DotNetAngular/src/Application/Services/AuthenticationService.cs

using System.Security.Cryptography;
using Application.Common.Results;
using Application.DTOs;
using Application.Errors;
using Application.Interfaces;
using Application.Models;
using Application.Validators;
using Domain.Entities;
using Domain.Interface;
using Infrastructure.Utilities;
using Microsoft.AspNetCore.Identity;

namespace Application.Services;

public class AuthenticationService(
    IUnitOfWork unitOfWork,
    IUserRepository iUserRepository,
    LoginRequestValidator loginRequestValidator,
    RegisterRequestValidator registerRequestValidator,
    IJwtService jwtService,
    IEmailService emailService) : IAuthenticationService
{
    public async Task<Result> RegisterAsync(RegisterRequest registerRequest)
    {
        var validationResult = await registerRequestValidator.ValidateAsync(registerRequest);
        if (!validationResult.IsValid)
        {
            var errors = validationResult.Errors.Select(x => x.ErrorMessage);
            return Result.Failure(AuthError.CreateInvalidRegisterRequestError(errors));
        }

        var emailExists = await iUserRepository.GetUserByEmailAsync(registerRequest.Email);
        if (emailExists is not null) return Result.Failure(AuthError.EmailAlreadyExists);

        var usernameExists = await iUserRepository.GetUserByUsernameAsync(registerRequest.Username);
        if (usernameExists is not null) return Result.Failure(AuthError.UsernameAlreadyExists);

        var user = new User
        {
            Username = registerRequest.Username,
            Email = registerRequest.Email,
            Password = registerRequest.Password,
            UserRoles = [new UserRole { RoleId = 3 }]
        };

        var passwordHasher = new PasswordHasher<User>();
        var hashedPassword = passwordHasher.HashPassword(user, registerRequest.Password);
        user.Password = hashedPassword;

        await iUserRepository.AddAsync(user);
        await unitOfWork.CommitAsync();
        return Result.Success("User registered successfully.");
    }

    public async Task<Result> LoginAsync(LoginRequest loginRequest)
    {
        var validationResult = await loginRequestValidator.ValidateAsync(loginRequest);
        if (!validationResult.IsValid)
        {
            var errors = validationResult.Errors.Select(x => x.ErrorMessage);
            return Result.Failure(AuthError.CreateInvalidLoginRequestError(errors));
        }

        var (email, password) = loginRequest;
        var user = await iUserRepository.GetUserByEmailAsync(email);
        if (user is null) return Result.Failure(AuthError.UserNotFound);

        var passwordHasher = new PasswordHasher<User>();
        var verificationResult = passwordHasher.VerifyHashedPassword(user, user.Password, password);
        if (verificationResult == PasswordVerificationResult.Failed)
            return Result.Failure(AuthError.InvalidPassword);

        user.LastLogin = DateTime.UtcNow;
        iUserRepository.Update(user);


        var token = new TokenResponse
        {
            AccessToken = await jwtService.GenerateTokenAsync(user),
            RefreshToken = await jwtService.GenerateAndSaveRefreshTokenAsync(user)
        };
        var result = new
        {
            Token = token, user.Username
        };

        return Result.Success(result);
    }

    public async Task<Result> RefreshTokensAsync(RefreshTokenRequest request)
    {
        var user = await jwtService.ValidateRefreshTokenAsync(request.UserId, request.RefreshToken);
        if (user is null) return Result.Failure(AuthError.UserNotFound);

        var result = new TokenResponse
        {
            AccessToken = await jwtService.GenerateTokenAsync(user),
            RefreshToken = await jwtService.GenerateAndSaveRefreshTokenAsync(user)
        };

        return Result.Success(result);
    }

    public async Task<Result> SendResetEmailAsync(string email)
    {
        var user = await iUserRepository.GetUserByEmailAsync(email);
        if (user is null) return Result.Failure(AuthError.UserNotFound);

        var tokenBytes = RandomNumberGenerator.GetBytes(64);
        var emailToken = Convert.ToBase64String(tokenBytes);
        user.ResetPasswordToken = emailToken;
        user.ResetPasswordTokenExpiryTime = DateTime.UtcNow.AddMinutes(15);
        var emailModel = new EmailRequest(email, "Reset Password!!", EmailBody.EmailStringBody(email, emailToken));
        emailService.SendEmailAsync(emailModel);
        iUserRepository.Update(user);
        await unitOfWork.CommitAsync();
        return Result.Success("Reset email sent successfully");
    }

    public async Task<Result> ResetPasswordAsync(ResetPasswordDto resetPasswordDto)
    {
        // Normalize the incoming token if '+' was converted to space by transport layers.
        var normalizedToken = (resetPasswordDto.EmailToken ?? string.Empty).Replace(" ", "+");

        var user = await iUserRepository.GetUserByEmailAsync(resetPasswordDto.Email);
        if (user is null) return Result.Failure(AuthError.UserNotFound);

        var tokenCode = user.ResetPasswordToken;
        var emailTokenExpiryTime = user.ResetPasswordTokenExpiryTime;

        // Validate token and expiration using UTC to match stored times
        if (string.IsNullOrWhiteSpace(normalizedToken) || tokenCode != normalizedToken ||
            emailTokenExpiryTime < DateTime.UtcNow) return Result.Failure(AuthError.InvalidResetLink);

        var passwordHasher = new PasswordHasher<User>();
        var hashedPassword = passwordHasher.HashPassword(user, resetPasswordDto.NewPassword);
        user.Password = hashedPassword;

        // Invalidate the reset token after successful use
        user.ResetPasswordToken = null;
        user.ResetPasswordTokenExpiryTime = default;

        iUserRepository.Update(user);
        await unitOfWork.CommitAsync();
        return Result.Success("Password reset successfully");
    }
}