using MediatR;
using Microsoft.Extensions.Logging;
using TakeoutSaaS.Application.App.Stores.Commands;
using TakeoutSaaS.Application.App.Stores.Dto;
using TakeoutSaaS.Domain.Merchants.Repositories;
using TakeoutSaaS.Domain.Stores.Entities;
using TakeoutSaaS.Domain.Stores.Repositories;
using TakeoutSaaS.Shared.Abstractions.Constants;
using TakeoutSaaS.Shared.Abstractions.Exceptions;
using TakeoutSaaS.Shared.Abstractions.Tenancy;

namespace TakeoutSaaS.Application.App.Stores.Handlers;

/// <summary>
/// 创建排班处理器。
/// </summary>
public sealed class CreateStoreEmployeeShiftCommandHandler(
    IStoreRepository storeRepository,
    IMerchantRepository merchantRepository,
    ITenantProvider tenantProvider,
    ILogger<CreateStoreEmployeeShiftCommandHandler> logger)
    : IRequestHandler<CreateStoreEmployeeShiftCommand, StoreEmployeeShiftDto>
{
    /// <inheritdoc />
    public async Task<StoreEmployeeShiftDto> Handle(CreateStoreEmployeeShiftCommand request, CancellationToken cancellationToken)
    {
        // 1. 校验门店存在
        var tenantId = tenantProvider.GetCurrentTenantId();
        var store = await storeRepository.FindByIdAsync(request.StoreId, tenantId, cancellationToken);
        if (store is null)
        {
            throw new BusinessException(ErrorCodes.NotFound, "门店不存在");
        }

        // 2. 校验员工归属与状态
        var staff = await merchantRepository.FindStaffByIdAsync(request.StaffId, tenantId, cancellationToken);
        if (staff is null || (staff.StoreId.HasValue && staff.StoreId != request.StoreId))
        {
            throw new BusinessException(ErrorCodes.ValidationFailed, "员工不存在或不属于该门店");
        }

        // 3. 校验日期与冲突
        var from = request.ShiftDate.Date;
        var to = request.ShiftDate.Date;
        var shifts = await storeRepository.GetShiftsAsync(request.StoreId, tenantId, from, to, cancellationToken);
        var hasConflict = shifts.Any(x => x.StaffId == request.StaffId && x.ShiftDate == request.ShiftDate);
        if (hasConflict)
        {
            throw new BusinessException(ErrorCodes.Conflict, "该员工当日已存在排班");
        }

        // 4. 构建实体
        var shift = new StoreEmployeeShift
        {
            StoreId = request.StoreId,
            StaffId = request.StaffId,
            ShiftDate = request.ShiftDate.Date,
            StartTime = request.StartTime,
            EndTime = request.EndTime,
            RoleType = request.RoleType,
            Notes = request.Notes?.Trim()
        };

        // 5. 持久化
        await storeRepository.AddShiftsAsync(new[] { shift }, cancellationToken);
        await storeRepository.SaveChangesAsync(cancellationToken);
        logger.LogInformation("创建排班 {ShiftId} 员工 {StaffId} 门店 {StoreId}", shift.Id, shift.StaffId, shift.StoreId);

        // 6. 返回 DTO
        return StoreMapping.ToDto(shift);
    }
}