<?php
/**
 * Implements hook_menu().
 */
function extlink_menu() {
  $items = array();
  $items['admin/config/user-interface/extlink'] = array(
    'title' => 'External links',
    'description' => 'Alter the display of external links on the site.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('extlink_admin_settings'),
    'access callback' => 'user_access',
    'access arguments' => array('administer site configuration'),
  );
  return $items;
}

/**
 * Implements hook_page_build().
 */
function extlink_page_build() {
  $path = drupal_get_path('module', 'extlink');
  drupal_add_js($path .'/extlink.js', array('every_page' => TRUE));
  drupal_add_js(array('extlink' => array(
    'extTarget'     => variable_get('extlink_target', 0),
    'extClass'      => variable_get('extlink_class', 'ext'),
    'extLabel'      => check_plain(variable_get('extlink_label', t('(link is external)'))),
    'extImgClass'   => variable_get('extlink_img_class', 0),
    'extSubdomains' => variable_get('extlink_subdomains', 1),
    'extExclude'    => variable_get('extlink_exclude', ''),
    'extInclude'    => variable_get('extlink_include', ''),
    'extCssExclude' => variable_get('extlink_css_exclude', ''),
    'extCssExplicit' => variable_get('extlink_css_explicit', ''),
    'extAlert'      => variable_get('extlink_alert', 0),
    'extAlertText'  => variable_get('extlink_alert_text', 'This link will take you to an external web site. We are not responsible for their content.'),
    'mailtoClass'   => variable_get('extlink_mailto_class', 'mailto'),
    'mailtoLabel'   => check_plain(variable_get('extlink_mailto_label', t('(link sends e-mail)'))),
  )), 'setting');
}

function extlink_admin_settings() {
  $form = array();

  $form['extlink_class'] = array(
    '#type' => 'checkbox',
    '#title' => t('Place an icon next to external links.'),
    '#return_value' => 'ext',
    '#default_value' => variable_get('extlink_class', 'ext'),
    '#description' => t('Places an !icon icon next to external links.', array('!icon' => theme('image', array('path' => drupal_get_path('module', 'extlink') . '/extlink.png', 'alt' => t('External Links icon'))))),
  );

  $form['extlink_mailto_class'] = array(
    '#type' => 'checkbox',
    '#title' => t('Place an icon next to mailto links.'),
    '#return_value' => 'mailto',
    '#default_value' => variable_get('extlink_mailto_class', 'mailto'),
    '#description' => t('Places an !icon icon next to mailto links.', array('!icon' => theme('image',array('path' => drupal_get_path('module', 'extlink') . '/mailto.png', 'alt' => t('Email links icon'))))),
  );

  $form['extlink_img_class'] = array(
    '#type' => 'checkbox',
    '#title' => t('Place an icon next to image links.'),
    '#return_value' => TRUE,
    '#default_value' => variable_get('extlink_img_class', FALSE),
    '#description' => t('If checked, images wrapped in an anchor tag will be treated as external links.'),
  );

  $form['extlink_subdomains'] = array(
    '#type' => 'checkbox',
    '#title' => t('Exclude links with the same primary domain.'),
    '#default_value' => variable_get('extlink_subdomains', 1),
    '#description' => t("For example, a link from 'www.example.com' to the subdomain of 'my.example.com' would be excluded."),
  );

  $form['extlink_target'] = array(
    '#type' => 'checkbox',
    '#title' => t('Open external links in a new window.'),
    '#return_value' => '_blank',
    '#default_value' => variable_get('extlink_target', 0),
  );

  $form['extlink_alert'] = array(
    '#type' => 'checkbox',
    '#title' => t('Display a pop-up warning when any external link is clicked.'),
    '#return_value' => '_blank',
    '#default_value' => variable_get('extlink_alert', 0),
  );

  $form['extlink_alert_text'] = array(
    '#type' => 'textarea',
    '#title' => t('Text to display in the pop-up warning box.'),
    '#rows' => 3,
    '#default_value' => variable_get('extlink_alert_text', 'This link will take you to an external web site.'),
    '#wysiwyg' => FALSE,
    '#states' => array(
      // Only show this field when user opts to display a pop-up warning.
      'visible' => array(
        ':input[name="extlink_alert"]' => array('checked' => TRUE),
      ),
    ),
  );

