<?php
// $Id$

/**
 * @file
 * Hooks provided by the Node module.
 */

/**
 * @addtogroup hooks
 * @{
 */

/**
 * Inform the node access system what permissions the user has.
 *
 * This hook is for implementation by node access modules. In addition to
 * managing access rights for nodes, the node access module must tell
 * the node access system what 'grant IDs' the current user has. In many
 * cases, the grant IDs will simply be role IDs, but grant IDs can be
 * arbitrary based upon the module.
 *
 * For example, modules can maintain their own lists of users, where each
 * list has an ID. In that case, the module could return a list of all
 * IDs of all lists that the current user is a member of.
 *
 * A node access module may implement as many realms as necessary to
 * properly define the access privileges for the nodes.
 *
 * @param $user
 *   The user object whose grants are requested.
 * @param $op
 *   The node operation to be performed, such as "view", "update", or "delete".
 * @return
 *   An array whose keys are "realms" of grants such as "user" or "role", and
 *   whose values are linear lists of grant IDs.
 *
 * For a detailed example, see node_access_example.module.
 *
 * @ingroup node_access
 */
function hook_node_grants($account, $op) {
  if (user_access('access private content', $account)) {
    $grants['example'] = array(1);
  }
  $grants['example_owner'] = array($user->uid);
  return $grants;
}

/**
 * Set permissions for a node to be written to the database.
 *
 * When a node is saved, a module implementing node access will be asked
 * if it is interested in the access permissions to a node. If it is
 * interested, it must respond with an array of array of permissions for that
 * node.
 *
 * Each item in the array should contain:
 *
 * 'realm'
 *    This should only be realms for which the module has returned
 *    grant IDs in hook_node_grants.
 * 'gid'
 *    This is a 'grant ID', which can have an arbitrary meaning per realm.
 * 'grant_view'
 *    If set to TRUE a user with the gid in the realm can view this node.
 * 'grant_edit'
 *    If set to TRUE a user with the gid in the realm can edit this node.
 * 'grant_delete'
 *    If set to TRUE a user with the gid in the realm can delete this node.
 * 'priority'
 *    If multiple modules seek to set permissions on a node, the realms
 *    that have the highest priority will win out, and realms with a lower
 *    priority will not be written. If there is any doubt, it is best to
 *    leave this 0.
 *
 * @ingroup node_access
 */
function hook_node_access_records($node) {
  if (node_access_example_disabling()) {
    return;
  }

  // We only care about the node if it has been marked private. If not, it is
  // treated just like any other node and we completely ignore it.
  if ($node->private) {
    $grants = array();
    $grants[] = array(
      'realm' => 'example',
      'gid' => TRUE,
      'grant_view' => TRUE,
      'grant_update' => FALSE,
      'grant_delete' => FALSE,
      'priority' => 0,
    );

    // For the example_author array, the GID is equivalent to a UID, which
    // means there are many many groups of just 1 user.
    $grants[] = array(
      'realm' => 'example_author',
      'gid' => $node->uid,
      'grant_view' => TRUE,
      'grant_update' => TRUE,
      'grant_delete' => TRUE,
      'priority' => 0,
    );
    return $grants;
  }
}

