Comment Paths

<?php

/**
 * Implements hook_hook_info().
 */
function comment_paths_hook_info() {
  $info['comment_paths'] = array('group' => 'comment_paths');
  return $info;
}

/**
 * Implements hook_help().
 */
function comment_paths_help($path, $arg) {
  switch ($path) {
    case 'admin/help#comment_paths':
      $output = '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('Allow custom paths for comments') . '</p>';
      return $output;
  }
}

/**
 * Implements hook_boot().
 * To make the module load prior to bootstrap
 */
function comment_paths_boot() {}

/**
 * Implements hook_url_inbound_alter().
 */
function comment_paths_url_inbound_alter(&$path, $original_path, $path_language) {
  // check if this is a comment URL
  if(preg_match('@^([^\?]+)/comment/(add|edit|reply|delete)(/(\d+))?$@', $original_path, $matches)) {
    // Get the internal path of the node (blog/title)/comment/action
    // Where blog/title is the alias of the node
    $source_path = drupal_lookup_path('source', $matches[1]);

    if(!$source_path) {
      return;
    }

    // Get the node ID
    preg_match('@^node/(\d+)$@', $source_path, $node_match);
    $nid = isset($node_match[1]) ? intval($node_match[1]) : 0;

    if(!$nid) {
      return;
    }

    $node = node_load($nid);

    // Stop if no node is found
    if(!$node) {
      return;
    }

    // Actions that requires comment ID
    $comment_id_actions = array('edit', 'reply', 'delete');

    // 'Add' actions, requires no comment ID
    $comment_add_actions = array('add');

    // Set the action (edit/reply/delete/add)
    $action = $matches[2];
    $comment_id = isset($matches[4]) ? intval($matches[4]) : 0;

    // Change the path for comment ID actions
    if(in_array($action, $comment_id_actions) && $comment_id) {
      $path = 'comment/' . ($action == 'reply' ? "reply/{$node->nid}/{$comment_id}" : "{$comment_id}/{$action}");
    }

    // Change the path for add actions
    if(in_array($action, $comment_add_actions)) {
      $path = "comment/reply/{$node->nid}";
    }
  }
}

/**
 * Implements hook_url_outbound_alter().
 */
function comment_paths_url_outbound_alter(&$path, &$options, $original_path) {
  // Match paths starting with comment/*
  if(preg_match('@^comment/(reply|\d+)(/(\w+|\d+)(/(\d+))?)?@', $path, $matches)) {

    // If action is reply the structure in the URL is a little different from the other actions
    if($matches[1] === 'reply') {

      // If there is no nodeID, exit the function
      if(!isset($matches[3]) || !preg_match('@^[0-9]+$@', $matches[3])) {
        return;
      }

      $nid = intval($matches[3]);
      $action = 'reply';

      // If commentID is defined, extract it
      if(isset($matches[5])) {
        $cid = intval($matches[5]);
      } else {
        $action = 'add';
      }
    } else {
      // All the other actions should have a commentID
      $cid = intval($matches[1]);

      if(count($matches) > 3) {
        $action = $matches[3];
      }
    }

    // If there is no nodeID from the URL, load it from the comment
    if(!isset($nid)) {
      $comment = comment_load($cid);

      if(!$comment) {
        return;
      }

      $nid = $comment->nid;
    }

    // Build path from the node alias
    $path_builder = drupal_get_path_alias("node/{$nid}");

    // If no action is set, it's a comment permalink
    if(!isset($action)) {
      $path = $path_builder;
      $options['fragment'] = "comment-{$cid}";
      return;
    }

    $path_builder .= "/comment/{$action}";

    // Add the commentID, only 'add' will not have this
    if(isset($cid)) {
      $path_builder .= "/{$cid}";
    }

    $path = $path_builder;
  }
}