<?php
// $Id$

/**
 * @file
 * Lets users make redirects to external sites in the form http://example.com/go/alias.
 *
 * These addresses are tracked and redirected to the external site.
 */

function go_help($section) {
  switch ($section) {
    case 'admin/modules#description':
      return t('Allows you to make redirects to external sites in the form http://example.com/go/alias');
    case 'admin/build/go':
      return t('This is a list of all aliases currently set up.');
    case 'admin/help#go':
      return t('
<h3> Go module </h3>
This module allows you to create links to external sites in the form: <br />
<pre>    http://example.com/go/your_alias </pre> <br />
Where <em>your_alias<em> is whatever you choose. These addresses are intercepted and redirected to the external site. <br />
<br />
Go module can be useful for monitoring the number of people on your mailing list who follow any links you include.
');
  }
} 


/**
 * Implementation of hook_menu().
 */
function go_menu($may_cache) {
  $items = array();
  if ($may_cache) {
    $items[] = array(
      'path' => 'admin/build/go',
      'title' => t('External redirects'),
      'callback' => 'go_admin',
      'access' => user_access('administer external redirects')
    );
    $items[] = array(
      'path' => 'admin/build/go/edit',
      'title' => t('Edit redirect'),
      'callback' => 'drupal_get_form',
      'callback arguments' => array('go_entry_form'),
      'access' => user_access('administer external redirects'),
      'type' => MENU_CALLBACK
    );
    $items[] = array(
      'path' => 'admin/build/go/delete',
      'title' => t('Delete redirect'),
      'callback' => 'go_admin_delete',
      'access' => user_access('administer external redirects'),
      'type' => MENU_CALLBACK
    );
    $items[] = array(
      'path' => 'admin/build/go/list',
      'title' => t('List'),
      'type' => MENU_DEFAULT_LOCAL_TASK,
      'weight' => -10);
    $items[] = array(
      'path' => 'admin/build/go/add',
      'title' => t('Add'),
      'callback' => 'drupal_get_form',
      'callback arguments' => array('go_entry_form'),
      'access' => user_access('administer external redirects'),
      'type' => MENU_LOCAL_TASK
    );
  }
  return $items;
}

/**
 * Menu callback; presents an overview of all URL aliases.
 */
function go_admin() {
  print theme('page', go_overview());
}

/**
 * Menu callback; handles page for editing URL aliases.
 */
function go_entry_form($redirect = NULL) {
  $form['redirect'] = array(
    '#type' => 'fieldset',
    '#title' => t('External link'),
  );
  $form['redirect']['alias'] = array(
    '#type'        => 'textfield',
    '#title'       => t('Alias'),
    '#description' => t('Specify the alias you wish to use. This will appear in the redirect address like: %url.',
                          array('%url' => 'http://'. $_SERVER['HTTP_HOST'] . base_path() .'go/alias')),
    '#size'        => 50,
    '#maxlength'   => 64,
  );
  $form['redirect']['dest'] = array(
    '#type'        => 'textfield',
    '#title'       => t('Target'),
    '#description' => t('Specify the external website to which you want this address to redirect.'),
    '#size'        => 50,
    '#maxlength'   => 64,
  );
  $form['redirect']['submit'] = array(
    '#type' => 'submit',
    '#value' => t('Add'),
  );
  if ($redirect) {
    $redirect = go_load($redirect);
    $form['redirect']['alias']['#default_value'] = $redirect['alias'];
    $form['redirect']['alias']['#disabled'] = TRUE;
    $form['redirect']['dest']['#default_value'] = $redirect['dest'];
    $form['redirect']['submit']['#value'] = t('Update');
    $form['go_edit'] = array(
      '#type' => 'hidden',
      '#value' => 1,
    );
  }
  $form['#validate'] = array(
    'go_entry_form_validate' => array(),
  );
  return $form;
}

function go_entry_form_validate($form_id, $form_values) {
  if (empty($_POST['go_edit']) && db_result(db_query("SELECT COUNT(dest) FROM {go} WHERE alias = '%s'", $form_values['alias']))) {
    form_set_error('alias', t('The alias %alias has already been used.', array('%alias' => $form_values['alias'])));
  }
  if (!valid_url($form_values['dest'], TRUE)) {
    form_set_error('dest', t('The url %dest is invalid.', array('%dest' => $form_values['dest'])));
  }
}

