# Complete Game Workflow Documentation

**Version**: 2.0  
**Last Updated**: October 30, 2025  
**Document Type**: Complete System Reference

---

## Table of Contents

1. [System Overview](#system-overview)
2. [Game Flow Diagram](#game-flow-diagram)
3. [REST API Endpoints](#rest-api-endpoints)
4. [WebSocket Events](#websocket-events)
5. [Interfaces & Data Structures](#interfaces--data-structures)
6. [Domain Aggregates](#domain-aggregates)
7. [Complete Game Scenarios](#complete-game-scenarios)
8. [Turn Tracking System](#turn-tracking-system)
9. [Position Guessing Mechanic](#position-guessing-mechanic)
10. [Error Handling](#error-handling)

---

## System Overview

The SerpentRace game system uses a **hybrid architecture**:
- **REST API**: Game creation, joining, and initial setup
- **WebSocket (Socket.IO)**: Real-time gameplay, card interactions, and game state updates
- **Redis**: Session management, pending states, turn tracking
- **PostgreSQL**: Persistent game data, user profiles, decks

### Technology Stack
- **Backend**: Node.js + TypeScript + Express
- **Real-time**: Socket.IO (WebSocket library)
- **Database**: TypeORM + PostgreSQL
- **Cache/Session**: Redis
- **Authentication**: JWT tokens (Access + Refresh)

---

## Game Flow Diagram

```
┌──────────────────────────────────────────────────────────────────────────┐
│                          GAME LIFECYCLE                                   │
└──────────────────────────────────────────────────────────────────────────┘

1. GAME CREATION (REST)
   │
   ├─ POST /api/v1/game/start
   │  ├─ Gamemaster creates game with deck selection
   │  ├─ Game Code generated (6 characters)
   │  └─ Game state: "waiting"
   │
   ▼

2. PLAYER JOINING (REST + WebSocket)
   │
   ├─ POST /api/v1/game/join
   │  ├─ Validate game code
   │  ├─ Check game type (PUBLIC/PRIVATE/ORGANIZATION)
   │  ├─ Add player to game.players[]
   │  └─ Return gameToken for WebSocket auth
   │
   ├─ WebSocket Connection
   │  ├─ Connect to /game namespace
   │  ├─ Emit: game:join with gameToken
   │  ├─ Server validates & joins rooms
   │  └─ Broadcast: game:player-joined to all
   │
   ├─ Emit: game:ready (player marks ready)
   └─ Broadcast: game:player-ready to all
   │
   ▼

3. GAME START (REST)
   │
   ├─ POST /api/v1/game/:gameId/start
   │  ├─ Only gamemaster can start
   │  ├─ Check minimum players (2+)
   │  ├─ Generate board (100 fields with pattern)
   │  ├─ Shuffle and assign turn sequence
   │  ├─ Initialize player positions (all at 0)
   │  └─ Game state: "active"
   │
   ├─ Broadcast: game:started
   │  ├─ Board data sent to all players
   │  ├─ Turn sequence revealed
   │  └─ First player notified
   │
   ▼

4. GAMEPLAY LOOP (WebSocket)
   │
   ├─ DICE ROLL
   │  ├─ Emit: game:dice-roll { diceValue: 1-6 }
   │  ├─ Broadcast: game:dice-rolled
   │  ├─ Calculate new position
   │  ├─ Update player position
   │  ├─ Broadcast: game:player-moved
   │  └─ Check field type at new position
   │
   ├─ SPECIAL FIELD LANDING (positive/negative/luck)
   │  ├─ Wait 2 seconds (frontend animation)
   │  ├─ Draw card from appropriate deck
   │  ├─ Broadcast: game:card-drawn
   │  └─ Branch based on card type:
   │
   │     ┌─ QUESTION CARD (types 0-4)
   │     │  ├─ Emit to player: game:card-drawn-self (60s)
   │     │  ├─ Player answers
   │     │  ├─ Emit: game:card-answer
   │     │  ├─ Broadcast: game:answer-submitted
   │     │  ├─ Validate answer
   │     │  ├─ Broadcast: game:answer-validated
   │     │  ├─ Determine if guess required:
   │     │  │  ├─ Positive field + correct = GUESS
   │     │  │  ├─ Negative field + wrong = GUESS
   │     │  │  ├─ Positive field + wrong = NO MOVEMENT
   │     │  │  └─ Negative field + correct = NO MOVEMENT
   │     │  │
   │     │  └─ IF GUESS REQUIRED:
   │     │     ├─ Emit: game:position-guess-request (30s)
   │     │     ├─ Show pattern modifier, dice, stepValue
   │     │     ├─ Player guesses position
   │     │     ├─ Emit: game:position-guess
   │     │     ├─ Broadcast: game:position-guess-broadcast
   │     │     ├─ Calculate with BoardGenerationService
   │     │     ├─ Apply -2 penalty if wrong
   │     │     ├─ Broadcast: game:guess-result
   │     │     ├─ Check win condition (position >= 100)
   │     │     └─ Check secondary landing
   │
   │     ┌─ LUCK CARD (type 6)
   │     │  ├─ Process immediately (no answer)
   │     │  ├─ Broadcast: game:card-result
   │     │  ├─ Apply consequence:
   │     │  │  ├─ MOVE_FORWARD (0): Move X steps
   │     │  │  ├─ MOVE_BACKWARD (1): Move X steps back
   │     │  │  ├─ LOSE_TURN (2): Store X turns to lose
   │     │  │  ├─ EXTRA_TURN (3): Store X extra turns
   │     │  │  └─ GO_TO_START (5): Return to position 1
   │     │  ├─ Broadcast: game:luck-consequence
   │     │  └─ Advance turn (with turn tracking)
   │
   │     └─ JOKER CARD (type 5) - Secondary Landing Only
   │        ├─ Broadcast: game:joker-drawn
   │        ├─ Request gamemaster decision
   │        ├─ Emit to gamemaster: game:gamemaster-decision-request (120s)
   │        ├─ Gamemaster decides (approve/reject)
   │        ├─ Emit: game:gamemaster-decision
   │        ├─ Broadcast: game:gamemaster-decision-result
   │        ├─ Determine if guess required:
   │        │  ├─ Positive field + approved = GUESS
   │        │  ├─ Negative field + rejected = GUESS
   │        │  ├─ Positive field + rejected = NO MOVEMENT
   │        │  └─ Negative field + approved = NO MOVEMENT
   │        │
   │        └─ IF GUESS REQUIRED:
   │           ├─ Emit: game:joker-position-guess-request (30s)
   │           ├─ Player guesses with dice=6
   │           ├─ Emit: game:joker-position-guess
   │           ├─ Calculate with BoardGenerationService
   │           ├─ Apply -2 penalty if wrong
   │           ├─ Broadcast: game:joker-complete
   │           └─ Check secondary landing
   │
   ├─ TURN ADVANCEMENT
   │  ├─ Check if current player has extra turns
   │  │  └─ IF YES: Same player continues, decrement counter
   │  ├─ Find next player in sequence
   │  ├─ Skip players with turns to lose
   │  │  └─ Broadcast: game:players-skipped
   │  ├─ Broadcast: game:turn-changed
   │  └─ Emit to next player: game:your-turn
   │
   └─ WIN CONDITION
      ├─ Player reaches position >= 100
      ├─ Broadcast: game:ended
      ├─ Update database (finished=true, winner)
      └─ Cleanup all Redis data and disconnect
   │
   ▼

5. GAME END & CLEANUP
   │
   ├─ Clear all Redis keys:
   │  ├─ gameplay:{gameCode}
   │  ├─ game_positions:{gameCode}
   │  ├─ pending_card:{gameCode}:{playerId}
   │  ├─ pending_decision:{gameCode}:{requestId}
   │  ├─ player_extra_turns:{gameCode}:{playerId}
   │  └─ player_turns_to_lose:{gameCode}:{playerId}
   │
   ├─ Force disconnect all players from rooms
   ├─ Emit: game:cleanup-complete
   └─ Database updated with final state
```

