EnvelopeGenerator/EnvelopeGenerator.Application/PdfSigning/SignPdfByEnvelopeCommand.cs

using DigitalData.Core.Abstraction.Application.Repository;
using DigitalData.Core.Exceptions;
using EnvelopeGenerator.Application.Common.Query;
using EnvelopeGenerator.Domain.Entities;
using EnvelopeGenerator.Domain.Exceptions;
using MediatR;
using Microsoft.EntityFrameworkCore;

namespace EnvelopeGenerator.Application.PdfSigning;
/// <summary>
/// 
/// </summary>
public record SignPdfByEnvelopeCommand : EnvelopeQueryBase, IRequest<Stream>
{
    /// <summary>
    /// 
    /// </summary>
    public int? ReceiverId { get; init; } = null;

    internal int? UserId { get; private set; } = null;

    /// <summary>
    /// 
    /// </summary>
    /// <param name="userId"></param>
    /// <returns></returns>
    public SignPdfByEnvelopeCommand Authorized(int userId)
    {
        UserId = userId;
        return this;
    }
}

/// <summary>
/// 
/// </summary>
public class SignPdfByEnvelopeCommandHandler(IRepository<Envelope> Repo, ISender sender) : IRequestHandler<SignPdfByEnvelopeCommand, Stream>
{
    /// <summary>
    /// 
    /// </summary>
    /// <param name="request"></param>
    /// <param name="cancel"></param>
    /// <returns></returns>
    /// <exception cref="NotImplementedException"></exception>
    public async Task<Stream> Handle(SignPdfByEnvelopeCommand request, CancellationToken cancel)
    {
        var envelopeQuery = Repo.Query;

        if (request.Id is int id)
            envelopeQuery = envelopeQuery.Where(e => e.Id == id);
        else if (request.Uuid is string uuid)
            envelopeQuery = envelopeQuery.Where(e => e.Uuid == uuid);

        var envelope = await envelopeQuery.Include(e => e.EnvelopeReceivers).Include(e => e.Documents).SingleOrDefaultAsync(cancel)
            ?? throw new NotFoundException($"Envelope is not found ID: {request.Id} UUID: {request.Uuid}");

        if (request.UserId is int userId && userId != envelope.UserId)
            throw new AuthorizationException($"Envelope is not authorized for user with Id: {request.UserId} Envelope ID: {request.Id} UUID: {request.Uuid}");

        if (envelope.EnvelopeReceivers.Count == 0)
            throw new NotFoundException($"Envelope has no receivers to sign ID: {request.Id} UUID: {request.Uuid}");

        if(envelope.Documents.FirstOrDefault() is not Document document || document.ByteData is not byte[] byteData || byteData.Length == 0)
            throw new NotFoundException($"Envelope has no documents to sign ID: {request.Id} UUID: {request.Uuid}");

        Stream doc = new MemoryStream(byteData);

        var eReceivers = request.ReceiverId is int receiverId
            ? envelope.EnvelopeReceivers.Where(e => e.ReceiverId == receiverId)
            : envelope.EnvelopeReceivers;

        foreach (var eReceiver in eReceivers)
        {
            var signedDoc = await sender.Send(new SignPdfByEnvelopeReceiverCommand()
            {
                EnvelopeId = eReceiver.EnvelopeId,
                ReceiverId = eReceiver.ReceiverId
            }, cancel);

            await doc.DisposeAsync();
            doc = signedDoc;
        }

        return doc;
    }
}