source: ChapterX.Application/Auth/LoginHandler.cs@ e294f7d

using ChapterX.Domain.Repositories;
using MediatR;

namespace ChapterX.Application.Auth
{
    public class LoginHandler : IRequestHandler<LoginRequest, LoginResponse>
    {
        private readonly IUserRepository _userRepository;
        private readonly IJwtTokenService _jwtTokenService;

        public LoginHandler(IUserRepository userRepository, IJwtTokenService jwtTokenService)
        {
            _userRepository = userRepository;
            _jwtTokenService = jwtTokenService;
        }

        public async Task<LoginResponse> Handle(LoginRequest request, CancellationToken cancellationToken)
        {
            var user = await _userRepository.GetByEmailAsync(request.Email, cancellationToken)
                ?? throw new UnauthorizedAccessException("Invalid email or password.");

            if (!BCrypt.Net.BCrypt.Verify(request.Password, user.Password))
                throw new UnauthorizedAccessException("Invalid email or password.");

            var token = _jwtTokenService.GenerateToken(user);

            return new LoginResponse(token, user.Id, user.Username, user.Email);
        }
    }
}