package blob

import (
	"context"
	"io"

	"forge.cadoles.com/arcad/edge/pkg/storage"
	"github.com/pkg/errors"
)

type NewBlobReaderArgs struct {
	BlobID   storage.BlobID
	BucketID BucketID
}

type NewBlobReaderReply struct {
	ReaderID ReaderID
}

func (s *Service) NewBlobReader(ctx context.Context, args *NewBlobReaderArgs, reply *NewBlobReaderReply) error {
	bucket, err := s.getOpenedBucket(args.BucketID)
	if err != nil {
		return errors.WithStack(err)
	}

	readerID, err := NewReaderID()
	if err != nil {
		return errors.WithStack(err)
	}

	reader, err := bucket.NewReader(ctx, args.BlobID)
	if err != nil {
		return errors.WithStack(err)
	}

	s.readers.Store(readerID, reader)

	*reply = NewBlobReaderReply{
		ReaderID: readerID,
	}

	return nil
}

func (s *Service) getOpenedReader(id ReaderID) (io.ReadSeekCloser, error) {
	raw, exists := s.readers.Load(id)
	if !exists {
		return nil, errors.Errorf("could not find writer '%s'", id)
	}

	reader, ok := raw.(io.ReadSeekCloser)
	if !ok {
		return nil, errors.Errorf("unexpected type '%T' for writer", raw)
	}

	return reader, nil
}