//ES6
let a = msg => alert(msg);

let cube = number => number * number * number;

let avg2 = (a, b) => (a + b) / 2;

let sum3 = (a = 0, b = 0, c = 0) => a + b + c;

let intRandom = (a = 0, b = 0) => Math.round(Math.random() * (b - a)) + a;

let greetAll = (...arguments) => {
    for (let i in arguments) {
        alert(arguments[i])
    }
}

let sum = (...arguments) => {
    let sumAll = 0
    for (let i in arguments) {
        sumAll += arguments[i]
    }
    return sumAll;
}

//sort
var persons = [
    { name: "Иван", age: 17 },
    { name: "Мария", age: 35 },
    { name: "Алексей", age: 73 },
    { name: "Яков", age: 12 },
]

function sort(objectName, keyName, boolean = true) {
    if (boolean) {
        objectName.sort((a, b) => a[keyName] > b[keyName] ? 1 : -1)
    } else {
        objectName.sort((a, b) => a[keyName] - b[keyName])
    }
}

sort(persons, "age"); //сортирует по возрасту по возрастанию
console.log(persons)
sort(persons, "name", false); //сортирует по имени по убыванию
console.log(persons)

//array map
let arrToNumber = ["1", {}, null, undefined, "500", 700].map(elem => +elem ? +elem : elem);

//array reduce
let arrResult = ["0", 5, 3, "string", null].reduce((result, current) => {
    if (typeof current === "number" && current !== null) {
        return result * current;
    } else {
        return result;
    }
}, 1)

//object filter
function filter(obj, func) {
    let newObj = {};

    for (let key in obj) {

        if (func(key, obj[key])) {
            newObj[key] = obj[key];
        }
    }

    return newObj;
}

var phone = {
    brand: "meizu",
    model: "m2",
    ram: 2,
    color: "black",
};

let a = filter(phone, (key, value) => key == "color" || value == 2);
console.log(a)

//object map
function map(obj, func) {
    let newObj = {};

    for (let key in obj) {
        newObj[(Object.keys(func(key, obj[key])))[0]] = Object.values(func(key, obj[key]))[0];
    }

    return newObj;
}

let obj2 = map({ name: "Иван", age: 17 }, function (key, value) {
    var result = {};
    result[key + "_"] = value + "$";
    return result;
})

console.log(obj2)// возвращает {name_: "Иван$", age_: "17$"}

//Рекурсия Sum
let sum = (firstNumber, step, n) => {
    return n == 1 ? firstNumber : firstNumber + sum(firstNumber + step, step, n - 1);    //сумма арифметической прогресии (начиная с firstNumber, шаг step, n элементов)
}

//Рекурсия HTML Tree
var someTree = {
    tagName: "table", //html tag
    children: [ //вложенные тэги
        {
            tagName: "tr",
            children: [
                {
                    tagName: "td",
                    text: "some text",
                },
                {
                    tagName: "td",
                    text: "some text 2",
                }
            ]
        }
    ],
    attrs:
    {
        border: 1,
    },
}

function constructorHtml(obj, parent = obj.tagName, childKeyName = "children") {
    let elem = document.createElement(parent);

    if (obj[childKeyName]) {
        for (let child of obj[childKeyName]) {
            elem.append(constructorHtml(child, parent = child.tagName, childKeyName));
        }
    }

    if (obj.attrs) {
        for (let key in obj.attrs) {
            elem.setAttribute(key, obj.attrs[key]);
        }
    }

    if (obj.text) {
        elem.innerText = obj.text;
    }

    return elem;
}

document.body.append(constructorHtml(someTree));