using System.Globalization;
using ClosedXML.Excel;
using SPMS.Application.DTOs.Stats;
using SPMS.Application.Interfaces;
using SPMS.Domain.Common;
using SPMS.Domain.Entities;
using SPMS.Domain.Enums;
using SPMS.Domain.Exceptions;
using SPMS.Domain.Interfaces;

namespace SPMS.Application.Services;

public class StatsService : IStatsService
{
    private readonly IDailyStatRepository _dailyStatRepository;
    private readonly IPushSendLogRepository _pushSendLogRepository;
    private readonly IDeviceRepository _deviceRepository;
    private readonly IMessageRepository _messageRepository;

    public StatsService(
        IDailyStatRepository dailyStatRepository,
        IPushSendLogRepository pushSendLogRepository,
        IDeviceRepository deviceRepository,
        IMessageRepository messageRepository)
    {
        _dailyStatRepository = dailyStatRepository;
        _pushSendLogRepository = pushSendLogRepository;
        _deviceRepository = deviceRepository;
        _messageRepository = messageRepository;
    }

    public async Task<DailyStatResponseDto> GetDailyAsync(long? serviceId, DailyStatRequestDto request)
    {
        var (startDate, endDate) = ParseDateRange(request.StartDate, request.EndDate);

        var stats = await _dailyStatRepository.GetByDateRangeAsync(serviceId, startDate, endDate);

        var items = stats.Select(s => new DailyStatItemDto
        {
            StatDate = s.StatDate.ToString("yyyy-MM-dd"),
            SendCount = s.SentCnt,
            SuccessCount = s.SuccessCnt,
            FailCount = s.FailCnt,
            OpenCount = s.OpenCnt,
            Ctr = CalcCtr(s.OpenCnt, s.SuccessCnt)
        }).ToList();

        var totalSend = stats.Sum(s => s.SentCnt);
        var totalSuccess = stats.Sum(s => s.SuccessCnt);
        var totalFail = stats.Sum(s => s.FailCnt);
        var totalOpen = stats.Sum(s => s.OpenCnt);

        return new DailyStatResponseDto
        {
            Items = items,
            Summary = new DailyStatSummaryDto
            {
                TotalSend = totalSend,
                TotalSuccess = totalSuccess,
                TotalFail = totalFail,
                TotalOpen = totalOpen,
                AvgCtr = CalcCtr(totalOpen, totalSuccess)
            }
        };
    }

    public async Task<SummaryStatResponseDto> GetSummaryAsync(long? serviceId)
    {
        var totalDevices = serviceId.HasValue
            ? await _deviceRepository.CountAsync(d => d.ServiceId == serviceId.Value)
            : await _deviceRepository.CountAsync(d => true);
        var activeDevices = serviceId.HasValue
            ? await _deviceRepository.CountAsync(d => d.ServiceId == serviceId.Value && d.IsActive)
            : await _deviceRepository.CountAsync(d => d.IsActive);
        var totalMessages = serviceId.HasValue
            ? await _messageRepository.CountAsync(m => m.ServiceId == serviceId.Value && !m.IsDeleted)
            : await _messageRepository.CountAsync(m => !m.IsDeleted);

        var allStats = serviceId.HasValue
            ? await _dailyStatRepository.FindAsync(s => s.ServiceId == serviceId.Value)
            : await _dailyStatRepository.FindAsync(s => true);
        var totalSend = allStats.Sum(s => (long)s.SentCnt);
        var totalSuccess = allStats.Sum(s => (long)s.SuccessCnt);
        var totalOpen = allStats.Sum(s => (long)s.OpenCnt);

        var today = DateOnly.FromDateTime(DateTime.UtcNow);
        var todayStat = await _dailyStatRepository.GetByDateAsync(serviceId, today);

        var monthStart = new DateOnly(today.Year, today.Month, 1);
        var monthStats = await _dailyStatRepository.GetByDateRangeAsync(serviceId, monthStart, today);

        return new SummaryStatResponseDto
        {
            TotalDevices = totalDevices,
            ActiveDevices = activeDevices,
            TotalMessages = totalMessages,
            TotalSend = totalSend,
            TotalSuccess = totalSuccess,
            TotalOpen = totalOpen,
            AvgCtr = totalSuccess > 0 ? Math.Round((double)totalOpen / totalSuccess * 100, 2) : 0,
            Today = new PeriodStatDto
            {
                SendCount = todayStat?.SentCnt ?? 0,
                SuccessCount = todayStat?.SuccessCnt ?? 0,
                OpenCount = todayStat?.OpenCnt ?? 0,
                Ctr = CalcCtr(todayStat?.OpenCnt ?? 0, todayStat?.SuccessCnt ?? 0)
            },
            ThisMonth = new PeriodStatDto
            {
                SendCount = monthStats.Sum(s => s.SentCnt),
                SuccessCount = monthStats.Sum(s => s.SuccessCnt),
                OpenCount = monthStats.Sum(s => s.OpenCnt),
                Ctr = CalcCtr(monthStats.Sum(s => s.OpenCnt), monthStats.Sum(s => s.SuccessCnt))
            }
        };
    }

