using AutoMapper;
using AutoMapper.QueryableExtensions;
using DigitalData.Core.Abstraction.Application.Repository;
using EnvelopeGenerator.Application.Common.Dto;
using EnvelopeGenerator.Domain.Entities;
using MediatR;
using Microsoft.EntityFrameworkCore;

namespace EnvelopeGenerator.Application.Documents.Queries;

/// <summary>
/// Represents a query to read document metadata/details without binary payload.
/// </summary>
/// <param name="EnvelopeId">The identifier of the envelope associated with the document.</param>
/// <param name="UserId">The unique identifier of the sending user. Optional.</param>
public record ReadDocumentDetailsQuery(int EnvelopeId, int? UserId = null) : IRequest<DocumentDetailsDto?>;

/// <summary>
/// Handles queries for reading document details without loading BYTE_DATA.
/// </summary>
public class ReadDocumentDetailsQueryHandler : IRequestHandler<ReadDocumentDetailsQuery, DocumentDetailsDto?>
{
    private readonly IRepository<Document> _repo;
    private readonly IMapper _mapper;

    public ReadDocumentDetailsQueryHandler(IRepository<Document> repo, IMapper mapper)
    {
        _repo = repo;
        _mapper = mapper;
    }

    public async Task<DocumentDetailsDto?> Handle(ReadDocumentDetailsQuery query, CancellationToken cancel)
    {
        var docQuery = _repo.Query.AsNoTracking();

        if (query.UserId is int userId)
            docQuery = docQuery.Where(doc => doc.Envelope.UserId == userId);

        return await docQuery
            .Where(d => d.EnvelopeId == query.EnvelopeId)
            .ProjectTo<DocumentDetailsDto>(_mapper.ConfigurationProvider)
            .FirstOrDefaultAsync(cancel);
    }
}