package modules

import "errors"

type MsgQueue struct {
	queue     chan Message
	QueueFunc QueueOperate
}

type QueueOperate interface {
	//queue 초기화
	queue_init() error
	//queue push
	push(msg Message) bool
	//pop message (wait -> busy waiting 여부 결정)
	pop(wait bool) (Message, error)
}

func (mq *MsgQueue) queue_init() error {
	if mq.queue != nil && len(mq.queue) != 0 {
		return errors.New("Queue Hadlerer Error: Already initialized.")
	} else if mq.queue == nil {
		mq.queue = make(chan Message)
		return nil
	} else {
		close(mq.queue)
		mq.queue = make(chan Message)
		return nil
	}
}

func (mq *MsgQueue) push(msg Message) bool {
	mq.queue <- msg
	return true
}

func (mq *MsgQueue) pop(wait bool) (Message, error) {
	if wait == true {
		if len(mq.queue) == 0 {
			return Message{}, errors.New("Queue Handler Alert: Queue is Empty")
		} else {
			return <-mq.queue, nil
		}
	} else {
		//queue에 데이터가 들어올 때까지 block
		return <-mq.queue, nil
	}
}