/**
 * Alter permissions for a node before it is written to the database.
 *
 * Node access modules establish rules for user access to content. Node access
 * records are stored in the {node_access} table and define which permissions
 * are required to access a node. This hook is invoked after node access modules
 * returned their requirements via hook_node_access_records(); doing so allows
 * modules to modify the $grants array by reference before it is stored, so
 * custom or advanced business logic can be applied.
 *
 * @see hook_node_access_records()
 *
 * Upon viewing, editing or deleting a node, hook_node_grants() builds a
 * permissions array that is compared against the stored access records. The
 * user must have one or more matching permissions in order to complete the
 * requested operation.
 *
 * @see hook_node_grants()
 * @see hook_node_grants_alter()
 *
 * @param &$grants
 *   The $grants array returned by hook_node_access_records().
 * @param $node
 *   The node for which the grants were acquired.
 *
 * The preferred use of this hook is in a module that bridges multiple node
 * access modules with a configurable behavior, as shown in the example
 * by the variable 'example_preview_terms'. This variable would
 * be a configuration setting for your module.
 *
 * @ingroup node_access
 */
function hook_node_access_records_alter(&$grants, $node) {
  // Our module allows editors to tag specific articles as 'preview'
  // content using the taxonomy system. If the node being saved
  // contains one of the preview terms defined in our variable
  // 'example_preview_terms', then only our grants are retained,
  // and other grants are removed. Doing so ensures that our rules
  // are enforced no matter what priority other grants are given.
  $preview = variable_get('example_preview_terms', array());
  // Check to see if we have enabled complex behavior.
  if (!empty($preview)) {
    foreach ($preview as $term_id) {
      if (isset($node->taxonomy[$term_id])) {
        // Our module grants are set in $grants['example'].
        $temp = $grants['example'];
        // Now remove all module grants but our own.
        $grants = array('example' => $temp);
        // No need to check additonal terms.
        break;
      }
    }
  }
}

/**
 * Alter user access rules when trying to view, edit or delete a node.
 *
 * Node access modules establish rules for user access to content.
 * hook_node_grants() defines permissions for a user to view, edit or
 * delete nodes by building a $grants array that indicates the permissions
 * assigned to the user by each node access module. This hook is called to allow
 * modules to modify the $grants array by reference, so the interaction of
 * multiple node access modules can be altered or advanced business logic can be
 * applied.
 *
 * @see hook_node_grants()
 *
 * The resulting grants are then checked against the records stored in the
 * {node_access} table to determine if the operation may be completed.
 *
 * @see hook_node_access_records()
 * @see hook_node_access_records_alter()
 *
 * @param &$grants
 *   The $grants array returned by hook_node_grants().
 * @param $account
 *   The user account requesting access to content.
 * @param $op
 *   The operation being performed, 'view', 'update' or 'delete'.
 *
 * Developers may use this hook to either add additional grants to a user
 * or to remove existing grants. These rules are typically based on either the
 * permissions assigned to a user role, or specific attributes of a user
 * account.
 *
 * @ingroup node_access
 */
function hook_node_grants_alter(&$grants, $account, $op) {
  // Our sample module never allows certain roles to edit or delete
  // content. Since some other node access modules might allow this
  // permission, we expressly remove it by returning an empty $grants
  // array for roles specified in our variable setting.

  // Get our list of banned roles.
  $restricted = variable_get('example_restricted_roles', array());

  if ($op != 'view' && !empty($restricted)) {
    // Now check the roles for this account against the restrictions.
    foreach ($restricted as $role_id) {
      if (isset($user->roles[$role_id])) {
        $grants = array();
      }
    }
  }
}

/**
 * Add mass node operations.
 *
 * This hook enables modules to inject custom operations into the mass operations
 * dropdown found at admin/content/node, by associating a callback function with
 * the operation, which is called when the form is submitted. The callback function
 * receives one initial argument, which is an array of the checked nodes.
 *
 * @return
 *   An array of operations. Each operation is an associative array that may
 *   contain the following key-value pairs:
 *   - "label": Required. The label for the operation, displayed in the dropdown menu.
 *   - "callback": Required. The function to call for the operation.
 *   - "callback arguments": Optional. An array of additional arguments to pass to
 *     the callback function.
 *
 */
function hook_node_operations() {
  $operations = array(
    'approve' => array(
      'label' => t('Approve the selected posts'),
      'callback' => 'node_operations_approve',
    ),
    'promote' => array(
      'label' => t('Promote the selected posts'),
      'callback' => 'node_operations_promote',
    ),
    'sticky' => array(
      'label' => t('Make the selected posts sticky'),
      'callback' => 'node_operations_sticky',
    ),
    'demote' => array(
      'label' => t('Demote the selected posts'),
      'callback' => 'node_operations_demote',
    ),
    'unpublish' => array(
      'label' => t('Unpublish the selected posts'),
      'callback' => 'node_operations_unpublish',
    ),
    'delete' => array(
      'label' => t('Delete the selected posts'),
    ),
  );
  return $operations;
}

