MOCHA — Massively Online Collaborative Housie App

A real-time multiplayer Tambola (Indian bingo/housie) game server. One GenServer process per active game, capable of hosting 100k+ concurrent games on a single machine.

Backend: Elixir/Phoenix, Phoenix Channels, Phoenix Presence Frontend: Vue 3, TypeScript, Pinia, Vite, Tailwind CSS

Prerequisites

• Erlang/OTP 27+
• Elixir 1.18+
• Node.js 20+ and npm
• PostgreSQL 15+

Setup

# Clone and setup
git clone <repo-url> && cd mocha
mix setup                          # deps.get + ecto.setup + assets.setup

# Start development server
mix phx.server                     # Phoenix on :4000, Vite on :5173

Visit localhost:4000 in your browser.

Architecture

Game Engine

Pure Elixir — no web dependency. One GenServer per active game holds all in-memory state (board, tickets, struck numbers, prizes, bogeys). State changes are broadcast via Phoenix.PubSub as {event_atom, payload} tuples.

Real-time Communication

Phoenix Channels provide the real-time layer:

• UserSocket authenticates via bearer token
• GameChannel translates PubSub events to JSON pushes, handles player actions (strike, claim, chat, reaction)
• Presence tracks online players per game

Frontend

Vue 3 SPA with hash-based routing:

• Pinia stores manage auth, theme, game state, chat, and presence
• useChannel composable wraps the Phoenix socket/channel lifecycle
• Pages: Auth, Home, Profile, NewGame, GamePlay, HostDashboard

Auth

• Google OAuth (redirects with bearer token)
• Magic link email (passwordless login)
• Bearer tokens for API + WebSocket auth

Commands

# Development
mix phx.server                     # start everything
iex -S mix phx.server              # with interactive shell

# Backend tests
mix test                           # 79 tests + property tests
mix test test/mocha/game/server_test.exs     # single file

# Frontend tests
cd assets && npx vitest run        # unit tests
cd assets && npx tsc --noEmit      # type check

# Production build
cd assets && npm run build         # outputs to priv/static/

Configuration

Environment variables for OAuth:

GOOGLE_CLIENT_ID=your-client-id
GOOGLE_CLIENT_SECRET=your-client-secret

Database config is in config/dev.exs (defaults to postgres:postgres@localhost/mocha_dev).