---

## REST API Endpoints

### Authentication Headers
All authenticated endpoints require:
```
Authorization: Bearer <access_token>
```

### 1. Create Game

**Endpoint**: `POST /api/v1/game/start`  
**Auth**: Required  
**Description**: Create a new game session with selected decks

**Request Body**:
```typescript
{
  deckids: string[];      // Array of deck UUIDs (at least 1)
  maxplayers: number;     // Maximum players (2-10)
  logintype: number;      // 0=PUBLIC, 1=PRIVATE, 2=ORGANIZATION
}
```

**Response** (200 OK):
```typescript
{
  id: string;                    // Game UUID
  gamecode: string;              // 6-character game code
  maxplayers: number;
  logintype: number;
  boardsize: number;             // Default 100
  createdby: string;             // Gamemaster user ID
  orgid: string | null;          // Organization ID (for ORG games)
  gamedecks: GameDeck[];         // Array of decks with cards
  players: string[];             // Empty array initially
  startdate: Date | null;
  enddate: Date | null;
  finished: boolean;
  winner: string | null;
  totaltiles: number;
}
```

**Errors**:
- `400`: Invalid input (missing deckids, invalid maxplayers, etc.)
- `401`: Not authenticated
- `404`: Deck not found
- `500`: Internal server error

---

### 2. Join Game

**Endpoint**: `POST /api/v1/game/join`  
**Auth**: Optional (depends on game type)  
**Description**: Join an existing game using game code

**Request Body**:
```typescript
{
  gameCode: string;       // 6-character game code
  playerName?: string;    // Required for PUBLIC, optional for authenticated
}
```

**Authentication Requirements by Game Type**:
- **PUBLIC (0)**: No auth required, playerName mandatory
- **PRIVATE (1)**: Auth required
- **ORGANIZATION (2)**: Auth + organization membership required

**Response** (200 OK):
```typescript
{
  id: string;                    // Game UUID
  gamecode: string;              // Game code
  playerName: string;            // Player's display name
  playerCount: number;           // Current number of players
  maxPlayers: number;
  gameType: string;              // "PUBLIC" | "PRIVATE" | "ORGANIZATION"
  isAuthenticated: boolean;
  gameToken: string;             // JWT token for WebSocket authentication
}
```

**Game Token Payload**:
```typescript
{
  gameId: string;
  gameCode: string;
  playerName: string;
  playerId?: string;      // Only if authenticated
  iat: number;            // Issued at
  exp: number;            // Expires in 24 hours
}
```

**Errors**:
- `400`: Invalid gameCode format or missing playerName
- `401`: Authentication required (PRIVATE/ORGANIZATION games)
- `403`: Organization membership required or mismatch
- `404`: Game not found
- `409`: Game full or already started
- `500`: Internal server error

---

### 3. Start Game Play

**Endpoint**: `POST /api/v1/game/:gameId/start`  
**Auth**: Required (only gamemaster)  
**Description**: Start the actual gameplay after all players are ready

**Path Parameters**:
- `gameId`: UUID of the game

**Request Body**: Empty `{}`

**Response** (200 OK):
```typescript
{
  message: string;               // "Game started successfully"
  gameId: string;
  playerCount: number;
  game: GameAggregate;           // Full game object
  boardData: {
    gameId: string;
    fields: GameField[];         // 100 fields with positions, types, stepValues
    generationComplete: boolean;
    generatedAt: Date;
  }
}
```

**Board Generation**:
- Generates 100 fields with pattern-based distribution
- Field types: `regular`, `positive`, `negative`, `luck`
- Each field has `stepValue` (0-3) for movement calculations
- Pattern modifiers by zones:
  - Positions 1-20: +2 (easier start)
  - Positions 21-40: -1 (early challenge)
  - Positions 41-60: +1 (mid-game boost)
  - Positions 61-80: -2 (late challenge)
  - Positions 81-100: +3 (final stretch)

**Game State Changes**:
- `game.startdate` set to current date
- `game.gamePhase` set to "active"
- Turn sequence randomized
- Player positions initialized to 0

**Errors**:
- `400`: Invalid gameId
- `403`: Only gamemaster can start game
- `404`: Game not found
- `409`: Game already started, not enough players, or players not ready
- `500`: Board generation failed or internal error

---

## WebSocket Events

### Connection & Authentication

**Namespace**: `/game`

**Connection**:
```typescript
const socket = io('http://localhost:3000/game', {
  auth: {
    token: gameToken  // JWT token from /game/join endpoint
  }
});
```

**Authentication Flow**:
1. Client connects with `gameToken` in auth
2. Server validates token using `GameTokenService`
3. Server extracts: `gameId`, `gameCode`, `playerName`, `playerId`
4. Server joins socket to rooms:
   - `game_{gameCode}` (all players)
   - `game_{gameCode}:{playerName}` (individual player)
5. Server emits `authenticated` event

**Events**:

```typescript
// Client → Server: Initial join
socket.emit('game:join', { gameToken: string });

// Server → Client: Authentication success
socket.on('authenticated', {
  gameCode: string;
  playerName: string;
  message: string;
});

// Server → All Players: Player joined
socket.on('game:player-joined', {
  playerId: string;
  playerName: string;
  playerCount: number;
  timestamp: string;
});
```

---

### Pre-Game Events

#### Ready System

```typescript
// Client → Server: Mark player as ready
socket.emit('game:ready', { 
  gameCode: string; 
  ready: boolean; 
});

// Server → All Players: Player ready status changed
socket.on('game:player-ready', {
  playerId: string;
  playerName: string;
  ready: boolean;
  readyCount: number;
  totalPlayers: number;
  allReady: boolean;
  timestamp: string;
});
```

#### Game Start Notification

```typescript
// Server → All Players: Game started (after REST /start call)
socket.on('game:started', {
  message: string;
  boardData: BoardData;
  turnSequence: string[];        // Array of player IDs in turn order
  currentPlayer: string;         // First player ID
  currentPlayerName: string;
  timestamp: string;
});

// Server → Current Player: Your turn notification
socket.on('game:your-turn', {
  message: string;
  canRoll: boolean;
  isExtraTurn?: boolean;         // True if using extra turn
  timestamp: string;
});
```

---

### Gameplay Events

#### Dice Roll

```typescript
// Client → Server: Roll dice
socket.emit('game:dice-roll', { 
  gameCode: string; 
  diceValue: number;  // 1-6
});

// Server → All Players: Dice rolled
socket.on('game:dice-rolled', {
  playerId: string;
  playerName: string;
  diceValue: number;
  timestamp: string;
});

// Server → All Players: Player moved
socket.on('game:player-moved', {
  playerId: string;
  playerName: string;
  oldPosition: number;
  newPosition: number;
  diceValue: number;
  timestamp: string;
});
```