/**
 * Act on node deletion.
 *
 * @param $node
 *   The node that is being deleted.
 */
function hook_node_delete($node) {
  db_delete('mytable')
    ->condition('nid', $node->nid)
    ->execute();
}

/**
 * A revision of the node is deleted.
 *
 * You can delete data associated with that revision.
 *
 * @param $node
 *   The node the action is being performed on.
 */
function hook_node_delete_revision($node) {
  db_delete('upload')->condition('vid', $node->vid)->execute();
  if (!is_array($node->files)) {
    return;
  }
  foreach ($node->files as $file) {
    file_delete($file);
  }
}

/**
 * Respond to node insertion.
 *
 * Take action when a new node of any type is being inserted in the database.
 *
 * @param $node
 *   The node the action is being performed on.
 */
function hook_node_insert($node) {
  db_insert('mytable')
    ->fields(array(
      'nid' => $node->nid,
      'extra' => $node->extra,
    ))
    ->execute();
}

/**
 * Act on node objects when loaded.
 *
 * This hook allows you to add information to node objects when loaded from
 * the database. It takes an array of nodes indexed by nid as its first
 * parameter. For performance reasons, information for all available nodes
 * should be loaded in a single query where possible.
 *
 * The types of all nodes being passed in are also available in the $types
 * parameter. If your module keeps track of the node types it supports, this
 * allows for an early return if nothing needs to be done.
 *
 * Due to the internal cache in node_load_multiple(), you should not use this
 * hook to modify information returned from the {node} table itself, since
 * this may affect the way nodes are returned from the cache in subsequent
 * calls to the function.
 *
 * @see comment_node_load()
 * @see taxonomy_node_load()
 * @see forum_node_load()
 *
 * @param $nodes
 *   An array of node objects indexed by nid.
 * @param $types
 *   An array containing the types of the nodes.
 */
function hook_node_load($nodes, $types) {
  $result = db_query('SELECT nid, foo FROM {mytable} WHERE nid IN(:nids)', array(':nids' => array_keys($nodes)));
  foreach ($result as $record) {
    $nodes[$record->nid]->foo = $record->foo;
  }
}

/**
 * The node is about to be shown on the add/edit form.
 *
 * @param $node
 *   The node the action is being performed on.
 */
function hook_node_prepare($node) {
  if (!isset($node->comment)) {
    $node->comment = variable_get("comment_$node->type", COMMENT_NODE_OPEN);
  }
}

/**
 * The node is being cloned for translation.
 *
 * This hook can be used to load additional data or copy values from
 * $node->translation_source.
 *
 * @param $node
 *   The node the action is being performed on.
 */
function hook_node_prepare_translation($node) {
}

/**
 * The node is being displayed as a search result.
 *
 * If you want to display extra information with the result, return it.
 *
 * @param $node
 *   The node the action is being performed on.
 * @return
 *   Extra information to be displayed with search result.
 */
function hook_node_search_result($node) {
  $comments = db_query('SELECT comment_count FROM {node_comment_statistics} WHERE nid = :nid', array('nid' => $node->nid))->fetchField();
  return format_plural($comments, '1 comment', '@count comments');
}

/**
 * The node passed validation and is about to be saved.
 *
 * Modules may make changes to the node before it is saved to the database.
 *
 * @param $node
 *   The node the action is being performed on.
 */
function hook_node_presave($node) {
  if ($node->nid && $node->moderate) {
    // Reset votes when node is updated:
    $node->score = 0;
    $node->users = '';
    $node->votes = 0;
  }
}

