EnvelopeGenerator/EnvelopeGenerator.Application/Receivers/Commands/CreateReceiverCommand.cs

using DigitalData.Core.Abstraction.Application.Repository;
using EnvelopeGenerator.Domain.Entities;
using MediatR;
using Microsoft.AspNetCore.Mvc;
using Microsoft.EntityFrameworkCore;
using System.ComponentModel.DataAnnotations;
using System.Security.Cryptography;
using System.Text;

namespace EnvelopeGenerator.Application.Receivers.Commands;

/// <summary>
/// 
/// </summary>
[ApiExplorerSettings(IgnoreApi = true)]
public record CreateReceiverCommand : IRequest<(int Id, bool AlreadyExists)>
{
    /// <summary>
    /// 
    /// </summary>
    [EmailAddress]
    public required string EmailAddress { get; init; }

    /// <summary>
    /// 
    /// </summary>
    public string? TotpSecretkey { get; init; }

    /// <summary>
    /// var bytes_arr = Encoding.UTF8.GetBytes(EmailAddress.ToUpper());<br/>
    /// var hash_arr = SHA256.HashData(bytes_arr);
    /// var hexa_str = BitConverter.ToString(hash_arr);
    /// return hexa_str.Replace("-", string.Empty);
    /// </summary>
    public string Signature
    {
        get
        {
            var bytes_arr = Encoding.UTF8.GetBytes(EmailAddress!.ToUpper());
            var hash_arr = SHA256.HashData(bytes_arr);
            var hexa_str = BitConverter.ToString(hash_arr);
            return hexa_str.Replace("-", string.Empty);
        }
    }

    /// <summary>
    /// Default value is DateTime.Now
    /// </summary>
    public DateTime AddedWhen { get; } = DateTime.Now;
};

/// <summary>
/// 
/// </summary>
public class CreateReceiverCommandHandler : IRequestHandler<CreateReceiverCommand, (int Id, bool AlreadyExists)>
{
    /// <summary>
    /// 
    /// </summary>
    private readonly IRepository<Receiver> _repo;

    /// <summary>
    /// 
    /// </summary>
    /// <param name="repo"></param>
    public CreateReceiverCommandHandler(IRepository<Receiver> repo)
    {
        _repo = repo;
    }

    /// <summary>
    /// 
    /// </summary>
    /// <param name="request"></param>
    /// <param name="cancel"></param>
    /// <returns></returns>
    public async Task<(int Id, bool AlreadyExists)> Handle(CreateReceiverCommand request, CancellationToken cancel)
    {
        var receiver = await _repo.ReadOnly()
            .Where(r => r.EmailAddress == request.EmailAddress)
            .SingleOrDefaultAsync(cancel);

        var alreadyExists = receiver is not null;

        if (!alreadyExists)
            receiver = await _repo.CreateAsync(request, cancel);

        return (receiver!.Id, alreadyExists);
    }
}