SerpentRace/SerpentRace_Backend/src/Application/Services/GameSnapshotService.ts

import { IGameSnapshotRepository } from '../../Domain/IRepository/IGameSnapshotRepository';
import { GameSnapshotAggregate, SnapshotTrigger, GameStateSnapshot, PlayerSnapshot } from '../../Domain/Game/GameSnapshotAggregate';
import { RedisService } from './RedisService';
import { logOther, logError } from './Logger';

export class GameSnapshotService {
    private static readonly SNAPSHOT_INTERVAL = 5; // Every 5 turns
    private static readonly MAX_SNAPSHOTS_PER_GAME = 20; // Keep last 20 snapshots

    constructor(
        private snapshotRepository: IGameSnapshotRepository,
        private redisService: RedisService
    ) {}

    /**
     * Create a game state snapshot
     */
    async createSnapshot(
        gameId: string,
        turnNumber: number,
        trigger: SnapshotTrigger,
        notes?: string
    ): Promise<void> {
        try {
            // Gather current game state from Redis
            const gameState = await this.getCurrentGameState(gameId);
            if (!gameState) {
                logError('Cannot create snapshot: game state not found', new Error(`Game ${gameId} not in Redis`));
                return;
            }

            // Gather Redis state (pending actions, timers, etc.)
            const redisState = await this.getRedisState(gameId);

            // Create snapshot
            const snapshot = new GameSnapshotAggregate();
            snapshot.gameid = gameId;
            snapshot.turnNumber = turnNumber;
            snapshot.trigger = trigger;
            snapshot.gameState = gameState;
            snapshot.redisState = redisState;
            snapshot.notes = notes || null;

            await this.snapshotRepository.save(snapshot);

            // Cleanup old snapshots
            await this.snapshotRepository.deleteOldSnapshots(
                gameId, 
                GameSnapshotService.MAX_SNAPSHOTS_PER_GAME
            );

            logOther(`Game snapshot created: ${trigger}`, {
                gameId,
                turnNumber,
                trigger
            });
        } catch (error) {
            logError('Failed to create game snapshot', error as Error);
            // Don't throw - snapshots shouldn't break game flow
        }
    }

    /**
     * Check if snapshot should be created (every N turns)
     */
    shouldCreateSnapshot(turnNumber: number): boolean {
        return turnNumber % GameSnapshotService.SNAPSHOT_INTERVAL === 0;
    }

    /**
     * Restore game state from latest snapshot
     */
    async restoreFromSnapshot(gameId: string): Promise<boolean> {
        try {
            const snapshot = await this.snapshotRepository.findLatestByGameId(gameId);
            if (!snapshot) {
                logOther(`No snapshot found for game ${gameId}`);
                return false;
            }

            // Restore game state to Redis
            await this.restoreGameState(gameId, snapshot.gameState);

            // Restore Redis state (pending actions, timers)
            if (snapshot.redisState) {
                await this.restoreRedisState(gameId, snapshot.redisState);
            }

            logOther(`Game state restored from snapshot`, {
                gameId,
                turnNumber: snapshot.turnNumber,
                trigger: snapshot.trigger,
                age: Date.now() - snapshot.createdat.getTime()
            });

            return true;
        } catch (error) {
            logError('Failed to restore game from snapshot', error as Error);
            return false;
        }
    }

    /**
     * Get current game state from Redis
     */
    private async getCurrentGameState(gameId: string): Promise<GameStateSnapshot | null> {
        try {
            // Get game state
            const gameStateKey = `game_state:${gameId}`;
            const gameStateJson = await this.redisService.get(gameStateKey);
            if (!gameStateJson) return null;

            const gameState = JSON.parse(gameStateJson);

            // Get player positions
            const playerPositions: PlayerSnapshot[] = [];
            const positionsKey = `player_positions:${gameId}`;
            const positionsJson = await this.redisService.get(positionsKey);
            
            if (positionsJson) {
                const positions = JSON.parse(positionsJson);
                for (const [playerId, data] of Object.entries(positions)) {
                    const posData = data as any;
                    
                    // Get extra turns
                    const extraTurnsKey = `extra_turns:${gameId}:${playerId}`;
                    const extraTurns = parseInt(await this.redisService.get(extraTurnsKey) || '0');
                    