/**
 * The node being updated.
 *
 * @param $node
 *   The node the action is being performed on.
 */
function hook_node_update($node) {
  db_update('mytable')
    ->fields(array('extra' => $node->extra))
    ->condition('nid', $node->nid)
    ->execute();
}

/**
 * The node is being indexed.
 *
 * If you want additional information to be indexed which is not already
 * visible through node "view", then you should return it here.
 *
 * @param $node
 *   The node the action is being performed on.
 * @return
 *   Array of additional information to be indexed.
 */
function hook_node_update_index($node) {
  $text = '';
  $comments = db_query('SELECT subject, comment, format FROM {comment} WHERE nid = :nid AND status = :status', array(':nid' => $node->nid, ':status' => COMMENT_PUBLISHED));
  foreach ($comments as $comment) {
    $text .= '<h2>' . check_plain($comment->subject) . '</h2>' . check_markup($comment->comment, $comment->format, '', FALSE);
  }
  return $text;
}

/**
 * The user has finished editing the node and is previewing or submitting it.
 *
 * This hook can be used to check the node data. Errors should be set with
 * form_set_error().
 *
 * @param $node
 *   The node the action is being performed on.
 * @param $form
 *   The $form parameter from node_validate().
 */
function hook_node_validate($node, $form) {
  if (isset($node->end) && isset($node->start)) {
    if ($node->start > $node->end) {
      form_set_error('time', t('An event may not end before it starts.'));
    }
  }
}

/**
 * The node content is being assembled before rendering.
 *
 * TODO D7 This needs work to clearly explain the different build modes.
 *
 * The module may add elements to $node->content prior to rendering. This hook
 * will be called after hook_view(). The structure of $node->content is a
 * renderable array as expected by drupal_render().
 *
 * When $build_mode is 'rss', modules can also add extra RSS elements and
 * namespaces to $node->rss_elements and $node->rss_namespaces respectively for
 * the RSS item generated for this node.
 * For details on how this is used @see node_feed()
 *
 * @see taxonomy_node_view()
 * @see upload_node_view()
 * @see comment_node_view()
 *
 * @param $node
 *   The node the action is being performed on.
 * @param $build_mode
 *   The $build_mode parameter from node_build().
 */
function hook_node_view($node, $build_mode) {
  $node->content['my_additional_field'] = array(
    '#value' => $additional_field,
    '#weight' => 10,
    '#theme' => 'mymodule_my_additional_field',
  );
}

/**
 * The node content was built, the module may modify the structured content.
 *
 * This hook is called after the content has been assembled in $node->content
 * and may be used for doing processing which requires that the complete node
 * content structure has been built.
 *
 * If the module wishes to act on the rendered HTML of the node rather than the
 * structured content array, it may use this hook to add a #post_render callback.
 * Alternatively, it could also implement hook_preprocess_node(). See
 * drupal_render() and theme() documentation respectively for details.
 *
 * @param $node
 *   The node the action is being performed on.
 * @param $build_mode
 *   The $build_mode parameter from node_build().
 */
function hook_node_build_alter($node, $build_mode) {
  // Check for the existence of a field added by another module.
  if (isset($node->content['an_additional_field'])) {
    // Change its weight.
    $node->content['an_additional_field']['#weight'] = -10;
  }

  // Add a #post_render callback to act on the rendered HTML of the node.
  $node->content['#post_render'][] = 'my_module_node_post_render';
}

