using Application.Abstractions.Data;
using Application.Abstractions.Messaging;
using SharedKernel.Results;
using Domain.Entities.Donations;
using Domain.Entities.Donations.ValueObject;
using Microsoft.EntityFrameworkCore;

namespace Application.Features.Api.DonationRemote.TestDonate;

internal sealed class Handler(IAppDbContext db) : ICommandHandler<Command, Result<Response>>
{
    public async Task<Result<Response>> Handle(Command r, CancellationToken ct)
    {
        if (r.Amount <= 0)
        {
            return Result.Failure<Response>(Error.Problem("Donation.InvalidAmount", "금액은 0보다 커야 합니다."));
        }

        if (r.Amount < DonationConstants.MinAmount)
        {
            return Result.Failure<Response>(Error.Problem("Donation.BelowMinAmount", $"최소 후원 금액은 {DonationConstants.MinAmount}원입니다."));
        }

        if (r.Amount > DonationConstants.MaxAmount)
        {
            return Result.Failure<Response>(Error.Problem("Donation.AboveMaxAmount", $"최대 후원 금액은 {DonationConstants.MaxAmount:N0}원입니다."));
        }

        if (string.IsNullOrWhiteSpace(r.SendName))
        {
            return Result.Failure<Response>(Error.Problem("Donation.SendNameRequired", "별명이 필요합니다."));
        }

        var channel = await db.Channel.AsNoTracking()
            .Where(c => c.WidgetToken == r.WidgetToken && c.IsActive)
            .Select(c => new { c.ID, c.MemberID, c.PlatformFeeRate, c.Name })
            .FirstOrDefaultAsync(ct);

        if (channel is null)
        {
            return Result.Failure<Response>(Error.NotFound("Channel.NotFound", "채널을 찾을 수 없습니다."));
        }

        if (channel.MemberID != r.RequesterMemberID)
        {
            return Result.Failure<Response>(Error.Forbidden("Remote.Forbidden", "권한이 없습니다."));
        }

        // 크루 후원 검증 + 활성 세션 조회 (영구 반영 시에만 세션 필요)
        int? crewSessionID = null;
        string? crewMemberNickname = null;

        if (r.CrewMemberID.HasValue)
        {
            var crewMember = await db.CrewMember.AsNoTracking()
                .Where(m => m.ID == r.CrewMemberID.Value && m.IsActive)
                .Select(m => new { m.ID, m.CrewID, m.Nickname, CrewChannelID = m.Crew!.ChannelID })
                .FirstOrDefaultAsync(ct);

            if (crewMember is null)
            {
                return Result.Failure<Response>(Error.NotFound("CrewMember.NotFound", "크루원을 찾을 수 없습니다."));
            }

            if (crewMember.CrewChannelID != channel.ID)
            {
                return Result.Failure<Response>(Error.Forbidden("CrewMember.Forbidden", "다른 채널의 크루원입니다."));
            }

            crewMemberNickname = crewMember.Nickname;

            if (!r.IsTest)
            {
                crewSessionID = await db.CrewSession.AsNoTracking()
                    .Where(s => s.CrewID == crewMember.CrewID && s.Status == CrewSessionStatus.Active)
                    .OrderByDescending(s => s.CreatedAt)
                    .Select(s => (int?)s.ID)
                    .FirstOrDefaultAsync(ct);
            }
        }

        // Donation 생성 (Wallet/PG 우회 — Send Handler와 다른 흐름)
        var donation = Domain.Entities.Donations.Donation.Create(
            sponsorMemberID: channel.MemberID,
            receiverMemberID: channel.MemberID,
            channelID: channel.ID,
            amount: r.Amount,
            feeRate: channel.PlatformFeeRate,
            message: r.Message,
            sendName: r.SendName,
            crewSessionID: crewSessionID,
            crewMemberID: r.CrewMemberID,
            isTest: r.IsTest
        );

        db.Donation.Add(donation);
        await db.SaveChangesAsync(ct);

        // DonationAlert 생성
        var alert = Domain.Entities.Donations.DonationAlert.Create(
            donationID: donation.ID,
            sponsorMemberID: channel.MemberID,
            receiverMemberID: channel.MemberID
        );

        db.DonationAlert.Add(alert);
        await db.SaveChangesAsync(ct);

        // 첫 Alert Attempt 기록 (재전송 일관성)
        var firstAttempt = DonationAlertAttempt.Create(donation.ID, alert.ID);
        db.DonationAlertAttempt.Add(firstAttempt);

        // 영구 반영(IsTest=false)일 때만 크루 집계 갱신 — 테스트 모드는 SignalR로만 broadcast
        if (!r.IsTest && crewSessionID.HasValue && r.CrewMemberID.HasValue)
        {
            var summary = await db.CrewDonationSummary
                .FirstOrDefaultAsync(s => s.CrewSessionID == crewSessionID.Value && s.CrewMemberID == r.CrewMemberID.Value, ct);

            if (summary is null)
            {
                summary = CrewDonationSummary.Create(crewSessionID.Value, r.CrewMemberID.Value);
                db.CrewDonationSummary.Add(summary);
            }

            summary.AddDonation(r.Amount);

            var session = await db.CrewSession.FindAsync([crewSessionID.Value], ct);
            session?.AddDonation(r.Amount);

            if (session is not null && session.TotalAmount > 0)
            {
                var allSummaries = await db.CrewDonationSummary
                    .Where(s => s.CrewSessionID == session.ID)
                    .OrderByDescending(s => s.TotalAmount)
                    .ToListAsync(ct);

                var rank = 1;
                foreach (var s in allSummaries)
                {
                    var rate = (decimal)s.TotalAmount / session.TotalAmount * 100;
                    s.UpdateContribution(rate, rank++);
                }
            }
        }

        await db.SaveChangesAsync(ct);

        return Result.Success(new Response(
            donation.ID,
            alert.ID,
            alert.CorrelationID,
            donation.Amount,
            donation.FeeAmount,
            donation.NetAmount,
            r.SendName,
            r.Message,
            channel.ID,
            channel.Name,
            r.WidgetToken,
            crewSessionID,
            r.CrewMemberID,
            crewMemberNickname,
            r.IsTest
        ));
    }
}