// Copyright 2019 The Wuffs Authors.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// https://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or https://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
//
// SPDX-License-Identifier: Apache-2.0 OR MIT

//go:build !cgo
// +build !cgo

package raczlib

import (
	"compress/zlib"
	"io"

	"github.com/google/wuffs/lib/compression"
)

func (r *CodecReader) makeDecompressor(compressed io.Reader, dict []byte) (io.Reader, error) {
	if r.cachedReader != nil {
		if err := r.cachedReader.Reset(compressed, dict); err != nil {
			return nil, err
		}
		return r.cachedReader, nil
	}

	zlibReader, err := zlib.NewReaderDict(compressed, dict)
	if err != nil {
		return nil, err
	}
	r.cachedReader = zlibReader.(compression.Reader)
	return zlibReader, nil
}