/**
 * Define module-provided node types.
 *
 * This is a hook used by node modules. This hook is required for modules to
 * define one or more node types. It is called to determine the names and the
 * attributes of a module's node types.
 *
 * Only module-provided node types should be defined through this hook. User-
 * provided (or 'custom') node types should be defined only in the 'node_type'
 * database table, and should be maintained by using the node_type_save() and
 * node_type_delete() functions.
 *
 * @return
 *   An array of information on the module's node types. The array contains a
 *   sub-array for each node type, with the machine-readable type name as the
 *   key. Each sub-array has up to 10 attributes. Possible attributes:
 *   - "name": the human-readable name of the node type. Required.
 *   - "module": a string telling Drupal how a module's functions map to hooks
 *      (i.e. if module is defined as example_foo, then example_foo_insert will
 *      be called when inserting a node of that type). This string is usually
 *      the name of the module in question, but not always. Required.
 *   - "description": a brief description of the node type. Required.
 *   - "help": text that will be displayed at the top of the submission form for
 *      this content type. Optional (defaults to '').
 *   - "has_title": boolean indicating whether or not this node type has a title
 *      field. Optional (defaults to TRUE).
 *   - "title_label": the label for the title field of this content type.
 *      Optional (defaults to 'Title').
 *   - "has_body": boolean indicating whether or not this node type has a  body
 *      field. Optional (defaults to TRUE).
 *   - "body_label": the label for the body field of this content type. Optional
 *      (defaults to 'Body').
 *   - "locked": boolean indicating whether the machine-readable name of this
 *      content type can (FALSE) or cannot (TRUE) be edited by a site
 *      administrator. Optional (defaults to TRUE).
 *
 * The machine-readable name of a node type should contain only letters,
 * numbers, and underscores. Underscores will be converted into hyphens for the
 * purpose of contructing URLs.
 *
 * All attributes of a node type that are defined through this hook (except for
 * 'locked') can be edited by a site administrator. This includes the
 * machine-readable name of a node type, if 'locked' is set to FALSE.
 *
 * For a detailed usage example, see node_example.module.
 */
function hook_node_info() {
  return array(
    'book' => array(
      'name' => t('book page'),
      'module' => 'book',
      'description' => t("A book is a collaborative writing effort: users can collaborate writing the pages of the book, positioning the pages in the right order, and reviewing or modifying pages previously written. So when you have some information to share or when you read a page of the book and you didn't like it, or if you think a certain page could have been written better, you can do something about it."),
    )
  );
}

/**
 * Act on node type changes.
 *
 * This hook allows modules to take action when a node type is modified.
 *
 * @param $op
 *   What is being done to $info. Possible values:
 *   - "delete"
 *   - "insert"
 *   - "update"
 * @param $info
 *   The node type object on which $op is being performed.
 */
function hook_node_type($op, $info) {

  switch ($op) {
    case 'delete':
      variable_del('comment_' . $info->type);
      break;
    case 'update':
      if (!empty($info->old_type) && $info->old_type != $info->type) {
        $setting = variable_get('comment_' . $info->old_type, COMMENT_NODE_OPEN);
        variable_del('comment_' . $info->old_type);
        variable_set('comment_' . $info->type, $setting);
      }
      break;
  }
}

/**
 * Define access restrictions.
 *
 * This hook allows node modules to limit access to the node types they
 * define.
 *
 * @param $op
 *   The operation to be performed. Possible values:
 *   - "create"
 *   - "delete"
 *   - "update"
 *   - "view"
 * @param $node
 *   The node on which the operation is to be performed, or, if it does
 *   not yet exist, the type of node to be created.
 * @param $account
 *   A user object representing the user for whom the operation is to be
 *   performed.
 * @return
 *   TRUE if the operation is  to be allowed;
 *   FALSE if the operation is to be denied;
 *   NULL to not override the settings in the node_access table, or access
 *     control modules.
 *
 * The administrative account (user ID #1) always passes any access check,
 * so this hook is not called in that case. If this hook is not defined for
 * a node type, all access checks will fail, so only the administrator will
 * be able to see content of that type. However, users with the "administer
 * nodes" permission may always view and edit content through the
 * administrative interface.
 * @see http://api.drupal.org/api/group/node_access/7
 *
 * For a detailed usage example, see node_example.module.
 *
 * @ingroup node_access
 */
function hook_access($op, $node, $account) {
  if ($op == 'create') {
    return user_access('create stories', $account);
  }

  if ($op == 'update' || $op == 'delete') {
    if (user_access('edit own stories', $account) && ($account->uid == $node->uid)) {
      return TRUE;
    }
  }
}

