//assign: evaluation 
var a = 5;
var b, c;

//if we delete brackets functionality is same
// b = (a * 5);
// b = (c = b/2);
// a = 5
// b = 12,5
// c = 12,5

//one line variant
c = b = (a * 5) / 2;

// forgot one semicolon!
// for(let i = 0 i < 5; i++) {
//     console.log(i)
// }
// wrong usage of semicolon
//let a; b = 5;
//b = 5 c = b + 1;

//semicolon logic errors
// if(a === 5) {
//     console.log('FIVE!')
// }else; console.log('not five(')

//GET YEAR TASK:
function getAge(age, currentYear = new Date().getFullYear()) {
    try { 
        age = Math.trunc(Number(age))
        if(!age || isNaN(age) || age > 200 || age < 0) {
            throw e
        } else {
            currentYear = currentYear - age
            return [currentYear, currentYear-1]
        }
    } catch(e) {
        return 0
    }
}

let year = getAge(prompt("input your age",""))
if(year) {
    alert(`Looks like you've been born in ${year[0]} or ${year[1]}`)
} else {
    alert('whoops, looks like invalid input value has been given!')
}


//GET TEMPERATURE TASK:
try {
    let grad = Number(prompt("Input temperature",""))
    let sys = prompt(`
        Type:
            F - to translate to Fahrenheit
            C - to translate to Celsius
    `)
    let res = getTemperature(grad, sys)
    if(res) {
        alert(`${grad}${sys.toLowerCase() === 'c'? '°F':'°C'} = ${res}${sys.toLowerCase() === 'c'? '°C':'°F'}`)
    } else {
        throw e;
    }
} catch(e) {
    alert('invalid input!')
}

function getTemperature(value, system="c") {
    if(isNaN(Number(value))) return false

    switch(system.toLowerCase()) {
        case 'f':
            return ((value * 9/5) + 32).toFixed(2)
        case 'c':
            return ((value - 32) * 5/9).toFixed(2)
        default:
            return false
    }
}

//divide using floor
function flooredDivide(num1, num2) {
    console.log(num1 / num2)
    return Math.floor(num1 / num2)
}

//infor user if number given is odd task
function oddInformer() {
    let num = prompt("input a number:", "")
    if(isNaN(+num) || !num) {
        alert("not a number!!!")
    } else {
        if(num % 2 !== 0) {
            alert(`${num} is odd`)
        } else {
            alert(`${num} is even`)
        }
    }
}
oddInformer()

//greet user using alert() and prompt()
function greeting() {
    let name = prompt("Hey user, what's your name")
    alert(`Hello, ${name? name : 'Namless One...'}`)
}
greeting()

//check if text contains desired words 
function lexis(string, word) {
    if(string.indexOf(word) > 0) {
        return true
    } else {
        return false
    }
}