---

#### Card Drawing & Question Cards

```typescript
// Server → All Players: Card drawn (everyone sees question)
socket.on('game:card-drawn', {
  playerName: string;
  playerId: string;
  cardType: string;              // "QUIZ", "SENTENCE_PAIRING", etc.
  question: string;              // The question text
  fieldType: string;             // "positive" | "negative" | "luck"
  timestamp: string;
});

// Server → Drawing Player: Interactive card details
socket.on('game:card-drawn-self', {
  cardData: {
    cardid: string;
    question: string;
    type: CardType;
    timeLimit: number;             // 60 seconds
    answerOptions?: QuizOption[];  // For QUIZ (multiple choice)
    sentencePairs?: SentencePair[]; // For SENTENCE_PAIRING (left-right matching)
    words?: string[];              // For SENTENCE_PAIRING (legacy scrambled words)
    // ... type-specific data
  };
  timestamp: string;
});

// SENTENCE_PAIRING Data Structures

/**
 * Sentence pair for left-right matching
 */
interface SentencePair {
  id: string;           // Unique identifier (e.g., "pair_0", "pair_1")
  left: string;         // Left part to match (shown in order)
  right: string;        // Right part (scrambled position)
}

/**
 * Player's answer for sentence pairing
 */
interface SentencePairingAnswer {
  pairId: string;       // ID of the pair being matched
  leftText: string;     // Left part text
  rightText: string;    // Player's chosen right part
}

// Example: Matching fruits to colors
// Card data sent to player:
{
  sentencePairs: [
    { id: "pair_0", left: "Apple", right: "Yellow" },      // Right parts
    { id: "pair_1", left: "Banana", right: "Orange" },     // are scrambled
    { id: "pair_2", left: "Orange", right: "Red" }
  ]
}

// Player's answer:
{
  answer: [
    { pairId: "pair_0", leftText: "Apple", rightText: "Red" },
    { pairId: "pair_1", leftText: "Banana", rightText: "Yellow" },
    { pairId: "pair_2", leftText: "Orange", rightText: "Orange" }
  ]
}

// Client → Server: Submit answer
socket.emit('game:card-answer', { 
  gameCode: string; 
  answer: any;  // Type depends on card type:
                // - QUIZ: string (A/B/C/D)
                // - SENTENCE_PAIRING: SentencePairingAnswer[] or string (legacy)
                // - OWN_ANSWER: string
                // - TRUE_FALSE: boolean or "true"/"false"
                // - CLOSER: number
});

// Server → All Players: Answer submitted (before validation)
socket.on('game:answer-submitted', {
  playerName: string;
  playerId: string;
  answer: any;
  message: string;
  timestamp: string;
});

// Server → All Players: Answer validated
socket.on('game:answer-validated', {
  playerName: string;
  playerId: string;
  isCorrect: boolean;
  correctAnswer: any;
  message: string;
  timestamp: string;
});
```

---

#### Position Guessing (Question Cards)

```typescript
// Server → Player: Request position guess
socket.on('game:position-guess-request', {
  message: string;
  currentPosition: number;       // Starting position
  diceRoll: number;              // Original dice value
  fieldStepValue: number;        // Field's step value
  patternModifier: number;       // Zone-based modifier
  timeLimit: number;             // 30 seconds
  timestamp: string;
});

// Client → Server: Submit position guess
socket.emit('game:position-guess', { 
  gameCode: string; 
  guessedPosition: number; 
});

// Server → All Players: Player's guess broadcast
socket.on('game:position-guess-broadcast', {
  playerId: string;
  playerName: string;
  guessedPosition: number;
  message: string;
  timestamp: string;
});

// Server → All Players: Guess result with full calculation
socket.on('game:guess-result', {
  playerId: string;
  playerName: string;
  guessedPosition: number;
  actualPosition: number;        // Calculated position
  finalPosition: number;         // After penalty (if wrong)
  guessCorrect: boolean;
  penaltyApplied: boolean;       // -2 if wrong
  calculation: {
    startPosition: number;
    diceRoll: number;
    stepValue: number;
    patternModifier: number;
    calculatedPosition: number;
    penalty: number;             // 0 or -2
  };
  message: string;
  timestamp: string;
});

// Server → All Players: Player didn't move
socket.on('game:no-movement', {
  playerId: string;
  playerName: string;
  reason: string;                // "Wrong answer on positive field"
  message: string;
  timestamp: string;
});

// Server → All Players: Penalty avoided
socket.on('game:penalty-avoided', {
  playerId: string;
  playerName: string;
  message: string;               // "Avoided penalty on negative field"
  timestamp: string;
});
```

---

#### Luck Cards

```typescript
// Server → All Players: Luck card consequence applied
socket.on('game:luck-consequence', {
  playerId: string;
  playerName: string;
  consequenceType: string;       // "MOVE_FORWARD" | "MOVE_BACKWARD" | etc.
  value: number;                 // Magnitude of effect
  newPosition?: number;          // For movement consequences
  turnsToLose?: number;          // For LOSE_TURN
  extraTurns?: number;           // For EXTRA_TURN
  message: string;
  timestamp: string;
});
```

**Consequence Types**:
- `MOVE_FORWARD` (0): Move forward X steps
- `MOVE_BACKWARD` (1): Move backward X steps
- `LOSE_TURN` (2): Lose X turns
- `EXTRA_TURN` (3): Gain X extra turns
- `GO_TO_START` (5): Return to position 1

---

#### Joker Cards & Gamemaster Decisions

```typescript
// Server → All Players: Joker card drawn
socket.on('game:joker-drawn', {
  playerName: string;
  playerId: string;
  jokerCard: {
    question: string;
    consequence: Consequence;
  };
  waitingForGamemaster: boolean;
  timestamp: string;
});

// Server → Gamemaster: Decision request
socket.on('game:gamemaster-decision-request', {
  requestId: string;
  playerName: string;
  playerId: string;
  jokerCard: {
    question: string;
    consequence: Consequence;
  };
  timeLimit: number;             // 120 seconds
  timestamp: string;
});

// Client → Server: Gamemaster decision
socket.emit('game:gamemaster-decision', { 
  gameCode: string; 
  requestId: string; 
  decision: 'approve' | 'reject'; 
});

// Server → All Players: Decision result
socket.on('game:gamemaster-decision-result', {
  playerName: string;
  playerId: string;
  gamemasterName: string;
  decision: string;              // "approve" | "reject"
  approved: boolean;
  consequence: number | null;
  description: string;
  timestamp: string;
});

// Server → Player: Joker position guess request
socket.on('game:joker-position-guess-request', {
  message: string;
  currentPosition: number;
  diceRoll: number;              // Always 6 for jokers
  fieldStepValue: number;
  patternModifier: number;
  timeLimit: number;             // 30 seconds
  timestamp: string;
});

// Client → Server: Joker position guess
socket.emit('game:joker-position-guess', { 
  gameCode: string; 
  guessedPosition: number; 
});

// Server → All Players: Joker card complete
socket.on('game:joker-complete', {
  playerId: string;
  playerName: string;
  guessedPosition: number;
  actualPosition: number;
  finalPosition: number;         // Current position if didn't move
  guessCorrect: boolean;
  penaltyApplied: boolean;
  moved: boolean;                // Based on field type + decision
  calculation: {
    startPosition: number;
    diceRoll: number;            // 6
    stepValue: number;
    patternModifier: number;
    calculatedPosition: number;
    penalty: number;
  };
  message: string;
  timestamp: string;
});
```