  $patterns = array(
    '<code>(example\.com)</code> ' . t('Matches example.com.'),
    '<code>(example\.com)|(example\.net)</code> ' . t('Multiple patterns can be strung together by using a pipe. Matches example.com OR example.net.'),
    '<code>(links/goto/[0-9]+/[0-9]+)</code> ' . t('Matches links that go through the <a href="http://drupal.org/project/links">Links module</a> redirect.'),
  );

  $wildcards = array(
    '<code>.</code> ' . t('Matches any character.'),
    '<code>?</code> ' . t('The previous character or set is optional.'),
    '<code>\d</code> ' . t('Matches any digit (0-9).'),
    '<code>[a-z]</code> ' . t('Brackets may be used to match a custom set of characters. This matches any alphabetic letter.'),
  );

  $form['patterns'] = array(
    '#tree' => FALSE,
    '#type' => 'fieldset',
    '#title' => t('Pattern matching'),
    '#collapsible' => TRUE,
    '#collapsed' => TRUE,
    '#description' =>
      '<p>' . t('External links uses patterns (regular expressions) to match the "href" property of links.') . '</p>' .
      t('Here are some common patterns.') .
      theme('item_list', array('items' => $patterns)) .
      t('Common special characters:') .
      theme('item_list', array('items' => $wildcards)) .
      '<p>' . t('All special characters (!characters) must also be escaped with backslashes. Patterns are not case-sensitive. Any <a href="http://www.javascriptkit.com/javatutors/redev2.shtml">pattern supported by JavaScript</a> may be used.', array('!characters' => '<code>^ $ . ? ( ) | * +</code>')) . '</p>',
  );

  $form['patterns']['extlink_exclude'] = array(
    '#type' => 'textfield',
    '#title' => t('Exclude links matching the pattern'),
    '#maxlength' => NULL,
    '#default_value' => variable_get('extlink_exclude', ''),
    '#description' => t('Enter a regular expression for links that you wish to exclude from being considered external.'),
  );

  $form['patterns']['extlink_include'] = array(
    '#type' => 'textfield',
    '#title' => t('Include links matching the pattern'),
    '#maxlength' => NULL,
    '#default_value' => variable_get('extlink_include', ''),
    '#description' => t('Enter a regular expression for internal links that you wish to be considered external.'),
  );

  $form['css_matching'] = array(
    '#tree' => FALSE,
    '#type' => 'fieldset',
    '#title' => t('CSS Matching'),
    '#collapsible' => TRUE,
    '#collapsed' => TRUE,
    '#description' =>
      '<p>' . t('Use CSS selectors to exclude entirely or only look inside explicitly specified classes and IDs for external links.  These will be passed straight to jQuery for matching.') . '</p>',
  );

  $form['css_matching']['extlink_css_exclude'] = array(
    '#type' => 'textarea',
    '#title' => t('Exclude links inside these CSS selectors'),
    '#maxlength' => NULL,
    '#default_value' => variable_get('extlink_css_exclude', ''),
    '#description' => t('Enter a comma-separated list of CSS selectors (ie "#block-block-2 .content, ul.menu")'),
  );

  $form['css_matching']['extlink_css_explicit'] = array(
    '#type' => 'textarea',
    '#title' => t('Only look for links inside these CSS selectors'),
    '#maxlength' => NULL,
    '#default_value' => variable_get('extlink_css_explicit', ''),
    '#description' => t('Enter a comma-separated list of CSS selectors (ie "#block-block-2 .content, ul.menu")'),
  );

  return system_settings_form($form);
}

function extlink_admin_settings_validate($form, &$form_state) {
  // Check if the exclude pattern is a valid regular expression
  if ($exclude = $form_state['values']['extlink_exclude']) {
    // Testing the regex via replace
    $regexeval = @preg_replace('/' . $exclude . '/', '', 'Lorem ipsum');
    // If the regex returns NULL, then throw an error and reset the variable
    if ($regexeval === NULL) {
      form_set_error('extlink_exclude', t('Invalid regular expression.'));
      variable_set('extlink_exclude', '');
    }
  }
  // Check if the include pattern is a valid regular expression
  if ($include = $form_state['values']['extlink_include']) {
  // Testing the regex via replace
  $regexeval = @preg_replace('/' . $include . '/', '', 'Lorem ipsum');
    // If the regex returns NULL, then throw an error and reset the variable
    if ($regexeval === NULL) {
      form_set_error('extlink_include', t('Invalid regular expression.'));
      variable_set('extlink_include', '');
    }
  }
}
