feat(backend): Wrap getAPI met Redis

backend/package.json

@@ -38,6 +38,7 @@
         "loki-logger-ts": "^1.0.2",
         "marked": "^15.0.7",
         "nanoid": "^5.1.5",
+        "redis": "^5.0.1",
         "response-time": "^2.3.3",
         "swagger-ui-express": "^5.0.1",
         "uuid": "^11.1.0",

backend/src/services/learning-objects.ts

@@ -1,5 +1,5 @@
 import { DWENGO_API_BASE } from '../config.js';
-import { fetchWithLogging } from '../util/api-helper.js';
+import { fetchRemote } from '../util/api-helper.js';
 
 import {
     FilteredLearningObject,
@@ -39,7 +39,7 @@ function filterData(data: LearningObjectMetadata, htmlUrl: string): FilteredLear
  */
 export async function getLearningObjectById(hruid: string, language: string): Promise<FilteredLearningObject | null> {
     const metadataUrl = `${DWENGO_API_BASE}/learningObject/getMetadata?hruid=${hruid}&language=${language}`;
-    const metadata = await fetchWithLogging<LearningObjectMetadata>(
+    const metadata = await fetchRemote<LearningObjectMetadata>(
         metadataUrl,
         `Metadata for Learning Object HRUID "${hruid}" (language ${language})`
     );

backend/src/services/learning-objects/dwengo-api-learning-object-provider.ts

@@ -1,5 +1,5 @@
 import { DWENGO_API_BASE } from '../../config.js';
-import { fetchWithLogging } from '../../util/api-helper.js';
+import { fetchRemote } from '../../util/api-helper.js';
 import dwengoApiLearningPathProvider from '../learning-paths/dwengo-api-learning-path-provider.js';
 import { LearningObjectProvider } from './learning-object-provider.js';
 import { getLogger, Logger } from '../../logging/initalize.js';
@@ -88,7 +88,7 @@ const dwengoApiLearningObjectProvider: LearningObjectProvider = {
      */
     async getLearningObjectById(id: LearningObjectIdentifierDTO): Promise<FilteredLearningObject | null> {
         const metadataUrl = `${DWENGO_API_BASE}/learningObject/getMetadata`;
-        const metadata = await fetchWithLogging<LearningObjectMetadata>(
+        const metadata = await fetchRemote<LearningObjectMetadata>(
             metadataUrl,
             `Metadata for Learning Object HRUID "${id.hruid}" (language ${id.language})`,
             {
@@ -124,7 +124,7 @@ const dwengoApiLearningObjectProvider: LearningObjectProvider = {
      */
     async getLearningObjectHTML(id: LearningObjectIdentifierDTO): Promise<string | null> {
         const htmlUrl = `${DWENGO_API_BASE}/learningObject/getRaw`;
-        const html = await fetchWithLogging<string>(htmlUrl, `Metadata for Learning Object HRUID "${id.hruid}" (language ${id.language})`, {
+        const html = await fetchRemote<string>(htmlUrl, `Metadata for Learning Object HRUID "${id.hruid}" (language ${id.language})`, {
             params: { ...id },
         });
 

backend/src/services/learning-paths/dwengo-api-learning-path-provider.ts

@@ -1,4 +1,4 @@
-import { fetchWithLogging } from '../../util/api-helper.js';
+import { fetchRemote } from '../../util/api-helper.js';
 import { DWENGO_API_BASE } from '../../config.js';
 import { LearningPathProvider } from './learning-path-provider.js';
 import { getLogger, Logger } from '../../logging/initalize.js';
@@ -20,7 +20,7 @@ const dwengoApiLearningPathProvider: LearningPathProvider = {
         const apiUrl = `${DWENGO_API_BASE}/learningPath/getPathsFromIdList`;
         const params = { pathIdList: JSON.stringify({ hruids }), language };
 
-        const learningPaths = await fetchWithLogging<LearningPath[]>(apiUrl, `Learning paths for ${source}`, { params });
+        const learningPaths = await fetchRemote<LearningPath[]>(apiUrl, `Learning paths for ${source}`, { params });
 
         if (!learningPaths || learningPaths.length === 0) {
             logger.warn(`⚠️ WARNING: No learning paths found for ${source}.`);
@@ -42,7 +42,7 @@ const dwengoApiLearningPathProvider: LearningPathProvider = {
         const apiUrl = `${DWENGO_API_BASE}/learningPath/search`;
         const params = { all: query, language };
 
