<?php
// $Id$

/**
 * Number of items on one page of the revision list.
 */
define('REVISION_LIST_SIZE', 50);


// Menu callback - show latest diff for a given node.
function node_diff_latest($node) {
  $revisions = node_revision_list($node);
  $new = array_shift($revisions);
  $old = array_shift($revisions);
  drupal_goto("node/$node->nid/revisions/view/$old->vid/$new->vid");
}

/**
 * Menu callback. Show differences between two node revisions.
 *
 * @param $node
 *   Node on which to perform comparison
 * @param $old_vid
 *   Version ID of the old revision.
 * @param $new_vid
 *   Version ID of the new revision.
 */
function node_diffs_show($node, $old_vid, $new_vid) {

  // Set same title as on the 'Revisions' tab for consistency
  drupal_set_title(t('Revisions for %title', array('%title' => $node->title)));

  $node_revisions = node_revision_list($node);

  $old_node = node_load($node->nid, $old_vid);
  $new_node = node_load($node->nid, $new_vid);

  // Generate table header (date, username, logmessage).
  $old_header = t('!date by !username', array(
    '!date' => l(format_date($old_node->revision_timestamp), "node/$node->nid/revisions/$old_node->vid/view"), 
    '!username' => theme('username', $node_revisions[$old_vid]),
  ));
  $new_header = t('!date by !username', array(
    '!date' => l(format_date($new_node->revision_timestamp), "node/$node->nid/revisions/$new_node->vid/view"), 
    '!username' => theme('username', $node_revisions[$new_vid]),
  ));

  $old_log = $old_node->log != '' ? '<p class="revision-log">'. filter_xss($old_node->log) .'</p>' : '';
  $new_log = $new_node->log != '' ? '<p class="revision-log">'. filter_xss($new_node->log) .'</p>' : '';

  // Generate previous diff/next diff links.
  $next_vid = _diff_get_next_vid($node_revisions, $new_vid);
  if ($next_vid) {
    $next_link = l(t('next diff >'), 'node/'. $node->nid .'/revisions/view/'. $new_vid .'/'. $next_vid);
  }
  else {
    $next_link = '';
  }
  $prev_vid = _diff_get_previous_vid($node_revisions, $old_vid);
  if ($prev_vid) {
    $prev_link = l(t('< previous diff'), 'node/'. $node->nid .'/revisions/view/'. $prev_vid .'/'. $old_vid);
  }
  else {
    $prev_link = '';
  }

  $cols = _diff_default_cols();
  $header = _diff_default_header($old_header, $new_header);
  $rows = array();
  if ($old_log || $new_log) {
    $rows[] = array(
      array(
        'data' => $old_log,
        'colspan' => 2
      ),
      array(
        'data' => $new_log,
        'colspan' => 2
      )
    );
  }
  $rows[] = array(
    array(
      'data' => $prev_link,
      'class' => 'diff-prevlink',
      'colspan' => 2
    ),
    array(
      'data' => $next_link,
      'class' => 'diff-nextlink',
      'colspan' => 2
    )
  );
  $rows = array_merge($rows, _diff_body_rows($old_node, $new_node));
  $output = theme('table', $header, $rows, array('class' => 'diff'), NULL, $cols);

  if ($node->vid == $new_vid) {
    $output .= '<div class="diff-section-title">'. t('Current revision:') .'</div>';
  }
  else {
    $output .= '<div class="diff-section-title">'. t('Revision of !new_date:', array('!new_date' => format_date($new_node->revision_timestamp))) .'</div>';
  }
  // Don't include node links (final argument) when viewing the diff.
  $output .= node_view($new_node, FALSE, FALSE, FALSE);
  return $output;
}

/**
 * Generate an overview table of older revisions of a node.
 */
function node_revisions_overview($form_state, $node) {
  $form = array();

  $form['nid'] = array(
    '#type' => 'hidden',
    '#value' => $node->nid,
  );

  $revision_list = node_revision_list($node);

  if (count($revision_list) > REVISION_LIST_SIZE) {
    // If the list of revisions is longer than the number shown on one page split the array.
    $page = isset($_GET['page']) ? $_GET['page'] : '0';
    $revision_chunks = array_chunk(node_revision_list($node), REVISION_LIST_SIZE);
    $revisions = $revision_chunks[$page];
    // Set up global pager variables as would 'pager_query' do.
    // These variables are then used in the theme('pager') call later.
    global $pager_page_array, $pager_total, $pager_total_items;
    $pager_total_items[0] = count($revision_list);
    $pager_total[0] = ceil(count($revision_list) / REVISION_LIST_SIZE);
    $pager_page_array[0] = max(0, min($page, ((int)$pager_total[0]) - 1));
  }
  else {
    $revisions = $revision_list;
  }

