package zim

import (
	"io"

	"github.com/klauspost/compress/zstd"
	"github.com/pkg/errors"
)

type ZstdBlobReader struct {
	decoder *zstd.Decoder
}

// Close implements io.ReadCloser.
func (r *ZstdBlobReader) Close() error {
	r.decoder.Close()
	return nil
}

// Read implements io.ReadCloser.
func (r *ZstdBlobReader) Read(p []byte) (n int, err error) {
	return r.decoder.Read(p)
}

var _ io.ReadCloser = &ZstdBlobReader{}

func NewZStdBlobReader(reader *Reader, clusterStartOffset, clusterEndOffset uint64, blobIndex uint32, blobSize int) *CompressedBlobReader {
	return NewCompressedBlobReader(
		reader,
		func(r io.Reader) (io.ReadCloser, error) {
			decoder, err := zstd.NewReader(r)
			if err != nil {
				return nil, errors.WithStack(err)
			}

			return &ZstdBlobReader{decoder}, nil
		},
		clusterStartOffset,
		clusterEndOffset,
		blobIndex,
		blobSize,
	)
}