<?php

/**
 * @file
 * Module implementation for nodeapi_example module.
 */

/**
 * @defgroup nodeapi_example Example: NodeAPI
 * @ingroup examples
 * @{
 * Example using NodeAPI.
 *
 * This is an example demonstrating how a module can be used to extend existing
 * node types.
 *
 * hook_nodeapi() has been replaced in Drupal 7 with a set of different hooks
 * providing the same or improved functionality. See the NodeAPI hooks list
 * at api.drupal.org (linked below).
 *
 * 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.
 *
 * @see node_api_hooks
 */

/**
 * 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 radios in
 * the node's content type configuration page.
 *
 * Changes made by this hook will be shown 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_node_type'] = array(
      '#type' => 'radios',
      '#title' => t('NodeAPI Example Rating'),
      '#default_value' => variable_get('nodeapi_example_node_type_' . $form['#node_type']->type, FALSE),
      '#options' => array(
        FALSE => t('Disabled'),
        TRUE => t('Enabled'),
      ),
      '#description' => t('Should this node have a rating attached to it?'),
    );
  }
  // Here we check to see if the type and node field are set. If so, it could
  // be a node edit form.
  elseif (isset($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_node_type_' . $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,
      );
    }
  }
}

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

/**
 * Implements hook_node_load().
 *
 * Loads the rating information if available for any of the nodes in the
 * argument list.
 */
function nodeapi_example_node_load($nodes, $types) {
  // We can use $types to figure out if we need to process any of these nodes.
  $our_types = array();
  foreach ($types as $type) {
    if (variable_get('nodeapi_example_node_type_' . $type, FALSE)) {
      $our_types[] = $type;
    }
  }

  // Now $our_types contains all the types from $types that we want
  // to deal with. If it's empty, we can safely return.
  if (!count($our_types)) {
    return;
  }

  // Now we need to make a list of revisions based on $our_types
  foreach ($nodes as $node) {
    // We are using the revision id instead of node id.
    if (variable_get('nodeapi_example_node_type_' . $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; 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_' . $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.
 *
 * This hook is called when an existing node has been changed. We can't simply
 * update, since the node may not have a rating saved, thus no
 * database field. So we first check the database for a rating. If there is one,
 * we update it. Otherwise, we call nodeapi_example_node_insert() to create one.
 */
function nodeapi_example_node_update($node) {
  if (variable_get('nodeapi_example_node_type_' . $node->type, FALSE)) {
    // Check first if this node has a saved rating.
    $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_node_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_' . $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;
}

/**
 * @} End of "defgroup nodeapi_example".
 */