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<?php

/**

 * @file

 * Provides functionality to show a diff between two node revisions.

 */

/**

 * Number of items on one page of the revision list.

 */

define('REVISION_LIST_SIZE', 50);

/**

 * Exposed sorting options.

 *

 * No sorting means sorting by delta value for fields.

 */

define('DIFF_SORT_NONE', '0');

/**

 * Exposed sorting options.

 *

 * This normally sorts by the rendered comparison.

 */

define('DIFF_SORT_VALUE', '1');

/**

 * Exposed sorting options.

 *

 * It is up to the field / entity to decide how to handle the sort.

 */

define('DIFF_SORT_CUSTOM', '-1');

/**

 * Implements hook_help().

 */

function diff_help($path, $arg) {

  switch ($path) {

    case 'admin/help#diff':

      $output = '<p>' . t('The Diff module replaces the normal <em>Revisions</em> node tab. Diff enhances the listing of revisions with an option to view the differences between any two content revisions. Access to this feature is controlled with the <em>View revisions</em> permission. The feature can be disabled for an entire content type on the content type configuration page. Diff also provides an optional <em>View changes</em> button while editing a node.') . '</p>';

      return $output;

    case 'node/%/revisions/%/view':

      // The translated strings should match node_help('node/%/revisions').

      return '<p>' . t('Revisions allow you to track differences between multiple versions of your content, and revert back to older versions.') . '</p>';

    case 'node/%/revisions/view/%/%':

      return '<p>' . t('Comparing two revisions:') . '</p>';

  }

}

/**

 * The various states that are available.

 */

function diff_available_states($entity_type = NULL) {

  $states = array(

    'raw' => t('Standard'),

    'raw_plain' => t('Marked down'),

  );

  return $states;

}

/**

 * Implements hook_menu().

 *

 * @todo: Review this.

 */

function diff_menu() {

  /*

   * By using MENU_LOCAL_TASK (and 'tab_parent') we can get the various

   * revision-views to show the View|Edit|Revision-tabs of the node on top,

   * and have the Revisions-tab open. To avoid creating/showing any extra tabs

   * or sub-tabs (tasks below top level) for the various paths (i.e. "Diff",

   * "Show latest" and "Show a specific revision") that need a revision-id (vid)

   * parameter, we make sure to set 'tab_parent' a bit odd. This solution may

   * not be the prettiest one, but by avoiding having two _LOCAL_TASKs sharing

   * a parent that can be accessed by its full path, it seems to work as

   * desired. Breadcrumbs work decently, at least the node link is among the

   * crumbs. For some reason any breadcrumbs "before/above" the node is only

   * seen at 'node/%node/revisions/%/view'.

   */

  // Not used directly, but was created to get the other menu items to work.

  $items['node/%node/revisions/list'] = array(

    'title' => 'List revisions',

    'page callback' => 'diff_diffs_overview',

    'type' => MENU_DEFAULT_LOCAL_TASK,

    'access callback' => 'diff_node_revision_access',

    'access arguments' => array(1),

    'file' => 'diff.pages.inc',

  );

  $items['node/%node/revisions/view'] = array(

    'title' => 'Compare revisions',

    'page callback' => 'diff_diffs_show',

    'page arguments' => array(1, 4, 5, 6),

    'type' => MENU_LOCAL_TASK,

    'access callback' => 'diff_node_revision_access',

    'access arguments' => array(1),

    'tab_parent' => 'node/%/revisions/list',

    'file' => 'diff.pages.inc',

  );

  $items['node/%node/revisions/view/latest'] = array(

    'title' => 'Show latest difference',

    'page callback' => 'diff_latest',

    'page arguments' => array(1),

    'type' => MENU_LOCAL_TASK,

    'access callback' => 'diff_node_revision_access',

    'access arguments' => array(1),

    'tab_parent' => 'node/%/revisions/view',

    'file' => 'diff.pages.inc',

  );

  // Administrative settings.

