<?php
// $Id: nodeapi_example.module,v 1.5 2010-12-10 06:49:28 rfay Exp $

/**
 * @file
 * This is an example outlining how a module can be used to extend existing
 * content types.
 *
 * We will add the ability for each node to have a "rating," which will be a
 * number from one to five. The rating will be tracked using the revision
 * system also, so every node revision may have different rating values.
 */

/**
 * Implements hook_form_alter().
 *
 * By implementing this hook, we're able to modify any form. We'll only make
 * changes to two types: a node's content type configuration and edit forms.
 *
 * We need to have a way for administrators to indicate which content types
 * should have our rating field added. This is done by inserting a checkbox in
 * the node's content type configuration page.
 *
 * Changes made by this hook will be show when editing the settings of any
 * content type.
 *
 * Optionally, hook_form_FORM_ID_alter() could be used with the function name
 * nodeapi_example_form_node_type_form_alter
 */
function nodeapi_example_form_alter(&$form, $form_state, $form_id) {
  // First, check for the node type configuration form.
  if ($form_id == 'node_type_form') {
    // Alter the node type's configuration form to add our setting. We don't
    // need to worry about saving this value back to the variable, the form
    // we're altering will do it for us.
    $form['rating'] = array(
      '#type' => 'fieldset',
      '#title' => t('Rating settings'),
      '#collapsible' => TRUE,
      '#collapsed' => TRUE,
      '#group' => 'additional_settings',
      '#weight' => -1,
    );

    $form['rating']['nodeapi_example'] = array(
      '#type' => 'radios',
      '#title' => t('NodeAPI Example Rating'),
      '#default_value' => variable_get('nodeapi_example_' . $form['#node_type']->type, FALSE),
      '#options' => array(FALSE => t('Disabled'), TRUE => t('Enabled')),
      '#description' => t('Should this node have a rating attached to it?'),
    );
  }
  // If the type and node field are set this may be a node edit form.
  elseif (isset($form['type']) && isset($form['#node']) && $form['type']['#value'] . '_node_form' == $form_id) {
    // If the rating is enabled for this node type, we insert our control
    // into the form.
    $node = $form['#node'];
    if (variable_get('nodeapi_example_' . $form['type']['#value'], FALSE)) {
      $form['nodeapi_example_rating'] = array(
        '#type' => 'select',
        '#title' => t('Rating'),
        '#default_value' => isset($node->nodeapi_example_rating) ? $node->nodeapi_example_rating : '',
        '#options' => array(0 => t('Unrated'), 1, 2, 3, 4, 5),
        '#required' => TRUE,
        '#weight' => 0,
      );
    }
  }
}

/**
 * hook_nodeapi() has been replaced in Drupal 7 with a set of different hooks
 * providing the same or improved functionality.
 *
 * The replacement functions providing access to events ocurred to content in
 * Drupal is listed below, and detailled in the following location:
 * http://api.drupal.org/api/group/hooks/7
 * or in the node API declaration file: modules/node/node.api.php
 *
 * hook_node_access()	- Control access to a node.
 * hook_node_access_records()	-	Set permissions for a node to be written to the database.
 * hook_node_access_records_alter()	-	Alter permissions for a node before it is written to the database.
 * hook_node_build_alter()	-	The node content was built, the module may modify the structured content.
 * hook_node_delete()	-	Act on node deletion.
 * hook_node_grants()	-	Inform the node access system what permissions the user has.
 * hook_node_grants_alter()	-	Alter user access rules when trying to view, edit or delete a node.
 * hook_node_info()	-	Defines module-provided node types.
 * hook_node_insert()	-	Respond to node insertion.
 * hook_node_load()	-	Act on node objects when loaded.
 * hook_node_operations()	-	Add mass node operations.
 * hook_node_prepare()	-	The node is about to be shown on the add/edit form.
 * hook_node_prepare_translation()	-	The node is being cloned for translation.
 * hook_node_presave()	-	The node passed validation and is about to be saved.
 * hook_node_revision_delete()	-	A revision of the node is deleted.
 * hook_node_search_result()	-	The node is being displayed as a search result.
 * hook_node_type_delete()	-	Act on node type deletion.
 * hook_node_type_insert()	-	Act on node type creation.
 * hook_node_type_update()	-	Act on node type changes.
 * hook_node_update()	-	The node being updated.
 * hook_node_update_index()	-	The node is being indexed.
 * hook_node_validate()	-	The user has finished editing the node and is previewing or submitting it.
 * hook_node_view()	-	The node content is being assembled before rendering.
 *
 */

/**
 * Implements hook_node_validate().
 *
 * Check that rating attribute is set in the form submission, the field is
 * required
 */
function nodeapi_example_node_validate($node, $form) {
  if (variable_get('nodeapi_example_' . $node->type, FALSE)) {
    if (isset($node->nodeapi_example_rating) && !$node->nodeapi_example_rating) {
      form_set_error('nodeapi_example_rating', t('You must rate this content.'));
    }
  }
}

