using System.Text;
using AutoMapper;
using MediatR;
using mws.backend.dotnet.application.Common;
using mws.backend.dotnet.domain.Documents;

namespace mws.backend.dotnet.application.Documents;

public record GetDocumentQuery(Guid UserId, Guid DocumentId) : IRequest<DocumentDto>;

public class GetDocumentHandler(IUnitOfWork uow, IMapper mapper, IDocumentContentStore contentStore)
    : IRequestHandler<GetDocumentQuery, DocumentDto>
{
    public async Task<DocumentDto> Handle(GetDocumentQuery query, CancellationToken ct)
    {
        var doc = await DocumentAccess.GetDocumentForUserAsync(uow, query.UserId, query.DocumentId, ct);
        var dto = mapper.Map<DocumentDto>(doc);

        if (doc.Type == DocumentType.Document && !string.IsNullOrEmpty(doc.StorageKey))
        {
            await using var stream = await contentStore.DownloadAsync(doc.StorageKey, ct);
            if (stream != Stream.Null)
            {
                using var reader = new StreamReader(stream, Encoding.UTF8);
                var content = await reader.ReadToEndAsync(ct);
                dto.Content = string.IsNullOrEmpty(content) ? null : content;
            }
            else
            {
                dto.Content = null;
            }
        }

        return dto;
    }
}