  $items['admin/config/content/diff'] = array(

    'title' => 'Diff',

    'description' => 'Diff settings.',

    'file' => 'diff.admin.inc',

    'page callback' => 'drupal_get_form',

    'page arguments' => array('diff_admin_settings'),

    'access arguments' => array('administer site configuration'),

  );

  $items['admin/config/content/diff/settings'] = array(

    'title' => 'Settings',

    'type' => MENU_DEFAULT_LOCAL_TASK,

    'weight' => -10,

  );

  $items['admin/config/content/diff/fields'] = array(

    'title' => 'Fields',

    'description' => 'Field support and settings overview.',

    'file' => 'diff.admin.inc',

    'page callback' => 'diff_admin_field_overview',

    'access arguments' => array('administer site configuration'),

    'type' => MENU_LOCAL_TASK,

  );

  $items['admin/config/content/diff/fields/%'] = array(

    'title' => 'Global field settings',

    'page callback' => 'drupal_get_form',

    'page arguments' => array('diff_admin_global_field_settings', 5),

    'access arguments' => array('administer site configuration'),

    'type' => MENU_VISIBLE_IN_BREADCRUMB,

    'file' => 'diff.admin.inc',

  );

  $items['admin/config/content/diff/entities'] = array(

    'title' => 'Entities',

    'description' => 'Entity settings.',

    'file' => 'diff.admin.inc',

    'page callback' => 'drupal_get_form',

    'page arguments' => array('diff_admin_global_entity_settings', 'node'),

    'access arguments' => array('administer site configuration'),

    'type' => MENU_LOCAL_TASK,

  );

  $items['admin/config/content/diff/entities/node'] = array(

    'title' => 'Node',

    'type' => MENU_DEFAULT_LOCAL_TASK,

    'weight' => -10,

  );

  return $items;

}

/**

 * Implements hook_menu_alter().

 */

function diff_menu_alter(&$callbacks) {

  // Overwrite the default 'Revisions' page.

  $callbacks['node/%node/revisions']['page callback'] = 'diff_diffs_overview';

  $callbacks['node/%node/revisions']['module'] = 'diff';

  $callbacks['node/%node/revisions']['file'] = 'diff.pages.inc';

  $callbacks['node/%node/revisions/%/view']['tab_parent'] = 'node/%/revisions/list';

  $callbacks['node/%node/revisions/%/revert']['tab_parent'] = 'node/%/revisions/%/view';

  $callbacks['node/%node/revisions/%/delete']['tab_parent'] = 'node/%/revisions/%/view';

  $callbacks['node/%node/revisions']['access callback']

      = $callbacks['node/%node/revisions/%/view']['access callback']

      = $callbacks['node/%node/revisions/%/revert']['access callback']

      = $callbacks['node/%node/revisions/%/delete']['access callback'] = 'diff_node_revision_access';

}

/**

 * Implements hook_admin_paths_alter().

 */

function diff_admin_paths_alter(&$paths) {

  // By default, treat all diff pages as administrative.

  if (variable_get('diff_admin_path_node', 1)) {

    $paths['node/*/revisions/view/*/*'] = TRUE;

  }

}

/**

 * Access callback for the node revisions page.

 */

function diff_node_revision_access($node, $op = 'view') {

  $may_revision_this_type = variable_get('diff_enable_revisions_page_node_' . $node->type, TRUE) || user_access('administer nodes');

  return $may_revision_this_type && _node_revision_access($node, $op);

}

/**

 * Implements hook_hook_info().

 */

function diff_hook_info() {

  $hooks['entity_diff'] = array(

    'group' => 'diff',

  );

  $hooks['diff'] = array(

    'group' => 'diff',

  );

  $hooks['field_diff_view_prepare_alter'] = array(

    'group' => 'diff',

  );

  $hooks['field_diff_view_alter'] = array(

    'group' => 'diff',

  );

  return $hooks;

}

/**

 * Implements hook_entity_info_alter().

 *

 * Although the module only provides an UI for comparing nodes, it has an

 * extendable API for any entity, so we supply two view modes for all entities.

 * - diff_standard: This view mode is used to tell the module how to compare

 *                  individual fields. This is used on the revisions page.

 */

function diff_entity_info_alter(&$entity_info) {

  foreach (array_keys($entity_info) as $entity_type) {

    if (!empty($entity_info[$entity_type]['view modes'])) {

      $entity_info[$entity_type]['view modes'] += array(

        'diff_standard' => array(

          'label' => t('Revision comparison'),

          'custom settings' => FALSE,

        ),

      );

    }

  }

}

/**

 * Implements hook_block_info().

