http-api/src/Application/Identity/Accounts/Commands/UpdateAccount/UpdateAccountCommandHandler.cs

using MediatR;
using cuqmbr.TravelGuide.Application.Common.Persistence;
using AutoMapper;
using cuqmbr.TravelGuide.Application.Common.Exceptions;
using System.Security.Cryptography;
using System.Text;
using cuqmbr.TravelGuide.Application.Common.Services;
using cuqmbr.TravelGuide.Domain.Entities;

namespace cuqmbr.TravelGuide.Application
    .Identity.Accounts.Commands.UpdateAccount;

public class UpdateAccountCommandHandler :
    IRequestHandler<UpdateAccountCommand, AccountDto>
{
    private readonly UnitOfWork _unitOfWork;
    private readonly IMapper _mapper;
    private readonly PasswordHasherService _passwordHasher;

    public UpdateAccountCommandHandler(UnitOfWork unitOfWork,
        IMapper mapper, PasswordHasherService passwordHasher)
    {
        _unitOfWork = unitOfWork;
        _mapper = mapper;
        _passwordHasher = passwordHasher;
    }

    public async Task<AccountDto> Handle(
        UpdateAccountCommand request,
        CancellationToken cancellationToken)
    {
        var account = await _unitOfWork.AccountRepository
            .GetOneAsync(e => e.Guid == request.Guid,
                e => e.AccountRoles, cancellationToken);

        if (account == null)
        {
            throw new NotFoundException();
        }

        
        account.Username = request.Username ?? account.Username;
        account.Email = request.Email ?? account.Email;

        if (request.Password != null)
        {
            var salt = RandomNumberGenerator.GetBytes(128 / 8);
            var hash = await _passwordHasher.HashAsync(
                Encoding.UTF8.GetBytes(request.Password),
                salt, cancellationToken);

            var saltBase64 = Convert.ToBase64String(salt);
            var hashBase64 = Convert.ToBase64String(hash);

            account.PasswordHash = hashBase64;
            account.PasswordSalt = saltBase64;
        }


        if (request.Roles != null)
        {
            var requestRoleIds = (await _unitOfWork.RoleRepository
                .GetPageAsync(
                    r => request.Roles.Contains(r.Value),
                    1, request.Roles.Count, cancellationToken))
                .Items
                .Select(r => r.Id);

            var accountRoles = account.AccountRoles;
            var accountRoleIds = accountRoles.Select(ar => ar.RoleId);

            var commonRoleIds = requestRoleIds.Intersect(accountRoleIds);

            var newRoleIds = requestRoleIds.Except(accountRoleIds);

            var combinedRoleIds = commonRoleIds.Union(newRoleIds);

            account.AccountRoles = combinedRoleIds.Select(rId =>
                new AccountRole()
                {
                    Id = accountRoles.FirstOrDefault(ar =>
                        ar.RoleId == rId)?.Id ?? default,
                    RoleId = rId
                })
                .ToList();
        }
        else
        {
            var accountRoleIds = account.AccountRoles.Select(ar => ar.RoleId);
            var accountRoles = (await _unitOfWork.AccountRoleRepository
                .GetPageAsync(
                    ar => accountRoleIds.Contains(ar.RoleId),
                    ar => ar.Role,
                    1, accountRoleIds.Count(), cancellationToken))
                .Items;

            account.AccountRoles = accountRoles.ToList();
        }


        account = await _unitOfWork.AccountRepository.UpdateOneAsync(
            account, cancellationToken);

        await _unitOfWork.SaveAsync(cancellationToken);
        _unitOfWork.Dispose();

        return _mapper.Map<AccountDto>(account);
    }
}