revisioning.module in Revisioning 6.4

Allows the creation and modification of pre-published as well as live content while the current revision remains unchanged and publicly visible until the changes have been reviewed by a moderator.

File

revisioning.module

<?php

/**
 * @file
 * Allows the creation and modification of pre-published as well as live
 * content while the current revision remains unchanged and publicly visible
 * until the changes have been reviewed by a moderator.
 */
define('REVISIONING_LOAD_CURRENT', 0);

// node/%node/view, node/%node/edit opens current revision
define('REVISIONING_LOAD_LATEST', 1);

// node/%node/view, node/%node/edit opens latest revison
define('NEW_REVISION_WHEN_NOT_PENDING', 0);
define('NEW_REVISION_EVERY_SAVE', 1);
define('REVISIONS_BLOCK_OLDEST_AT_TOP', 0);
define('REVISIONS_BLOCK_NEWEST_AT_TOP', 1);
require_once drupal_get_path('module', 'revisioning') . '/revisioning_api.inc';
require_once drupal_get_path('module', 'revisioning') . '/revisioning.pages.inc';
require_once drupal_get_path('module', 'revisioning') . '/revisioning_theme.inc';
require_once drupal_get_path('module', 'revisioning') . '/revisioning_tokens.inc';
require_once drupal_get_path('module', 'revisioning') . '/revisioning_triggers_actions.inc';

// No need to include Rules integration file - Rules module does it for us automatically.

/**
 * Implementation of hook_help().
 */
function revisioning_help($path, $arg) {
  switch ($path) {
    case 'admin/help#revisioning':
      $s = t('For documentation and tutorials see the <a href="@revisioning">Revisioning project page</a>', array(
        '@revisioning' => url('http://drupal.org/project/revisioning'),
      ));
      break;
    case 'node/%/revisions':
      $s = t('To edit, publish or delete one of the revisions below, click on its saved date.');
      break;
    case 'admin/build/trigger/revisioning':
      $s = t("Below you can assign actions to run when certain publication-related events happen. For example, you could send an e-mail to an author when their content is pubished.");
      break;
    case 'accessible-content/i-created/pending':
      $s = t('Showing all <em>pending</em> content <em>you created</em> and still have at least view access to.');
      break;
    case 'accessible-content/i-last-modified/pending':
      $s = t('Showing all <em>pending</em> content <em>you last modified</em> and still have at least view access to.');
      break;
    case 'accessible-content/i-can-edit/pending':
      $s = t('Showing all <em>pending</em> content you can <em>edit</em>.');
      break;
    case 'accessible-content/i-can-view/pending':
      $s = t('Showing all <em>pending</em> content you have at least <em>view</em> access to.');
      break;
  }
  return empty($s) ? '' : '<p>' . $s . '</p>';
}

/**
 * Implementation of hook_perm().
 *
 * Revisioning permissions. Note that permissions to view, revert and delete
 * revisions already exist in node.module.
 */
function revisioning_perm() {
  $perms = module_exists('module_grants_monitor') ? array(
    'access Pending tab',
  ) : array();
  $perms = array_merge($perms, array(
    'view revision status messages',
    'edit revisions',
    'publish revisions',
    'unpublish current revision',
  ));

  // Add per node-type view perms in same way as edit perms of node module.
  foreach (node_get_types() as $type) {
    $name = check_plain($type->type);
    $perms[] = 'view revisions of own ' . $name . ' content';
    $perms[] = 'view revisions of any ' . $name . ' content';
  }
  return $perms;
}

/**
 * Implementation of hook_menu().
 *
 * Define new menu items.
 * Existing menu items are modified through hook_menu_alter().
 */
function revisioning_menu() {
  $items = array();
  if (module_exists('module_grants_monitor')) {

    // Add a tab to the 'I created' tab (defined in module_grants_monitor.module)
    $items['accessible-content/i-created/pending'] = array(
      'title' => 'In draft/Pending publication',
      'page callback' => '_revisioning_show_pending_nodes',
      'page arguments' => array(
        'view',
        I_CREATED,
      ),
      'access callback' => 'revisioning_user_all_access',
      'access arguments' => array(
        array(
          'access I Created tab',
          'access Pending tab',
        ),
      ),
      'type' => MENU_LOCAL_TASK,
      'weight' => -1,
    );

    // Add a tab to the 'I last modified' tab
    $items['accessible-content/i-last-modified/pending'] = array(
      'title' => 'In draft/Pending publication',
      'page callback' => '_revisioning_show_pending_nodes',
      'page arguments' => array(
        'view',
        I_LAST_MODIFIED,
      ),
      'access callback' => 'revisioning_user_all_access',
      'access arguments' => array(
        array(
          'access I Last Modified tab',
          'access Pending tab',
        ),
      ),
      'type' => MENU_LOCAL_TASK,
      'weight' => -1,
    );

