feat(insights): introduce insights middleware (1/4)

src/lib/main.ts

@@ -4,6 +4,7 @@ import version from './version';
 import * as connectors from '../connectors/index';
 import * as widgets from '../widgets/index';
 import * as helpers from '../helpers/index';
+import * as middleware from '../middleware/index';
 
 import * as routers from './routers/index';
 import * as stateMappings from './stateMappings/index';
@@ -39,5 +40,6 @@ instantsearch.createInfiniteHitsSessionStorageCache = createInfiniteHitsSessionS
 instantsearch.highlight = helpers.highlight;
 instantsearch.snippet = helpers.snippet;
 instantsearch.insights = helpers.insights;
+instantsearch.middleware = middleware;
 
 export default instantsearch;

src/middleware/index.ts

@@ -11,3 +11,4 @@ export type Middleware = ({
 }) => MiddlewareDefinition;
 
 export { createRouter, RouterProps } from './createRouter';
+export { createInsightsMiddleware } from './insights';

src/middleware/insights.ts

@@ -0,0 +1,40 @@
+import { Middleware } from '.';
+import { InsightsClient } from '../types';
+
+export type InsightsProps = {
+  insightsClient: InsightsClient;
+};
+
+export type CreateInsightsMiddleware = (props: InsightsProps) => Middleware;
+
+export const createInsightsMiddleware: CreateInsightsMiddleware = props => {
+  const { insightsClient } = props;
+  if (!insightsClient) {
+    throw new Error(
+      'passing insightsClient to instantsearch is required for insightsMiddleware'
+    );
+  }
+  return ({ instantSearchInstance }) => {
+    return {
+      onStateChange() {},
+      subscribe() {
+        instantSearchInstance.mainIndex
+          .getHelper()
+          .setQueryParameter('clickAnalytics', true);
+
+        insightsClient(
+          'onUserTokenChange',
+          userToken => {
+            instantSearchInstance.mainIndex
+              .getHelper()
+              .setQueryParameter('userToken', userToken);
+          },
+          { immediate: true }
+        );
+      },
+      unsubscribe() {
+        insightsClient('onUserTokenChange', () => {});
+      },
+    };
+  };
+};

src/types/insights.ts

@@ -10,11 +10,21 @@ export type InsightsClientPayload = {
   positions?: number[];
 };
 
-export type InsightsClient = (
+export type InsightsSendEvent = (
   method: InsightsClientMethod,
   payload: InsightsClientPayload
 ) => void;
 
+export type InsightsOnUserTokenChangeMethod = 'onUserTokenChange';
+
+export type InsightsOnUserTokenChange = (
+  method: InsightsOnUserTokenChangeMethod,
+  callback: (userToken: string) => void,
+  options?: { immediate?: boolean }
+) => void;
+
+export type InsightsClient = InsightsSendEvent & InsightsOnUserTokenChange;
+
 export type InsightsClientWrapper = (
   method: InsightsClientMethod,
   payload: Partial<InsightsClientPayload>