**Joker Flow Logic**:
- **Positive field + approved**: Player moves (with guess)
- **Positive field + rejected**: Player doesn't move
- **Negative field + approved**: Player doesn't move (avoided penalty)
- **Negative field + rejected**: Player moves (with guess - penalty)

---

#### Turn Advancement & Turn Tracking

```typescript
// Server → All Players: Turn changed
socket.on('game:turn-changed', {
  currentPlayer: string;         // Player ID
  currentPlayerName: string;
  turnNumber: number;
  message: string;
  timestamp: string;
});

// Server → All Players: Extra turn remaining
socket.on('game:extra-turn-remaining', {
  playerId: string;
  playerName: string;
  remainingExtraTurns: number;   // How many left after this one
  message: string;
  timestamp: string;
});

// Server → All Players: Players skipped
socket.on('game:players-skipped', {
  skippedPlayers: Array<{
    playerId: string;
    playerName: string;
    remainingTurnsToLose: number;
  }>;
  message: string;
  timestamp: string;
});
```

---

#### Game End & Cleanup

```typescript
// Server → All Players: Game ended
socket.on('game:ended', {
  winner: string;                // Player ID
  winnerName: string;
  message: string;
  finalPositions: PlayerPosition[];
  timestamp: string;
});

// Server → All Players: Cleanup complete
socket.on('game:cleanup-complete', {
  gameCode: string;
  message: string;
  timestamp: string;
});
```

---

#### Error Events

```typescript
// Server → Client: Error occurred
socket.on('game:error', {
  message: string;
  code?: string;
  timestamp: string;
});

// Server → All Players: Card error (no cards available)
socket.on('game:card-error', {
  playerName: string;
  playerId: string;
  error: string;
  timestamp: string;
});

// Server → All Players: Joker error
socket.on('game:joker-error', {
  playerName: string;
  playerId: string;
  error: string;
  timestamp: string;
});
```

---

## Interfaces & Data Structures

### WebSocket Interfaces

Located in: `src/Application/Services/Interfaces/GameInterfaces.ts`

```typescript
/**
 * Join game room data
 */
export interface JoinGameData {
  gameToken: string;  // JWT token from REST /join endpoint
}

/**
 * Leave game data
 */
export interface LeaveGameData {
  gameCode: string;
}

/**
 * Dice roll data
 */
export interface DiceRollData {
  gameCode: string;
  diceValue: number;  // 1-6
}

/**
 * Player position tracking
 */
export interface PlayerPosition {
  playerId: string;
  playerName: string;
  boardPosition: number;
  turnOrder: number;
}

/**
 * Game chat message
 */
export interface GameChatData {
  gameCode: string;
  message: string;
}

/**
 * Card answer data
 */
export interface CardAnswerData {
  gameCode: string;
  answer: any;  // Type depends on card type
}

/**
 * Gamemaster decision data
 */
export interface GamemasterDecisionData {
  gameCode: string;
  requestId: string;
  decision: 'approve' | 'reject';
}

/**
 * Field effect calculation request
 */
export interface FieldEffectRequest {
  gameId: string;
  playerId: string;
  playerName: string;
  currentPosition: number;
  card: GameCard;
  field: GameField;
  dice: number;
  guessedPosition?: number;
}

/**
 * Field effect calculation result
 */
export interface FieldEffectResult {
  finalPosition: number;
  stepValue: number;
  dice: number;
  patternModifier: number;
  consequenceModifier: number;
  guessResult?: GuessResult;
  gamemasterResult?: GamemasterDecisionResult;
  description: string;
  effects: string[];
  turnEffect?: TurnEffect;
}

/**
 * Turn effect (for multi-turn tracking)
 */
export interface TurnEffect {
  type: 'LOSE_TURN' | 'EXTRA_TURN';
  playerId: string;
  value: number;  // Number of turns
}

/**
 * Guess result details
 */
export interface GuessResult {
  guessedPosition: number;
  actualPosition: number;
  isCorrect: boolean;
  penaltyApplied: boolean;
  description: string;
}
```

---

### Pending State Interfaces

Located in: `src/Application/Services/GameWebSocketService.ts`

```typescript
/**
 * Pending card state (stored in Redis)
 * Used for question cards requiring answers
 */
interface PendingCardState {
  playerId: string;
  playerName: string;
  card: GameCard;
  field: GameField;              // Field where card was drawn
  dice: number;                  // Original dice roll
  currentPosition: number;       // Position before card effect
  drawnAt: number;               // Timestamp
  answerGiven?: boolean;         // Has player answered?
  answerCorrect?: boolean;       // Was answer correct?
  requiresGuess?: boolean;       // Does this require position guess?
  guessedPosition?: number;      // Player's guessed position
}

/**
 * Pending gamemaster decision state (stored in Redis)
 * Used for joker cards
 */
interface PendingDecisionState {
  playerId: string;
  playerName: string;
  card: GameCard;
  field: GameField;              // Field where joker was drawn
  dice: number;                  // Always 6 for jokers
  currentPosition: number;       // Position before joker effect
  drawnAt: number;               // Timestamp
  recursionDepth: number;        // Prevent infinite secondary landings
  gamemasterDecided?: boolean;   // Has gamemaster decided?
  gamemasterApproved?: boolean;  // Was it approved?
  guessedPosition?: number;      // Player's guessed position (if required)
}
```

**Redis Keys**:
```
pending_card:{gameCode}:{playerId}              → PendingCardState (TTL: 60s)
pending_decision:{gameCode}:{requestId}         → PendingDecisionState (TTL: 120s)
player_extra_turns:{gameCode}:{playerId}        → number (extra turns remaining)
player_turns_to_lose:{gameCode}:{playerId}      → number (turns to skip)
```

---

## Domain Aggregates

### GameAggregate

Located in: `src/Domain/Game/GameAggregate.ts`

```typescript
/**
 * Main game entity
 */
@Entity('Games')
export class GameAggregate {
  @PrimaryGeneratedColumn('uuid')
  id: string;

  @Column({ type: 'varchar', length: 10, unique: true })
  gamecode: string;  // 6-character unique code

  @Column({ type: 'int' })
  maxplayers: number;

  @Column({ type: 'int', default: LoginType.PUBLIC })
  logintype: LoginType;  // 0=PUBLIC, 1=PRIVATE, 2=ORGANIZATION

  @Column({ type: 'int', default: 50 })
  boardsize: number;

  @Column({ type: 'uuid', nullable: false, name: 'createdBy' })
  createdby: string;  // Gamemaster user ID

  @Column({ type: 'uuid', nullable: true, name: 'organizationid' })
  orgid: string | null;

  @Column({ type: 'jsonb', default: () => "'[]'", name: 'decks' })
  gamedecks: GameDeck[];  // Decks with cards

  @Column({ type: 'simple-array', default: '' })
  players: string[];  // Array of player IDs/names

  @Column({ type: 'timestamp', nullable: true })
  startdate: Date | null;

  @Column({ type: 'timestamp', nullable: true })
  enddate: Date | null;

  @Column({ type: 'boolean', default: false })
  finished: boolean;

  @Column({ type: 'varchar', nullable: true })
  winner: string | null;

  @Column({ type: 'int', default: 100 })
  totaltiles: number;
}

/**
 * Login type enum
 */
export enum LoginType {
  PUBLIC = 0,        // Anyone can join with playerName
  PRIVATE = 1,       // Requires authentication
  ORGANIZATION = 2   // Requires auth + org membership
}
```