    // Add a tab to the 'I can edit' tab
    $items['accessible-content/i-can-edit/pending'] = array(
      'title' => 'In draft/Pending publication',
      'page callback' => '_revisioning_show_pending_nodes',
      'page arguments' => array(
        'update',
      ),
      'access callback' => 'revisioning_user_all_access',
      'access arguments' => array(
        array(
          'access I Can Edit tab',
          'access Pending tab',
        ),
      ),
      'type' => MENU_LOCAL_TASK,
      'weight' => -1,
    );

    // Add a tab to the 'I can view' tab (defined in module_grants.module)
    $items['accessible-content/i-can-view/pending'] = array(
      'title' => 'In draft/Pending publication',
      'page callback' => '_revisioning_show_pending_nodes',
      'page arguments' => array(
        'view',
      ),
      'access callback' => 'revisioning_user_all_access',
      'access arguments' => array(
        array(
          'access I Can View tab',
          'access Pending tab',
        ),
      ),
      'type' => MENU_LOCAL_TASK,
      'weight' => -1,
    );
  }

  // Callback (not a tab) to allow users to unpublish a node.
  // Note that is a node operation more so than a revision operation, but
  // we let _revisioning_node_revision_access() handle access anyway.
  $items['node/%node/unpublish'] = array(
    //'title' => t(Unpublish current revision'),
    'page callback' => 'drupal_get_form',
    'page arguments' => array(
      'revisioning_unpublish_confirm',
      1,
    ),
    'access callback' => '_revisioning_node_revision_access',
    // _revisioning_node_access ?
    'access arguments' => array(
      'unpublish current revision',
      1,
    ),
    'type' => MENU_CALLBACK,
  );

  // Revision tab local subtasks (i.e. secondary tabs), up to 7 of them:
  //  view, edit, publish, unpublish, revert, delete and compare.
  // All revision operations 'node/%node/revisions/%vid/<op>' are defined as
  // local tasks (tabs) secondary to the primary 'node/%node/revisions' local
  // task (tab).
  // The tricky part is to always set "tab_parent", core does NOT figure this
  // out based on the URL. %vid is optional, see vid_to_arg().
  // Note: the MENU_DEFAULT_LOCAL_TASK for 'node/%node/revisions' is defined in
  //       function revisioning_menu_alter()
  // View revision local subtask
  $items['node/%node/revisions/%vid/view'] = array(
    'title' => 'View',
    'load arguments' => array(
      3,
    ),
    'page callback' => '_revisioning_view_revision',
    'page arguments' => array(
      1,
    ),
    'access callback' => '_revisioning_node_revision_access',
    'access arguments' => array(
      'view revisions',
      1,
    ),
    'type' => MENU_LOCAL_TASK,
    'weight' => -10,
    'tab_parent' => 'node/%/revisions',
  );

  // Edit revision local subtask
  $items['node/%node/revisions/%vid/edit'] = array(
    'title' => 'Edit',
    'load arguments' => array(
      3,
    ),
    'page callback' => '_revisioning_edit_revision',
    'page arguments' => array(
      1,
    ),
    'access callback' => '_revisioning_node_revision_access',
    'access arguments' => array(
      'edit revisions',
      1,
    ),
    'file' => 'node.pages.inc',
    'file path' => drupal_get_path('module', 'node'),
    'type' => MENU_LOCAL_TASK,
    'weight' => -7,
    'tab_parent' => 'node/%/revisions',
  );

  // Publish revision local subtask
  $items['node/%node/revisions/%vid/publish'] = array(
    'title' => 'Publish this',
    'load arguments' => array(
      3,
    ),
    'page callback' => 'drupal_get_form',
    'page arguments' => array(
      'revisioning_publish_confirm',
      1,
    ),
    'access callback' => '_revisioning_node_revision_access',
    'access arguments' => array(
      'publish revisions',
      1,
    ),
    'type' => MENU_LOCAL_TASK,
    'weight' => -4,
    'tab_parent' => 'node/%/revisions',
  );

  // Unpublish node local subtask
  $items['node/%node/revisions/%vid/unpublish'] = array(
    'title' => 'Unpublish this',
    'load arguments' => array(
      3,
    ),
    'page callback' => 'drupal_get_form',
    'page arguments' => array(
      'revisioning_unpublish_confirm',
      1,
    ),
    'access callback' => '_revisioning_node_revision_access',
    'access arguments' => array(
      'unpublish current revision',
      1,
    ),
    'type' => MENU_LOCAL_TASK,
    'weight' => -3,
    'tab_parent' => 'node/%/revisions',
  );

