package utils

import (
	"bytes"
	"compress/zlib"
	"encoding/base64"
	"io"
	"sync"
)

var zlibWriterPool = sync.Pool{
	New: func() interface{} {
		return zlib.NewWriter(io.Discard)
	},
}

// GetZlibWriter 从对象池中获取 zlib 写入器
func GetZlibWriter(w io.Writer) *zlib.Writer {
	zw := zlibWriterPool.Get().(*zlib.Writer)
	zw.Reset(w)
	return zw
}

// PutZlibWriter 将 zlib 写入器还回对象池
func PutZlibWriter(zw *zlib.Writer) {
	zlibWriterPool.Put(zw)
}

// CompressToBase64 compresses data using zlib and encodes to base64
func CompressToBase64(data string) (string, error) {
	if data == "" {
		return "", nil
	}
	var buf bytes.Buffer
	zw := GetZlibWriter(&buf)
	defer PutZlibWriter(zw)
	
	if _, err := zw.Write([]byte(data)); err != nil {
		return "", err
	}
	if err := zw.Close(); err != nil {
		return "", err
	}
	
	return base64.StdEncoding.EncodeToString(buf.Bytes()), nil
}

// DecompressFromBase64 decodes base64 and decompresses zlib data
func DecompressFromBase64(data string) (string, error) {
	if data == "" {
		return "", nil
	}
	decoded, err := base64.StdEncoding.DecodeString(data)
	if err != nil {
		return "", err
	}
	zr, err := zlib.NewReader(bytes.NewReader(decoded))
	if err != nil {
		return "", err
	}
	defer zr.Close()
	result, err := io.ReadAll(zr)
	if err != nil {
		return "", err
	}
	return string(result), nil
}