---

### GameField

```typescript
/**
 * Individual board field/tile
 */
export interface GameField {
  position: number;        // 0-100
  type: 'regular' | 'positive' | 'negative' | 'luck';
  stepValue?: number;      // 0-3, used in movement calculation
}

/**
 * Complete board data
 */
export interface BoardData {
  gameId?: string;
  fields: GameField[];     // 100 fields
  generationComplete?: boolean;
  generatedAt?: Date;
  error?: string;
}
```

**Field Type Distribution** (generated by `BoardGenerationService`):
- **Regular**: ~40% (no special card)
- **Positive**: ~25% (reward card)
- **Negative**: ~25% (penalty card)
- **Luck**: ~10% (instant consequence)

**Important**: Fields have NO consequences. Consequences come only from **cards**.

---

### GameCard

```typescript
/**
 * Card in a deck
 */
export interface GameCard {
  cardid: string;
  question?: string;
  answer?: any;                // Can be string, number, object, array
  type?: CardType;
  consequence?: Consequence | null;  // Only for LUCK and JOKER cards
  played?: boolean;
  playerid?: string;
}

/**
 * Card types
 */
export enum CardType {
  QUIZ = 0,              // Multiple choice (A/B/C/D)
  SENTENCE_PAIRING = 1,  // Match left parts to right parts
  OWN_ANSWER = 2,        // Free text answer
  TRUE_FALSE = 3,        // Boolean answer
  CLOSER = 4,            // Closest number answer
  JOKER = 5,             // Gamemaster decision (secondary landing only)
  LUCK = 6               // Instant consequence
}
```

**Card Answer Formats by Type:**

| Card Type | Answer Format in Database | Player Answer Format | Description |
|-----------|---------------------------|----------------------|-------------|
| **QUIZ** | `[{answer:"A", text:"...", correct:true}, ...]` | `"A"` (string) | Multiple choice with 4 options |
| **SENTENCE_PAIRING** | `[{left:"Apple", right:"Red"}, ...]` | `[{pairId, leftText, rightText}, ...]` | Match left to right parts |
| **SENTENCE_PAIRING (legacy)** | `"word1 word2 word3"` (string) | `["word1", "word2", "word3"]` or `"word1 word2 word3"` | Reconstruct scrambled sentence |
| **OWN_ANSWER** | `["answer1", "answer2", ...]` (string[]) | `"player answer"` (string) | Free text with acceptable answers |
| **TRUE_FALSE** | `true` or `false` (boolean) | `true/false` or `"true"/"false"` | True/False question |
| **CLOSER** | `{correct: 42, percent: 10}` (object) | `40` (number) | Closest number within percentage |
| **JOKER** | Not applicable | Not applicable | Gamemaster decides |
| **LUCK** | Not applicable | Not applicable | Instant consequence |

---

### Consequence

Located in: `src/Domain/Deck/DeckAggregate.ts`

```typescript
/**
 * Card consequence structure
 */
export interface Consequence {
  type: ConsequenceType;
  value?: number;  // Magnitude of effect (default: 1)
}

/**
 * Consequence types
 */
export enum ConsequenceType {
  MOVE_FORWARD = 0,    // Move forward X steps
  MOVE_BACKWARD = 1,   // Move backward X steps
  LOSE_TURN = 2,       // Skip X turns
  EXTRA_TURN = 3,      // Get X extra turns
  GO_TO_START = 5      // Return to position 1
}
```

**Multi-Turn Support**:
- `LOSE_TURN` with `value=3`: Player skips next 3 turns
- `EXTRA_TURN` with `value=2`: Player gets 2 additional turns after current

---

### GameDeck

```typescript
/**
 * Deck of cards
 */
export interface GameDeck {
  deckid: string;
  decktype: DeckType;
  cards: GameCard[];
}

/**
 * Deck types
 */
export enum DeckType {
  POSITIVE = 0,   // For positive fields
  NEGATIVE = 1,   // For negative fields
  LUCK = 2,       // For luck fields
  JOKER = 3       // For secondary landings
}
```

---

## Complete Game Scenarios

### Scenario 1: Question Card on Positive Field (Correct Answer)

```
1. Player at position 20, rolls dice = 4
2. Field at position 24 has stepValue = 2, type = "positive"
3. Player lands on position 24
4. Server waits 2 seconds (frontend animation)
5. Server draws POSITIVE deck card (type = QUIZ)
6. Server broadcasts: game:card-drawn (everyone sees question)
7. Server emits: game:card-drawn-self to player (60s timer)
8. Player answers correctly
9. Server broadcasts: game:answer-submitted
10. Server broadcasts: game:answer-validated { isCorrect: true }
11. Server determines: positive field + correct = GUESS REQUIRED
12. Server emits: game:position-guess-request to player (30s timer)
    - Shows: currentPosition=20, dice=4, stepValue=2, patternModifier=+2
13. Player calculates: 20 + 4 + 2 + 2 = 28, guesses 28
14. Server broadcasts: game:position-guess-broadcast { guessedPosition: 28 }
15. Server calculates: 20 + 4 + 2 + 2 = 28 (correct!)
16. Server broadcasts: game:guess-result { 
    guessCorrect: true, 
    finalPosition: 28, 
    penaltyApplied: false 
}
17. Player position updated to 28
18. Server checks: position 28 is not special field
19. Server calls: advanceTurn() → next player's turn
```

---

### Scenario 2: Question Card on Negative Field (Wrong Answer)

```
1. Player at position 50, rolls dice = 5
2. Field at position 55 has stepValue = 1, type = "negative"
3. Player lands on position 55
4. Server waits 2 seconds
5. Server draws NEGATIVE deck card (type = TRUE_FALSE)
6. Server broadcasts: game:card-drawn
7. Server emits: game:card-drawn-self to player
8. Player answers incorrectly
9. Server broadcasts: game:answer-validated { isCorrect: false }
10. Server determines: negative field + wrong = GUESS REQUIRED (penalty test)
11. Server emits: game:position-guess-request
    - Shows: currentPosition=50, dice=5, stepValue=1, patternModifier=+1
12. Player guesses: 57, but actual is: 50 + 5 + 1 + 1 = 57
13. Server calculates actual: 57, player guessed: 57 (CORRECT!)
14. Server broadcasts: game:guess-result { 
    guessCorrect: true, 
    finalPosition: 57, 
    penaltyApplied: false 
}
15. Player moves to 57 (avoided penalty despite wrong answer)
16. Server advances turn
```

