Backend Documentation

The backend is a Node.js application using Express and Mongoose.

Tech Stack

• Framework: Express.js (ES Modules)
• Database: MongoDB
• Real-time: Socket.io
• Auth: JWT (JSON Web Tokens) & Bcrypt.js
• File Storage: Cloudinary

API Reference

Auth Routes (/api/v1/auth)

| Method | Endpoint | Description | Auth Required |

|--------|----------|-------------|---------------|

| POST | /signup | Create a new user account | No |

| POST | /login | Authenticate user & get token | No |

| GET | /check-auth | Verify current token & get user data | Yes |

| PUT | /update-profile | Update user bio, name, or avatar | Yes |

Message Routes (/api/v1/messages)

| Method | Endpoint | Description | Auth Required |

|--------|----------|-------------|---------------|

| GET | / | Get list of users for sidebar with unseen counts | Yes |

| GET | /:userId | Get chat history between two users | Yes |

| POST | /send/:receiverId | Send a new text/image message | Yes |

| PUT | /mark-as-seen/:messageId | Mark a specific message as read | Yes |

Database Models

User Schema

• email: String (Unique, Lowercase)
• password: String (Hashed)
• name: String
• avatarUrl: String (Cloudinary URL)
• bio: String

Message Schema

• senderId: ObjectId (Ref: User)
• receiverId: ObjectId (Ref: User)
• text: String
• image: String (Cloudinary URL)
• seen: Boolean (Default: false)

Middleware

• protectRoute: Verifies the JWT in the Authorization header. If valid, attaches the user object to req.user.