/**
 * Verify that a new URL alias is valid, and save it to the database.
 */
function go_entry_form_submit($form_id, $form_values) {
  if (db_result(db_query("SELECT COUNT(dest) FROM {go} WHERE alias = '%s'", $form_values['alias']))) {
    db_query("UPDATE {go} SET dest = '%s', type = '%d' WHERE alias = '%s'",
             $form_values['dest'], $form_values['type'], $form_values['alias']);
  }
  else {
    db_query("INSERT INTO {go} (alias, dest, type) VALUES ('%s', '%s', '%d')",
             $form_values['alias'], $form_values['dest'], $form_values['type']);
  }
  drupal_set_message(t('External redirect has been saved.'));
  drupal_goto('admin/build/go');
}

function go_confirm_delete($alias) {
  return confirm_form(array(),
    t('Are you sure you want to delete the external redirect %alias?', array('%alias' => $alias)),
    'admin/build/go/edit/'. $alias,
    t('This action cannot be undone.'),
    t('Delete'), t('Cancel'));
}

/**
 * Delete an external redirect.
 *
 * @param $alias The alias of the external redirect to be deleted.
 */
function go_delete($alias) {
  db_query("DELETE FROM {go} WHERE alias = '%s'", $alias);
  watchdog('go', t('Deleted external redirect: %alias.', array('%alias' => $alias)), WATCHDOG_NOTICE);
  drupal_set_message(t('%alias has been deleted.', array('%alias' => $alias)));
}

/**
 * Menu callback; handles deletion of an URL alias.
 */
function go_admin_delete($alias) {
  if (!empty($_POST['confirm'])) {
    go_delete($alias);
    drupal_goto('admin/build/go');
  }
  else {
    return drupal_get_form('go_confirm_delete', $alias);
  }
}

/**
 * Return a listing of all defined external redirects
 */
function go_overview() {
  $sql = 'SELECT * FROM {go}';
  $header = array(
    array('data' => t('Alias'), 'field' => 'alias', 'sort' => 'asc'),
    array('data' => t('Target'), 'field' => 'dest'),
    //array('data' => t('Type'), 'field' => 'type'), - Only one type atm
    array('data' => t('Count'), 'field' => 'count'),
    array('data' => t('Operations'), 'colspan' => 2)
  );
  $sql .= tablesort_sql($header);
  $result = pager_query($sql, 50);

  while ($data = db_fetch_object($result)) {
    $rows[] = array(l($data->alias, "go/$data->alias", array('target' => '_blank')), $data->dest, intval($data->count), l(t('edit'), "admin/build/go/edit/$data->alias"), l(t('delete'), "admin/build/go/delete/$data->alias"));
  }

  if ($pager = theme('pager', NULL, 50, 0)) {
    $rows[] = array(array('data' => $pager, 'colspan' => '5'));
  }

  if (!$rows) {
    $rows[] = array(array('data' => t('No redirects set.'), 'colspan' => '5'));
  }

  return theme('table', $header, $rows);
}

/**
 * Fetch a specific URL alias from the database.
 */
function go_load($alias) {
  return db_fetch_array(db_query_range("SELECT * FROM {go} WHERE alias = '%s'", $alias, 0, 1));
}

function go_init() {
  // Is this a 'go' type node
  if (substr($_GET['q'], 0, 3) == 'go/') {
    $alias = substr($_GET['q'], 3); // Get the alias
    $result = go_load($alias);
    // Update the count
    db_query("UPDATE {go} SET count = count + 1 WHERE alias = '%s'", $alias);
    // Redirect
    switch ($result['type']) {
      case '0':
        // direct: Straight redirect
        header('Location: '.$result['dest']);
        die();
        break;
      case '1':
        // frame: Inside a frameset
        require_once 'frameset.inc';
        die();
        break;
      case '2':
        // splash: Exit splashscreen, with meta refresh after n seconds
        die();
        break;
      case '3':
        // manual: Exit splash with manual click through
        die();
        break;
    }
  }
}

function go_perm() {
  return array('administer external redirects');
}

?>