  // Revert to revision local subtask.
  // Difference from core version is %vid that's served by vid_to_arg() function.
  $items['node/%node/revisions/%vid/revert'] = array(
    'title' => 'Revert to this',
    'load arguments' => array(
      3,
    ),
    'page callback' => 'drupal_get_form',
    'page arguments' => array(
      'node_revision_revert_confirm',
      1,
    ),
    'access callback' => '_revisioning_node_revision_access',
    'access arguments' => array(
      'revert revisions',
      1,
    ),
    'file' => 'node.pages.inc',
    'file path' => drupal_get_path('module', 'node'),
    'type' => MENU_LOCAL_TASK,
    'weight' => -2,
    'tab_parent' => 'node/%/revisions',
  );

  // Delete revision local subtask.
  // Difference from core version is %vid that's served by vid_to_arg() function.
  $items['node/%node/revisions/%vid/delete'] = array(
    'title' => 'Delete',
    'load arguments' => array(
      3,
    ),
    'page callback' => 'drupal_get_form',
    'page arguments' => array(
      'node_revision_delete_confirm',
      1,
    ),
    'access callback' => '_revisioning_node_revision_access',
    'access arguments' => array(
      'delete revisions',
      1,
    ),
    'file' => 'node.pages.inc',
    'file path' => drupal_get_path('module', 'node'),
    'type' => MENU_LOCAL_TASK,
    'weight' => 10,
    'tab_parent' => 'node/%/revisions',
  );

  // If Diff module is enabled, provide a compare local subtask
  if (module_exists('diff')) {
    $items['node/%node/revisions/%vid/compare'] = array(
      'title' => 'Compare to current',
      'load arguments' => array(
        3,
      ),
      'page callback' => '_revisioning_compare_to_current_revision',
      'page arguments' => array(
        1,
      ),
      'access callback' => '_revisioning_node_revision_access',
      'access arguments' => array(
        'compare to current',
        1,
      ),
      'type' => MENU_LOCAL_TASK,
      'weight' => 0,
      'tab_parent' => 'node/%/revisions',
    );
  }

  // Finally, the Revisioning configuration menu item
  $items['admin/settings/revisioning'] = array(
    'title' => 'Revisioning',
    'description' => 'Configure how links to view and edit content behave.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array(
      'revisioning_admin_configure',
    ),
    'access arguments' => array(
      'administer site configuration',
    ),
    'file' => 'revisioning.admin.inc',
  );
  return $items;
}

/**
 * Implementation of hook_menu_alter().
 *
 * Modify menu items defined in other modules (in particular the Node and
 * Module Grants modules).
 */
function revisioning_menu_alter(&$items) {

  // Primary tabs for 'node/%node': View tab, Edit tab, Revisions tab ...
  // View tab can be either 'View current' or 'View latest'.
  // It should be suppressed when the 'Revisions' tab shows the same revision,
  // so we need a special access callback for this, which expands on the
  // callback defined in Module Grants.
  $items['node/%node']['access callback'] = $items['node/%node/view']['access callback'] = '_revisioning_view_edit_access_callback';
  $items['node/%node']['access arguments'] = $items['node/%node/view']['access arguments'] = array(
    'view',
    1,
  );
  $items['node/%node']['page callback'] = $items['node/%node/view']['page callback'] = '_revisioning_view';
  $items['node/%node']['page arguments'] = $items['node/%node/view']['page arguments'] = array(
    1,
  );
  $items['node/%node']['title callback'] = $items['node/%node/view']['title callback'] = '_revisioning_title_for_tab';
  $items['node/%node']['title arguments'] = $items['node/%node/view']['title arguments'] = array(
    1,
    FALSE,
  );

  // Edit tab can be either 'Edit current' or 'Edit latest'.
  // It should be suppressed when the 'Revisions' tab shows the same revision,
  // so we need a special access callback for this, which expands on the
  // callback defined in Module Grants.
  $items['node/%node/edit']['access callback'] = '_revisioning_view_edit_access_callback';
  $items['node/%node/edit']['access arguments'] = array(
    'edit',
    1,
  );
  $items['node/%node/edit']['page callback'] = '_revisioning_edit';
  $items['node/%node/edit']['title callback'] = '_revisioning_title_for_tab';
  $items['node/%node/edit']['title arguments'] = array(
    1,
    TRUE,
  );

  // 'Revisions' tab remains but points to new page callback, allowing users to
  // pick the revision to view, edit, publish, revert, unpublish, delete.
  // Need to override _node_revision_access() call back as it disallows access
  // to the 'Revisions' tab when there's only one revision, which will prevent
  // users from getting to the publish/unpublish links.
  $items['node/%node/revisions']['access callback'] = '_revisioning_node_revision_access';
  $items['node/%node/revisions']['access arguments'] = array(
    'view revision list',
    1,
  );
  $items['node/%node/revisions']['page callback'] = '_revisioning_present_node';
  $items['node/%node/revisions']['page arguments'] = array(
    1,
  );

