using AutoMapper;
using DigitalData.Core.Abstraction.Application.Repository;
using DigitalData.Core.Exceptions;
using EnvelopeGenerator.Application.Common.Dto;
using EnvelopeGenerator.Application.Common.Enums;
using EnvelopeGenerator.Application.Documents.Queries;
using EnvelopeGenerator.Application.EnvelopeReceivers.Queries;
using EnvelopeGenerator.Domain.Entities;
using EnvelopeGenerator.Domain.Exceptions;
using MediatR;
using Microsoft.EntityFrameworkCore;

namespace EnvelopeGenerator.Application.PdfSigning;

/// <summary>
/// 
/// </summary>
public record SignPdfByEnvelopeReceiverCommand : IRequest<Stream>
{
    /// <summary>
    /// 
    /// </summary>
    public int EnvelopeId { get; init; }

    /// <summary>
    /// 
    /// </summary>
    public int ReceiverId { get; init; }
}

/// <summary>
/// 
/// </summary>
public class SignPdfByEnvelopeReceiverCommandHandler(IRepository<DocReceiverElement> Repo, IMapper Mapper, ISender Sender) : IRequestHandler<SignPdfByEnvelopeReceiverCommand, Stream>
{

    /// <summary>
    /// 
    /// </summary>
    /// <param name="request"></param>
    /// <param name="cancel"></param>
    /// <returns></returns>
    /// <exception cref="NotFoundException"></exception>
    public async Task<Stream> Handle(SignPdfByEnvelopeReceiverCommand request, CancellationToken cancel)
    {
        cancel.ThrowIfCancellationRequested();

        // read elements
        var elements = await Repo.Where(el => el.ReceiverId == request.ReceiverId && el.Document.EnvelopeId == request.EnvelopeId)
            .Include(e => e.Receiver)
            .ToListAsync(cancel) ?? throw new NotFoundException($"No elements found for Envelope ID {request.EnvelopeId} and Receiver ID {request.ReceiverId}.");
        var elementDtos = Mapper.Map<List<DocReceiverElementDto>>(elements)
            .OrderBy(e => e.Page)
            .ThenBy(e => e.Id)
            .ToList();

        // read secrets for phone number
        var erSecrets = await Sender.Send(new ReadEnvelopeReceiverSecretQuery()
        {
            Envelope = new() { Id = request.EnvelopeId },
            Receiver = new() { Id = request.ReceiverId }
        }, cancel) ?? throw new DataIntegrityException($"No secrets found for Envelope ID {request.EnvelopeId} and Receiver ID {request.ReceiverId}.");

        // read document
        var unsignedDoc = await Sender.Send(new ReadDocumentQuery(EnvelopeId: request.EnvelopeId), cancel);
        var unsignedDocBytes = unsignedDoc.ByteData ?? throw new NotFoundException($"Document not found for Envelope ID {request.EnvelopeId} and Receiver ID {request.ReceiverId}.");
                
        Stream doc = new MemoryStream(unsignedDocBytes);

        // sign document for each element
        foreach (var element in elementDtos)
        {
            var lastElement = element == elementDtos.Last();

            var signedDoc = await Sender.Send(new SignPdfByElementCommand
            {
                Document = doc,
                Element = element,
                CertificationLevel = lastElement ? PdfSignatureCertificationLevel.NoChangesAllowed : PdfSignatureCertificationLevel.FillFormsAndAnnotate,
                Phone = erSecrets.PhoneNumber
            }, cancel);

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

        return doc;
    }
}