UserManager.cs

using Microsoft.AspNetCore.Cryptography.KeyDerivation;
using Microsoft.EntityFrameworkCore;
 
using TirsvadCLI.Portfolio.Core.Abstracts;
using TirsvadCLI.Portfolio.Domain.Entities;
namespace TirsvadCLI.Portfolio.Core.Managers;

public class UserManager
{
    private readonly Func<IApplicationDbContext> _dbContextFactory;

    public UserManager(Func<IApplicationDbContext> dbContextFactory)
    {
        _dbContextFactory = dbContextFactory;
    }

    public async Task<ApplicationUser?> FindByNameAsync(string username)
    {
        IApplicationDbContext context = _dbContextFactory();
        try
        {
            return await context.Users.FirstOrDefaultAsync(u => u.UserName == username);
        }
        finally
        {
            (context as IDisposable)?.Dispose();
        }
    }

    public static Task<bool> CheckPasswordAsync(ApplicationUser user, string password)
    {
        // Assumes PasswordHash is stored as "base64Salt:base64Hash"
        if (string.IsNullOrEmpty(user.PasswordHash) || !user.PasswordHash.Contains(':'))
            return Task.FromResult(false);
 
        string[] parts = user.PasswordHash.Split(':');
        if (parts.Length != 2)
            return Task.FromResult(false);
 
        byte[] saltBytes = Convert.FromBase64String(parts[0]);
        string storedHash = parts[1];
 
        string hash = HashPassword(password, saltBytes);
        return Task.FromResult(storedHash == hash);
    }

    public async Task AddUserAsync(ApplicationUser user)
    {
        IApplicationDbContext context = _dbContextFactory();
        try
        {
            _ = context.Users.Add(user);
            _ = await context.SaveChangesAsync();
        }
        finally
        {
            (context as IDisposable)?.Dispose();
        }
    }

    private static string HashPassword(string password, byte[] salt)
    {
        return Convert.ToBase64String(
            KeyDerivation.Pbkdf2(
                password: password,
                salt: salt,
                prf: KeyDerivationPrf.HMACSHA256,
                iterationCount: 10000,
                numBytesRequested: 256 / 8));
    }
}