bitforum-backend/Application/Features/Api/Auth/Login/Handler.cs

using SharedKernel;
using SharedKernel.Results;
using Application.Abstractions.Authentication;
using Application.Abstractions.Data;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Options;
using Microsoft.Extensions.Logging;
using MediatR;

namespace Application.Features.Api.Auth.Login;

internal sealed class Handler(
    IAppDbContext db,
    IJwtTokenProvider jwtTokenProvider,
    IOptions<AppSettings> options,
    ILogger<Handler> logger
) : IRequestHandler<Command, Result<Response>> {

    private readonly AppSettings.JwtSection _jwt = options.Value.JWT;

    public async Task<Result<Response>> Handle(Command request, CancellationToken ct)
    {
        // 유효성 검사
        if (string.IsNullOrWhiteSpace(request.Email))
        {
            return Result.Failure<Response>(Error.Problem("Auth.EmailRequired", "이메일은 필수입니다."));
        }

        if (string.IsNullOrWhiteSpace(request.Password))
        {
            return Result.Failure<Response>(Error.Problem("Auth.PasswordRequired", "비밀번호는 필수입니다."));
        }

        // Member 조회 (비밀번호 검증을 위해 Tracking 모드)
        var email = request.Email.Trim().ToLower();
        var member = await db.Member.FirstOrDefaultAsync(m => m.Email == email, ct);

        if (member is null)
        {
            return Result.Failure<Response>(Error.Unauthorized("Auth.InvalidCredentials", "이메일 또는 비밀번호가 올바르지 않습니다."));
        }

        // 비밀번호 검증
        if (!member.VerifyPassword(request.Password))
        {
            return Result.Failure<Response>(Error.Unauthorized("Auth.InvalidCredentials", "이메일 또는 비밀번호가 올바르지 않습니다."));
        }

        // JWT 토큰 생성
        var accessToken = jwtTokenProvider.CreateAccessToken(member.ID, member.Email, member.Name);
        var refreshToken = jwtTokenProvider.CreateRefreshToken();
        var expiresAt = DateTime.UtcNow.AddMinutes(_jwt.AccessTokenExpiration);

        // RefreshToken 저장
        var refreshTokenEntity = Domain.Entities.Members.RefreshToken.Create(
            member.ID,
            refreshToken,
            DateTime.UtcNow.AddDays(_jwt.RefreshTokenExpiration)
        );

        await db.RefreshToken.AddAsync(refreshTokenEntity, ct);

        // 로그인 횟수 증가
        var memberStats = await db.MemberStats.FirstOrDefaultAsync(x => x.MemberID == member.ID, ct);
        if (memberStats is not null)
        {
            memberStats.LoginCount++;
        }

        await db.SaveChangesAsync(ct);

        logger.LogInformation("{0} 로그인", member.Email);

        return Result.Success(new Response(accessToken, refreshToken, expiresAt));
    }
}