 */

function diff_block_info() {

  return array(

    'inline' => array(

      'info' => t('Inline differences'),

    ),

  );

}

/**

 * Implements hook_block_configure().

 */

function diff_block_configure($delta = '') {

  $form = array();

  switch ($delta) {

    case 'inline':

      $form['bundles'] = array(

        '#type' => 'checkboxes',

        '#title' => t('Enabled content types'),

        '#default_value' => variable_get('diff_show_diff_inline_node_bundles', array()),

        '#options' => node_type_get_names(),

        '#description' => t('Show this block only on pages that display content of the given type(s).'),

      );

      break;

  }

  return $form;

}

/**

 * Implements hook_block_save().

 */

function diff_block_save($delta = '', $edit = array()) {

  switch ($delta) {

    case 'inline':

      variable_set('diff_show_diff_inline_node_bundles', $edit['bundles']);

      break;

  }

}

/**

 * Implements hook_block_view().

 */

function diff_block_view($delta) {

  if ($delta === 'inline' && user_access('view revisions') && ($node = menu_get_object()) && arg(2) !== 'edit') {

    $enabled_types = variable_get('diff_show_diff_inline_node_bundles', array());

    if (!empty($enabled_types[$node->type])) {

      $block = array();

      $revisions = node_revision_list($node);

      if (count($revisions) > 1) {

        $block['subject'] = t('Highlight changes');

        $block['content'] = drupal_get_form('diff_inline_form', $node, $revisions);

      }

      return $block;

    }

  }

}

/**

 * Implements hook_node_view_alter().

 */

function diff_node_view_alter(&$build) {

  $node = $build['#node'];

  if (user_access('view revisions') && in_array($node->type, variable_get('diff_show_diff_inline_node_bundles', array()))) {

    // Ugly but cheap way to check that we are viewing a node's revision page.

    if (arg(2) === 'revisions' && arg(3) === $node->vid) {

      module_load_include('inc', 'diff', 'diff.pages');

      $old_vid = _diff_get_previous_vid(node_revision_list($node), $node->vid);

      $build = array('#markup' => diff_inline_show($node, $old_vid));

    }

    $build['#prefix'] = isset($build['#prefix']) ? "<div id='diff-inline-{$node->nid}'>" . $build['#prefix'] : "<div id='diff-inline-{$node->nid}'>";

    $build['#suffix'] = isset($build['#suffix']) ? $build['#suffix'] . "</div>" : "</div>";

  }

}

/**

 * Implements hook_form_BASE_FORM_ID_alter().

 */

function diff_form_node_form_alter(&$form, $form_state) {

  // Add a 'View changes' button on the node edit form.

  $node = $form['#node'];

  if (variable_get('diff_show_preview_changes_node_' . $node->type, TRUE) && !empty($node->nid)) {

    $form['actions']['preview_changes'] = array(

      '#type' => 'submit',

      '#value' => t('View changes'),

      '#weight' => 12,

      '#submit' => array('diff_node_form_build_preview_changes'),

    );

  }

}

/**

 * Implements hook_form_BASE_FORM_ID_alter().

 */

function diff_form_node_type_form_alter(&$form, $form_state) {

  if (isset($form['type'])) {

    $type = $form['#node_type'];

    $form['diff'] = array(

      '#title' => t('Compare revisions'),

      '#type' => 'fieldset',

      '#group' => 'additional_settings',

      '#tree' => FALSE,

    );

    $form['diff']['diff_show_preview_changes_node'] = array(

      '#type' => 'checkbox',

      '#title' => t('Show <em>View changes</em> button on node edit form'),

      '#weight' => 10,

      '#default_value' => variable_get('diff_show_preview_changes_node_' . $type->type, TRUE),

    );

    $form['diff']['diff_enable_revisions_page_node'] = array(

      '#type' => 'checkbox',

      '#title' => t('Enable the <em>Revisions</em> page for this content type'),

      '#weight' => 11,

      '#default_value' => variable_get('diff_enable_revisions_page_node_' . $type->type, TRUE),

    );

    $options = array();

