feat(atomic): add middleware preprocessor for the recommendation engi…

…ne (#4164)

https://coveord.atlassian.net/browse/KIT-3370

packages/headless/src/api/search/search-api-client.test.ts

@@ -177,6 +177,29 @@ describe('search api client', () => {
       const res = await searchAPIClient.facetSearch(req);
       expect(res.moreValuesAvailable).toEqual(true);
     });
+
+    describe('when calling SearchAPIClient.recommendations', () => {
+      it('should preprocess the response', async () => {
+        const recommendationState = createMockRecommendationState();
+        const processedRecommendations = buildMockSearchResponse();
+
+        buildSearchAPIClient({
+          postprocessSearchResponseMiddleware: (response) => {
+            return {
+              ...response,
+              body: processedRecommendations,
+            };
+          },
+        });
+
+        const req = await buildRecommendationRequest(recommendationState);
+        const res = await searchAPIClient.recommendations(req);
+
+        if (!isErrorResponse(res)) {
+          expect(res.success).toEqual(processedRecommendations);
+        }
+      });
+    });
   });
 
   describe('noop middleware', () => {

packages/headless/src/api/search/search-api-client.ts

@@ -211,7 +211,13 @@ export class SearchAPIClient implements FacetSearchAPIClient {
     const body = await response.json();
 
     if (isSuccessSearchResponse(body)) {
-      return {success: body};
+      const payload = {response, body};
+      payload.body = shimResponse(body);
+      const processedResponse =
+        await this.options.postprocessSearchResponseMiddleware(payload);
+      return {
+        success: processedResponse.body,
+      };
     }
 
     return {

packages/headless/src/app/recommendation-engine/recommendation-engine-configuration.ts

@@ -1,4 +1,5 @@
 import {Schema, StringValue} from '@coveo/bueno';
+import {PostprocessSearchResponseMiddleware} from '../../api/search/search-api-client-middleware';
 import {nonEmptyString} from '../../utils/validate-payload';
 import {
   EngineConfiguration,
@@ -40,6 +41,10 @@ export interface RecommendationEngineConfiguration extends EngineConfiguration {
    * America/Montreal
    */
   timezone?: string;
+  /**
+   * Allows for augmenting a search response before the state is updated.
+   */
+  preprocessSearchResponseMiddleware?: PostprocessSearchResponseMiddleware;
 }
 
 export const recommendationEngineConfigurationSchema =

packages/headless/src/app/recommendation-engine/recommendation-engine.ts

@@ -132,6 +132,7 @@ function createSearchAPIClient(
     logger,
     preprocessRequest: configuration.preprocessRequest || NoopPreprocessRequest,
     postprocessSearchResponseMiddleware:
+      configuration.preprocessSearchResponseMiddleware ||
       NoopPostprocessSearchResponseMiddleware,
     postprocessFacetSearchResponseMiddleware:
       NoopPostprocessFacetSearchResponseMiddleware,