    public async Task<MessageStatResponseDto> GetMessageStatAsync(long? serviceId, MessageStatRequestDto request)
    {
        if (string.IsNullOrWhiteSpace(request.MessageCode))
            throw new SpmsException(ErrorCodes.BadRequest, "message_code는 필수입니다.", 400);

        var message = serviceId.HasValue
            ? await _messageRepository.GetByMessageCodeAndServiceAsync(request.MessageCode, serviceId.Value)
            : await _messageRepository.GetByMessageCodeAsync(request.MessageCode);
        if (message == null)
            throw new SpmsException(ErrorCodes.MessageNotFound, "존재하지 않는 메시지 코드입니다.", 404);

        DateTime? startDate = ParseOptionalDate(request.StartDate);
        DateTime? endDate = ParseOptionalDate(request.EndDate);

        var stats = await _pushSendLogRepository.GetMessageStatsAsync(message.ServiceId, message.Id, startDate, endDate);
        var dailyStats = await _pushSendLogRepository.GetMessageDailyStatsAsync(message.ServiceId, message.Id, startDate, endDate);

        return new MessageStatResponseDto
        {
            MessageCode = message.MessageCode,
            Title = message.Title,
            TotalSend = stats?.TotalSend ?? 0,
            TotalSuccess = stats?.TotalSuccess ?? 0,
            TotalFail = stats?.TotalFail ?? 0,
            TotalOpen = 0,
            Ctr = 0,
            FirstSentAt = stats?.FirstSentAt,
            LastSentAt = stats?.LastSentAt,
            Daily = dailyStats.Select(d => new MessageDailyItemDto
            {
                StatDate = d.StatDate.ToString("yyyy-MM-dd"),
                SendCount = d.SendCount,
                OpenCount = 0,
                Ctr = 0
            }).ToList()
        };
    }

    public async Task<HourlyStatResponseDto> GetHourlyAsync(long? serviceId, HourlyStatRequestDto request)
    {
        var (startDate, endDate) = ParseDateRange(request.StartDate, request.EndDate);

        var startDateTime = startDate.ToDateTime(TimeOnly.MinValue);
        var endDateTime = endDate.ToDateTime(TimeOnly.MinValue).AddDays(1);

        var hourlyStats = await _pushSendLogRepository.GetHourlyStatsAsync(serviceId, startDateTime, endDateTime);

        var items = Enumerable.Range(0, 24).Select(hour =>
        {
            var stat = hourlyStats.FirstOrDefault(h => h.Hour == hour);
            return new HourlyStatItemDto
            {
                Hour = hour,
                SendCount = stat?.SendCount ?? 0,
                OpenCount = 0,
                Ctr = 0
            };
        }).ToList();

        var bestHours = items
            .Where(i => i.SendCount > 0)
            .OrderByDescending(i => i.SendCount)
            .Take(3)
            .Select(i => i.Hour)
            .ToList();

        return new HourlyStatResponseDto
        {
            Items = items,
            BestHours = bestHours
        };
    }

    public async Task<DeviceStatResponseDto> GetDeviceStatAsync(long? serviceId)
    {
        var devices = serviceId.HasValue
            ? await _deviceRepository.FindAsync(d => d.ServiceId == serviceId.Value && d.IsActive)
            : await _deviceRepository.FindAsync(d => d.IsActive);
        var total = devices.Count;

        var byPlatform = devices
            .GroupBy(d => d.Platform)
            .Select(g => new PlatformStatDto
            {
                Platform = g.Key.ToString().ToLowerInvariant(),
                Count = g.Count(),
                Ratio = total > 0 ? Math.Round((double)g.Count() / total * 100, 2) : 0
            })
            .OrderByDescending(p => p.Count)
            .ToList();

        var byPushAgreed = devices
            .GroupBy(d => d.PushAgreed)
            .Select(g => new PushAgreedStatDto
            {
                Agreed = g.Key,
                Count = g.Count(),
                Ratio = total > 0 ? Math.Round((double)g.Count() / total * 100, 2) : 0
            })
            .OrderByDescending(p => p.Count)
            .ToList();

        var tagCounts = new Dictionary<string, int>();
        foreach (var device in devices)
        {
            if (string.IsNullOrWhiteSpace(device.Tags)) continue;
            var tags = device.Tags.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);
            foreach (var tag in tags)
            {
                tagCounts.TryGetValue(tag, out var count);
                tagCounts[tag] = count + 1;
            }
        }