  $revert_permission = FALSE;
  if ((user_access('revert revisions') || user_access('administer nodes')) && node_access('update', $node)) {
    $revert_permission = TRUE;
  }
  $delete_permission = FALSE;
  if (user_access('administer nodes')) {
    $delete_permission = TRUE;
  }

  foreach ($revisions as $revision) {
    $operations = array();
    $revision_ids[$revision->vid] = '';
    if ($revision->current_vid > 0) {
      $form['info'][$revision->vid] = array(
        '#markup' => t('!date by !username', array(
          '!date' => l(format_date($revision->timestamp, 'small'), "node/$node->nid"), 
          '!username' => theme('username', $revision)))
        . (($revision->log != '') ? '<p class="revision-log">'. filter_xss($revision->log) .'</p>' : ''),
      );
    }
    else {
      $form['info'][$revision->vid] = array(
        '#markup' => t('!date by !username', array(
          '!date' => l(format_date($revision->timestamp, 'small'), "node/$node->nid/revisions/$revision->vid/view"), 
          '!username' => theme('username', $revision)))
        . (($revision->log != '') ? '<p class="revision-log">'. filter_xss($revision->log) .'</p>' : '')
      );
      if ($revert_permission) {
        $operations[] = array('#markup' => l(t('revert'), "node/$node->nid/revisions/$revision->vid/revert"));
      }
      if ($delete_permission) {
        $operations[] = array('#markup' => l(t('delete'), "node/$node->nid/revisions/$revision->vid/delete"));
      }
      // Set a dummy, even if the user has no permission for the other
      // operations, so that we can check if the operations array is
      // empty to know if the row denotes the current revision.
      $operations[] = array();
    }
    $form['operations'][$revision->vid] = $operations;

  }
  $new_vid = key($revision_ids);
  next($revision_ids);
  $old_vid = key($revision_ids);
  $form['diff']['old'] = array(
    '#type' => 'radios', 
    '#options' => $revision_ids,
    '#default_value' => $old_vid
  );
  $form['diff']['new'] = array(
    '#type' => 'radios', 
    '#options' => $revision_ids,
    '#default_value' => $new_vid
  );
  $form['submit'] = array(
    '#type' => 'submit', 
    '#value' => t('Show diff')
  );

  if (count($revision_list) > REVISION_LIST_SIZE) {
    $form['#suffix'] = theme('pager', NULL, REVISION_LIST_SIZE, 0);
  }

  return $form;
}

/**
 * Theme function to display the revisions table with means to select
 * two revisions.
 */
function theme_node_revisions_overview($form) {
  $output = '';

  // Overview table:
  $header = array(
    t('Revision'),
    array('data' => drupal_render($form['submit']), 'colspan' => 2),
    array('data' => t('Operations'), 'colspan' => 2)
  );
  if (isset($form['info']) && is_array($form['info'])) {
    foreach (element_children($form['info']) as $key) {
      $row = array();
      if (isset($form['operations'][$key][0])) {
        // Note: even if the commands for revert and delete are not permitted,
        // the array is not empty since we set a dummy in this case.
        $row[] = drupal_render($form['info'][$key]);
        $row[] = drupal_render($form['diff']['old'][$key]);
        $row[] = drupal_render($form['diff']['new'][$key]);
        $row[] = drupal_render($form['operations'][$key][0]);
        $row[] = drupal_render($form['operations'][$key][1]);
        $rows[] = $row;
      }
      else {
        // its the current revision (no commands to revert or delete)
        $row[] = array('data' => drupal_render($form['info'][$key]), 'class' => 'revision-current');
        $row[] = array('data' => drupal_render($form['diff']['old'][$key]), 'class' => 'revision-current');
        $row[] = array('data' => drupal_render($form['diff']['new'][$key]), 'class' => 'revision-current');
        $row[] = array('data' => theme('placeholder', t('current revision')), 'class' => 'revision-current', 'colspan' => '2');
        $rows[] = array(
          'data' => $row,
          'class' => 'error',
        );
      }
    }
  }
  $output .= theme('table', $header, $rows);
  $output .= drupal_render($form);
  return $output;
}

/**
 * Validation for input form to select two revisions.
 */
function node_revisions_overview_validate($form, &$form_state) {
  $old_vid = $form_state['values']['old'];
  $new_vid = $form_state['values']['new'];
  if ($old_vid==$new_vid || !$old_vid || !$new_vid) {
    form_set_error('diff', t('Select different revisions to compare.'));
  }
}

/**
 * Submit handler which redirects to the selected diff page.
 */
function node_revisions_overview_submit($form, &$form_state) {
  // The ids are ordered so the old revision is always on the left.
  $old_vid = min($form_state['values']['old'], $form_state['values']['new']);
  $new_vid = max($form_state['values']['old'], $form_state['values']['new']);
  $form_state['redirect'] =  'node/'. $form_state['values']['nid'] .'/revisions/view/'. $old_vid .'/'. $new_vid;
}