    $info = entity_get_info('node');

    foreach ($info['view modes'] as $view_mode => $view_mode_info) {

      $options[$view_mode] = $view_mode_info['label'];

    }

    $form['diff']['diff_view_mode_preview_node'] = array(

      '#type' => 'select',

      '#title' => t('Standard comparison preview'),

      '#description' => t('Governs the <em>Current revision</em> view mode when doing standard comparisons.'),

      '#options' => $options,

      '#weight' => 13,

      '#default_value' => variable_get('diff_view_mode_preview_node_' . $type->type, 'full'),

      '#empty_value' => '',

      '#empty_option' => t('- Do not display -'),

    );

  }

}

/**

 * Implements hook_node_type_update().

 *

 * This tracks the diff settings in case the node content type is renamed.

 */

function diff_node_type_update($info) {

  if (!empty($info->old_type) && $info->old_type != $info->type) {

    $type_variables = array(

      'diff_show_preview_changes_node',

      'diff_enable_revisions_page_node',

      'diff_view_mode_preview_node',

    );

    foreach ($type_variables as $prefix) {

      $setting = variable_get($prefix . '_' . $info->old_type, NULL);

      if (isset($setting)) {

        variable_del($prefix . '_' . $info->old_type);

        variable_set($prefix . '_' . $info->type, $setting);

      }

    }

    // Block settings are combined in a single variable.

    $inline_block_types = variable_get('diff_show_diff_inline_node_bundles', array());

    if (isset($inline_block_types[$info->old_type])) {

      if (!empty($inline_block_types[$info->old_type])) {

        $inline_block_types[$info->type] = $info->type;

      }

      unset($inline_block_types[$info->old_type]);

      variable_set('diff_show_diff_inline_node_bundles', $inline_block_types);

    }

  }

}

/**

 * Implements hook_node_type_delete().

 */

function diff_node_type_delete($info) {

  variable_del('diff_show_preview_changes_node_' . $info->type);

  variable_del('diff_enable_revisions_page_node_' . $info->type);

  variable_del('diff_view_mode_preview_node_' . $info->type);

}

/**

 * Submit handler for the 'View changes' action.

 *

 * @see node_form_build_preview()

 */

function diff_node_form_build_preview_changes($form, &$form_state) {

  module_load_include('inc', 'diff', 'diff.pages');

  $old_node = clone node_load($form_state['values']['nid']);

  $node = node_form_submit_build_node($form, $form_state);

  // Create diff of old node and edited node.

  $rows = _diff_body_rows($old_node, $node);

  $header = _diff_default_header(t('Original'), t('Changes'));

  $changes = theme('table__diff__preview', array(

    'header' => $header,

    'rows' => $rows,

    'attributes' => array('class' => 'diff'),

    'colgroups' => _diff_default_cols(),

    'sticky' => FALSE,

  ));

  // Prepend diff to edit form.

  $form_state['node_preview'] = $changes;

  $form_state['rebuild'] = TRUE;

}

/**

 * Implements hook_theme().

 */

function diff_theme() {

  return array(

    'diff_node_revisions' => array(

      'render element' => 'form',

      'file' => 'diff.theme.inc',

    ),

    'diff_header_line' => array(

      'arguments' => array('lineno' => NULL),

      'file' => 'diff.theme.inc',

    ),

    'diff_content_line' => array(

      'arguments' => array('line' => NULL),

      'file' => 'diff.theme.inc',

    ),

    'diff_empty_line' => array(

      'arguments' => array('line' => NULL),

      'file' => 'diff.theme.inc',

    ),

    'diff_inline_form' => array(

      'render element' => 'form',

      'file' => 'diff.theme.inc',

    ),

    'diff_inline_metadata' => array(

      'arguments' => array('node' => NULL),

      'file' => 'diff.theme.inc',

    ),

    'diff_inline_chunk' => array(

      'arguments' => array('text' => '', 'type' => NULL),

      'file' => 'diff.theme.inc',

    ),

  );

}

/**

 * Render the table rows for theme('table').

 *

 * @param string $a

 *   The source string to compare from.

 * @param string $b

 *   The target string to compare to.

 * @param boolean $show_header

 *   Display diff context headers. For example, "Line x".