        var byTag = tagCounts
            .OrderByDescending(kv => kv.Value)
            .Select((kv, index) => new TagStatDto
            {
                TagIndex = index,
                TagName = kv.Key,
                Count = kv.Value
            })
            .ToList();

        return new DeviceStatResponseDto
        {
            Total = total,
            ByPlatform = byPlatform,
            ByPushAgreed = byPushAgreed,
            ByTag = byTag
        };
    }

    public async Task<SendLogDetailResponseDto> GetSendLogDetailAsync(long? serviceId, SendLogDetailRequestDto request)
    {
        var message = serviceId.HasValue
            ? await _messageRepository.GetByMessageCodeAndServiceAsync(request.MessageCode, serviceId.Value)
            : await _messageRepository.GetByMessageCodeAsync(request.MessageCode);
        if (message == null)
            throw new SpmsException(ErrorCodes.MessageNotFound, "존재하지 않는 메시지 코드입니다.", 404);

        PushResult? status = null;
        if (!string.IsNullOrWhiteSpace(request.Status))
        {
            status = request.Status.ToLowerInvariant() switch
            {
                "success" => PushResult.Success,
                "failed" => PushResult.Failed,
                _ => null
            };
        }

        Platform? platform = null;
        if (!string.IsNullOrWhiteSpace(request.Platform))
        {
            platform = request.Platform.ToLowerInvariant() switch
            {
                "ios" => Domain.Enums.Platform.iOS,
                "android" => Domain.Enums.Platform.Android,
                "web" => Domain.Enums.Platform.Web,
                _ => null
            };
        }

        var (items, totalCount) = await _pushSendLogRepository.GetDetailLogPagedAsync(
            message.ServiceId, message.Id, request.Page, request.Size, status, platform);

        var totalPages = (int)Math.Ceiling((double)totalCount / request.Size);

        return new SendLogDetailResponseDto
        {
            Items = items.Select(l => new SendLogDetailItemDto
            {
                DeviceId = l.DeviceId,
                DeviceToken = l.Device?.DeviceToken ?? string.Empty,
                Platform = l.Device?.Platform.ToString().ToLowerInvariant() ?? string.Empty,
                Status = l.Status.ToString().ToLowerInvariant(),
                FailReason = l.FailReason,
                SentAt = l.SentAt
            }).ToList(),
            Pagination = new DTOs.Notice.PaginationDto
            {
                Page = request.Page,
                Size = request.Size,
                TotalCount = totalCount,
                TotalPages = totalPages
            }
        };
    }

    public async Task<byte[]> ExportReportAsync(long? serviceId, StatsExportRequestDto request)
    {
        var (startDate, endDate) = ParseDateRange(request.StartDate, request.EndDate);

        using var workbook = new XLWorkbook();

        // Sheet 1: 일별 통계
        var dailyStats = await _dailyStatRepository.GetByDateRangeAsync(serviceId, startDate, endDate);
        var ws1 = workbook.Worksheets.Add("일별 통계");
        ws1.Cell(1, 1).Value = "날짜";
        ws1.Cell(1, 2).Value = "발송";
        ws1.Cell(1, 3).Value = "성공";
        ws1.Cell(1, 4).Value = "실패";
        ws1.Cell(1, 5).Value = "열람";
        ws1.Cell(1, 6).Value = "CTR(%)";
        ws1.Row(1).Style.Font.Bold = true;

        var row = 2;
        foreach (var s in dailyStats.OrderBy(s => s.StatDate))
        {
            ws1.Cell(row, 1).Value = s.StatDate.ToString("yyyy-MM-dd");
            ws1.Cell(row, 2).Value = s.SentCnt;
            ws1.Cell(row, 3).Value = s.SuccessCnt;
            ws1.Cell(row, 4).Value = s.FailCnt;
            ws1.Cell(row, 5).Value = s.OpenCnt;
            ws1.Cell(row, 6).Value = CalcCtr(s.OpenCnt, s.SuccessCnt);
            row++;
        }
        ws1.Columns().AdjustToContents();

        // Sheet 2: 시간대별 통계
        var startDateTime = startDate.ToDateTime(TimeOnly.MinValue);
        var endDateTime = endDate.ToDateTime(TimeOnly.MinValue).AddDays(1);
        var hourlyStats = await _pushSendLogRepository.GetHourlyStatsAsync(serviceId, startDateTime, endDateTime);

        var ws2 = workbook.Worksheets.Add("시간대별 통계");
        ws2.Cell(1, 1).Value = "시간";
        ws2.Cell(1, 2).Value = "발송";
        ws2.Cell(1, 3).Value = "성공";
        ws2.Cell(1, 4).Value = "실패";
        ws2.Row(1).Style.Font.Bold = true;

        for (var hour = 0; hour < 24; hour++)
        {
            var stat = hourlyStats.FirstOrDefault(h => h.Hour == hour);
            ws2.Cell(hour + 2, 1).Value = $"{hour:D2}:00";
            ws2.Cell(hour + 2, 2).Value = stat?.SendCount ?? 0;
            ws2.Cell(hour + 2, 3).Value = stat?.SuccessCount ?? 0;
            ws2.Cell(hour + 2, 4).Value = stat?.FailCount ?? 0;
        }
        ws2.Columns().AdjustToContents();

