Redirect local media URLs to cdn URLs. (#796)

* Redirect local media URLs to cdn URLs.

* Update amazon-s3-and-cloudfront.php

public/app/themes/clarity/inc/amazon-s3-and-cloudfront.php

@@ -15,18 +15,67 @@ class AmazonS3AndCloudFrontTweaks
     public function __construct()
     {
         // Increase limits from 50 to 5000. 
-        add_filter( 'as3cf_update_replace_provider_urls_batch_size', fn() => 5000);
-        add_filter( 'as3cf_update_filter_post_excerpt_batch_size', fn() => 5000);
+        add_filter('as3cf_update_replace_provider_urls_batch_size', fn() => 5000);
+        add_filter('as3cf_update_filter_post_excerpt_batch_size', fn() => 5000);
 
         // Increase limits from 500 to 3500, duration is about 45 seconds.
-        add_filter( 'as3cf_update_fix_broken_item_extra_data_batch_size', fn() => 3500);
+        add_filter('as3cf_update_fix_broken_item_extra_data_batch_size', fn() => 3500);
 
         // Increase limit from 50 to 750.
-        add_filter( 'as3cf_update_as3cf_items_table_batch_size', fn() => 750);
+        add_filter('as3cf_update_as3cf_items_table_batch_size', fn() => 750);
         // 750 items take ~20 secs, so decrease interval from 2 to 1 minute.
-        add_filter( 'as3cf_update_as3cf_items_table_interval', fn() => 1);
+        add_filter('as3cf_update_as3cf_items_table_interval', fn() => 1);
+
+        // Redirect legacy URLs to cdn URLs.
+        add_action('template_redirect', [$this, 'maybeRedirect404s']);
     }
 
+    /**
+     * Redirect local media URLs to cdn URLs.
+     * 
+     * Some content has links to documents and media that have the path `/wp-content/uploads/`.
+     * These paths are redirected to `/app/uploads/` by Bedrock.
+     * 
+     * A further redirect is required to redirect `/app/uploads/` to the CDN URL.
+     * 
+     * @return void
+     */
+
+    public function maybeRedirect404s(): void
+    {
+        if (!is_404()) {
+            return;
+        }
+
+        // Check if the request is for a local upload URL.
+        if (!str_starts_with($_SERVER['REQUEST_URI'], '/app/uploads/')) {
+            return;
+        }
+
+        // Replace '/app/uploads/' with '/media/'.
+        $media_uri = str_replace('/app/uploads/', '/media/', $_SERVER['REQUEST_URI']);
+
+        // Make it an absolute URL for `attachment_url_to_postid`.
+        $absolute_url = get_home_url(null, $media_uri);
+
+        // Get the attachment id from the url.
+        $attachment_id = attachment_url_to_postid($absolute_url);
+
+        if (!$attachment_id) {
+            return;
+        }
+
+        // Get the url from the attachment id.
+        $cdn_url = wp_get_attachment_url($attachment_id);
+
+        if (!$cdn_url) {
+            return;
+        }
+
+        // Redirect to the CDN URL.
+        wp_redirect($cdn_url, 301);
+        exit;
+    }
 }
 
 new AmazonS3AndCloudFrontTweaks();