city/project_summary.md

# City Builder - Project Summary

## Project Overview
A fully functional multiplayer city building game inspired by Transport Tycoon's visual style, built with FastAPI backend and Three.js frontend.

## What Was Built

### Backend (Python/FastAPI)
All backend files are in the `server/` directory:

1. **main.py** - FastAPI application entry point
   - WebSocket endpoint for multiplayer
   - Static file serving
   - Game loop for economy ticks and persistence

2. **websocket_manager.py** - WebSocket connection management
   - Player connection/disconnection
   - Message broadcasting
   - Cursor synchronization

3. **models.py** - Data models
   - 13 building types with unique properties
   - Player model with economy tracking
   - Building configurations with costs and benefits

4. **game_state.py** - Game state management
   - Building placement/removal logic
   - Road network connectivity (flood fill algorithm)
   - Zone size calculation for economy bonuses

5. **economy.py** - Economy engine
   - Tick-based economy processing
   - Offline player support (10% power)
   - Connectivity-based income bonuses

6. **database.py** - SQLite persistence
   - Auto-save every 10 seconds
   - Player data persistence
   - Building state persistence

### Frontend (JavaScript/Three.js)
All frontend files are in the `static/` directory:

1. **App.js** - Main application controller
   - Coordinates all systems
   - Handles game state updates
   - Player action processing

2. **WebSocketClient.js** - Real-time communication
   - WebSocket connection management
   - Message handling and routing
   - Auto-reconnect logic

3. **GameRenderer.js** - Three.js 3D rendering
   - Orthographic camera (Transport Tycoon style)
   - Building mesh creation
   - Tile highlighting
   - Player cursor rendering

4. **InputHandler.js** - User input processing
   - Mouse controls (left/right click, wheel)
   - Keyboard shortcuts
   - Camera pan and zoom
   - Tile coordinate conversion

5. **UIManager.js** - UI component coordination
   - Component initialization
   - State updates
   - Event routing

### UI Components (Web Components)
All components extend HTMLElement:

1. **LoginScreen.js** - Nickname entry screen
2. **StatsDisplay.js** - Money and population display
3. **BuildingToolbox.js** - Building selection menu
4. **ChatBox.js** - IRC-style chat interface
5. **ContextMenu.js** - Right-click building menu

### Configuration Files
- **requirements.txt** - Python dependencies
- **.gitignore** - Git ignore rules
- **run.py** - Convenient startup script
- **README.md** - Complete documentation

## Key Features Implemented

### Core Gameplay
- ✅ 13 unique building types (houses, shops, factories, infrastructure, special)
- ✅ Realistic building costs ($500 - $100,000)
- ✅ Economic system with income/expenses per tick
- ✅ Population management
- ✅ Building requirements (population, power)

### Road System
- ✅ Road construction ($500 per tile)
- ✅ Connectivity algorithm (flood fill)
- ✅ Economy bonuses based on network size (5% per road)
- ✅ Multiple disconnected zones support

### Multiplayer
- ✅ Real-time WebSocket communication
- ✅ Live cursor synchronization
- ✅ Building synchronization across clients
- ✅ Player-specific colors
- ✅ Join/leave notifications
- ✅ IRC-style chat system

### Persistence
- ✅ SQLite database storage
- ✅ Auto-save every 10 seconds
- ✅ Nickname-based login (no passwords)
- ✅ Offline economy processing (10%)
- ✅ Session resumption

### User Interface
- ✅ Login screen (Enter to submit)
- ✅ Stats display (money, population)
- ✅ Building toolbox with prices
- ✅ Grayed out unaffordable options
- ✅ Context menu (Edit/Delete)
- ✅ Chat box with timestamps
- ✅ No buttons - keyboard shortcuts

### Controls
- ✅ Right mouse drag - Pan camera
- ✅ Mouse wheel - Zoom in/out
- ✅ Left click - Place building
- ✅ Right click on building - Context menu
- ✅ Enter - Confirm input
- ✅ Escape - Cancel input
- ✅ Tile highlighting on hover

### Rendering Optimization
- ✅ Viewport culling (only render visible tiles)
- ✅ Throttled cursor updates (100ms)
- ✅ Efficient building mesh management
- ✅ Three.js orthographic camera for performance

## Game Mechanics

### Building Types & Economics

**Residential** (Provide Population)
- Small House: -$50/tick, +10 pop
- Medium House: -$120/tick, +25 pop
- Large House: -$250/tick, +50 pop

**Commercial** (Generate Income)
- Small Shop: +$100/tick, -5 pop, needs 20 pop
- Supermarket: +$300/tick, -15 pop, needs 50 pop
- Mall: +$800/tick, -40 pop, needs 100 pop

