let exersice = prompt("Chose exersice: \n switch: sizes - 1 \n switch: if - 2 \n prompt: or - 3 \n confirm: or this days - 4 \n confirm: if this days - 5\n triple prompt + default: or - 6 \n default: if - 7 \n login and password - 8 \n currency calc + currency calc: improved + currency calc: two rates - 9\n corrency calc: if - 10 \n scissors - 11 \n blue belt - 12 \n black belt - 13" )
switch (exersice){
    case "1": searchSize(); break; 
    case "2": color(); break;
    case "3": year(); break;
    case "4": Shopping(); break;
    case "5": ShoppingIf(); break;
    case "6": yourName(); break;
    case "7": yourNameSecond(); break;
    case "8": Log(); break;
    case "9": currencyCalc(); break;
    case "10": currencyCalc2(); break;
    case "11": scissors(); break;
    case "12": blueBelt(); break;
    case "13": blackBelt(); break;
    default: alert("Error. Try again") 
}

//////
////switch: sizes 1
 function searchSize (styleWear, firstMassive, firstSize) {
    sizeWear = {
        russia: [40, 42, 44, 46, 48, 50, 52, 54],
        USA: ["S", "M", "M", "L", "L", "XL", "XL", "XXL"]
    }
    womanSize = {
        russia: [42 ,44, 46, 48, 50, 52, 54, 56],
        USA: ["XXS", "XS", "S", "M", "L", "XL", "XXL", "XXXL"]
    }
    sizeStockings = {
        russia: [21, 21, 23, 23, 25, 25, 27],
        USA: [8, 8.5, 9, 9.5, 10, 10.5, 11]
    }
    styleWear = prompt("What size chart do you need?(dress/outerwear/pants - 1, lingerie - 2, tights/stockings - 3", "");
    switch (styleWear) {
        case "1": styleWear = sizeWear, firstMassive = sizeWear.russia; break;
        case "2": styleWear = womanSize, firstMassive = womanSize.russia; break;
        case "3": styleWear = sizeStockings, firstMassive = sizeStockings.russia; break;
        default: alert ("Error. Please try again");
        return
    }
    firstSize = +prompt("Please give me your size in Russia/Urkaine style");
    firstSize = firstMassive.indexOf(firstSize)
    if (firstSize == -1) {
        return alert("Error. Please check your data")
    }
    alert ("Your size in USA chart is " + styleWear.USA[firstSize])
}
// searchSize()
///////

//////
////switch: if 2
function color() {
    let color = prompt("Введите цвет","");
    if (color === "red") {
        document.write("<div style='background-color: red;'>красный</div>")
        document.write("<div style='background-color: black; color: white;'>черный</div>")
    } else if (color === "black") {
        document.write("<div style='background-color: black; color: white;'>черный</div>")
    } else if (color === "blue") {
        document.write("<div style='background-color: blue;'>синий</div>")
        document.write("<div style='background-color: green;'>зеленый</div>")
    } else if ( color === "green") {
        document.write("<div style='background-color: green;'>зеленый</div>")
    }
    else {
        document.write("<div style='background-color: gray;'>Я не понял</div>")
    }
}
// color()
////////

///////
///prompt: or 3
function year (yearBorn) {
    var today = new Date();
    var year = today.getFullYear();
    yearBorn = + prompt ("How old are you?");
    if (yearBorn == null || yearBorn == undefined || isNaN(yearBorn) || yearBorn == false) {
        return alert("Error. Please try again")
    } else {
        yearBorn = year - yearBorn;
        return alert ("The year when you're born is " + yearBorn)
    }
}
// year()
////////


/////
//confirm: or this days 4
function Shopping() {
    (confirm ("Шопинг?")) ? alert("Уиии") : alert("Ты - бяка")
}
// Shopping()
//////

///////
//confirm: if this days 5
function ShoppingIf (answer) {
    answer = confirm("Шопинг?")
    if (answer === false) {
            return alert("ты-бяка")
    } else {
        return alert ("Уиии")
    }
}
// ShoppingIf()
////////

////////
//triple prompt
//default: or 6
function yourName (surname, name, yourFather) {
    surname = prompt ("Напишите, пожалуйста, вашу фамилию") 
    surname = surname ? surname : "Хренова"
    name = prompt("Напишите, пожалуйста, как вас зовут.")
    name =  name ? name : "Гадя"
    yourFather = prompt ("Напишите, пожалуйста, ваше отчество")
    yourFather = yourFather  ? yourFather : "Петрович"
    return alert ("Здравствуйте, " + name + " " + yourFather + " " + surname)
}
// yourName()
////////