---

### Scenario 3: Luck Card with Multi-Turn EXTRA_TURN

```
1. Player at position 30, rolls dice = 3
2. Field at position 33 has type = "luck"
3. Player lands on position 33
4. Server draws LUCK deck card
5. Card has: { type: EXTRA_TURN (3), value: 3 }
6. Server broadcasts: game:card-result
7. Server broadcasts: game:luck-consequence { 
    consequenceType: "EXTRA_TURN", 
    value: 3, 
    extraTurns: 3 
}
8. Server calls: setPlayerExtraTurns(gameCode, playerId, 3)
   - Redis: player_extra_turns:{gameCode}:{playerId} = 3
9. Server calls: advanceTurn()
10. advanceTurn() checks: getPlayerExtraTurns() = 3 > 0
11. Server emits: game:extra-turn-remaining { remainingExtraTurns: 2 }
12. Same player continues (no turn advance)
13. Player rolls again...
14. After turn ends, advanceTurn() checks again: extraTurns = 2 > 0
15. Process repeats until extraTurns = 0
16. Player gets 4 total turns (1 original + 3 extra)
```

---

### Scenario 4: Luck Card with Multi-Turn LOSE_TURN

```
1. Player A draws luck card: { type: LOSE_TURN (2), value: 2 }
2. Server calls: setPlayerTurnsToLose(gameCode, playerA, 2)
   - Redis: player_turns_to_lose:{gameCode}:{playerA} = 2
3. Server broadcasts: game:luck-consequence { 
    consequenceType: "LOSE_TURN", 
    turnsToLose: 2 
}
4. Server calls: advanceTurn() → skip to Player B

--- Later, when it's Player A's turn in sequence ---

5. advanceTurn() reaches Player A in turn sequence
6. Checks: getPlayerTurnsToLose(playerA) = 2 > 0
7. Decrements: 2 → 1
8. Adds to skippedPlayers array
9. Continues to next player in sequence (Player B)
10. Server broadcasts: game:players-skipped { 
    skippedPlayers: [{ 
      playerName: "Player A", 
      remainingTurnsToLose: 1 
    }] 
}
11. Server broadcasts: game:turn-changed { currentPlayer: "Player B" }

--- Next round ---

12. advanceTurn() reaches Player A again
13. Checks: getPlayerTurnsToLose(playerA) = 1 > 0
14. Decrements: 1 → 0, deletes Redis key
15. Skips Player A again
16. Player A skipped 2 times total
```

---

### Scenario 5: Joker Card on Positive Field (Approved by Gamemaster)

```
1. Player completes question card, lands on position 70 (positive field)
2. Server checks secondary landing
3. Server draws JOKER deck card
4. Server broadcasts: game:joker-drawn { waitingForGamemaster: true }
5. Server emits to gamemaster: game:gamemaster-decision-request (120s timer)
6. Gamemaster approves
7. Server broadcasts: game:gamemaster-decision-result { 
    decision: "approve", 
    approved: true 
}
8. Server determines: positive field + approved = GUESS REQUIRED
9. Server emits: game:joker-position-guess-request
   - Shows: currentPosition=70, dice=6, stepValue=1, patternModifier=-2
10. Player guesses: 75, actual: 70 + 6 + 1 - 2 = 75 (CORRECT!)
11. Server broadcasts: game:joker-complete { 
    guessCorrect: true, 
    moved: true, 
    finalPosition: 75 
}
12. Player moves to 75
13. Server checks for tertiary landing (not allowed - recursion depth)
14. Server advances turn
```

---

### Scenario 6: Multiple Players with Turn Tracking

```
Turn Sequence: [PlayerA, PlayerB, PlayerC]

--- Turn 1 ---
PlayerA: Gets EXTRA_TURN (value=2)
- Redis: player_extra_turns:game:PlayerA = 2
- PlayerA plays again

--- Turn 2 (PlayerA extra turn 1) ---
PlayerA: Gets LOSE_TURN (value=1)
- Redis: player_turns_to_lose:game:PlayerA = 1
- Redis: player_extra_turns:game:PlayerA = 1 (still has 1 left)
- advanceTurn() checks: extraTurns = 1 > 0
- PlayerA plays AGAIN (extra turn takes priority)

--- Turn 3 (PlayerA extra turn 2) ---
PlayerA: Normal turn
- Redis: player_extra_turns:game:PlayerA = 0 (deleted)
- advanceTurn() → next player

--- Turn 4 ---
Sequence reaches PlayerA
- Checks: turnsToLose = 1 > 0
- Skip PlayerA, decrement to 0
- Server broadcasts: game:players-skipped
- PlayerB plays

--- Turn 5 ---
PlayerB: Normal turn

--- Turn 6 ---
PlayerC: Normal turn

--- Turn 7 ---
Back to PlayerA (turnsToLose = 0)
- PlayerA plays normally
```

---

## Turn Tracking System

### Redis Storage

```typescript
// Extra turns storage
player_extra_turns:{gameCode}:{playerId} → "3"  // Number as string
TTL: None (cleared on cleanup or use)

// Turns to lose storage
player_turns_to_lose:{gameCode}:{playerId} → "2"  // Number as string
TTL: None (cleared on cleanup or use)
```

### Turn Tracking Methods

```typescript
class GameWebSocketService {
  // Extra turns
  private async setPlayerExtraTurns(
    gameCode: string, 
    playerId: string, 
    count: number
  ): Promise<void>;
  
  private async getPlayerExtraTurns(
    gameCode: string, 
    playerId: string
  ): Promise<number>;  // Returns 0 if not found
  
  private async decrementPlayerExtraTurns(
    gameCode: string, 
    playerId: string
  ): Promise<void>;  // Decrements or deletes if reaches 0
  
  // Turns to lose
  private async setPlayerTurnsToLose(
    gameCode: string, 
    playerId: string, 
    count: number
  ): Promise<void>;
  
  private async getPlayerTurnsToLose(
    gameCode: string, 
    playerId: string
  ): Promise<number>;  // Returns 0 if not found
  
  private async decrementPlayerTurnsToLose(
    gameCode: string, 
    playerId: string
  ): Promise<void>;  // Decrements or deletes if reaches 0
  
  // Cleanup
  private async clearPlayerTurnData(
    gameCode: string, 
    playerId: string
  ): Promise<void>;  // Deletes both keys
}
```

### Enhanced advanceTurn() Logic

```typescript
private async advanceTurn(gameCode: string): Promise<void> {
  // PHASE 1: Check if current player has extra turns
  const extraTurns = await this.getPlayerExtraTurns(gameCode, currentPlayerId);
  if (extraTurns > 0) {
    await this.decrementPlayerExtraTurns(gameCode, currentPlayerId);
    emit('game:extra-turn-remaining', { remainingExtraTurns: extraTurns - 1 });
    emit('game:your-turn', { isExtraTurn: true });
    return;  // Same player continues
  }
  
  // PHASE 2: Find next player, skipping those with lost turns
  let nextTurnIndex = (currentTurnIndex + 1) % turnSequence.length;
  const skippedPlayers = [];
  let loopGuard = 0;
  
  while (loopGuard < turnSequence.length) {
    const candidatePlayerId = turnSequence[nextTurnIndex];
    const turnsToLose = await this.getPlayerTurnsToLose(gameCode, candidatePlayerId);
    
    if (turnsToLose > 0) {
      await this.decrementPlayerTurnsToLose(gameCode, candidatePlayerId);
      skippedPlayers.push({ 
        playerId: candidatePlayerId, 
        remainingTurnsToLose: turnsToLose - 1 
      });
      nextTurnIndex = (nextTurnIndex + 1) % turnSequence.length;
      loopGuard++;
    } else {
      break;  // Found valid player
    }
  }
  
  // PHASE 3: Update game state
  gameState.currentTurn = nextTurnIndex;
  gameState.currentPlayer = turnSequence[nextTurnIndex];
  
  // PHASE 4: Notify about skipped players
  if (skippedPlayers.length > 0) {
    emit('game:players-skipped', { skippedPlayers });
  }
  
  // PHASE 5: Notify about turn change
  emit('game:turn-changed', { currentPlayer, currentPlayerName });
}
```

