From c1f160ce691b7eb82eae6d4a5c1b7b76da5f8737 Mon Sep 17 00:00:00 2001
From: orakili <github@orakili.net>
Date: Wed, 27 Sep 2023 01:21:54 +0000
Subject: [PATCH] fix: add target and rel attributes to external links to open
 in new tab for links inside fields using the markdown_editor (ckeditor 5)
 format

Refs: RW-812
---
 config/filter.format.markdown_editor.yml      |  89 ++++++++++-
 .../src/Plugin/Filter/ExternalLinkFilter.php  | 146 ++++++++++++++++++
 2 files changed, 230 insertions(+), 5 deletions(-)
 create mode 100644 html/modules/custom/reliefweb_utility/src/Plugin/Filter/ExternalLinkFilter.php

diff --git a/config/filter.format.markdown_editor.yml b/config/filter.format.markdown_editor.yml
index beb80d89b..16e6c1add 100644
--- a/config/filter.format.markdown_editor.yml
+++ b/config/filter.format.markdown_editor.yml
@@ -3,7 +3,10 @@ langcode: en
 status: true
 dependencies:
   module:
+    - editor
+    - media
     - reliefweb_fields
+    - reliefweb_guidelines
     - reliefweb_utility
 name: 'Markdown with Editor'
 format: markdown_editor
@@ -13,7 +16,7 @@ filters:
     id: filter_html
     provider: filter
     status: true
-    weight: -10
+    weight: -49
     settings:
       allowed_html: '<br> <p> <h2> <h3> <h4> <h5> <h6> <strong> <em> <a href> <ul> <ol> <li>'
       filter_html_help: false
@@ -22,24 +25,100 @@ filters:
     id: filter_htmlcorrector
     provider: filter
     status: true
-    weight: 10
+    weight: -47
     settings: {  }
   filter_markdown:
     id: filter_markdown
     provider: reliefweb_utility
     status: true
-    weight: -20
+    weight: -50
     settings: {  }
   reliefweb_token_filter:
     id: reliefweb_token_filter
     provider: reliefweb_utility
     status: false
-    weight: 0
+    weight: -37
     settings:
       replace_empty: '0'
   reliefweb_formatted_text:
     id: reliefweb_formatted_text
     provider: reliefweb_fields
     status: true
-    weight: 0
+    weight: -48
+    settings: {  }
+  reliefweb_external_link_filter:
+    id: reliefweb_external_link_filter
+    provider: reliefweb_utility
+    status: true
+    weight: -46
+    settings: {  }
+  editor_file_reference:
+    id: editor_file_reference
+    provider: editor
+    status: false
+    weight: -44
+    settings: {  }
+  filter_html_escape:
+    id: filter_html_escape
+    provider: filter
+    status: false
+    weight: -45
+    settings: {  }
+  filter_url:
+    id: filter_url
+    provider: filter
+    status: false
+    weight: -40
+    settings:
+      filter_url_length: 72
+  filter_html_image_secure:
+    id: filter_html_image_secure
+    provider: filter
+    status: false
+    weight: -36
+    settings: {  }
+  filter_image_lazy_load:
+    id: filter_image_lazy_load
+    provider: filter
+    status: false
+    weight: -35
+    settings: {  }
+  filter_caption:
+    id: filter_caption
+    provider: filter
+    status: false
+    weight: -41
+    settings: {  }
+  filter_autop:
+    id: filter_autop
+    provider: filter
+    status: false
+    weight: -42
+    settings: {  }
+  filter_align:
+    id: filter_align
+    provider: filter
+    status: false
+    weight: -43
+    settings: {  }
+  media_embed:
+    id: media_embed
+    provider: media
+    status: false
+    weight: -34
+    settings:
+      default_view_mode: default
+      allowed_view_modes: {  }
+      allowed_media_types: {  }
+  filter_guideline_link:
+    id: filter_guideline_link
+    provider: reliefweb_guidelines
+    status: false
+    weight: -39
+    settings: {  }
+  filter_iframe:
+    id: filter_iframe
+    provider: reliefweb_utility
+    status: false
+    weight: -38
     settings: {  }
diff --git a/html/modules/custom/reliefweb_utility/src/Plugin/Filter/ExternalLinkFilter.php b/html/modules/custom/reliefweb_utility/src/Plugin/Filter/ExternalLinkFilter.php
new file mode 100644
index 000000000..4dcd1bdaf
--- /dev/null
+++ b/html/modules/custom/reliefweb_utility/src/Plugin/Filter/ExternalLinkFilter.php
@@ -0,0 +1,146 @@
+<?php
+
+namespace Drupal\reliefweb_utility\Plugin\Filter;
+
+use Drupal\Component\Render\MarkupInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\filter\FilterProcessResult;
+use Drupal\filter\Plugin\FilterBase;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\HttpFoundation\RequestStack;
+
+/**
+ * Provides a filter to add attributes to external links to open in a new tab.