  // Unset old menu items defined in node.module, as these are replaced by
  // ones that use the %vid wildcard instead of % and have proper callbacks.
  unset($items['node/%node/revisions/%/view']);
  unset($items['node/%node/revisions/%/revert']);
  unset($items['node/%node/revisions/%/delete']);
  if (module_exists('diff')) {

    // If Diff module is enabled, make sure it uses correct access callback
    $items['node/%node/revisions/view/%/%']['access callback'] = '_revisioning_node_revision_access';
    $items['node/%node/revisions/view/%/%']['access arguments'] = array(
      'view revisions',
      1,
    );
  }

  // This is here rather than in revisioning_menu() as Diff may redefine
  // the node/%node/revisions/list item.
  $items['node/%node/revisions/list'] = array(
    'title' => 'List all revisions',
    'access callback' => '_revisioning_node_revision_access',
    'access arguments' => array(
      'view revision list',
      1,
    ),
    'file' => 'node.pages.inc',
    'module' => 'node',
    //'file path' => drupal_get_path('module', 'node'),
    'type' => MENU_LOCAL_TASK,
    // was: MENU_DEFAULT_LOCAL_TASK; changed for Smart tabs
    'weight' => -20,
  );

  // Apart from administrators, allow those that pass the 'trigger_access_check'
  // to configure the revisioning triggers. This means that users must have at
  // least 'administer actions' and 'access administration pages' (the latter is
  // to allow them to navigate to the trigger page via the menu).
  if (module_exists('trigger')) {
    $items['admin/build/trigger/revisioning']['access callback'] = 'trigger_access_check';
  }
}

/**
 * Implementation of hook_nodeapi().
 *
 * This function is called serveral times during the node's life cycle, with
 * different node operations passed in.
 *
 * Typically when loading a node for viewing, the order is:
 *   'load', 'view', 'alter'
 *
 * When creating new content:
 *   Before displaying the creation form: 'prepare'
 *   When saving: 'validate', 'presave', 'insert'
 *
 * When editing an existing node:
 *   Before displaying the edit form: 'load', 'prepare'
 *   When saving: 'load', 'validate', 'presave', 'update'
 *
 * The same $op may be requested multiple times during the same HTTP request,
 * especially 'load'.
 */
function revisioning_nodeapi(&$node, $op, $teaser = NULL, $page = NULL) {
  switch ($op) {
    case 'load':

      // called at the end of node_load()
      // The revision_moderation flag may be overridden on the node edit form
      // by users with the "administer nodes" permission
      $node->revision_moderation = node_tools_content_is_moderated($node->type);
      $node->is_pending = _revisioning_node_is_pending($node);

      // Could use following, but this seems old style, i.e. when $node is not a &ref

      //$node_extras['revision_moderation'] = $node->revision_moderation;

      //$node_extras['is_pending'] = $node->is_pending;
      break;
    case 'view':

      // called from called from node_view() before $node is fully built
      break;
    case 'alter':

      // called from node_view() after $node is fully built for display
      if (!$teaser && $node->nid == arg(1) && $node->revision_moderation && user_access('view revision status messages')) {
        drupal_set_message(_revisioning_node_info_msg($node));
      }
      break;
    case 'prepare':

      // presenting edit form
      _revisioning_prepare_msg($node);
      break;
    case 'presave':

      // for edits, called from node_save(), prior to _node_save_revision()
      if ($node->revision_moderation) {

        // Tick-box on edit form
        $node->is_pending = _revisioning_node_is_pending($node);
        if ($node->revision && $node->is_pending && variable_get('new_revisions_' . $node->type, NEW_REVISION_WHEN_NOT_PENDING) == NEW_REVISION_WHEN_NOT_PENDING) {
          drupal_set_message(t('Updating existing copy, not creating new revision as this one is still pending.'));

          // Update the $node object just before it is saved to the db
          $node->revision = FALSE;
        }
        if (!$node->status && user_access('publish revisions') && variable_get('revisioning_auto_publish_' . $node->type, FALSE)) {
          drupal_set_message(t('Auto-publishing this revision.'));
          $node->status = TRUE;

          // Make sure current_revision_id is pointing to right revision or
          // subsequent $op='update' will reset it
          $node->current_revision_id = $node->vid;
        }
      }
      break;
    case 'insert':

      // new node, called from node_save(), after _node_save_revision()
      _revisioning_insert_msg($node);
      break;
    case 'update':

      // new node, called from node_save(), after _node_save_revision()
      if ($node->revision_moderation && isset($node->current_revision_id) && $node->current_revision_id != $node->vid) {

