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;

    public ReadDocumentDetailsQueryHandler(IRepository<Document> repo)
    {
        _repo = repo;
    }

    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);

        // shortcut: manual select avoids AutoMapper ProjectTo pulling BYTE_DATA and the full navigation
        // graph (Envelope → History → User etc.) which caused an extremely slow query (~87s).
        // Annotations navigation is IEnumerable<T> on the entity (not ICollection<T>), so EF Core
        // cannot translate it in a Select projection — we skip it entirely here; sender editor only
        // needs element coordinates, not annotation payloads.
        var raw = await docQuery
            .Where(d => d.EnvelopeId == query.EnvelopeId)
            .Select(d => new
            {
                d.Id,
                d.EnvelopeId,
                d.AddedWhen,
                Elements = d.Elements == null ? null : d.Elements.Select(e => new
                {
                    e.Id,
                    e.DocumentId,
                    e.ReceiverId,
                    e.ElementType,
                    e.X,
                    e.Y,
                    e.Width,
                    e.Height,
                    e.Page,
                    e.Required,
                    e.Tooltip,
                    e.ReadOnly,
                    e.AnnotationIndex,
                    e.AddedWhen,
                    e.ChangedWhen,
                    e.FullName,
                    e.Position,
                    e.Place,
                }).ToList()
            })
            .FirstOrDefaultAsync(cancel);

        if (raw is null)
            return null;

        return new DocumentDetailsDto
        {
            Id = raw.Id,
            EnvelopeId = raw.EnvelopeId,
            AddedWhen = raw.AddedWhen,
            Elements = raw.Elements?.Select(e => new DocReceiverElementDto
            {
                Id = e.Id,
                DocumentId = e.DocumentId,
                ReceiverId = e.ReceiverId,
                ElementType = e.ElementType,
                X = e.X,
                Y = e.Y,
                Width = e.Width,
                Height = e.Height,
                Page = e.Page,
                Required = e.Required,
                Tooltip = e.Tooltip,
                ReadOnly = e.ReadOnly,
                AnnotationIndex = e.AnnotationIndex,
                AddedWhen = e.AddedWhen,
                ChangedWhen = e.ChangedWhen,
                FullName = e.FullName,
                Position = e.Position,
                Place = e.Place,
            })
        };
    }
}