifies the service that will be called.
 *    0 - publish (default value)
 *    1 - update
 *    2 - delete
 */
function _lr_send_to_registry($nid, $json, $service_num = 0) {
  $services = array(
    'publish',
    'update',
    'delete',
  );

  if ($service_num >= count($services)) {
    return;
  }

  $ch = curl_init();
  $curl_options = array(
    // TODO: allow more than publish! Currently hardcoding the publish
    // bit. this function needs to take an argument to add the appropriate
    // service at the end of the curl URL
    CURLOPT_URL => variable_get('lr_publish_node_url', NULL) . "/publish",
    CURLOPT_POST => TRUE,
    CURLOPT_POSTFIELDS => $json,
    CURLOPT_RETURNTRANSFER => 1,
    CURLOPT_HTTPHEADER => array("Content-type: application/json",),
  );
  // file_put_contents("/tmp/foo.json", $json);
  curl_setopt_array($ch, $curl_options);
  $result=curl_exec($ch);

  if ($result)
   _lr_update_submission_status($nid, $result);

}


/**
 * Define the Learning Registry resource data.
 *
 * @param array $content_info

 * @returns object $resource_data
 */
function _lr_def_resource_data ($content_info) {
  // values specified as immutable in the LR spec.
  define("LR_DOC_TYPE", "resource_data");
  define("LR_DOC_VERSION", "0.23.0");
  define("LR_SUBMITTER_TYPE", "agent");
  define("LR_SUBMISSION_TOS", "yes");
  // commented since we aren't signing submissions
  // define("LR_SIGNING_METHOD", "LR-PGP.1.0");
  define("LR_PAYLOAD_PLACEMENT", "inline");

  $opt_id_fields = array(
    'curator',
    'owner',
    'signer',
  );

  $opt_res_fields = array(
    'submitter_timestamp',
    'submitter_TTL',
    'keys',
    'resource_TTL',
    'payload_schema_locator',
    'payload_schema_format',
  );

  // we don't really do much with these since we aren't currently signing
  // submissions.
  $opt_sig_fields = array(
    'signature',
    'key_server',
    'key_locations',
    'key_owner',
    'signing_method',
  );

  $opt_tos_fields = array(
    'tos_submission_attribution', // need to figure out more about this value.
  );
  $identity->submitter_type = LR_SUBMITTER_TYPE;
  $identity->submitter = $content_info["submitter"];

  // not sure what the value for this should be, does it depend on the LR
  // node,currently set to "yes" to indicate agreement?
  $tos->submission_TOS = LR_SUBMISSION_TOS;

  //TODO: extract these foreach calls into their own function
  // Add the optional keys / objects if they are passed in $content_info

  // optional identity values.
  foreach ($opt_id_fields as $field) {
    if (array_key_exists($field, $content_info)) {
      $identity->$field = $content_info[$field];
    }
  }

  // optional resource_data values
  foreach ($opt_res_fields as $field) {
    if (array_key_exists($field, $content_info)) {
      $resource_data->$field = $content_info[$field];
    }
  }

  // create an empty stdClass since the digital_signature is completely
  // optional.
  $digital_signature = new stdClass;
  // optional digital signature  values
  foreach ($opt_sig_fields as $field) {
    if (array_key_exists($field, $content_info)) {
      $digital_signature->$field = $content_info[$field];
    }
  }

  // optional TOS values
  foreach ($opt_tos_fields as $field) {
    if (array_key_exists($field, $content_info)) {
      $tos->$field = $content_info[$field];
    }
  }


  $resource_data->doc_type = LR_DOC_TYPE;
  $resource_data->doc_version = LR_DOC_VERSION;
  $resource_data->resource_data_type = $content_info['resource_data_type'];
  $resource_data->active = $content_info['active'];
  $resource_data->identity = $identity;
  $resource_data->TOS = $tos;

  // only add the signature key if signature data are defined.
  if (!empty($digital_signature)) {
    $resource_data->digital_signature = $digital_signature;
  }

  $resource_data->resource_locator = $content_info['resource_locator'];
  $resource_data->payload_placement = LR_PAYLOAD_PLACEMENT;
  $resource_data->payload_schema = array($content_info['payload_schema']);
  $resource_data->resource_data = $content_info['resource_data'];

  return $resource_data;
}


/**
 * Return a basic LR submission envelope.
 *
 * @return object $submission
 *   An empty LR submission envelop.
 */
function _lr_build_envelope() {
  $submission->documents = array();
  return $submission;
}


/**
 * Adds resource data to a LR submission envelope.
 *
 * @param object $submission
 *    An LR submission object.
 * @param object $resource_data
 *    An LR resource data object.
 *
 * @return object $submission
 *    The submission object with $resource data pushed on to the documents array.
 */
function _lr_add_resource_data_to_submission($submission, $resource_data) {
  $submission->documents[] = $resource_data;
  return $submission;
}


/**
 * Adds a status record in the lr_publish table to record submission
 *
 * @param int $nid
 *    Drupal node ID of item to submit.
 * @param string $result
 *    JSON response from Learning Registry.
 *
 */
function _lr_update_submission_status($nid, $result) {
  if ($result) {

    $result_array = json_decode($result);

    if ($result_array->document_results[0]->OK) {
    // check to see if submission already in database
      $submission_check_result = db_query('SELECT COUNT(nid) as CNT FROM {lr_publish} WHERE nid = %d', $nid);
      $count = db_fetch_object($submission_check_result);

      if ($count->CNT) {
      // Record already exists, update timestamp
        db_query('UPDATE {lr_publish} SET updated=%d WHERE nid = %d', time(), $nid);
      }
      else {
      // Insert new record

      // fill parameter array
        $data = array(
            'nid' => $nid,
            'published' => time(),
            'docid' => $result_array->document_results[0]->doc_ID,
        );
        // write it to the database
        drupal_write_record('lr_publish', $data);
      }
    }
    else {
      watchdog('lr_publish', "Error publishing node ID %nid to the registry.  Full response: %msg",
          array ('%nid' => $nid,'%msg' => $result));
    }

  }

}