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

namespace Application.Features.Admin.Store.Shipment.UpdateStatus;

public sealed class Handler(IAppDbContext db) : ICommandHandler<Command, Result>
{
    public async Task<Result> Handle(Command request, CancellationToken ct)
    {
        var shipment = await db.Shipment
            .Include(s => s.Order)
            .FirstOrDefaultAsync(s => s.ID == request.ShipmentID, ct);

        if (shipment is null)
        {
            return Result.Failure(Error.NotFound("Shipment.NotFound", "배송 정보를 찾을 수 없습니다."));
        }

        try
        {
            switch (request.Action)
            {
                case "RegisterTracking":
                    if (string.IsNullOrWhiteSpace(request.Carrier) || string.IsNullOrWhiteSpace(request.TrackingNumber))
                    {
                        return Result.Failure(Error.Problem("Shipment.TrackingRequired", "택배사와 송장번호를 모두 입력해주세요."));
                    }
                    shipment.RegisterTracking(request.Carrier, request.TrackingNumber);
                    if (shipment.Order is not null && shipment.Order.Status == OrderStatus.Paid)
                    {
                        shipment.Order.MarkPreparing();
                    }
                    break;

                case "InTransit":
                    shipment.MarkInTransit();
                    if (shipment.Order is not null && shipment.Order.Status is OrderStatus.Paid or OrderStatus.Preparing)
                    {
                        shipment.Order.MarkShipped();
                    }
                    break;

                case "Delivered":
                    shipment.MarkDelivered();
                    if (shipment.Order is not null && shipment.Order.Status is OrderStatus.Paid or OrderStatus.Preparing or OrderStatus.Shipped)
                    {
                        shipment.Order.MarkDelivered();
                    }
                    break;

                case "Failed":
                    shipment.MarkFailed();
                    break;

                case "UpdateBilling":
                    if (request.ShippingFee is null)
                    {
                        return Result.Failure(Error.Problem("Shipment.ShippingFeeRequired", "배송비를 입력해주세요."));
                    }
                    if (request.ShippingFee < 0)
                    {
                        return Result.Failure(Error.Problem("Shipment.ShippingFeeNegative", "배송비는 0 이상이어야 합니다."));
                    }
                    if (request.AdminMemo is { Length: > 500 })
                    {
                        return Result.Failure(Error.Problem("Shipment.AdminMemoTooLong", "관리자 메모는 500자 이하여야 합니다."));
                    }
                    shipment.UpdateBillingInfo(request.ShippingFee.Value, request.AdminMemo);
                    break;

                default:
                    return Result.Failure(Error.Problem("Shipment.UnknownAction", $"알 수 없는 액션: {request.Action}"));
            }
        }
        catch (InvalidOperationException ex)
        {
            return Result.Failure(Error.Problem("Shipment.InvalidTransition", ex.Message));
        }

        await db.SaveChangesAsync(ct);

        return Result.Success();
    }
}