using MediatR;
using TakeoutSaaS.Application.App.Merchants.Dto;
using TakeoutSaaS.Application.App.Merchants.Queries;
using TakeoutSaaS.Domain.Merchants.Repositories;
using TakeoutSaaS.Shared.Abstractions.Constants;
using TakeoutSaaS.Shared.Abstractions.Exceptions;
using TakeoutSaaS.Shared.Abstractions.Tenancy;

namespace TakeoutSaaS.Application.App.Merchants.Handlers;

/// <summary>
/// 查询合同列表。
/// </summary>
public sealed class GetMerchantContractsQueryHandler(
    IMerchantRepository merchantRepository,
    ITenantProvider tenantProvider)
    : IRequestHandler<GetMerchantContractsQuery, IReadOnlyList<MerchantContractDto>>
{
    public async Task<IReadOnlyList<MerchantContractDto>> Handle(GetMerchantContractsQuery request, CancellationToken cancellationToken)
    {
        // 1. 获取租户上下文并校验商户存在
        var tenantId = tenantProvider.GetCurrentTenantId();
        _ = await merchantRepository.FindByIdAsync(request.MerchantId, tenantId, cancellationToken)
            ?? throw new BusinessException(ErrorCodes.NotFound, "商户不存在");

        // 2. 查询合同列表
        var contracts = await merchantRepository.GetContractsAsync(request.MerchantId, tenantId, cancellationToken);
        return MerchantMapping.ToContractDtos(contracts);
    }
}