using LiveRecorder.Application.Abstractions.Persistence;
using LiveRecorder.Application.Abstractions.Settings;
using LiveRecorder.Application.Abstractions.Storage;
using LiveRecorder.Application.Models.Reports;
using LiveRecorder.Application.Common;
using LiveRecorder.Domain.Enums;

namespace LiveRecorder.Application.Services;

public sealed class DashboardService
{
    private readonly ILiveRoomRepository _liveRoomRepository;
    private readonly IRecordSessionRepository _recordSessionRepository;
    private readonly IRecordTaskRepository _recordTaskRepository;
    private readonly IRecordResultRepository _recordResultRepository;
    private readonly ISystemLogRepository _systemLogRepository;
    private readonly ISystemSettingsService _systemSettingsService;
    private readonly IStorageGuardService _storageGuardService;
    private readonly IOperationsMetricsRepository _operationsMetricsRepository;

    public DashboardService(
        ILiveRoomRepository liveRoomRepository,
        IRecordSessionRepository recordSessionRepository,
        IRecordTaskRepository recordTaskRepository,
        IRecordResultRepository recordResultRepository,
        ISystemLogRepository systemLogRepository,
        ISystemSettingsService systemSettingsService,
        IStorageGuardService storageGuardService,
        IOperationsMetricsRepository operationsMetricsRepository)
    {
        _liveRoomRepository = liveRoomRepository;
        _recordSessionRepository = recordSessionRepository;
        _recordTaskRepository = recordTaskRepository;
        _recordResultRepository = recordResultRepository;
        _systemLogRepository = systemLogRepository;
        _systemSettingsService = systemSettingsService;
        _storageGuardService = storageGuardService;
        _operationsMetricsRepository = operationsMetricsRepository;
    }

    public async Task<DashboardDto> GetDashboardAsync(CancellationToken cancellationToken = default)
    {
        var now = DateTimeOffset.UtcNow;
        var beijingNow = ChinaTime.ToBeijingTime(now);
        var todayBeijingDate = DateOnly.FromDateTime(beijingNow.DateTime);
        // Bound "today in Beijing" but normalize to UTC — Npgsql only accepts offset 0
        // when writing to a `timestamp with time zone` column.
        var todayUtcStart = new DateTimeOffset(todayBeijingDate.ToDateTime(TimeOnly.MinValue), ChinaTime.Zone.GetUtcOffset(beijingNow.DateTime)).ToUniversalTime();
        var todayUtcEnd = new DateTimeOffset(todayBeijingDate.ToDateTime(TimeOnly.MaxValue), ChinaTime.Zone.GetUtcOffset(beijingNow.DateTime)).ToUniversalTime();
        var recentErrorSince = now.AddHours(-24);
        var currentErrorSince = now.AddMinutes(-30);

        // Run queries sequentially — DbContext is not thread-safe
        var activeRecordingCount = await _recordSessionRepository.CountByStatusAsync(RecordSessionStatus.Running, cancellationToken);
        var liveRoomCount = await _liveRoomRepository.CountByAvailabilityAsync(LiveRoomAvailabilityStatus.Live, cancellationToken);
        var offlineRoomCount = await _liveRoomRepository.CountByAvailabilityAsync(LiveRoomAvailabilityStatus.Offline, cancellationToken);
        var totalRoomCount = await _liveRoomRepository.CountAsync(cancellationToken);
        var activeSessionCount = await _recordSessionRepository.CountActiveAsync(cancellationToken);
        var recentErrorCount = await _systemLogRepository.CountRecentErrorsAsync(recentErrorSince, cancellationToken);
        var currentErrorCount = await _systemLogRepository.CountRecentErrorsAsync(currentErrorSince, cancellationToken);
        var todayRecordingSeconds = await _recordTaskRepository.SumDurationSecondsAsync(todayUtcStart, todayUtcEnd, cancellationToken);
        var (todayTotalBytes, todayTotalDanmaku) = await _recordResultRepository.GetTodayAggregateAsync(todayUtcStart, todayUtcEnd, cancellationToken);
        var recentSessions = await _recordSessionRepository.ListRecentAsync(5, cancellationToken);
        var todaySessions = await _recordSessionRepository.ListInDateRangeAsync(todayUtcStart, todayUtcEnd, cancellationToken);
        var settings = await _systemSettingsService.GetAsync(cancellationToken);
        var storageCheck = _storageGuardService.CheckCanStartOrResume(settings);
        var pendingTranscodeCount = await _recordTaskRepository.CountByStatusAsync(RecordTaskStatus.Processing, cancellationToken);
        var pendingUploadCount = await _recordResultRepository.CountPendingUploadAsync(cancellationToken);
        var queuedDataBytes = await _recordResultRepository.SumPendingUploadBytesAsync(cancellationToken);
        var operationsMetrics = await _operationsMetricsRepository.GetAsync(cancellationToken);

