classlib/ExpenseTracker.Application/Accounts/Commands/Create/CreateAccountCommandHandler.cs

using AutoMapper;
using MediatR;
using ExpenseTracker.Domain.Entities;
using ExpenseTracker.Application.Common.Interfaces.Services;
using ExpenseTracker.Domain.Enums;
using ExpenseTracker.Application.Common.Interfaces;

namespace ExpenseTracker.Application.Accounts.Commands.Create;

public class CreateAccountCommandHandler : IRequestHandler<CreateAccountCommand, AccountDto>
{
    private readonly IMapper _mapper;
    private readonly IUnitOfWork _unitOfWork;
    private readonly ISessionUserService _sessionUserService;

    public CreateAccountCommandHandler(
        IMapper mapper,
        IUnitOfWork unitOfWork,
        ISessionUserService sessionUserService)
    {
        _mapper = mapper;
        _unitOfWork = unitOfWork;
        _sessionUserService = sessionUserService;
    }

    public async Task<AccountDto> Handle(CreateAccountCommand request, CancellationToken cancellationToken)
    {
        // TODO: Add UserId validation. Throw ValidationException when there is no user with given UserId

        var parentUuid = Guid.NewGuid().ToString();
        var childUuid = Guid.NewGuid().ToString();

        var newAccount = new Account()
        {
            Id = parentUuid,
            Name = request.Name,
            Description = request.Description,
            Currency = Currency.FromName(request.Currency),
            UserId = request.UserId ?? _sessionUserService.Id
        };

        var databaseAccount = await _unitOfWork.AccountRepository.AddOneAsync(newAccount, cancellationToken);

        var newTransaction = new Transaction()
        {
            Id = childUuid,
            Amount = request.InitialBalance,
            Category = Domain.Enums.Category.InitialBalance,
            Time = DateTimeOffset.UtcNow,
            AccountId = parentUuid
        };

        var databaseTransaction = await _unitOfWork.TransactionRepository.AddOneAsync(newTransaction, cancellationToken);

        await _unitOfWork.SaveAsync(cancellationToken);

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