+ *
+ * @Filter(
+ *   id = "reliefweb_external_link_filter",
+ *   title = @Translation("Open external Links in new tab."),
+ *   description = @Translation("Add target and rel attributes to external links so they open in a new tab."),
+ *   type = Drupal\filter\Plugin\FilterInterface::TYPE_TRANSFORM_IRREVERSIBLE,
+ * )
+ */
+class ExternalLinkFilter extends FilterBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * Current request.
+   *
+   * @var \Symfony\Component\HttpFoundation\RequestStack
+   */
+  protected $requestStack;
+
+  /**
+   * Internal host pattern.
+   *
+   * @var string
+   */
+  protected $internalHostPattern;
+
+  /**
+   * Constructs a markdown filter plugin.
+   *
+   * @param array $configuration
+   *   A configuration array containing information about the plugin instance.
+   * @param string $plugin_id
+   *   The plugin_id for the plugin instance.
+   * @param mixed $plugin_definition
+   *   The plugin implementation definition.
+   * @param \Symfony\Component\HttpFoundation\RequestStack $request_stack
+   *   The request stack.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, RequestStack $request_stack) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->requestStack = $request_stack;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('request_stack')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function process($text, $langcode) {
+    if (is_string($text) || $text instanceof MarkupInterface) {
+      $html = trim($text);
+      if ($html !== '') {
+        // Adding this meta tag is necessary to tell \DOMDocument we are dealing
+        // with UTF-8 encoded html.
+        $flags = LIBXML_NONET | LIBXML_NOBLANKS | LIBXML_NOERROR | LIBXML_NOWARNING;
+        $meta = '<meta http-equiv="Content-Type" content="text/html; charset=utf-8">';
+        $prefix = '<!DOCTYPE html><html><head>' . $meta . '</head><body>';
+        $suffix = '</body></html>';
+        $dom = new \DOMDocument();
+        $dom->loadHTML($prefix . $text . $suffix, $flags);
+
+        // Process the links.
+        $links = $dom->getElementsByTagName('a');
+        foreach ($links as $link) {
+          $this->handleLink($link);
+        }
+
+        // Get the modified html.
+        $html = $dom->saveHTML();
+
+        // Search for the body tag and return its content.
+        $start = mb_strpos($html, '<body>');
+        $end = mb_strrpos($html, '</body>');
+        if ($start !== FALSE && $end !== FALSE) {
+          $start += 6;
+          $text = trim(mb_substr($html, $start, $end - $start));
+        }
+      }
+    }
+    return new FilterProcessResult($text);
+  }
+
+  /**
+   * Check if a URL is an ReliefWeb URL.
+   *
+   * @param string $url
+   *   URL to check.
+   *
+   * @return bool
+   *   TRUE if the URL is internal.
+   */
+  protected function isInternalUrl($url) {
+    if (empty($url)) {
+      return TRUE;
+    }
+
+    if (!isset($this->internalHostPattern)) {
+      $internal_hosts = [
+        preg_quote($this->requestStack->getCurrentRequest()->getHost()),
+        preg_quote('reliefweb.int'),
+      ];
+
+      $this->internalHostPattern = '#^https?://(' . implode('|', $internal_hosts) . ')(/|$)#';
+    }
+
+    return preg_match('#^https?://#', $url) !== 1 ||
+      preg_match($this->internalHostPattern, $url) === 1;
+  }
+
+  /**
+   * Add the target and rel attributes to external links to open in a new tab.
+   *
+   * @param \DOMNode $node
+   *   Link node.
+   */
+  protected function handleLink(\DOMNode $node) {
+    $url = $node->getAttribute('href');
+
+    if (!$this->isInternalUrl($url)) {
+      $node->setAttribute('target', '_blank');
+      $node->setAttribute('rel', 'noreferrer noopener');
+    }
+  }
+
+}