using ChessGameDomain;
using ChessGameService;
using CommonDomain;
using CommonDomain.BaseModel;
using CommonDomain.Enum;
using Microsoft.AspNetCore.SignalR;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using MongoRepository;
using RedisHelper;
using RedisService;
using Common.Redis;

namespace ChessGameHost.Services;

public class ChessBotService : BackgroundService
{
    private readonly ILogger<ChessBotService> _logger;
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly IHubContext<ChessGameHub> _hubContext;
    private static readonly Random _random = new();

    public ChessBotService(
        ILogger<ChessBotService> logger,
        IServiceScopeFactory scopeFactory,
        IHubContext<ChessGameHub> hubContext)
    {
        _logger = logger;
        _scopeFactory = scopeFactory;
        _hubContext = hubContext;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        await Task.Delay(TimeSpan.FromSeconds(10), stoppingToken);

        await CleanStaleRooms();

        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                using var scope = _scopeFactory.CreateScope();
                var redisService = scope.ServiceProvider.GetRequiredService<IRedisService>();
                var distributedLock = scope.ServiceProvider.GetRequiredService<IDistributedLock>();
                var emptyRoomRateRepo = scope.ServiceProvider.GetRequiredService<IMongoBaseRepository<EmptyRoomRateConfig>>();

                var rooms = redisService.GetAllChessRooms();
                if (rooms == null) rooms = new List<ChessGameDomain.ChessGameRoom>();

                if (rooms.Count > 0)
                {
                    var robotRoomAllowance = await EnsureChessEmptyRoomRate(
                        emptyRoomRateRepo, redisService, distributedLock, rooms);

                    var candidateRooms = rooms.Where(r =>
                        r != null
                        && r.state == 0
                        && (r.users == null || r.users.Count == 0)
                        && r.robotCount == 0
                    ).ToList();

                    int maxBatch = Math.Min(Math.Min(candidateRooms.Count, robotRoomAllowance), 5);
                    for (int i = 0; i < maxBatch; i++)
                    {
                        var candidate = candidateRooms[i];
                        ChessGameRoom? updatedRoom = null;
                        await distributedLock.TryExecuteAsync(
                            $"{RedisKey.DistributedLockPrefix}chess:room:{candidate.RoomId}",
                            () =>
                            {
                                var target = redisService.GetChessRoom(candidate.RoomId);
                                if (target == null || target.state == 3 ||
                                    (target.users != null && target.users.Count > 0))
                                    return Task.CompletedTask;

                                target.robotCount = 1;
                                target.state = 1;
                                if (string.IsNullOrEmpty(target.password))
                                    target.password = _random.Next(100000, 999999).ToString();

                                redisService.SetChessRoom(target);
                                updatedRoom = target;
                                return Task.CompletedTask;
                            },
                            expiry: 10);

                        if (updatedRoom != null)
                            await _hubContext.Clients.Group(ChessGameHub.LobbyGroup).SendAsync("JoinRoomNotice", updatedRoom);
                    }

                }

            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "ChessBotService 执行异常");
            }

            await Task.Delay(TimeSpan.FromMinutes(2), stoppingToken);
        }
    }

    private async Task CleanStaleRooms()
    {
        try
        {
            using var scope = _scopeFactory.CreateScope();
            var redisService = scope.ServiceProvider.GetRequiredService<IRedisService>();
            var distributedLock = scope.ServiceProvider.GetRequiredService<IDistributedLock>();

            var rooms = redisService.GetAllChessRooms();
            if (rooms == null) return;

            var staleRooms = rooms.Where(r => r != null
                && (r.users == null || r.users.Count == 0)
                && (r.state == 3 || (r.state == 1 && string.IsNullOrWhiteSpace(r.createUserId))))
                .ToList();

            if (staleRooms.Count == 0) return;

            foreach (var room in staleRooms)
            {
                await distributedLock.TryExecuteAsync(
                    $"{RedisKey.DistributedLockPrefix}chess:room:{room.RoomId}",
                    () =>
                    {
                        var target = redisService.GetChessRoom(room.RoomId);
                        if (target == null) return Task.CompletedTask;

