package utils

import (
	"time"
)

// pool for get byte slice
type BytePool struct {
	c      chan []byte
	length int
	ticker *Ticker

	lastSize int
}

// 创建新对象
func NewBytePool(maxSize, length int) *BytePool {
	if maxSize <= 0 {
		maxSize = 1024
	}
	if length <= 0 {
		length = 128
	}
	pool := &BytePool{
		c:      make(chan []byte, maxSize),
		length: length,
	}
	pool.start()
	return pool
}

func (this *BytePool) start() {
	// 清除Timer
	this.ticker = NewTicker(1 * time.Minute)
	go func() {
		for this.ticker.Next() {
			currentSize := len(this.c)
			if currentSize <= 32 || this.lastSize == 0 || this.lastSize != currentSize {
				this.lastSize = currentSize
				continue
			}

			i := 0
		For:
			for {
				select {
				case _ = <-this.c:
					i++
					if i >= currentSize/2 {
						break For
					}
				default:
					break For
				}
			}
		}
	}()
}

// 获取一个新的byte slice
func (this *BytePool) Get() (b []byte) {
	select {
	case b = <-this.c:
	default:
		b = make([]byte, this.length)
	}
	return
}

// 放回一个使用过的byte slice
func (this *BytePool) Put(b []byte) {
	if cap(b) != this.length {
		return
	}
	select {
	case this.c <- b:
	default:
		// 已达最大容量，则抛弃
	}
}

// 当前的数量
func (this *BytePool) Size() int {
	return len(this.c)
}

// 销毁
func (this *BytePool) Destroy() {
	this.ticker.Stop()
}