        // Resetting vid back to its originial value, thus creating pending revision
        db_query('UPDATE {node} SET vid=%d WHERE nid=%d', $node->current_revision_id, $node->nid);

        //$node->is_pending = TRUE;
      }
      break;
    case 'delete revision':
      module_invoke_all('revisionapi', 'post delete', $node);
      break;
  }
  return;

  // $node_extras;
}

/**
 * Implementation of hook_block().
 *
 * A block that may be placed on all or selected pages, alerting the user
 * (moderator) when new content has been submitted for review. Shows titles
 * of pending revisions as a series of links (max. number configurable).
 * Clicking a link takes the moderator straight to the revision in question.
 */
function revisioning_block($op = 'list', $delta = 0, $edit = array()) {
  switch ($op) {
    case 'list':

      // Set up the defaults for the Site configuration>>Blocks page
      // Return a list of (1) block(s) and the default values
      $blocks[0]['info'] = t('Pending revisions');
      $blocks[0]['cache'] = BLOCK_NO_CACHE;
      $blocks[0]['weight'] = -10;

      // top of whatever region is chosen
      $blocks[0]['custom'] = FALSE;

      // block is implemented by this module;
      return $blocks;
    case 'configure':
      $form['revisioning_block_num_pending'] = array(
        '#type' => 'textfield',
        '#title' => t('Maximum number of pending revisions displayed'),
        '#default_value' => variable_get('revisioning_block_num_pending', 5),
        '#description' => t('Note: the title of this block mentions the total number of revisions pending, which may be greater than the number of revisions displayed.'),
      );
      $form['revisioning_block_order'] = array(
        '#type' => 'radios',
        '#title' => t('Order in which pending revisions are displayed'),
        '#options' => array(
          REVISIONS_BLOCK_OLDEST_AT_TOP => t('Oldest at top'),
          REVISIONS_BLOCK_NEWEST_AT_TOP => t('Newest at top'),
        ),
        '#default_value' => variable_get('revisioning_block_order', REVISIONS_BLOCK_OLDEST_AT_TOP),
        '#description' => t('Note: order is based on revision timestamps.'),
      );
      $form['revisioning_content_summary_page'] = array(
        '#type' => 'textfield',
        '#title' => t('Page to go to when the block title is clicked'),
        '#default_value' => variable_get('revisioning_content_summary_page', ''),
        '#description' => t('When left blank this will default to %accessible_content, provided Module Grants Montior is enabled and the user has sufficient permissions. Otherwise %admin_content is used, subject to permissions. For any of this to work the above <strong>Block title</strong> field must be left blank.', array(
          '%accessible_content' => 'accessible-content',
          '%admin_content' => 'admin/content/node',
        )),
      );
      return $form;
    case 'save':
      variable_set('revisioning_block_num_pending', (int) $edit['revisioning_block_num_pending']);
      variable_set('revisioning_block_order', (int) $edit['revisioning_block_order']);
      variable_set('revisioning_content_summary_page', $edit['revisioning_content_summary_page']);
      break;
    case 'view':
      $order = variable_get('revisioning_block_order', REVISIONS_BLOCK_OLDEST_AT_TOP) == REVISIONS_BLOCK_OLDEST_AT_TOP ? 'ASC' : 'DESC';
      $nodes = node_tools_get_nodes('update', NO_FILTER, NO_FILTER, NO_FILTER, TRUE, TRUE, 100, 'timestamp ' . $order);
      if (!empty($nodes)) {
        return _theme_revisions_pending_block($nodes);
      }
  }
}

/**
 * Implementation of hook_views_api().
 */
function revisioning_views_api() {
  return array(
    'api' => views_api_version(),
    'path' => drupal_get_path('module', 'revisioning'),
  );
}

/**
 * Perform path manipulations for menu items containing %vid wildcard. $map
 * contains what arg() function returns, eg. $map[0]=='node', $map[1]=='123'.
 *
 * When vid is absent, return $map as empty array. This seems to disable menu
 * items which require a vid context to work. So on the page
 * "node/123/revisions" we won't see tasks like "node/123/revisions/456/edit".
 *
 * An alternative implementation would be to substitute an empty vid with
 * current revision id. In that case we should also change the tab titles
 * (via title callbacks) for an enhanced user experience. For example: we'd
 * change "Edit" to "Edit current".
 *
 * See http://drupal.org/node/500864
 */
function vid_to_arg($arg, &$map, $index) {
  if (empty($arg)) {

    //return node_tools_get_current_node_revision_id($nid = $map[1]);
    $map = array();
    return '';
  }
  return $arg;
}