                        if (target.state == 1 && string.IsNullOrWhiteSpace(target.createUserId)
                            && (target.users == null || target.users.Count == 0))
                        {
                            redisService.RemoveChessRoom(target.RoomId);
                            return Task.CompletedTask;
                        }

                        target.users = new List<ChessGameDomain.RedisChessGameUser>();
                        target.state = 0;
                        target.password = "";
                        target.createUserId = "";
                        target.gold = 0;
                        target.gameType = 0;
                        target.robotCount = 0;
                        target.IsGameEnded = false;
                        target.EndGameRequests?.Clear();
                        target.PendingWinUserId = null;
                        target.TimeoutLoserUserId = "";
                        target.LastActiveTime = 0;

                        redisService.SetChessRoom(target);
                        return Task.CompletedTask;
                    },
                    expiry: 5);

                await Task.Delay(50);
            }

        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "[ChessBot] 启动清理异常");
        }
    }

    private async Task<int> EnsureChessEmptyRoomRate(
        IMongoBaseRepository<EmptyRoomRateConfig> emptyRoomRateRepo,
        IRedisService redisService,
        IDistributedLock distributedLock,
        List<ChessGameRoom> rooms)
    {
        try
        {
            var chessConfigs = emptyRoomRateRepo
                .FilterBy(c => c.GameType == GameTypeEnum.中国象棋 && !c.IsDelete)
                .ToList();
            if (chessConfigs == null || chessConfigs.Count == 0)
                return 0;

            var threshold = chessConfigs.Max(c => c.EmptyRoomRate);
            if (threshold <= 0)
                return rooms.Count;

            if (rooms == null || rooms.Count == 0)
                return 0;

            var total = rooms.Count(r => r != null);
            var requiredEmpty = (int)Math.Ceiling(total * Math.Clamp(threshold, 0, 100) / 100.0);
            var empty = rooms.Count(IsAvailableEmptyRoom);
            var needRelease = Math.Max(0, requiredEmpty - empty);

            if (needRelease > 0)
            {
                var robotOnlyRooms = rooms
                    .Where(r => r != null && !HasActiveHuman(r) && r.robotCount > 0)
                    .OrderBy(r => r.CreateTime)
                    .Take(needRelease)
                    .ToList();

                foreach (var room in robotOnlyRooms)
                {
                    ChessGameRoom? releasedRoom = null;
                    await distributedLock.TryExecuteAsync(
                        $"{RedisKey.DistributedLockPrefix}chess:room:{room.RoomId}",
                        () =>
                        {
                            var target = redisService.GetChessRoom(room.RoomId);
                            if (target == null || HasActiveHuman(target) || target.robotCount <= 0)
                                return Task.CompletedTask;

                            ResetToEmptyRoom(target);
                            redisService.SetChessRoom(target);
                            releasedRoom = target;
                            return Task.CompletedTask;
                        },
                        expiry: 10,
                        retry: true,
                        retryDelay: 50);

                    if (releasedRoom != null)
                    {
                        empty++;
                        await _hubContext.Clients.Group(ChessGameHub.LobbyGroup)
                            .SendAsync("ExitRoomNotice", releasedRoom);
                    }
                }
            }

            return Math.Max(0, empty - requiredEmpty);
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "ChessBotService 维护空房率失败");
            return 0;
        }
    }

    private static bool IsAvailableEmptyRoom(ChessGameRoom room)
    {
        return room != null
            && !HasActiveHuman(room)
            && room.robotCount == 0
            && room.state != 2;
    }

    private static void ResetToEmptyRoom(ChessGameRoom room)
    {
        room.users = new List<RedisChessGameUser>();
        room.state = 0;
        room.password = "";
        room.createUserId = "";
        room.gold = 0;
        room.gameType = 0;
        room.robotCount = 0;
        room.IsGameEnded = false;
        room.EndGameRequests?.Clear();
        room.PendingWinUserId = null;
        room.TimeoutLoserUserId = "";
        room.LastActiveTime = 0;
    }

    private static bool HasActiveHuman(ChessGameRoom room)
    {
        return room?.users != null && room.users.Any(u => u != null && !u.IsLeave);
    }
}