'use strict'
/**
 * Copyright (c) 2017~2020, OBCon Inc.
 * All rights reserved.
 */

/**
 * @file
 * @copyright 2017~2020, OBCon Inc.
 * @author gye hyun james kim [pnuskgh@gmail.com]
 */

class Queue {                                               //--- FIFO (First In First Out)
    constructor(data) {
        this._maxSize = 0;                                  //--- 0. 크기 제한 없음
        this._data = data || [];
    }

    get maxSize() {
        return this._maxSize;
    }

    set maxSize(newValue) {
        this._maxSize = newValue;
    }

    getBuffer() {                                           //--- Stack 복사
        return this._data.slice();
    }

    isEmpty() {
        return this._data.length == 0;
    }

    peek() {                                                //--- 첫번째 항목 조회
        return (this.isEmpty()) ? null : this._data[0];
    }

    enqueue(item) {                                         //--- 항목 추가
        this._data.push(item);
        if ((0 < this._maxSize) && (this._maxSize < this._data.length)) {
            this._data.slice();
        }
    }

    dequeue() {                                             //--- 항목 제거
        return this._data.shift();
    }
}

module.exports = Queue;