/**
 * Creates an array of rows which represent a diff between $old_node and $new_node.
 *
 * @param $old_node
 *   Node for comparison which will be displayed on the left side.
 * @param $new_node
 *   Node for comparison which will be displayed on the right side.
 */
function _diff_body_rows(&$old_node, &$new_node) {
  drupal_add_css(drupal_get_path('module', 'node') .'/node.css');
  module_load_include('inc', 'node', 'node.diff');
  
  $rows = array();
  $any_visible_change = FALSE;
  $node_diffs = module_invoke_all('diff', $old_node, $new_node);
  
  // We start off assuming all form elements are in the correct order.
  $node_diffs['#sorted'] = TRUE;
  
  // Recurse through all child elements.
  $count = 0;
  foreach (element_children($node_diffs) as $key) {
    // Assign a decimal placeholder weight to preserve original array order.
    if (!isset($node_diffs[$key]['#weight'])) {
      $node_diffs[$key]['#weight'] = $count/1000;
    }
    else {
      // If one of the child elements has a weight then we will need to sort
      // later.
      unset($node_diffs['#sorted']);
    }
    $count++;
  }
  
  // One of the children has a #weight.
  if (!isset($node_diffs['#sorted'])) {
    uasort($node_diffs, "element_sort");
  }
  
  foreach ($node_diffs as $node_diff) {
    $diff = new Diff($node_diff['#old'], $node_diff['#new']);
    $formatter = new DrupalDiffFormatter();
    if (isset($node_diff['#format'])) {
      $formatter->show_header = $node_diff['#format']['show_header'];
    }
    $diff_rows = $formatter->format($diff);
    if (count($diff_rows)) {
      $rows[] = array(
        array(
          'data' => t('Changes to %name', array('%name' => $node_diff['#name'])),
          'class' => 'diff-section-title',
          'colspan' => 4
        )
      );
      $rows = array_merge($rows, $diff_rows);
      $any_visible_change = TRUE;
    }
  }
  if (!$any_visible_change) {
    $rows[] = array(
      array(
        'data' => t('No visible changes'),
        'class' => 'diff-section-title',
        'colspan' => 4
      ),
    );
    // Needed to keep Safari happy.
    $rows[] = array(
      array('data' => ''),
      array('data' => ''),
      array('data' => ''),
      array('data' => ''),
    );
  }
  return $rows;
}

/**
 * Get the entry in the revisions list after $vid.
 * Returns FALSE if $vid is the last entry.
 *
 * @param $node_revisions
 *   Array of node revision IDs in descending order.
 * @param $vid
 *   Version ID to look for.
 */
function _diff_get_next_vid(&$node_revisions, $vid) {
  $previous = NULL;
  foreach ($node_revisions as $revision) {
    if ($revision->vid == $vid) {
      return ($previous ? $previous->vid : FALSE);
    }
    $previous = $revision;
  }
  return FALSE;
}

/**
 * Get the entry in the revision list before $vid.
 * Returns FALSE if $vid is the first entry.
 *
 * @param $node_revisions
 *   Array of node revision IDs in descending order.
 * @param $vid
 *   Version ID to look for.
 */
function _diff_get_previous_vid(&$node_revisions, $vid) {
  $previous = NULL;
  foreach ($node_revisions as $revision) {
    if ($previous && $previous->vid == $vid) {
      return $revision->vid;
    }
    $previous = $revision;
  }
  return FALSE;
}

/**
 * Submit handler for 'Preview changes' button.
 */
function node_form_preview_changes_submit($form, &$form_state) {
  $node = node_form_submit_build_node($form, $form_state);

  // Create diff of old node and edited node
  $rows = _diff_body_rows(node_load($form_state['values']['nid']), $node);
  $cols = _diff_default_cols();
  $header = _diff_default_header();
  $changes = theme('table', $header, $rows, array('class' => 'diff'), NULL, $cols);
  // Prepend diff to edit form
  $form_state['node_preview'] = isset($form_state['node_preview']) ? $changes . $form_state['node_preview'] : $changes;
}

/**
 * Theme function for a header line in the diff.
 */
function theme_diff_header_line($lineno) {
  return '<strong>'. t('Line %lineno', array('%lineno' => $lineno)) .'</strong>';
}

/**
 * Theme function for a content line in the diff.
 */
function theme_diff_content_line($line) {
  return '<div>'. $line .'</div>';
}

/**
 * Theme function for an empty line in the diff.
 */
function theme_diff_empty_line($line) {
  return $line;
}

/**
 * Helper function to create default 'cols' array for diff table.
 */
function _diff_default_cols() {
  return array(
    array(
      array(
        'class' => 'diff-marker',
      ),
      array(
        'class' => 'diff-content',
      ),
      array(
        'class' => 'diff-marker',
      ),
      array(
        'class' => 'diff-content',
      ),
    ),
  );
}

/**
 * Helper function to create default 'header' array for diff table.
 */
function _diff_default_header($old_header = '', $new_header = '') {
  return array(
    array(
      'data' => $old_header,
      'colspan' => 2
    ),
    array(
      'data' => $new_header,
      'colspan' => 2
    )
  );
}