                    // Get turns to lose
                    const turnsToLoseKey = `turns_to_lose:${gameId}:${playerId}`;
                    const turnsToLose = parseInt(await this.redisService.get(turnsToLoseKey) || '0');

                    playerPositions.push({
                        playerId: playerId,
                        playerName: posData.playerName || 'Unknown',
                        boardPosition: posData.boardPosition || 0,
                        extraTurns,
                        turnsToLose,
                        isOnline: posData.isOnline !== false
                    });
                }
            }

            // Get board data
            const boardKey = `board_data:${gameId}`;
            const boardJson = await this.redisService.get(boardKey);
            const boardFields = boardJson ? JSON.parse(boardJson).fields : undefined;

            return {
                currentPlayer: gameState.currentPlayer,
                currentPlayerName: gameState.currentPlayerName || 'Unknown',
                turnNumber: gameState.turnNumber || 1,
                turnOrder: gameState.turnOrder || [],
                playerPositions,
                boardFields,
                deckStates: undefined, // TODO: Add deck states if needed
                pendingActions: undefined
            };
        } catch (error) {
            logError('Error getting current game state', error as Error);
            return null;
        }
    }

    /**
     * Get Redis state (pending cards, decisions, etc.)
     */
    private async getRedisState(gameId: string): Promise<any> {
        const redisState: any = {
            pendingCards: {},
            pendingDecisions: {},
            timers: {}
        };

        try {
            // Get all keys for this game
            const pattern = `*${gameId}*`;
            const keys = await this.redisService['client'].keys(pattern);

            for (const key of keys) {
                // Store non-critical state for reference
                if (key.includes('pending_card') || key.includes('pending_decision')) {
                    const value = await this.redisService.get(key);
                    if (value) {
                        redisState.pendingCards[key] = value;
                    }
                }
            }
        } catch (error) {
            logError('Error getting Redis state', error as Error);
        }

        return redisState;
    }

    /**
     * Restore game state to Redis
     */
    private async restoreGameState(gameId: string, state: GameStateSnapshot): Promise<void> {
        // Restore game state
        const gameStateKey = `game_state:${gameId}`;
        await this.redisService.setWithExpiry(gameStateKey, JSON.stringify({
            currentPlayer: state.currentPlayer,
            currentPlayerName: state.currentPlayerName,
            turnNumber: state.turnNumber,
            turnOrder: state.turnOrder
        }), 3600);

        // Restore player positions
        const positionsKey = `player_positions:${gameId}`;
        const positions: any = {};
        for (const player of state.playerPositions) {
            positions[player.playerId] = {
                playerName: player.playerName,
                boardPosition: player.boardPosition,
                isOnline: player.isOnline
            };

            // Restore extra turns
            if (player.extraTurns > 0) {
                const extraTurnsKey = `extra_turns:${gameId}:${player.playerId}`;
                await this.redisService.setWithExpiry(extraTurnsKey, player.extraTurns.toString(), 3600);
            }

            // Restore turns to lose
            if (player.turnsToLose > 0) {
                const turnsToLoseKey = `turns_to_lose:${gameId}:${player.playerId}`;
                await this.redisService.setWithExpiry(turnsToLoseKey, player.turnsToLose.toString(), 3600);
            }
        }
        await this.redisService.setWithExpiry(positionsKey, JSON.stringify(positions), 3600);

        // Restore board data if available
        if (state.boardFields) {
            const boardKey = `board_data:${gameId}`;
            await this.redisService.setWithExpiry(boardKey, JSON.stringify({ fields: state.boardFields }), 3600);
        }
    }

    /**
     * Restore Redis state (partial - pending actions may need re-triggering)
     */
    private async restoreRedisState(gameId: string, redisState: any): Promise<void> {
        // Note: Pending cards and timers should be recreated by game logic
        // This is just for reference/debugging
        logOther('Redis state reference saved (timers/pending actions need manual restart)');
    }

    /**
     * Cleanup snapshots for finished game
     */
    async cleanupGameSnapshots(gameId: string): Promise<void> {
        try {
            await this.snapshotRepository.deleteByGameId(gameId);
            logOther(`Game snapshots cleaned up for game ${gameId}`);
        } catch (error) {
            logError('Failed to cleanup game snapshots', error as Error);
        }
    }

    /**
     * Get snapshot history for debugging
     */
    async getSnapshotHistory(gameId: string): Promise<GameSnapshotAggregate[]> {
        return await this.snapshotRepository.findByGameId(gameId);
    }
}