/**
 * Implementation of hook_user_node_access().
 *
 * @see module_grants_node_revision_access()
 *
 * @param $revision_op
 *   node or revision operation e.g. 'view revisions'
 * @param $node
 * @return the associated node operation required for this revision_op, or
 *   FALSE if access to the node is to be denied.
 *   Valid node operations to return are 'view', 'update', 'delete'.
 */
function revisioning_user_node_access($revision_op, $node) {
  global $user;
  switch ($revision_op) {
    case 'view current':
      break;
    case 'compare to current':
    case 'view revisions':
    case 'view revision list':
      if (user_access('view revisions', $user)) {

        // node.module
        break;
      }
      $type = check_plain($node->type);
      if (user_access('view revisions of any ' . $type . ' content', $user)) {
        break;
      }
      if ($node->uid == $account->uid && user_access('view revisions of own ' . $type . ' content', $user)) {
        break;
      }
      return FALSE;
    case 'edit current':
      return 'update';
    case 'edit revisions':
    case 'revert revisions':
      return user_access($revision_op, $user) ? 'update' : FALSE;
    case 'publish revisions':
    case 'unpublish current revision':
      return user_access($revision_op, $user) ? 'view' : FALSE;
    case 'delete revisions':
      if (!user_access($revision_op, $user)) {
        return FALSE;
      }
    case 'delete node':
      return 'delete';
    default:
      drupal_set_message("Unknown Revisioning operation '{$revision_op}'. Treating as 'view'.", 'warning', FALSE);
  }
  return 'view';
}

/**
 * Test whether the supplied revision operation is appropriate for the node.
 * This is irrespective of user permissions, e.g. even for an administrator it
 * doesn't make sense to publish a node that is already published or to
 * "revert" to the current revision.
 *
 * @param $revision_op
 * @param $node
 * @return TRUE if the operation is appropriate for this node at this point
 */
function _revisioning_operation_appropriate($revision_op, $node) {
  switch ($revision_op) {
    case 'compare to current':

    // Can't compare against itself
    case 'delete revisions':

      // If the revision is the current one, suppress the delete operation
      // @TODO ...unless it's the only revision, in which case delete the
      // entire node; however this requires a different URL.
      return !$node->is_current;
    case 'view revision list':

      // i.e. node revisions summary
      if ($node->num_revisions == 1 && !$node->revision_moderation) {

        // Suppress Revisions tab when when there's only 1 revision -- consistent with core.
        // However, when content is moderated (i.e. "New revision in draft,
        // pending moderation" is ticked) we want to be able to get to the
        // 'Unpublish current' link on this page and the 'Publish this' tab on
        // the next. Also when user has permission to delete node, we need to
        // present the Delete link, unless we assume that this privilege
        // assumes the 'edit' permission.
        return FALSE;
      }
      break;
    case 'publish revisions':

      // If the node isn't meant to be moderated or the revision is not either
      // pending or current but not published, then disallow publication.
      if (!$node->revision_moderation || !($node->is_pending || $node->is_current && !$node->status)) {
        return FALSE;
      }
      break;
    case 'unpublish current revision':

      // If the node isn't meant to be moderated, or it is unpublished already
      // or we're not looking at the current revision, then unpublication is off.
      if (!$node->revision_moderation || !$node->status || !$node->is_current) {
        return FALSE;
      }
      break;
    case 'revert revisions':

      // If this revision is pending or current, suppress the reversion
      if ($node->is_pending || $node->is_current) {
        return FALSE;
      }
      break;
  }
  return TRUE;
}

/**
 * Determine whether the supplied revision operation is permitted on the node.
 * This requires getting through three levels of defence:
 * o Is the operation appropriate for this node at this time, e.g. a node must
 *   not be published if it already is or if it isn't under moderation control
 * o Does the user have permissions to operations of this kind in general?
 * o Does the user have the node access rights (view/update/delete) required
 *   for this operation?
 *
 * @param $revision_op
 *   For instance 'publish revisions', 'delete revisions'
 * @param $node
 * @return bool
 */
function _revisioning_node_revision_access($revision_op, $node) {
  if (!isset($node->num_revisions) || !isset($node->is_current)) {
    drupal_set_message('Node object data incomplete -- have you enabled the Node Tools submodule?', 'warning', FALSE);
  }
  if (!_revisioning_operation_appropriate($revision_op, $node)) {
    return FALSE;
  }
  if (module_exists('module_grants')) {
    $access = module_grants_node_revision_access($revision_op, $node);
  }
  else {

    // Fall back to core to assess permissions (even though they suck)
    $access = ($node_op = revisioning_user_node_access($revision_op, $node)) && node_access($node_op, $node);
  }
  return $access;
}