---

## Position Guessing Mechanic

### Pattern-Based Movement Calculation

**Formula**:
```
finalPosition = currentPosition + dice + stepValue + patternModifier
```

**Pattern Modifiers by Zone**:
```typescript
private getPatternModifier(position: number): number {
  if (position <= 20) return 2;   // Positions 1-20
  if (position <= 40) return -1;  // Positions 21-40
  if (position <= 60) return 1;   // Positions 41-60
  if (position <= 80) return -2;  // Positions 61-80
  return 3;                       // Positions 81-100
}
```

### Guess Requirement Logic

```typescript
private determineGuessRequirement(
  fieldType: 'regular' | 'positive' | 'negative' | 'luck',
  answerCorrect: boolean
): boolean {
  if (fieldType === 'positive') {
    return answerCorrect;  // Correct = guess for REWARD
  } else if (fieldType === 'negative') {
    return !answerCorrect;  // Wrong = guess for PENALTY
  }
  return false;  // Regular and luck fields never require guess
}
```

### Question Card Guess Flow

**Matrix**:
| Field Type | Answer  | Guess Required? | Reason                    |
|------------|---------|-----------------|---------------------------|
| Positive   | Correct | **YES**         | Reward scenario           |
| Positive   | Wrong   | NO              | No movement               |
| Negative   | Correct | NO              | Avoided penalty           |
| Negative   | Wrong   | **YES**         | Penalty test              |
| Regular    | Any     | NO              | No special fields         |
| Luck       | N/A     | NO              | Instant consequence       |

### Joker Card Guess Flow

**Matrix** (dice always = 6):
| Field Type | Gamemaster | Guess Required? | Movement            |
|------------|------------|-----------------|---------------------|
| Positive   | Approved   | **YES**         | Move if guess       |
| Positive   | Rejected   | NO              | No movement         |
| Negative   | Approved   | NO              | No movement (avoid) |
| Negative   | Rejected   | **YES**         | Move if guess       |

### Penalty System

- **Wrong guess**: -2 steps from calculated position
- **Minimum position**: 1 (can't go below start)
- **Applied after calculation**: `finalPosition = max(1, calculatedPosition - 2)`

### Calculation Examples

**Example 1**: Position 15, dice 4, stepValue 2
```
patternModifier = 2 (position 15 is in zone 1-20)
calculation = 15 + 4 + 2 + 2 = 23
```

**Example 2**: Position 35, dice 6, stepValue 1
```
patternModifier = -1 (position 35 is in zone 21-40)
calculation = 35 + 6 + 1 - 1 = 41
```

**Example 3**: Position 75 (joker), stepValue 3
```
dice = 6 (always for jokers)
patternModifier = -2 (position 75 is in zone 61-80)
calculation = 75 + 6 + 3 - 2 = 82
if wrong guess: 82 - 2 = 80
```

---

## Error Handling

### REST API Error Responses

**Format**:
```typescript
{
  error: string;  // Human-readable error message
  code?: string;  // Optional error code
}
```

**Status Codes**:
- `400`: Bad Request (validation errors, missing fields)
- `401`: Unauthorized (authentication required)
- `403`: Forbidden (insufficient permissions, org mismatch)
- `404`: Not Found (game, deck, user not found)
- `409`: Conflict (game full, already started, player already in game)
- `500`: Internal Server Error

### WebSocket Error Events

```typescript
socket.on('game:error', {
  message: string;
  code?: string;
  timestamp: string;
});
```

**Common Errors**:
- Authentication failed
- Invalid game code
- Game already started
- Not your turn
- Invalid answer format
- Timeout expired
- No cards available
- Internal server error

### Timeout Handling

**Card Answer Timeout** (60 seconds):
```typescript
// Server auto-processes as wrong answer
socket.on('game:card-timeout', {
  playerName: string;
  message: string;
  timestamp: string;
});
```

**Gamemaster Decision Timeout** (120 seconds):
```typescript
// Server auto-rejects joker card
socket.on('game:gamemaster-timeout', {
  requestId: string;
  playerName: string;
  message: string;
  timestamp: string;
});
```

**Position Guess Timeout** (30 seconds):
```typescript
// Server treats as no movement
socket.on('game:guess-timeout', {
  playerName: string;
  message: string;
  timestamp: string;
});
```

### Redis Cleanup

**Automatic Cleanup**:
- Game end: All keys deleted
- Player disconnect: Pending states cleared
- Timeout: Keys expire naturally (TTL)

**Manual Cleanup**:
```typescript
// Called on game:ended or disconnect
await cleanupGameData(gameCode, gameId);
```

**Keys Cleaned**:
```
gameplay:{gameCode}
game_state:{gameCode}
game_board_{gameCode}
game_connections:{gameCode}
game_ready:{gameCode}
game_pending:{gameCode}
game_positions:{gameCode}
pending_card:{gameCode}:{playerId}
pending_decision:{gameCode}:{requestId}
player_extra_turns:{gameCode}:{playerId}
player_turns_to_lose:{gameCode}:{playerId}
```

---

## Card Type Implementation Details

### SENTENCE_PAIRING Card Type

**Purpose**: Test player's ability to match related items (left parts to right parts)

**Use Cases**:
- Match words to definitions
- Match questions to answers  
- Match countries to capitals
- Match names to descriptions
- Match terms to translations

#### Database Format (NEW)

```typescript
// In DeckAggregate Card.answer field
{
  text: "Match each fruit to its color",
  type: CardType.SENTENCE_PAIRING,  // 1
  answer: [
    { left: "Apple", right: "Red" },
    { left: "Banana", right: "Yellow" },
    { left: "Orange", right: "Orange" },
    { left: "Grape", right: "Purple" }
  ]
}
```

#### Client Preparation

Server scrambles the **right parts** while keeping left parts in order:

```typescript
// Sent to client in game:card-drawn-self
{
  cardData: {
    question: "Match each fruit to its color",
    type: 1,  // SENTENCE_PAIRING
    sentencePairs: [
      { id: "pair_0", left: "Apple", right: "Purple" },   // Scrambled!
      { id: "pair_1", left: "Banana", right: "Orange" },
      { id: "pair_2", left: "Orange", right: "Red" },
      { id: "pair_3", left: "Grape", right: "Yellow" }
    ],
    timeLimit: 60
  }
}
```