**Industrial** (Generate Income)
- Small Factory: +$200/tick, -20 pop
- Large Factory: +$500/tick, -50 pop

**Infrastructure**
- Road: Connects buildings, boosts economy
- Park: -$20/tick, +5 pop
- Plaza: -$40/tick, +10 pop

**Special**
- Town Hall: -$100/tick, +100 pop
- Power Plant: -$500/tick, -30 pop, enables large buildings

### Economy Formula
```
Building Income = Base Income × Connectivity Bonus
Connectivity Bonus = 1.0 + (Road Network Size × 0.05)
```

### Offline Economy
When a player is offline, their economy continues at 10% power:
```
Offline Income = Base Income × 0.10
```

## Technical Specifications

### Server
- **Framework**: FastAPI 0.118.0
- **WebSocket**: Native FastAPI WebSocket support
- **Database**: SQLite3 (built-in)
- **Host**: 127.0.0.1:9901
- **Game Tick**: Every 10 seconds
- **Persistence**: Every 10 seconds

### Client
- **Renderer**: Three.js r128
- **View**: Orthographic camera (Transport Tycoon style)
- **Architecture**: ES6 Modules
- **Components**: Web Components (Custom Elements)
- **No frameworks**: Pure vanilla JavaScript

### Communication Protocol
All WebSocket messages are JSON with a `type` field:

**Client → Server**
- `cursor_move`: {x, y}
- `place_building`: {building_type, x, y}
- `remove_building`: {x, y}
- `edit_building`: {x, y, name}
- `chat`: {message, timestamp}

**Server → Client**
- `init`: Initial player and game state
- `game_state_update`: Periodic full state sync
- `building_placed`: Building added
- `building_removed`: Building removed
- `building_updated`: Building name changed
- `cursor_move`: Player cursor moved
- `player_joined`: Player connected
- `player_left`: Player disconnected
- `chat`: Chat message
- `error`: Error message

## Project Structure
```
city-builder/
├── server/              # Backend Python code
│   ├── __init__.py
│   ├── main.py
│   ├── websocket_manager.py
│   ├── game_state.py
│   ├── economy.py
│   ├── database.py
│   └── models.py
├── static/              # Frontend code
│   ├── index.html
│   ├── css/
│   │   └── style.css
│   └── js/
│       ├── App.js
│       ├── WebSocketClient.js
│       ├── GameRenderer.js
│       ├── InputHandler.js
│       ├── UIManager.js
│       └── components/
│           ├── LoginScreen.js
│           ├── StatsDisplay.js
│           ├── BuildingToolbox.js
│           ├── ChatBox.js
│           └── ContextMenu.js
├── data/                # SQLite database (auto-created)
│   └── game.db
├── requirements.txt
├── .gitignore
├── run.py
├── README.md
└── PROJECT_SUMMARY.md
```

## Development Approach

The project follows modern best practices:

1. **Separation of Concerns**: Clear separation between backend, frontend, and UI
2. **Component Architecture**: Each component is self-contained
3. **ES6 Modules**: Modern JavaScript module system
4. **Web Components**: Custom HTML elements for reusability
5. **Real-time Communication**: WebSocket for instant updates
6. **Optimistic Updates**: UI updates immediately, server validates
7. **Error Handling**: Graceful error messages to users
8. **Performance**: Only render what's visible
9. **Persistence**: Auto-save prevents data loss
10. **Multiplayer**: True multiplayer with shared game state

## How to Run

```bash
# Install dependencies
python -m venv .venv
source .venv/bin/activate
pip install -r requirements.txt

# Start server
python run.py

# Open in browser
http://127.0.0.1:9901
```

## Testing the Game

1. Open browser to http://127.0.0.1:9901
2. Enter a nickname (press Enter)
3. Try building:
   - Click "Small House" in the toolbox
   - Click on the map to place it
   - Build more houses to increase population
   - Build roads to connect buildings
   - Build shops once you have enough population
4. Try multiplayer:
   - Open another browser tab/window
   - Enter a different nickname
   - See both players' cursors and buildings
5. Try chat:
   - Type in the chat box at the bottom
   - Press Enter to send
6. Try right-click menu:
   - Right-click your own building
   - Choose "Edit Name" or "Delete"

## Completion Status

**ALL REQUIREMENTS MET ✓**

Every feature from the original specification has been implemented:
- Transport Tycoon visual style with Three.js
- Real-time multiplayer via WebSocket
- 10+ building types with economic gameplay
- Road connectivity system
- Player-specific colors
- Live cursor tracking
- IRC-style chat
- Nickname-based login
- Offline economy (10% power)
- Context menus
- No-button inputs (Enter/Escape)
- Performance optimizations
- SQLite persistence

The game is fully playable and ready for deployment!