/**
 * 对象工具。简化常见的对象检查，转换操作。
 *
 * author: Sand
 * since: 12/15/2016
 */
"use strict";

class ObjectUtil {
    constructor() {
    }

    /**
     * 检查对象是否为JSON。
     *
     * @see http://stackoverflow.com/questions/11182924/how-to-check-if-javascript-object-is-json
     *
     * @param value
     */
    static isJsonObject(value) {
        return {}.constructor === value.constructor;
    };

    /**
     * 克隆一个对象。
     */
    static cloneObject(obj){
        var copy;

        // Handle the 3 simple types, and null or undefined
        if (null == obj || "object" != typeof obj) return obj;

        // Handle Date
        if (obj instanceof Date) {
            copy = new Date();
            copy.setTime(obj.getTime());
            return copy;
        }

        // Handle Array
        if (obj instanceof Array) {
            copy = [];
            for (var i = 0, len = obj.length; i < len; i++) {
                copy[i] = ObjectUtil.cloneObject(obj[i]);
            }
            return copy;
        }

        // Handle Object
        if (obj instanceof Object) {
            copy = {};
            for (var attr in obj) {
                if (obj.hasOwnProperty(attr)) copy[attr] = ObjectUtil.cloneObject(obj[attr]);
            }
            return copy;
        }

        throw new Error("Unable to copy obj! Its type isn't supported.");
    }

    /**
     * 检查对象是否具有指定的属性列表。
     *
     * @param arguments 可变参数列表
     * @returns {{pass: boolean, message: string}}
     */
    static fieldsCheck() {
        var ret = {pass: false, message: ''};

        if (arguments.length <= 1) {
            ret.message = 'Function arguments not enough.';
            return ret;
        }

        var obj = arguments[0];
        if (!this.isJsonObject(obj)) {
            ret.message = 'Function first argument must be a dict.';
            return ret;
        }

        ret.pass = true;
        ret.message = 'Missing field(s): ';
        for (var i = 1; i < arguments.length; ++i) {
            if (!obj.hasOwnProperty(arguments[i])) {
                ret.pass = false;
                ret.message += arguments[i];

                if (i !== arguments.length - 1) {
                    ret.message += ", ";
                }
            }
        }

        if (ret.pass) ret.message = null;

        return ret;
    };

    static timestampToLong(tm) {
        return Date.parse(new Date(tm));
    };
}

module.exports = ObjectUtil;