 * @param array $line_stats

 *   This structure tracks line numbers across multiple calls to DiffFormatter.

 *

 * @return array

 *   Array of rows usable with theme('table').

 */

function diff_get_rows($a, $b, $show_header = FALSE, &$line_stats = NULL) {

  $a = is_array($a) ? $a : explode("\n", $a);

  $b = is_array($b) ? $b : explode("\n", $b);

  if (!isset($line_stats)) {

    $line_stats = array(

      'counter' => array('x' => 0, 'y' => 0),

      'offset' => array('x' => 0, 'y' => 0),

    );

  }

  $formatter = new DrupalDiffFormatter();

  // Header is the line counter.

  $formatter->show_header = $show_header;

  $formatter->line_stats = &$line_stats;

  $diff = new Diff($a, $b);

  return $formatter->format($diff);

}

/**

 * Render and markup a diff of two strings into HTML markup.

 *

 * @param string $a

 *   The source string to compare from.

 * @param string $b

 *   The target string to compare to.

 *

 * @return string

 *   String containing HTML markup.

 */

function diff_get_inline($a, $b) {

  $diff = new DrupalDiffInline($a, $b);

  return $diff->render();

}

/**

 * Form builder: Inline diff controls.

 */

function diff_inline_form($form, $form_state, $node, $revisions) {

  $form = array();

  $form['node'] = array(

    '#type' => 'value',

    '#value' => $node,

  );

  $form['revision'] = array(

    '#type' => 'select',

    '#options' => array(0 => t('- No highlighting -')),

    '#default_value' => (arg(2) === 'revisions' && arg(3) === $node->vid) ? $node->vid : 0,

    '#ajax' => array(

      'callback' => 'diff_inline_ajax',

      'wrapper' => "node-{$node->nid}",

      'method' => 'replace',

    ),

  );

  foreach ($revisions as $revision) {

    $form['revision']['#options'][$revision->vid] = t('@revision by @name', array(

      '@revision' => format_date($revision->timestamp, 'short'),

      '@name' => format_username($revision),

    ));

  }

  $form['submit'] = array(

    '#type' => 'submit',

    '#value' => t('View'),

    '#submit' => array('diff_inline_form_submit'),

    '#attributes' => array('class' => array('diff-js-hidden')),

  );

  return $form;

}

/**

 * AHAH callback for rendering the inline diff of a node.

 */

function diff_inline_ajax($form, $form_state) {

  module_load_include('inc', 'diff', 'diff.pages');

  $node = $form['node']['#value'];

  $vid = isset($form_state['values']['revision']) ? $form_state['values']['revision'] : 0;

  return "<div id='node-{$node->nid}'>" . diff_inline_show($node, $vid) . "</div>";

}

/**

 * Form submission handler for diff_inline_form() for JS-disabled clients.

 */

function diff_inline_form_submit(&$form, &$form_state) {

  if (isset($form_state['values']['revision'], $form_state['values']['node'])) {

    $node = $form_state['values']['node'];

    $vid = $form_state['values']['revision'];

    $form_state['redirect'] = "node/{$node->nid}/revisions/{$vid}/view";

  }

}

/**

 * A helper function to normalise system differences.

 *

 * This handles differences in:

 * - line endings: Mac, Windows and UNIX all use different line endings.

 */

function diff_normalise_text($text) {

  $text = str_replace(array("\r\n", "\r"), "\n", $text);

  return $text;

}

/**

 * A wrapper function for filter_xss() to exclude all tags.

 */

function diff_filter_xss($string) {

  return filter_xss($string, array());

}

/**

 * Helper function to load any CSS or JScript files required by a page or form.

 */

function diff_build_attachments($jscript = FALSE) {

  $attachments = array();

  $theme = variable_get('diff_theme', 'default');

  if ($theme) {

    $attachments['css'] = array(

      drupal_get_path('module', 'diff') . "/css/diff.{$theme}.css",

    );

  }

  $type = variable_get('diff_radio_behavior', 'simple');

  if ($jscript && $type) {

    $attachments['js'] = array(

      drupal_get_path('module', 'diff') . "/js/diff.js",

      array(

        'data' => array('diffRevisionRadios' => $type),

        'type' => 'setting',

      ),

    );

  }

  return $attachments;

}