/**
 * Access callback for 'node/%', 'node/%/view' and 'node/%/edit' links that
 * may appear anywhere on the site.
 * At the time that this function is called the CURRENT revision will already
 * have been loaded by the system. However depending on the value of the
 * 'revisioning_view_callback' and 'revisioning_edit_callback' variables (as
 * set on the admin/settings/revisioning page), this may not be the desired
 * revision.
 * If these variables state that the LATEST revision should be loaded, we need
 * to check at this point whether the user has permission to view this revision.
 *
 * The 'View current' and/or 'Edit current' tabs are suppressed when the current
 * revision is already displayed via one of the Revisions subtabs.
 * The 'View latest' and/or 'Edit latest' tabs are suppressed when the latest
 * revision is already displayed via one of the Revisions subtabs.
 *
 * @param op, must be one of 'view' or 'edit'
 * @param $node
 * @return FALSE if access to the desired revision is denied
 *
 */
function _revisioning_view_edit_access_callback($op, $node) {
  $load_op = _revisioning_load_op($node, $op, TRUE);
  $vid = arg(3);
  if (is_numeric($vid)) {

    // The View, Edit primary tabs are requested indirectly, in the context of
    // the secondary tabs under Revisions, e.g. node/%/revisions/%
    if ($load_op == REVISIONING_LOAD_CURRENT && $vid == $node->current_revision_id) {

      // Suppress 'View current' and 'Edit current' primary tabs when viewing current
      return FALSE;
    }
    if ($load_op == REVISIONING_LOAD_LATEST && $vid == revisioning_get_latest_revision_id($node->nid)) {

      // Suppress 'View latest' and 'Edit latest' primary tabs when viewing latest
      return FALSE;
    }
    return TRUE;
  }
  if ($load_op == REVISIONING_LOAD_LATEST) {

    // _revisioning_load_op has already checked permission to view latest
    return TRUE;
  }
  $revision_op = $op == 'view' ? 'view current' : 'edit current';
  return _revisioning_node_revision_access($revision_op, $node);
}
function _revisioning_load_op($node, $op, $check_access = FALSE) {
  if ($node->revision_moderation) {
    $view_mode = (int) variable_get('revisioning_view_callback', REVISIONING_LOAD_CURRENT);
    $edit_mode = (int) variable_get('revisioning_edit_callback', REVISIONING_LOAD_CURRENT);
    $load_op = $op == 'edit' ? $edit_mode : $view_mode;
    if ($load_op == REVISIONING_LOAD_LATEST) {

      // Site is configured to load latest revision, but we'll only do this if
      // the latest isn't loaded already and the user has the permission to do so.
      $latest_vid = revisioning_get_latest_revision_id($node->nid);
      if ($latest_vid != $node->current_revision_id) {
        if (!$check_access) {
          return REVISIONING_LOAD_LATEST;
        }
        $original_vid = $node->vid;
        $node->vid = $latest_vid;
        $node->is_current = node_tools_revision_is_current($node);
        $revision_op = $op == 'view' ? 'view revisions' : 'edit revisions';
        $access = _revisioning_node_revision_access($revision_op, $node);

        // Restore $node (even though called by value), so that it remains consistent
        $node->vid = $original_vid;
        $node->is_current = node_tools_revision_is_current($node);
        if ($access) {
          return REVISIONING_LOAD_LATEST;
        }
      }
    }
  }
  return REVISIONING_LOAD_CURRENT;
}
function _revisioning_prepare_msg($node) {
  if (!$node->nid) {

    // new node
    return;
  }
  $count = _revisioning_get_number_of_revisions_newer_than($node->vid, $node->nid);
  if ($count == 1) {
    drupal_set_message(t('Please note there is one revision more recent than the one you are about to edit.'), 'warning');
  }
  elseif ($count > 1) {
    drupal_set_message(t('Please note there are !count revisions more recent than the one you are about to edit.', array(
      '!count' => $count,
    )), 'warning');
  }
}
function _revisioning_insert_msg($node) {
  if ($node->status) {
    drupal_set_message(t('Initial revision created and published.'));
  }
  else {
    drupal_set_message(t('Initial draft created, pending publication.'));
  }
}

/**
 * Display all revisions of the supplied node in a themed table with links for
 * the permitted operations above it.
 */
function _revisioning_present_node($node, $op = 'any') {
  return $op == 'edit' && !$node->revision_moderation ? node_page_edit($node) : _theme_revisions_summary($node);
}

/**
 * Menu callback for the primary View tab.
 */
function _revisioning_view($node) {
  if (_revisioning_load_op($node, 'view') == REVISIONING_LOAD_LATEST) {
    $vid_to_load = revisioning_get_latest_revision_id($node->nid);
    $node = node_load($node->nid, $vid_to_load);
  }

