using AutoMapper;
using EnvelopeGenerator.Application.Contracts.SQLExecutor;
using EnvelopeGenerator.Application.DTOs.Receiver;
using EnvelopeGenerator.Domain.Entities;
using MediatR;

namespace EnvelopeGenerator.Application.EnvelopeReceivers.Commands.Create;

/// <summary>
/// Handles the creation of an envelope along with its associated document and recipients.
/// This command processes the envelope data, including title, message, document content,
/// recipient list, and optional two-factor authentication settings.
/// </summary>
public class CreateEnvelopeReceiverCommandHandler : IRequestHandler<CreateEnvelopeReceiverCommand, CreateEnvelopeReceiverResponse>
{
    private readonly IMapper _mapper;

    private readonly IEnvelopeExecutor _envelopeExecutor;

    private readonly IEnvelopeReceiverExecutor _erExecutor;

    /// <summary>
    /// 
    /// </summary>
    /// <param name="mapper"></param>
    /// <param name="envelopeExecutor"></param>
    /// <param name="erExecutor"></param>
    public CreateEnvelopeReceiverCommandHandler(IMapper mapper, IEnvelopeExecutor envelopeExecutor, IEnvelopeReceiverExecutor erExecutor)
    {
        _mapper = mapper;
        _envelopeExecutor = envelopeExecutor;
        _erExecutor = erExecutor;
    }

    /// <summary>
    /// Handles the execution of the <see cref="CreateEnvelopeReceiverCommand"/>.
    /// Responsible for validating input data, creating or retrieving recipients, associating signatures,
    /// and storing the envelope and document details.
    /// </summary>
    /// <param name="request">The command containing all necessary information to create an envelope.</param>
    /// <param name="cancel">Token to observe while waiting for the task to complete.</param>
    /// <returns>A task representing the asynchronous operation.</returns>
    public async Task<CreateEnvelopeReceiverResponse> Handle(CreateEnvelopeReceiverCommand request, CancellationToken cancel)
    {
        int userId = request.UserId ?? throw new InvalidOperationException("UserId cannot be null when creating an envelope.");

        var envelope = await _envelopeExecutor.CreateEnvelopeAsync(userId, request.Title, request.Message, request.TFAEnabled, cancel);

        List<EnvelopeReceiver> sentRecipients = new();
        List<ReceiverGetOrCreateCommand> unsentRecipients = new();

        foreach (var receiver in request.Receivers)
        {
            var envelopeReceiver = await _erExecutor.AddEnvelopeReceiverAsync(envelope.Uuid, receiver.EmailAddress, receiver.Salution, receiver.PhoneNumber, cancel);

            if (envelopeReceiver is null)
                unsentRecipients.Add(receiver);
            else
                sentRecipients.Add(envelopeReceiver);
        }

        var res = _mapper.Map<CreateEnvelopeReceiverResponse>(envelope);
        res.UnsentReceivers = unsentRecipients;
        res.SentReceiver = _mapper.Map<IEnumerable<ReceiverReadDto>>(sentRecipients);
        return res;
    }
}