From 05447283d142ebdeb95cb63a00d9845a6e6a8b6a Mon Sep 17 00:00:00 2001
From: Patrik Oldsberg <poldsberg@gmail.com>
Date: Sat, 12 Aug 2023 12:01:45 +0200
Subject: [PATCH] search-backend-module-elasticsearch: switch translator
 customization to extension point

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>
---
 .changeset/popular-beds-invent.md             |  2 +-
 .../alpha-api-report.md                       | 11 +++
 .../src/alpha.ts                              | 68 +++++++++----------
 3 files changed, 46 insertions(+), 35 deletions(-)

diff --git a/.changeset/popular-beds-invent.md b/.changeset/popular-beds-invent.md
index 73c28d629e..61d0cf0545 100644
--- a/.changeset/popular-beds-invent.md
+++ b/.changeset/popular-beds-invent.md
@@ -4,4 +4,4 @@
 
 Index templates can now be configured through configuration under the `search.elasticsearch.indexTemplates`. In addition, the `ElasticSearchSearchEngine.fromConfig` now also accepts a `LoggerService` as the `logger` option as well as a new `translator` option.
 
-The alpha `searchModuleElasticsearchEngine` export no longer accepts options.
+The alpha `searchModuleElasticsearchEngine` export no longer accepts options and a new alpha `elasticsearchTranslatorExtensionPoint` export has been added which lets you customize the query translator.
diff --git a/plugins/search-backend-module-elasticsearch/alpha-api-report.md b/plugins/search-backend-module-elasticsearch/alpha-api-report.md
index ecbe3f2700..9e5e7c2136 100644
--- a/plugins/search-backend-module-elasticsearch/alpha-api-report.md
+++ b/plugins/search-backend-module-elasticsearch/alpha-api-report.md
@@ -4,6 +4,17 @@
 
 ```ts
 import { BackendFeature } from '@backstage/backend-plugin-api';
+import { ElasticSearchQueryTranslator } from '@backstage/plugin-search-backend-module-elasticsearch';
+import { ExtensionPoint } from '@backstage/backend-plugin-api';
+
+// @alpha (undocumented)
+export interface ElasticSearchQueryTranslatorExtensionPoint {
+  // (undocumented)
+  setTranslator(translator: ElasticSearchQueryTranslator): void;
+}
+
+// @alpha
+export const elasticsearchTranslatorExtensionPoint: ExtensionPoint<ElasticSearchQueryTranslatorExtensionPoint>;
 
 // @alpha
 export const searchModuleElasticsearchEngine: () => BackendFeature;
diff --git a/plugins/search-backend-module-elasticsearch/src/alpha.ts b/plugins/search-backend-module-elasticsearch/src/alpha.ts
index 54f5f07777..9801cf4643 100644
--- a/plugins/search-backend-module-elasticsearch/src/alpha.ts
+++ b/plugins/search-backend-module-elasticsearch/src/alpha.ts
@@ -16,52 +16,51 @@
 import {
   coreServices,
   createBackendModule,
+  createExtensionPoint,
 } from '@backstage/backend-plugin-api';
 import { searchEngineRegistryExtensionPoint } from '@backstage/plugin-search-backend-node/alpha';
-import { ElasticSearchSearchEngine } from '@backstage/plugin-search-backend-module-elasticsearch';
+import {
+  ElasticSearchQueryTranslator,
+  ElasticSearchSearchEngine,
+} from '@backstage/plugin-search-backend-module-elasticsearch';
+
+/** @alpha */
+export interface ElasticSearchQueryTranslatorExtensionPoint {
+  setTranslator(translator: ElasticSearchQueryTranslator): void;
+}
+
+/**
+ * Extension point used to customize the ElasticSearch query translator.
+ *
+ * @alpha
+ */
+export const elasticsearchTranslatorExtensionPoint =
+  createExtensionPoint<ElasticSearchQueryTranslatorExtensionPoint>({
+    id: 'search.elasticsearchEngine.translator',
+  });
 
 /**
  * Search backend module for the Elasticsearch engine.
  *
  * @alpha
- * @remarks
- *
- * If you need to customize the search engine beyond what is supported by the
- * static configuration, you can create a custom module using the `ElasticSearchSearchEngine`.
- *
- * For example, this lets you configure your own query translator:
- *
- * ```ts
- * export const searchModuleElasticsearchEngine = createBackendModule({
- *   moduleId: 'elasticsearchEngine',
- *   pluginId: 'search',
- *   register(env) {
- *     env.registerInit({
- *       deps: {
- *         searchEngineRegistry: searchEngineRegistryExtensionPoint,
- *         logger: coreServices.logger,
- *         config: coreServices.rootConfig,
- *       },
- *       async init({ searchEngineRegistry, logger, config }) {
- *         searchEngineRegistry.setSearchEngine(
- *           await ElasticSearchSearchEngine.fromConfig({
- *             logger,
- *             config,
- *             translator(query) {
- *               return ... // translated query
- *             }
- *           }),
- *         );
- *       },
- *     });
- *   },
- * });
- * ```
  */
 export const searchModuleElasticsearchEngine = createBackendModule({
   moduleId: 'elasticsearchEngine',
   pluginId: 'search',
   register(env) {
+    let translator: ElasticSearchQueryTranslator | undefined;
+
+    env.registerExtensionPoint(elasticsearchTranslatorExtensionPoint, {
+      setTranslator(newTranslator) {
+        if (translator) {
+          throw new Error(
+            'ElasticSearch query translator may only be set once',
+          );
+        }
+        translator = newTranslator;
+      },
+    });
+
     env.registerInit({
       deps: {
         searchEngineRegistry: searchEngineRegistryExtensionPoint,
@@ -73,6 +72,7 @@ export const searchModuleElasticsearchEngine = createBackendModule({
           await ElasticSearchSearchEngine.fromConfig({
             logger,
             config,
+            translator,
           }),
         );
       },