/**
 * Respond to node deletion.
 *
 * This is a hook used by node modules. It is called to allow the module
 * to take action when a node is being deleted from the database by, for
 * example, deleting information from related tables.
 *
 * @param $node
 *   The node being deleted.
 *
 * To take action when nodes of any type are deleted (not just nodes of
 * the type defined by this module), use hook_node() instead.
 *
 * For a detailed usage example, see node_example.module.
 */
function hook_delete($node) {
  db_delete('mytable')
    ->condition('nid', $nid->nid)
    ->execute();
}

/**
 * This is a hook used by node modules. It is called after load but before the
 * node is shown on the add/edit form.
 *
 * @param $node
 *   The node being saved.
 *
 * For a usage example, see image.module.
 */
function hook_prepare($node) {
  if ($file = file_check_upload($field_name)) {
    $file = file_save_upload($field_name, _image_filename($file->filename, NULL, TRUE));
    if ($file) {
      if (!image_get_info($file->filepath)) {
        form_set_error($field_name, t('Uploaded file is not a valid image'));
        return;
      }
    }
    else {
      return;
    }
    $node->images['_original'] = $file->filepath;
    _image_build_derivatives($node, TRUE);
    $node->new_file = TRUE;
  }
}

/**
 * Display a node editing form.
 *
 * This hook, implemented by node modules, is called to retrieve the form
 * that is displayed when one attempts to "create/edit" an item. This form is
 * displayed at the URI http://www.example.com/?q=node/<add|edit>/nodetype.
 *
 * @param $node
 *   The node being added or edited.
 * @param $form_state
 *   The form state array. Changes made to this variable will have no effect.
 * @return
 *   An array containing the form elements to be displayed in the node
 *   edit form.
 *
 * The submit and preview buttons, taxonomy controls, and administrative
 * accoutrements are displayed automatically by node.module. This hook
 * needs to return the node title, the body text area, and fields
 * specific to the node type.
 *
 * For a detailed usage example, see node_example.module.
 */
function hook_form($node, $form_state) {
  $type = node_type_get_type($node);

  $form['title'] = array(
    '#type' => 'textfield',
    '#title' => check_plain($type->title_label),
    '#required' => TRUE,
  );
  $form['body'] = array(
    '#type' => 'textarea',
    '#title' => check_plain($type->body_label),
    '#rows' => 20,
    '#required' => TRUE,
  );
  $form['field1'] = array(
    '#type' => 'textfield',
    '#title' => t('Custom field'),
    '#default_value' => $node->field1,
    '#maxlength' => 127,
  );
  $form['selectbox'] = array(
    '#type' => 'select',
    '#title' => t('Select box'),
    '#default_value' => $node->selectbox,
    '#options' => array(
      1 => 'Option A',
      2 => 'Option B',
      3 => 'Option C',
    ),
    '#description' => t('Please choose an option.'),
  );

  return $form;
}

/**
 * Respond to node insertion.
 *
 * This is a hook used by node modules. It is called to allow the module
 * to take action when a new node is being inserted in the database by,
 * for example, inserting information into related tables.
 *
 * @param $node
 *   The node being inserted.
 *
 * To take action when nodes of any type are inserted (not just nodes of
 * the type(s) defined by this module), use hook_node() instead.
 *
 * For a detailed usage example, see node_example.module.
 */
function hook_insert($node) {
  db_query("INSERT INTO {mytable} (nid, extra)
    VALUES (%d, '%s')", $node->nid, $node->extra);
}

