Add getClient function and delegator types for Elasticsearch clients

apps/app/src/server/service/search-delegator/elasticsearch-client-delegator/get-client.ts

@@ -0,0 +1,56 @@
+import type { ClientOptions as ES7ClientOptions } from '@elastic/elasticsearch7';
+import type { ClientOptions as ES8ClientOptions } from '@elastic/elasticsearch8';
+import type { ClientOptions as ES9ClientOptions } from '@elastic/elasticsearch9';
+
+import { ES7ClientDelegator } from './es7-client-delegator';
+import { ES8ClientDelegator } from './es8-client-delegator';
+import { ES9ClientDelegator } from './es9-client-delegator';
+
+export type ElasticSEarchClientDeletegator = ES7ClientDelegator | ES8ClientDelegator | ES9ClientDelegator;
+
+type GetDelegatorOptions = {
+  version: 7;
+  options: ES7ClientOptions;
+  rejectUnauthorized: boolean;
+} | {
+  version: 8;
+  options: ES8ClientOptions;
+  rejectUnauthorized: boolean;
+} | {
+  version: 9;
+  options: ES9ClientOptions;
+  rejectUnauthorized: boolean;
+}
+
+type IsAny<T> = 'dummy' extends (T & 'dummy') ? true : false;
+type Delegator<Opts extends GetDelegatorOptions> =
+  IsAny<Opts> extends true
+    ? ElasticSEarchClientDeletegator
+    : Opts extends { version: 7 }
+      ? ES7ClientDelegator
+      : Opts extends { version: 8 }
+        ? ES8ClientDelegator
+        : Opts extends { version: 9 }
+          ? ES9ClientDelegator
+          : ElasticSEarchClientDeletegator
+
+let instance: ElasticSEarchClientDeletegator;
+
+export const getClient = <Opts extends GetDelegatorOptions>(opts: Opts): Delegator<Opts> => {
+  if (instance == null) {
+    if (opts.version === 7) {
+      instance = new ES7ClientDelegator(opts.options, opts.rejectUnauthorized);
+      return instance as Delegator<Opts>;
+    }
+    if (opts.version === 8) {
+      instance = new ES8ClientDelegator(opts.options, opts.rejectUnauthorized);
+      return instance as Delegator<Opts>;
+    }
+    if (opts.version === 9) {
+      instance = new ES9ClientDelegator(opts.options, opts.rejectUnauthorized);
+      return instance as Delegator<Opts>;
+    }
+  }
+
+  return instance as Delegator<Opts>;
+};