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

namespace Application.Features.Api.Crew.AcceptInvite;

internal sealed class Handler(
    IAppDbContext db,
    INotificationService notificationService,
    ICrewHubBroadcaster crewBroadcaster
) : ICommandHandler<Command, Result<Response>>
{
    public async Task<Result<Response>> Handle(Command request, CancellationToken ct)
    {
        var invitation = await db.CrewInvitation.FirstOrDefaultAsync(i => i.ID == request.InvitationID, ct);

        if (invitation is null)
        {
            return Result.Failure<Response>(Error.NotFound("CrewInvitation.NotFound", "초대를 찾을 수 없습니다."));
        }

        if (invitation.TargetMemberID != request.MemberID)
        {
            return Result.Failure<Response>(Error.Forbidden("CrewInvitation.NotForYou", "본인에게 온 초대만 수락할 수 있습니다."));
        }

        if (invitation.Status == CrewInviteStatus.Accepted)
        {
            return Result.Failure<Response>(Error.Conflict("CrewInvitation.AlreadyAccepted", "이미 수락한 초대입니다."));
        }

        if (invitation.Status == CrewInviteStatus.Declined)
        {
            return Result.Failure<Response>(Error.Conflict("CrewInvitation.AlreadyDeclined", "이미 거절한 초대입니다."));
        }

        if (invitation.IsExpired() || invitation.Status == CrewInviteStatus.Expired)
        {
            // 자동 만료 마킹 (lazy expiration)
            if (invitation.Status == CrewInviteStatus.Pending)
            {
                invitation.MarkExpired();
                await db.SaveChangesAsync(ct);
            }

            return Result.Failure<Response>(Error.Problem("CrewInvitation.Expired", "초대가 만료되었습니다."));
        }

        var crew = await db.Crew.AsNoTracking().FirstOrDefaultAsync(c => c.ID == invitation.CrewID, ct);

        if (crew is null)
        {
            return Result.Failure<Response>(Error.NotFound("Crew.NotFound", "크루를 찾을 수 없습니다."));
        }

        // 동시 처리: 이미 멤버인지 한 번 더 확인
        var alreadyMember = await db.CrewMember.AnyAsync(m => m.CrewID == invitation.CrewID && m.MemberID == request.MemberID, ct);

        if (alreadyMember)
        {
            invitation.Accept();
            await db.SaveChangesAsync(ct);

            return Result.Failure<Response>(Error.Conflict("Crew.MemberAlreadyExists", "이미 등록된 크루원입니다."));
        }

        // 대상자의 채널 ID 조회
        var channel = await db.Channel.AsNoTracking().FirstOrDefaultAsync(c => c.MemberID == request.MemberID, ct);

        var crewMember = CrewMember.Create(
            invitation.CrewID,
            request.MemberID,
            invitation.Nickname,
            channel?.ID,
            invitation.Role,
            invitation.SortOrder
        );

        db.CrewMember.Add(crewMember);
        invitation.Accept();
        await db.SaveChangesAsync(ct);

        // 운영자(초대 발송자)에게 알림 (SignalR push 포함)
        await notificationService.SendAsync(
            memberID: invitation.InvitedByMemberID,
            type: NotificationType.CrewInvitation,
            title: $"크루 초대 수락",
            message: $"'{invitation.Nickname}' 님이 '{crew.Name}' 크루 초대를 수락했습니다.",
            actionUrl: $"/studio/donation/crew/{invitation.CrewID}",
            relatedType: "CrewInvitation",
            relatedID: invitation.ID,
            imageUrl: null,
            ct: ct
        );

        // 운영자 그룹(crew:{crewID})에 초대 응답 broadcast → 멤버 리스트 자동 새로고침
        await crewBroadcaster.BroadcastMemberChangeAsync(
            crewID: invitation.CrewID,
            kind: "invitationStatusChanged",
            data: new
            {
                invitationID = invitation.ID,
                status = "Accepted",
                crewID = invitation.CrewID,
                crewMemberID = crewMember.ID
            },
            ct: ct
        );

        return Result.Success(new Response(crewMember.ID));
    }
}