/**
 * Types utilities
 */

const UNDEFINED = void 0;

export default {
    /**
     * Check if argument is an object or a global object
     * @param  {String or Object}  v
     * @return {Boolean}
     */
    isObj(v) {
        let isO = false;
        if (typeof v === 'string') {
            if (window[v] && typeof window[v] === 'object') {
                isO = true;
            }
        } else {
            if (v && typeof v === 'object') {
                isO = true;
            }
        }
        return isO;
    },

    /**
     * Check if argument is a function
     * @param  {Function} fn
     * @return {Boolean}
     */
    isFn(fn) {
        return (fn && fn.constructor == Function);
    },

    /**
     * Check if argument is an array
     * @param  {Array}  obj
     * @return {Boolean}
     */
    isArray(obj) {
        return (obj && obj.constructor == Array);
    },

    /**
     * Check argument is a string
     * @param {String} val Value
     * @returns {Boolean}
     */
    isString(val) {
        return Object.prototype.toString.call(val) === '[object String]';
    },


    /**
     * Check argument is a number
     * @param {Number} val
     * @returns {Boolean}
     */
    isNumber(val) {
        return Object.prototype.toString.call(val) === '[object Number]';
    },

    /**
     * Determine if argument is undefined
     * @param  {Any}  o
     * @return {Boolean}
     */
    isUndef(o) {
        return o === UNDEFINED;
    },

    /**
     * Determine if argument is null
     * @param  {Any}  o
     * @return {Boolean}
     */
    isNull(o) {
        return o === null;
    },

    /**
     * Determine if argument is empty (undefined, null or empty string)
     * @param  {Any}  o
     * @return {Boolean}
     */
    isEmpty(o) {
        return this.isUndef(o) || this.isNull(o) || o.length === 0;
    }
};