        // Sheet 3: 플랫폼별 통계
        var devices = serviceId.HasValue
            ? await _deviceRepository.FindAsync(d => d.ServiceId == serviceId.Value && d.IsActive)
            : await _deviceRepository.FindAsync(d => d.IsActive);
        var total = devices.Count;

        var ws3 = workbook.Worksheets.Add("플랫폼별 통계");
        ws3.Cell(1, 1).Value = "플랫폼";
        ws3.Cell(1, 2).Value = "수량";
        ws3.Cell(1, 3).Value = "비율(%)";
        ws3.Row(1).Style.Font.Bold = true;

        var platformGroups = devices
            .GroupBy(d => d.Platform)
            .OrderByDescending(g => g.Count())
            .ToList();

        row = 2;
        foreach (var g in platformGroups)
        {
            ws3.Cell(row, 1).Value = g.Key.ToString();
            ws3.Cell(row, 2).Value = g.Count();
            ws3.Cell(row, 3).Value = total > 0 ? Math.Round((double)g.Count() / total * 100, 2) : 0;
            row++;
        }
        ws3.Columns().AdjustToContents();

        using var stream = new MemoryStream();
        workbook.SaveAs(stream);
        return stream.ToArray();
    }

    public async Task<FailureStatResponseDto> GetFailureStatAsync(long? serviceId, FailureStatRequestDto request)
    {
        var (startDate, endDate) = ParseDateRange(request.StartDate, request.EndDate);

        var startDateTime = startDate.ToDateTime(TimeOnly.MinValue);
        var endDateTime = endDate.ToDateTime(TimeOnly.MinValue).AddDays(1);

        var failureStats = await _pushSendLogRepository.GetFailureStatsAsync(serviceId, startDateTime, endDateTime, request.Limit);

        var totalFail = failureStats.Sum(f => f.Count);

        var items = failureStats.Select(f => new FailureStatItemDto
        {
            FailReason = f.FailReason,
            Count = f.Count,
            Ratio = totalFail > 0 ? Math.Round((double)f.Count / totalFail * 100, 2) : 0,
            Description = GetFailReasonDescription(f.FailReason)
        }).ToList();

        return new FailureStatResponseDto
        {
            TotalFail = totalFail,
            Period = new FailureStatPeriodDto
            {
                StartDate = request.StartDate,
                EndDate = request.EndDate
            },
            Items = items
        };
    }

    private static string GetFailReasonDescription(string failReason)
    {
        return failReason switch
        {
            "InvalidToken" => "만료/잘못된 디바이스 토큰",
            "NotRegistered" => "FCM/APNs에 미등록",
            "MessageTooBig" => "페이로드 크기 초과 (4KB)",
            "RateLimit" => "FCM/APNs 발송 제한 초과",
            "ServerError" => "FCM/APNs 서버 오류",
            "NetworkError" => "네트워크 연결 실패",
            "Unknown" => "분류 불가",
            _ => failReason
        };
    }

    private static double CalcCtr(int openCount, int successCount)
    {
        return successCount > 0 ? Math.Round((double)openCount / successCount * 100, 2) : 0;
    }

    private static (DateOnly Start, DateOnly End) ParseDateRange(string startStr, string endStr)
    {
        if (!DateOnly.TryParseExact(startStr, "yyyy-MM-dd", CultureInfo.InvariantCulture, DateTimeStyles.None, out var start))
            throw new SpmsException(ErrorCodes.StatsDateRangeInvalid, "start_date 형식이 올바르지 않습니다. (yyyy-MM-dd)", 400);

        if (!DateOnly.TryParseExact(endStr, "yyyy-MM-dd", CultureInfo.InvariantCulture, DateTimeStyles.None, out var end))
            throw new SpmsException(ErrorCodes.StatsDateRangeInvalid, "end_date 형식이 올바르지 않습니다. (yyyy-MM-dd)", 400);

        if (start > end)
            throw new SpmsException(ErrorCodes.StatsDateRangeInvalid, "start_date가 end_date보다 클 수 없습니다.", 400);

        return (start, end);
    }

    private static DateTime? ParseOptionalDate(string? dateStr)
    {
        if (string.IsNullOrWhiteSpace(dateStr)) return null;
        return DateTime.TryParseExact(dateStr, "yyyy-MM-dd", CultureInfo.InvariantCulture, DateTimeStyles.None, out var date)
            ? date : null;
    }
}