/**
 * Load node-type-specific information.
 *
 * This is a hook used by node modules. It is called to allow the module
 * a chance to load extra information that it stores about a node. The hook
 * should not be used to replace information from the core {node} table since
 * this may interfere with the way nodes are fetched from cache.
 *
 * @param $nodes
 *   An array of the nodes being loaded, keyed by nid. At call time,
 *   node.module has already loaded the basic information about the nodes, such
 *   as node ID (nid), title, and body.
 *
 * For a detailed usage example, see node_example.module.
 */
function hook_load($nodes) {
  $result = db_query('SELECT nid, foo FROM {mytable} WHERE nid IN (:nids)', array(':nids' => array_keys($nodes)));
  foreach ($result as $record) {
    $nodes[$record->nid]->foo = $record->foo;
  }
}

/**
 * Respond to node updating.
 *
 * This is a hook used by node modules. It is called to allow the module
 * to take action when an edited node is being updated in the database by,
 * for example, updating information in related tables.
 *
 * @param $node
 *   The node being updated.
 *
 * To take action when nodes of any type are updated (not just nodes of
 * the type(s) defined by this module), use hook_node() instead.
 *
 * For a detailed usage example, see node_example.module.
 */
function hook_update($node) {
  db_query("UPDATE {mytable} SET extra = '%s' WHERE nid = %d",
    $node->extra, $node->nid);
}

/**
 * Verify a node editing form.
 *
 * This is a hook used by node modules. It is called to allow the module
 * to verify that the node is in a format valid to post to the site.
 * Errors should be set with form_set_error().
 *
 * @param $node
 *   The node to be validated.
 * @param $form
 *   The node edit form array.
 *
 * To validate nodes of all types (not just nodes of the type(s) defined by
 * this module), use hook_node() instead.
 *
 * Changes made to the $node object within a hook_validate() function will
 * have no effect. The preferred method to change a node's content is to use
 * hook_node_presave() instead. If it is really necessary to change
 * the node at the validate stage, you can use function form_set_value().
 *
 * For a detailed usage example, see node_example.module.
 */
function hook_validate($node, &$form) {
  if (isset($node->end) && isset($node->start)) {
    if ($node->start > $node->end) {
      form_set_error('time', t('An event may not end before it starts.'));
    }
  }
}

/**
 * Display a node.
 *
 * This is a hook used by node modules. It allows a module to define a
 * custom method of displaying its nodes, usually by displaying extra
 * information particular to that node type.
 *
 * @param $node
 *   The node to be displayed, as returned by node_load().
 * @param $build_mode
 *   Build mode, e.g. 'full', 'teaser', ...
 * @return
 *   $node. The passed $node parameter should be modified as necessary and
 *   returned so it can be properly presented. Nodes are prepared for display
 *   by assembling a structured array, formatted as in the Form API, in 
 *   $node->content. As with Form API arrays, the #weight property can be 
 *   used to control the relative positions of added elements. After this
 *   hook is invoked, node_build() calls field_attach_view() to add field
 *   views to $node->content, and then invokes hook_node_view() and 
 *   hook_node_build_alter(), so if you want to affect the final
 *   view of the node, you might consider implementing one of these hooks
 *   instead.
 *
 * For a detailed usage example, see node_example.module.
 */
function hook_view($node, $build_mode = 'full') {
  if ((bool)menu_get_object()) {
    $breadcrumb = array();
    $breadcrumb[] = array('path' => 'example', 'title' => t('example'));
    $breadcrumb[] = array('path' => 'example/' . $node->field1,
      'title' => t('%category', array('%category' => $node->field1)));
    $breadcrumb[] = array('path' => 'node/' . $node->nid);
    menu_set_location($breadcrumb);
  }

  $node->content['myfield'] = array(
    '#value' => theme('mymodule_myfield', $node->myfield),
    '#weight' => 1,
  );

  return $node;
}

/**
 * @} End of "addtogroup hooks".
 */