#### Player Answer Format

```typescript
// Player submits array of matches
{
  answer: [
    { pairId: "pair_0", leftText: "Apple", rightText: "Red" },
    { pairId: "pair_1", leftText: "Banana", rightText: "Yellow" },
    { pairId: "pair_2", leftText: "Orange", rightText: "Orange" },
    { pairId: "pair_3", leftText: "Grape", rightText: "Purple" }
  ]
}
```

#### Validation Logic

```typescript
// For each correct pair in database:
1. Find player's match for the left part
2. Compare player's chosen right part to correct right part
3. Case-insensitive comparison with trimmed whitespace
4. ALL pairs must match correctly for answer to be correct

// Example validation result:
{
  isCorrect: true,  // Only if ALL pairs match
  submittedAnswer: [...],
  correctAnswer: [...],
  explanation: "✅ Perfect! All 4 pairs matched correctly!
    ✓ \"Apple\" → \"Red\"
    ✓ \"Banana\" → \"Yellow\"
    ✓ \"Orange\" → \"Orange\"
    ✓ \"Grape\" → \"Purple\""
}
```

#### Partial Match Example

```typescript
// Player gets 2 out of 4 correct:
{
  isCorrect: false,
  explanation: "❌ Only 2/4 pairs correct:
    ✓ \"Apple\" → \"Red\"
    ✗ \"Banana\" → \"Purple\" (should be \"Yellow\")
    ✗ \"Orange\" → \"Yellow\" (should be \"Orange\")
    ✓ \"Grape\" → \"Purple\""
}
```

#### Legacy Format (Backward Compatibility)

**Old Database Format**:
```typescript
{
  text: "The quick brown fox jumps over the lazy dog",
  type: CardType.SENTENCE_PAIRING,
  answer: "The quick brown fox jumps over the lazy dog"  // String
}
```

**Client Preparation (Legacy)**:
```typescript
{
  cardData: {
    question: "Arrange the words to form a sentence:",
    type: 1,
    words: ["lazy", "The", "dog", "fox", "over", "quick", "brown", "jumps", "the"],
    timeLimit: 60
  }
}
```

**Player Answer (Legacy)**:
```typescript
{
  answer: ["The", "quick", "brown", "fox", "jumps", "over", "the", "lazy", "dog"]
  // OR
  answer: "The quick brown fox jumps over the lazy dog"
}
```

#### Frontend Implementation Example

```typescript
// React/Vue component for SENTENCE_PAIRING
interface Props {
  sentencePairs: SentencePair[];
  onSubmit: (answer: SentencePairingAnswer[]) => void;
}

function SentencePairingCard({ sentencePairs, onSubmit }: Props) {
  const [matches, setMatches] = useState<Map<string, string>>(new Map());

  const handleMatch = (pairId: string, leftText: string, rightText: string) => {
    setMatches(prev => new Map(prev).set(pairId, rightText));
  };

  const handleSubmit = () => {
    const answer: SentencePairingAnswer[] = sentencePairs.map(pair => ({
      pairId: pair.id,
      leftText: pair.left,
      rightText: matches.get(pair.id) || ''
    }));
    onSubmit(answer);
  };

  return (
    <div>
      {sentencePairs.map(pair => (
        <div key={pair.id}>
          <span>{pair.left}</span>
          <select onChange={(e) => handleMatch(pair.id, pair.left, e.target.value)}>
            <option value="">-- Select --</option>
            {sentencePairs.map(p => (
              <option key={p.id} value={p.right}>{p.right}</option>
            ))}
          </select>
        </div>
      ))}
      <button onClick={handleSubmit}>Submit</button>
    </div>
  );
}
```

#### Database Migration

**No migration needed!** The implementation supports both formats:

1. **New cards**: Use array of `{left, right}` objects
2. **Existing cards**: Continue working with string format
3. Detection is automatic based on `answer` field type

**Creating New Sentence Pairing Cards**:
```sql
-- Example INSERT for new format
INSERT INTO "Cards" (deck_id, text, type, answer)
VALUES (
  'deck-uuid',
  'Match programming languages to their creators',
  1,  -- SENTENCE_PAIRING
  '[
    {"left": "Python", "right": "Guido van Rossum"},
    {"left": "JavaScript", "right": "Brendan Eich"},
    {"left": "C++", "right": "Bjarne Stroustrup"},
    {"left": "Ruby", "right": "Yukihiro Matsumoto"}
  ]'::jsonb
);
```

---

## Appendix: Complete Event Summary

### Client → Server Events

| Event | Data | Description |
|-------|------|-------------|
| `game:join` | `{ gameToken: string }` | Join game room with auth token |
| `game:ready` | `{ gameCode: string, ready: boolean }` | Mark player as ready/not ready |
| `game:dice-roll` | `{ gameCode: string, diceValue: number }` | Roll dice (1-6) |
| `game:card-answer` | `{ gameCode: string, answer: any }` | Submit card answer |
| `game:gamemaster-decision` | `{ gameCode: string, requestId: string, decision: string }` | Gamemaster decision on joker |
| `game:position-guess` | `{ gameCode: string, guessedPosition: number }` | Submit position guess (question) |
| `game:joker-position-guess` | `{ gameCode: string, guessedPosition: number }` | Submit position guess (joker) |
| `game:leave` | `{ gameCode: string }` | Leave game |

### Server → Client Events

| Event | Audience | Description |
|-------|----------|-------------|
| `authenticated` | Individual | Auth success, joined rooms |
| `game:player-joined` | All | Player joined game |
| `game:player-ready` | All | Player ready status changed |
| `game:started` | All | Game started, board generated |
| `game:turn-changed` | All | Turn advanced to next player |
| `game:your-turn` | Individual | Your turn notification |
| `game:dice-rolled` | All | Dice rolled by player |
| `game:player-moved` | All | Player moved to new position |
| `game:card-drawn` | All | Card drawn (question shown) |
| `game:card-drawn-self` | Individual | Interactive card data |
| `game:answer-submitted` | All | Answer submitted (pre-validation) |
| `game:answer-validated` | All | Answer validation result |
| `game:position-guess-request` | Individual | Request position guess |
| `game:position-guess-broadcast` | All | Player's guess shown |
| `game:guess-result` | All | Guess result with calculation |
| `game:no-movement` | All | Player didn't move |
| `game:penalty-avoided` | All | Player avoided penalty |
| `game:luck-consequence` | All | Luck card consequence applied |
| `game:joker-drawn` | All | Joker card drawn |
| `game:gamemaster-decision-request` | Gamemaster | Decision request |
| `game:gamemaster-decision-result` | All | Decision result |
| `game:joker-position-guess-request` | Individual | Joker position guess request |
| `game:joker-complete` | All | Joker card processing complete |
| `game:extra-turn-remaining` | All | Player using extra turn |
| `game:players-skipped` | All | Players skipped (lost turns) |
| `game:ended` | All | Game ended, winner declared |
| `game:cleanup-complete` | All | Cleanup finished |
| `game:error` | Individual | Error occurred |
| `game:card-error` | All | Card drawing error |

---

**End of Documentation**

For additional details, see:
- `FRONTEND_WEBSOCKET_EVENTS_REFERENCE.md` - Frontend event handling guide
- `DATABASE_MANAGEMENT_GUIDE.md` - Database schema and queries
- `BUILD.md` - Build and deployment instructions