        return new DashboardDto
        {
            ActiveRecordingCount = activeRecordingCount,
            LiveRoomCount = liveRoomCount,
            OfflineRoomCount = offlineRoomCount,
            TotalRoomCount = totalRoomCount,
            TodayRecordingSeconds = todayRecordingSeconds,
            TodayDataBytes = todayTotalBytes,
            TodayDanmakuCount = todayTotalDanmaku,
            ActiveSessionCount = activeSessionCount,
            RecentErrorCount = recentErrorCount,
            CurrentErrorCount = currentErrorCount,
            StorageStatus = new StorageStatusDto
            {
                IsEnabled = storageCheck.IsEnabled,
                IsAvailable = storageCheck.IsAvailable,
                HasEnoughSpace = storageCheck.HasEnoughSpace,
                Message = storageCheck.Message ?? string.Empty,
                CheckedPath = storageCheck.CheckedPath,
                TotalBytes = storageCheck.TotalBytes,
                UsedBytes = storageCheck.UsedBytes,
                AvailableBytes = storageCheck.AvailableBytes,
                RequiredBytes = storageCheck.RequiredBytes,
                Tier = storageCheck.Tier.ToString(),
                UsagePercent = storageCheck.UsagePercent,
                FreePercent = storageCheck.FreePercent,
                GreenThresholdPercent = storageCheck.GreenThresholdPercent,
                RedThresholdPercent = storageCheck.RedThresholdPercent
            },
            PendingTranscodeCount = pendingTranscodeCount,
            PendingUploadCount = pendingUploadCount,
            QueuedDataBytes = queuedDataBytes,
            OldestTranscodeUpdatedAt = operationsMetrics.OldestTranscodeUpdatedAt,
            OldestUploadProgressAt = operationsMetrics.OldestUploadProgressAt,
            StalledUploadCount = operationsMetrics.StalledUploadCount,
            UploadCleanupFailureCount = operationsMetrics.CleanupFailureCount,
            RecentSessions = recentSessions
                .Select(MapRecentSession)
                .ToList(),
            TopRooms = ComputeTopRooms(todaySessions)
        };
    }

    private static RecentSessionItemDto MapRecentSession(Domain.Entities.RecordSession session)
    {
        var duration = session.RecordTasks
            .Where(item => item.DurationSeconds.HasValue)
            .Sum(item => item.DurationSeconds ?? 0);

        return new RecentSessionItemDto
        {
            Id = session.Id,
            LiveRoomId = session.LiveRoomId,
            LiveRoomTitle = session.LiveRoom?.Title ?? session.LiveRoom?.Alias ?? session.LiveRoom?.AnchorName ?? "-",
            PlatformName = session.LiveRoom?.Platform.ToString() ?? "-",
            SegmentCount = session.SegmentCount,
            Status = (int)session.Status,
            StartedAt = session.StartedAt ?? session.CreatedAt,
            DurationSeconds = duration > 0 ? duration : null
        };
    }

    private static IReadOnlyList<TopRoomItemDto> ComputeTopRooms(IReadOnlyCollection<Domain.Entities.RecordSession> sessions)
    {
        return sessions
            .GroupBy(item => item.LiveRoomId)
            .Select(group =>
            {
                var first = group.First();
                var totalDuration = group
                    .SelectMany(item => item.RecordTasks)
                    .Sum(item => item.DurationSeconds ?? 0);

                return new TopRoomItemDto
                {
                    LiveRoomId = group.Key,
                    Title = first.LiveRoom?.Title ?? first.LiveRoom?.Alias ?? first.LiveRoom?.AnchorName,
                    AnchorName = first.LiveRoom?.AnchorName,
                    PlatformName = first.LiveRoom?.Platform.ToString() ?? "-",
                    RoomId = first.LiveRoom?.RoomId ?? "-",
                    SessionCount = group.Count(),
                    TotalDurationSeconds = totalDuration
                };
            })
            .OrderByDescending(item => item.TotalDurationSeconds)
            .Take(5)
            .ToList();
    }
}