-        const searchResults = await fetchWithLogging<LearningPath[]>(apiUrl, `Search learning paths with query "${query}"`, { params });
+        const searchResults = await fetchRemote<LearningPath[]>(apiUrl, `Search learning paths with query "${query}"`, { params });
         return searchResults ?? [];
     },
 };

backend/src/util/api-helper.ts

@@ -1,27 +1,75 @@
 import axios, { AxiosRequestConfig } from 'axios';
 import { getLogger, Logger } from '../logging/initalize.js';
 import { LearningObjectIdentifier } from '../entities/content/learning-object-identifier.js';
+import { getCacheClient } from '../caching.js';
+import { envVars, getEnvVar, getNumericEnvVar } from './envVars.js';
 
 const logger: Logger = getLogger();
+const runMode: string = getEnvVar(envVars.RunMode);
+const prefix: string = getEnvVar(envVars.CacheKeyPrefix);
+
+interface Options {
+    params?: Record<string, unknown> | LearningObjectIdentifier;
+    query?: Record<string, unknown>;
+    responseType?: 'json' | 'text';
+}
 
 /**
- * Utility function to fetch data from an API endpoint with error handling.
+ * Utility function to fetch data from an API endpoint with error handling and caching.
  * Logs errors but does NOT throw exceptions to keep the system running.
  *
  * @param url The API endpoint to fetch from.
  * @param description A short description of what is being fetched (for logging).
  * @param options Contains further options such as params (the query params) and responseType (whether the response
  *                should be parsed as JSON ("json") or whether it should be returned as plain text ("text")
+ * @param cacheTTL Time-to-live for the cache in seconds (default: 60 seconds).
  * @returns The response data if successful, or null if an error occurs.
  */
-export async function fetchWithLogging<T>(
+export async function fetchRemote<T>(
     url: string,
     description: string,
-    options?: {
-        params?: Record<string, unknown> | LearningObjectIdentifier;
-        query?: Record<string, unknown>;
-        responseType?: 'json' | 'text';
+    options?: Options,
+    cacheTTL?: number
+): Promise<T | null> {
+    if (runMode !== 'dev') {
+        return fetchWithCache<T>(url, description, options, cacheTTL);
     }
+
+    getLogger().info(`🔄 INFO: Bypassing cache for ${description} at "${url}".`);
+    return fetchWithLogging(url, description, options);
+}
+
+async function fetchWithCache<T>(
+    url: string,
+    description: string,
+    options?: Options,
+    cacheTTL?: number
+): Promise<T | null> {
+    // Create a unique cache key based on the URL and options
+    const cacheKey = `${prefix}:${url}${options?.params ? JSON.stringify(options.params) : ''}`;
+    const cacheClient = await getCacheClient();
+
+    const cachedData = await cacheClient.get(cacheKey);
+    if (cachedData !== null && cachedData !== undefined) { // TODO What should this condition actually be?
+        // Cache hit! :)
+        getLogger().debug(`✅ INFO: Cache hit for ${description} at "${url}".`);
+        return JSON.parse(cachedData) as T;
+    }
+
+    // Cache miss :(
+    logger.debug(`🔄 INFO: Cache miss for ${description} at "${url}". Fetching data...`);
+    const response = await fetchWithLogging<T>(url, description, options);
+    logger.debug(`🔄 INFO: Fetched data for ${description} at "${url}".`);
+    await cacheClient.setEx(cacheKey, cacheTTL || getNumericEnvVar(envVars.CacheTTL), JSON.stringify(response));
+    logger.debug(`✅ INFO: Cached response for ${description} at "${url}" for ${cacheTTL} seconds.`);
+
+    return response;
+}
+
+async function fetchWithLogging<T>(
+    url: string,
+    description: string,
+    options?: Options,
 ): Promise<T | null> {
     try {
         const config: AxiosRequestConfig = options || {};
@@ -34,7 +82,7 @@ export async function fetchWithLogging<T>(
                     logger.debug(`❌ ERROR: ${description} not found (404) at "${url}".`);
                 } else {
                     logger.debug(
-                        `❌ ERROR: Failed to fetch ${description}. Status: ${error.response.status} - ${error.response.statusText} (URL: "${url}")`
+                        `❌ ERROR: Failed to fetch ${description}. Status: ${error.response.status} - ${error.response.statusText} (URL: "${url}")`,
                     );
                 }
             } else {