  // In node.module, node_page_view() is used to display the current, while
  // node_show() is used for any other revision. The difference between the
  // two is that node_page_view() surpresses the message that tells us we're
  // viewing a revision, which is what we use here because we have our own
  // configurable message.
  return node_page_view($node);
}

/**
 * Callback for the primary Edit tab.
 */
function _revisioning_edit($node) {

  // Use the admin theme if the user specified this for node edit pages
  if (variable_get('node_admin_theme', FALSE)) {
    global $theme, $custom_theme;
    $custom_theme = variable_get('admin_theme', $theme);
  }
  if (_revisioning_load_op($node, 'edit') == REVISIONING_LOAD_LATEST) {
    $vid_to_load = revisioning_get_latest_revision_id($node->nid);
    $node = node_load($node->nid, $vid_to_load);
  }

  // Following is the same as node_page_edit().
  drupal_set_title(check_plain($node->title));
  return drupal_get_form($node->type . '_node_form', $node);
}

/**
 * Callback for the primary View and Edit tabs.
 * @param $node
 * @param $edit, bool
 * @return string
 */
function _revisioning_title_for_tab($node, $edit = FALSE) {
  if ($node->num_revisions <= 1) {
    return $edit ? t('Edit') : t('View');
  }
  $op = $edit ? 'edit' : 'view';
  if (_revisioning_load_op($node, $op) == REVISIONING_LOAD_LATEST) {
    return $edit ? t('Edit latest') : t('View latest');
  }
  return $edit ? t('Edit current') : t('View current');
}

/**
 * Callback to view a particular revision.
 */
function _revisioning_view_revision($node) {
  return node_page_view($node);
}

/**
 * Callback to edit a particular revision.
 */
function _revisioning_edit_revision($node) {

  // Use the admin theme if the user specified this for node edit pages
  if (variable_get('node_admin_theme', FALSE)) {
    global $theme, $custom_theme;
    $custom_theme = variable_get('admin_theme', $theme);
  }
  drupal_set_title(check_plain($node->title));
  return drupal_get_form($node->type . '_node_form', $node);
}

/**
 * Use diff's compare callback to compare specific revision to the current one
 */
if (module_exists('diff')) {
  function _revisioning_compare_to_current_revision($node) {
    module_load_include('inc', 'diff', 'diff.pages');

    // for diff_diffs_show()
    // Make sure that latest of the two revisions is on the right
    if ($node->is_pending) {
      return diff_diffs_show($node, $node->current_revision_id, $node->vid);
    }
    return diff_diffs_show($node, $node->vid, $node->current_revision_id);
  }
}

Functions

Name	Description
revisioning_block	Implementation of hook_block().
revisioning_help	Implementation of hook_help().
revisioning_menu	Implementation of hook_menu().
revisioning_menu_alter	Implementation of hook_menu_alter().
revisioning_nodeapi	Implementation of hook_nodeapi().
revisioning_perm	Implementation of hook_perm().
revisioning_user_node_access	Implementation of hook_user_node_access().
revisioning_views_api	Implementation of hook_views_api().
vid_to_arg	Perform path manipulations for menu items containing %vid wildcard. $map contains what arg() function returns, eg. $map[0]=='node', $map[1]=='123'.
_revisioning_edit	Callback for the primary Edit tab.
_revisioning_edit_revision	Callback to edit a particular revision.
_revisioning_insert_msg
_revisioning_load_op
_revisioning_node_revision_access	Determine whether the supplied revision operation is permitted on the node. This requires getting through three levels of defence: o Is the operation appropriate for this node at this time, e.g. a node must not be published if it already is or if it…
_revisioning_operation_appropriate	Test whether the supplied revision operation is appropriate for the node. This is irrespective of user permissions, e.g. even for an administrator it doesn't make sense to publish a node that is already published or to "revert" to the…
_revisioning_prepare_msg
_revisioning_present_node	Display all revisions of the supplied node in a themed table with links for the permitted operations above it.
_revisioning_title_for_tab	Callback for the primary View and Edit tabs.
_revisioning_view	Menu callback for the primary View tab.
_revisioning_view_edit_access_callback	Access callback for 'node/%', 'node/%/view' and 'node/%/edit' links that may appear anywhere on the site. At the time that this function is called the CURRENT revision will already have been loaded by the system. However…
_revisioning_view_revision	Callback to view a particular revision.

Constants

Name	Description
NEW_REVISION_EVERY_SAVE
NEW_REVISION_WHEN_NOT_PENDING
REVISIONING_LOAD_CURRENT	@file Allows the creation and modification of pre-published as well as live content while the current revision remains unchanged and publicly visible until the changes have been reviewed by a moderator.
REVISIONING_LOAD_LATEST
REVISIONS_BLOCK_NEWEST_AT_TOP
REVISIONS_BLOCK_OLDEST_AT_TOP