Issue #330640 by fgm: Theme module configuration form.

- Added requirements check for unused filter.
- Added configuration links on modules page, compatible with module_filter.

url_replace_filter.info

@@ -1,3 +1,3 @@
-name = URL Replace Filter
+name = "URL Replace Filter"
 description = "Allows administrators to replace base URLs in <img> and <a> elements."
 core = 6.x

url_replace_filter.install

@@ -0,0 +1,41 @@
+<?php
+/**
+ * @file
+ * Install file for URL Replace filter.
+ *
+ * @author: Frédéric G. MARAND <fgm@osinet.fr>
+ *
+ * @license General Public License version 2.0 or later
+ */
+
+/**
+ * Implementation of hook_requirements().
+ *
+ * Ensure the module is actually used in at least one filter.
+ */
+function url_replace_filter_requirements($phase) {
+  if ($phase != 'runtime') {
+    return array();
+  }
+
+  $formats = _url_replace_filter_get_formats();
+  $filter_id = 'url_replace_filter/0';
+  $count = 0;
+  foreach ($formats as $format) {
+    if (!empty($format->{$filter_id})) {
+      $count++;
+    }
+  }
+  $req = array(
+    'title' => t('URL replace filter'),
+  );
+  if ($count) {
+    $req['value'] = format_plural($count, "Used in 1 format.", "Used in @count formats.");
+    $req['severity'] = REQUIREMENT_OK;
+  } else {
+    $req['value'] = t('Module is enabled but no format uses its filter. You should disable the module or use the filter in at least one format.');
+    $req['severity'] = REQUIREMENT_INFO;
+  }
+
+  return array($req);
+}