Update app.js

backend/app.js

@@ -1,34 +1,52 @@
-import express from "express";
-import cors from "cors";
-import mongoose from "mongoose";
-import pino from "pino";
+// Import required modules
+import express from "express"; // Express framework for building the API
+import cors from "cors"; // Middleware to handle Cross-Origin Resource Sharing
+import mongoose from "mongoose"; // MongoDB ODM for database operations
+import pino from "pino"; // Logger for structured logging
 
+// Import controllers for different routes
 import HealthController from "./controllers/health/health-controller.js";
-
 import FileUploadController from "./controllers/file-upload/file-upload-controller.js";
-import file_utils from "./utils/file-utils.js";
-
+import file_utils from "./utils/file-utils.js"; // Utility for file handling
 import ResumeController from "./controllers/resume/resume-controller.js";
 
+// MongoDB connection string
+// If environment variable DB_CONNECTION_STRING exists, use it; otherwise, use local MongoDB
 const CONNECTION_STRING =
   process.env.DB_CONNECTION_STRING || "mongodb://localhost:27017/TemplateBuddy";
+
+// Connect to MongoDB
 mongoose.connect(CONNECTION_STRING);
+
+// Initialize logger with different levels depending on environment
 const logger = pino({
   level: process.env.NODE_ENV === "production" ? "info" : "debug",
 });
 
+// CORS options configuration
+// origin: "*" allows all domains to access the API
+// credentials: true allows cookies and authentication headers
+// optionSuccessStatus: 200 ensures preflight requests succeed
 const cors_options = {
   origin: "*",
   credentials: true,
   optionSuccessStatus: 200,
 };
+
+// Initialize Express app
 const app = express();
-app.use(cors(cors_options));
-app.use(express.json());
+
+// Apply middleware
+app.use(cors(cors_options)); // Enable CORS with the defined options
+app.use(express.json()); // Parse incoming JSON requests
+
+// Serve static files (like images) from the TEMPLATE_BUDDY_DIR
 app.use("/images", express.static(file_utils.TEMPLATE_BUDDY_DIR));
 
-HealthController(app, logger);
-FileUploadController(app, logger);
-ResumeController(app, logger);
+// Setup API routes using controllers
+HealthController(app, logger); // Health check endpoints
+FileUploadController(app, logger); // File upload endpoints
+ResumeController(app, logger); // Resume management endpoints
 
+// Start the server on the specified PORT environment variable or default to 4000
 app.listen(process.env.PORT || 4000);