/**
 * Implements hook_node_load().
 *
 * Load the rating information if available for any of the nodes in the argument
 * list.
 */
function nodeapi_example_node_load($nodes, $form) {
  foreach ($nodes as $node) {
    // We are using the revision id instead of node id
    if (variable_get('nodeapi_example_' . $node->type, FALSE)) {
      $vids[] = $node->vid;
    }
  }
  // Check if we should load rating for any of the nodes
  if (!isset($vids) || !count($vids)) {
    return;
  }

  // When we read, we don't care about the node->nid, but we look for the right
  // revision ID (node->vid)
  $result = db_select('nodeapi_example', 'e')
  ->fields('e', array(
        'nid',
        'vid',
        'rating',
  ))
  ->where('e.vid IN (:vids)', array(':vids' => $vids))
  ->execute();

  foreach ($result as $record) {
    $nodes[$record->nid]->nodeapi_example_rating = $record->rating;
  }
}

/**
 * Implements hook_node_insert().
 *
 * As a new node is being inserted into the database, we need to do our own
 * database inserts.
 */
function nodeapi_example_node_insert($node) {
  if (variable_get('nodeapi_example_' . $node->type, FALSE)) {
    // Notice that we are ignoring any revision information using $node->nid
    db_insert('nodeapi_example')
    ->fields(array(
        'nid' => $node->nid,
        'vid' => $node->vid,
        'rating' => $node->nodeapi_example_rating,
    ))
    ->execute();
  }
}

/**
 * Implements hook_node_delete().
 *
 * When a node is deleted, we need to remove all related records from our table,
 * including all revisions. For the delete operations we use node->nid.
 */
function nodeapi_example_node_delete($node) {
  // Notice that we're deleting even if the content type has no rating enabled.
  db_delete('nodeapi_example')
    ->condition('nid', $node->nid)
    ->execute();
}

/**
 * Implements hook_node_update().
 *
 * As an existing node is being updated in the database, we need to do our own
 * database updates.
 *
 * Update is called when an existing node has been changed. Here, we use a
 * DELETE then an INSERT rather than an UPDATE. The reason is that a node
 * created before this module was installed won't already have a rating
 * saved so there would be nothing to update.
 */
function nodeapi_example_node_update($node) {
  if (variable_get('nodeapi_example_' . $node->type, FALSE)) {
    // If may happen that this node does not have a previous saved rating
    // value, so we can't just update it, we need to check first if this
    $rating = db_select('nodeapi_example', 'e')
      ->fields('e', array(
        'rating',
      ))
      ->where('e.vid = (:vid)', array(':vid' => $node->vid))
      ->execute()->fetchField();

    if($rating) {
      // node has been rated before.
      db_update('nodeapi_example')
         ->fields(array('rating' => $node->nodeapi_example_rating))
         ->condition('vid', $node->vid)
         ->execute();
    }
    else {
      // Node was not previously rated, so insert a new rating in database.
      nodeapi_example_node_insert($node);
    }
  }
}

/**
 * Implements hook_view().
 *
 * This is a typical implementation that simply runs the node text through
 * the output filters.
 *
 * Finally, we need to take care of displaying our rating when the node is
 * viewed. This operation is called after the node has already been prepared
 * into HTML and filtered as necessary, so we know we are dealing with an
 * HTML teaser and body. We will inject our additional information at the front
 * of the node copy.
 *
 * Using node API 'hook_node_view' is more appropriate than using a filter here, because
 * filters transform user-supplied content, whereas we are extending it with
 * additional information.
 */
function nodeapi_example_node_view($node, $build_mode = 'full') {
  if (variable_get('nodeapi_example_' . $node->type, FALSE)) {
    // Make sure to set a rating, also for nodes saved previously and not yet rated.
    $rating = isset($node->nodeapi_example_rating) ? $node->nodeapi_example_rating : 0;
    $node->content['nodeapi_example'] = array(
      '#markup' => theme('nodeapi_example_rating', array('rating' => $rating)),
        '#weight' => -1,
    );
  }
}

/**
 * Implements hook_theme().
 *
 * This lets us tell Drupal about our theme functions and their arguments.
 */
function nodeapi_example_theme() {
  return array(
    'nodeapi_example_rating' => array(
      'variables' => array('rating' => NULL),
  ),
  );
}

/**
 * A custom theme function.
 *
 * By using this function to format our rating, themes can override this presentation
 * if they wish; for example, they could provide a star graphic for the rating. We
 * also wrap the default presentation in a CSS class that is prefixed by the module
 * name. This way, style sheets can modify the output without requiring theme code.
 */
function theme_nodeapi_example_rating($variables) {
  $options = array(
    0 => t('Unrated'),
    1 => t('Poor'),
    2 => t('Needs improvement'),
    3 => t('Acceptable'),
    4 => t('Good'),
    5 => t('Excellent'),
  );
  $output = '<div class="nodeapi_example_rating">';
  $output .= t('Rating: %rating', array('%rating' => $options[(int) $variables['rating']]));
  $output .= '</div>';
  return $output;
}