GoChat

A real-time chat application with a Go server, Rust TUI client, and Android client.

Overview

GoChat is a multi-platform messaging app built around a WebSocket-based protocol. Users can register accounts, create rooms, and exchange messages in real time. The server handles authentication via JWT, persists data in PostgreSQL, and broadcasts messages through WebSocket connections.

Architecture

┌──────────────┐     WebSocket     ┌──────────────┐
│  Rust Client │◄──────────────────►│              │
│   (ratatui)  │                   │   Go Server   │
└──────────────┘                   │  (port 1919)  │
                                   │              │
┌──────────────┐     WebSocket     │   PostgreSQL  │
│Android Client│◄──────────────────►│              │
│  (Compose)   │                   └──────────────┘
└──────────────┘

Components

Server (server/)

• Go with nhooyr.io/websocket
• JWT authentication (register/login via REST, connect via WebSocket)
• PostgreSQL for users, rooms, messages, and membership
• Real-time message broadcasting, typing indicators, and presence tracking
• Rate limiting (100ms between messages)

Rust TUI Client (client/)

• Terminal UI built with ratatui and crossterm
• Async networking with tokio and tokio-tungstenite
• Keyboard-driven interface with room switching, message history, and member lists

Android Client (android/)

• Kotlin with Jetpack Compose and Material 3
• MVVM architecture with ViewModels and StateFlow
• OkHttp WebSocket with automatic reconnection (exponential backoff)
• Retrofit for REST authentication, DataStore for token persistence
• Navigation drawer for room management, bottom sheet for members

Prerequisites

• Go 1.22+
• Rust (stable toolchain)
• Docker (for PostgreSQL)
• Android Studio Ladybug+ (for the Android client)

Getting Started

1. Start the database

make db

2. Run the server

make server

The server starts on port 1919 by default.

3. Run a client

Rust TUI:

make client

Android: Open the android/ directory in Android Studio and run on an emulator. The app connects to 10.0.2.2:1919 (emulator loopback to host).

Protocol

All real-time communication uses a JSON envelope format over WebSocket:

{
  "type": "chat.message",
  "payload": { ... },
  "timestamp": "2025-01-01T00:00:00Z"
}

Message Types

Type	Direction	Description
chat.send	client → server	Send a message to a room
chat.message	server → client	Broadcasted message
chat.edit	client → server	Edit own message
chat.edited	server → client	Broadcasted edit
chat.history	client → server	Request message history
chat.history.response	server → client	History response with pagination
room.create	client → server	Create a new room
room.created	server → client	Room creation confirmation
room.join	client → server	Join a room
room.joined	server → client	Join confirmation
room.leave	client → server	Leave a room
room.left	server → client	Leave confirmation
room.list	client → server	Request all rooms
room.list.response	server → client	List of available rooms
room.members	client → server	Request room members
room.members.response	server → client	Member list with online status
presence.online	server → client	User came online
presence.offline	server → client	User went offline
presence.typing	bidirectional	Typing indicator
system.ping	server → client	Keep-alive ping
system.pong	client → server	Keep-alive response
system.error	server → client	Error with code and message

REST Endpoints

Method	Path	Description
POST	/api/auth/register	Register a new account
POST	/api/auth/login	Login and receive JWT
GET	/ws?token=<jwt>	WebSocket connection

Configuration

Copy .env.example to .env and adjust as needed:

PORT=1919
DATABASE_URL=postgres://gochat:gochat@localhost:5432/gochat?sslmode=disable
JWT_SECRET=change-me-in-production
JWT_EXPIRY_HOURS=72

Building

make build          # builds both server and client
make build-server   # server only → bin/gochat
make build-client   # client only → bin/gochat-client

License

MIT