using MediatR;
using Microsoft.Extensions.Logging;
using TakeoutSaaS.Application.App.Merchants.Commands;
using TakeoutSaaS.Application.App.Merchants.Dto;
using TakeoutSaaS.Domain.Merchants.Entities;
using TakeoutSaaS.Domain.Merchants.Enums;
using TakeoutSaaS.Domain.Merchants.Repositories;
using TakeoutSaaS.Shared.Abstractions.Security;

namespace TakeoutSaaS.Application.App.Merchants.Handlers;

/// <summary>
/// 创建商户命令处理器。
/// </summary>
public sealed class CreateMerchantCommandHandler(
    IMerchantRepository merchantRepository,
    ICurrentUserAccessor currentUserAccessor,
    ILogger<CreateMerchantCommandHandler> logger)
    : IRequestHandler<CreateMerchantCommand, MerchantDto>
{
    /// <inheritdoc />
    public async Task<MerchantDto> Handle(CreateMerchantCommand request, CancellationToken cancellationToken)
    {
        // 1. 构建商户实体（RowVersion 由 PostgreSQL xmin 自动管理）
        var merchant = new Merchant
        {
            TenantId = request.TenantId,
            BrandName = request.BrandName.Trim(),
            BrandAlias = request.BrandAlias?.Trim(),
            LogoUrl = request.LogoUrl?.Trim(),
            Category = request.Category?.Trim(),
            ContactPhone = request.ContactPhone.Trim(),
            ContactEmail = request.ContactEmail?.Trim(),
            Status = request.Status,
            JoinedAt = DateTime.UtcNow
        };

        // 2. 如果状态为已通过，设置审核通过时间和审核人
        if (request.Status == MerchantStatus.Approved)
        {
            merchant.ApprovedAt = DateTime.UtcNow;
            merchant.ApprovedBy = currentUserAccessor.UserId;
        }

        // 3. 持久化商户
        await merchantRepository.AddMerchantAsync(merchant, cancellationToken);
        await merchantRepository.SaveChangesAsync(cancellationToken);

        // 4. 如果状态为已通过，添加默认审核通过记录
        if (request.Status == MerchantStatus.Approved)
        {
            var auditLog = new MerchantAuditLog
            {
                TenantId = merchant.TenantId,
                MerchantId = merchant.Id,
                Action = MerchantAuditAction.ReviewApproved,
                Title = "商户创建时直接通过审核",
                Description = "平台管理员创建商户时选择无需审核，系统自动通过",
                OperatorId = currentUserAccessor.UserId == 0 ? null : currentUserAccessor.UserId,
                OperatorName = currentUserAccessor.UserId == 0 ? "system" : $"user:{currentUserAccessor.UserId}"
            };
            await merchantRepository.AddAuditLogAsync(auditLog, cancellationToken);
            await merchantRepository.SaveChangesAsync(cancellationToken);
        }

        // 5. 记录日志
        logger.LogInformation("创建商户 {MerchantId} - {BrandName}，状态：{Status}", merchant.Id, merchant.BrandName, merchant.Status);
        return MapToDto(merchant);
    }

    private static MerchantDto MapToDto(Merchant merchant) => new()
    {
        Id = merchant.Id,
        TenantId = merchant.TenantId,
        BrandName = merchant.BrandName,
        BrandAlias = merchant.BrandAlias,
        LogoUrl = merchant.LogoUrl,
        Category = merchant.Category,
        ContactPhone = merchant.ContactPhone,
        ContactEmail = merchant.ContactEmail,
        Status = merchant.Status,
        JoinedAt = merchant.JoinedAt,
        CreatedAt = merchant.CreatedAt
    };
}