REFACTOR to use more generic approach for ignoring specific user agents

docs/en/Installation.md

@@ -3,3 +3,18 @@
 ```
 composer require axllent/silverstripe-trailing-slash
 ```
+
+
+## Caveats
+
+When using the silverstripe/silverstripe-staticpublishqueue module the REQUEST_URI is updated so what's used for the request will be different from what is defined in $_SERVER['REQUEST_URI']. As the REQUEST_URI can no longer be used to determine if a trailing slash is required then it makes more sense to ignore the user agent for staticpublishqueue.
+
+The User agent can be ignored by this module by setting;
+
+```yaml
+Axllent\TrailingSlash\Middleware\TrailingSlashRedirector:
+  ignore_agents:
+    - 'silverstripe/staticpublishqueue'
+```
+
+ref; https://github.com/silverstripe/silverstripe-staticpublishqueue/blob/master/src/Publisher.php#L82-L101

src/Middleware/TrailingSlashRedirector.php

@@ -25,6 +25,13 @@ class TrailingSlashRedirector implements HTTPMiddleware
         'dev/',
     ];
 
+    /**
+     * User-Agents to ignore
+     *
+     * @var array
+     */
+    private static $ignore_agents = [];
+
     /**
      * Process request
      *
@@ -67,8 +74,13 @@ public function process(HTTPRequest $request, callable $delegate)
 
             $params = $request->getVars();
 
+            $ignore_agents = Config::inst()->get(TrailingSlashRedirector::class, 'ignore_agents');
+
             if (!Director::is_ajax()
-                && $request->getHeader('User-Agent') != 'silverstripe/staticpublishqueue'
+                && !($ignore_agents && in_array(
+                    $request->getHeader('User-Agent'),
+                    $ignore_agents
+                ))
                 && !isset($urlPathInfo['extension'])
                 && empty($params)
                 && !preg_match(