package buf

import (
	"container/list"
)

// 블럭되지 않는 큐체널
func NewStringQueue() (chan<- string, <-chan string) {
	send := make(chan string, 1)
	receive := make(chan string, 1)
	go manageStringQueue(send, receive)
	return send, receive
}

func manageStringQueue(send <-chan string, receive chan<- string) {
	queue := list.New()
	for {
		if front := queue.Front(); front == nil {
			if send == nil {
				close(receive)
				return
			}
			value, ok := <-send
			if !ok {
				close(receive)
				return
			}
			queue.PushBack(value)
		} else {
			select {
			case receive <- front.Value.(string):
				queue.Remove(front)
			case value, ok := <-send:
				if ok {
					queue.PushBack(value)
				} else {
					send = nil
				}
			}
		}
	}
}