/////////
//defaut if 7
function yourNameSecond (surname, name, yourFather) {
    question1 = prompt ("Напишите, пожалуйста, вашу фамилию") 
    if (question1 === null || question1 === "") {
        surname = "Хренова"
    } else { surname = question1}
    question2 = prompt("Напишите, пожалуйста, как вас зовут.")
    if (question2 === null || question2 === "") {
        name = "Гадя"
    } else { name = question2 }
    question3 = prompt ("Напишите, пожалуйста, ваше отчество")
    if (question3 === null || question3 === "") {
        yourFather = "Петрович"
    } else { yourFather = question3 }
    return alert ("Здравствуйте, " + name + " " + yourFather + " " + surname)
}
// yourNameSecond()
//////////

////////
//login and password 8
function Log (yourLog, yourPass) {
    let login = "admin";
    let password = "qwerty";
    yourLog = prompt ("Please write correct login")
    if (yourLog === login){
        yourPass = prompt ("Please write correct password")
        if (yourPass === password) {
            alert ("Congratulations! You're in.")
        } else {
            alert ("Error. The password is wrong. Please try again")
        }
    } else {
        return alert ("Error. The login is wrong. Please try again")
    }
}
// Log()
//////////


//////////
///currency calc
////currency calc: improved
////currency calc: two rates 9
function currencyCalc (yourChoise, yourCount, result) {
    let usd = [28.31, 28.39];
    let eur = [33, 33.44];
    yourChoise = prompt("Please chose usd or eur.").toLowerCase();
    switch (yourChoise) {
        case "usd":yourChoise = usd; break;
        case "eur":yourChoise = eur; break;
        default: alert ("Error. Please try again");
        return
    }
    confirm ("If you want to buy click on 'ok' and on 'cancel' if want to sell") ? yourChoise = yourChoise[0] : yourChoise = yourChoise[1];
    yourCount = prompt("How much?");
    result = yourCount * yourChoise;
    (isNaN(result) ? alert ("Error. Please check your data") : alert ("Your result is " + result))
}
// currencyCalc()
/////////

///////
//currency calc: if 10
function currencyCalc2 (yourChoise, yourCount, BuySell, result) {
    let usd = [28.31, 28.39];
    let eur = [33, 33.44];
    yourChoise = prompt("Please chose usd or eur.").toLowerCase();
    if (yourChoise == "usd") {
        yourChoise = usd
    } else if ( yourChoise == "eur") {
        yourChoise = eur
    } else {
        return alert("Error. Please try again")    
    }
    BuySell = confirm ("If you want to buy click on 'ok' and on 'cancel' if want to sell")
    if (BuySell === true) {
        yourChoise = yourChoise[0]
    } else {
        yourChoise = yourChoise[1]
    }
    yourCount = prompt("How much?");
    if (isNaN(yourCount)) {
        return alert ("Error. Please cheack your data")
    } else {
        result = yourCount * yourChoise;
        return alert ("Your result is " + result)
    }

}
// currencyCalc2()
////////

///////
//scissors 11
function scissors (yourMove, myMove){
    let tools = ["rock", "scissors", "paper"];
    yourMove = prompt("Your move. Chose rock, scissors or paper").toLowerCase();
    myMove = tools[Math.floor(Math.random() * tools.length)];
    if (yourMove === myMove) {
        return alert("Dead heat")
    } else if (yourMove == "rock"&& myMove == "scissors" || yourMove == "scissors"&& myMove == "paper"  || yourMove == "paper"&& myMove == "rock" ) {
        return alert ("Congratulations. You're win")
    } else {
        return alert ("Sorry. You're lose")
    }
}
// scissors()
/////////

//////
///Задание на синий пояс 12
function blueBelt() {
    fetch('https://api.exchangeratesapi.io/latest')
        .then(res => res.json())
        .then(d => {
        let yourChoisefirst = prompt("What do you want yo sell?").toUpperCase();
        (yourChoisefirst === "EUR") ? yourChoisefirst = 1 : yourChoisefirst = (1 / d.rates[yourChoisefirst]);
        let yourChoisesecond = prompt("What do you want to buy?").toUpperCase();
        (yourChoisesecond === "EUR") ? yourChoisesecond = 1 : yourChoisesecond =  (1 / d.rates[yourChoisesecond]);
        let count = prompt("How much?");
        let howMuch = (yourChoisefirst / yourChoisesecond * count).toFixed(2);
        if (isNaN(howMuch)) {
            return alert ("Error. Please check your data")
        } else {
        return alert(howMuch)
        }
    })
}
// blueBelt()
////

//////
///Черный пояс 13

function blackBelt (yourMove, myMove){
    let tools = ["rock", "scissors", "paper"];
    yourMove = prompt("Your move. Chose rock, scissors or paper").toLowerCase();
    myMove = tools[Math.floor(Math.random() * tools.length)];
    (yourMove === "rock" || yourMove === "paper" || yourMove === "scissors") ? ((yourMove === myMove) ? alert ("Dead heat") : (yourMove == "rock"&& myMove == "scissors" || yourMove == "scissors"&& myMove == "paper"  || yourMove == "paper"&& myMove == "rock" ) ? alert("You're win") : alert ("You're lose")) : alert ("Error. Try again")
}
// blackBelt()
//////