using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using SPMS.Domain.Entities;
using SPMS.Domain.Enums;
using SPMS.Domain.Interfaces;
using SPMS.Infrastructure.Persistence;

namespace SPMS.Infrastructure.Workers;

public class DailyStatWorker : BackgroundService
{
    private readonly IServiceScopeFactory _scopeFactory;
    private readonly ILogger<DailyStatWorker> _logger;

    private static readonly TimeZoneInfo KstZone = TimeZoneInfo.FindSystemTimeZoneById("Asia/Seoul");

    public DailyStatWorker(
        IServiceScopeFactory scopeFactory,
        ILogger<DailyStatWorker> logger)
    {
        _scopeFactory = scopeFactory;
        _logger = logger;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        _logger.LogInformation("DailyStatWorker 시작");

        while (!stoppingToken.IsCancellationRequested)
        {
            var delay = CalculateDelayUntilNextRun();
            _logger.LogInformation("DailyStatWorker 다음 실행까지 {Delay} 대기", delay);

            try
            {
                await Task.Delay(delay, stoppingToken);
            }
            catch (TaskCanceledException)
            {
                break;
            }

            try
            {
                await AggregateAsync(stoppingToken);
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "DailyStatWorker 집계 중 오류 발생");
            }
        }
    }

    private TimeSpan CalculateDelayUntilNextRun()
    {
        var nowKst = TimeZoneInfo.ConvertTimeFromUtc(DateTime.UtcNow, KstZone);
        var nextRun = nowKst.Date.AddHours(0).AddMinutes(5);

        if (nowKst >= nextRun)
            nextRun = nextRun.AddDays(1);

        var delay = nextRun - nowKst;
        return delay;
    }

    private async Task AggregateAsync(CancellationToken stoppingToken)
    {
        using var scope = _scopeFactory.CreateScope();
        var context = scope.ServiceProvider.GetRequiredService<AppDbContext>();
        var dailyStatRepo = scope.ServiceProvider.GetRequiredService<IDailyStatRepository>();
        var unitOfWork = scope.ServiceProvider.GetRequiredService<IUnitOfWork>();

        var nowKst = TimeZoneInfo.ConvertTimeFromUtc(DateTime.UtcNow, KstZone);
        var yesterday = DateOnly.FromDateTime(nowKst.AddDays(-1));
        var startUtc = TimeZoneInfo.ConvertTimeToUtc(yesterday.ToDateTime(TimeOnly.MinValue), KstZone);
        var endUtc = startUtc.AddDays(1);

        _logger.LogInformation("DailyStatWorker 집계 시작: {Date}", yesterday);

        // 서비스별 발송 통계 집계
        var sendStats = await context.Set<PushSendLog>()
            .Where(l => l.SentAt >= startUtc && l.SentAt < endUtc)
            .GroupBy(l => l.ServiceId)
            .Select(g => new
            {
                ServiceId = g.Key,
                SentCnt = g.Count(),
                SuccessCnt = g.Count(l => l.Status == PushResult.Success),
                FailCnt = g.Count(l => l.Status == PushResult.Failed)
            })
            .ToListAsync(stoppingToken);

        // 서비스별 열람 통계 집계
        var openStats = await context.Set<PushOpenLog>()
            .Where(l => l.OpenedAt >= startUtc && l.OpenedAt < endUtc)
            .GroupBy(l => l.ServiceId)
            .Select(g => new
            {
                ServiceId = g.Key,
                OpenCnt = g.Count()
            })
            .ToListAsync(stoppingToken);

        var openDict = openStats.ToDictionary(o => o.ServiceId, o => o.OpenCnt);

        // 모든 서비스 ID 수집 (발송 + 열람)
        var allServiceIds = sendStats.Select(s => s.ServiceId)
            .Union(openStats.Select(o => o.ServiceId))
            .Distinct();

        foreach (var serviceId in allServiceIds)
        {
            var send = sendStats.FirstOrDefault(s => s.ServiceId == serviceId);
            var openCnt = openDict.GetValueOrDefault(serviceId, 0);

            await dailyStatRepo.UpsertAsync(
                serviceId, yesterday,
                send?.SentCnt ?? 0,
                send?.SuccessCnt ?? 0,
                send?.FailCnt ?? 0,
                openCnt);
        }

        await unitOfWork.SaveChangesAsync();

        // SystemLog에 집계 완료 기록
        context.Set<SystemLog>().Add(new SystemLog
        {
            Action = "DailyStatAggregation",
            Details = $"{yesterday:yyyy-MM-dd} 통계 집계 완료 (서비스 {allServiceIds.Count()}개)",
            CreatedAt = DateTime.UtcNow
        });
        await context.SaveChangesAsync(stoppingToken);

        _logger.LogInformation("DailyStatWorker 집계 완료: {Date}, 서비스 {Count}개", yesterday, allServiceIds.Count());
    }
}