package io

import (
	"io"

	"github.com/v2ray/v2ray-core/common/alloc"
)

type BufferedWriter struct {
	writer io.Writer
	buffer *alloc.Buffer
	cached bool
}

func NewBufferedWriter(rawWriter io.Writer) *BufferedWriter {
	return &BufferedWriter{
		writer: rawWriter,
		buffer: alloc.NewBuffer().Clear(),
		cached: true,
	}
}

func (this *BufferedWriter) Write(b []byte) (int, error) {
	if !this.cached {
		return this.writer.Write(b)
	}
	nBytes, _ := this.buffer.Write(b)
	if this.buffer.IsFull() {
		err := this.flush()
		if err != nil {
			return nBytes, err
		}
	}
	return nBytes, nil
}

func (this *BufferedWriter) flush() error {
	nBytes, err := this.writer.Write(this.buffer.Value)
	this.buffer.SliceFrom(nBytes)
	if !this.buffer.IsEmpty() {
		nBytes, err = this.writer.Write(this.buffer.Value)
		this.buffer.SliceFrom(nBytes)
	}
	if this.buffer.IsEmpty() {
		this.buffer.Clear()
	}
	return err
}

func (this *BufferedWriter) Cached() bool {
	return this.cached
}

func (this *BufferedWriter) SetCached(cached bool) {
	this.cached = cached
	if !cached && !this.buffer.IsEmpty() {
		this.flush()
	}
}

func (this *BufferedWriter) Release() {
	this.buffer.Release()
}