[TIL] 2019.04.09 - 다각형 넓이 구하기 (2)

다각형의 넓이 구하기 - getArea() 함수 구현

const { PI, pow } = Math;
const logArr = [],
    logRes = [];

const CIRCLE_NAME = "circle",
    RECT_NAME = "rect",
    TRAPE_NAME = "trapezoid";

const printExecutionSequence = _ => {
    let log = "";
    log = logArr.map((el, i) => `${logArr[i]} ${logRes[i]}`)
                .reduce((a, b) => `${a}, ${b}`, log);
    console.log(log);
};

const logExecution = (polygonName, polygonArea) => {
    logArr.push(polygonName);
    logRes.push(polygonArea);
};

const getCircleArea = r => {
    let area = 0;
    area = pow(r, 2) * PI;
    logExecution(CIRCLE_NAME, area);
    return area;
};

const getTotalCircleArea = (n, area = 0) => {
    if (n === 0) {
        logExecution(CIRCLE_NAME, area);
        return area;
    }
    return getTotalCircleArea(n - 1, (area += pow(n, 2) * PI));
};

const getRectArea = (w, h) => {
    let area = 0;
    area = w * h;
    logExecution(RECT_NAME, area);
    return area;
};

const getTrapezoidArea = (uw, dw, h) => {
    let area = 0;
    area = ((uw + dw) * h) / 2;
    logExecution(TRAPE_NAME, area);
    return area;
};

const getArea = (polygonName, ...params) => {
    let area = 0;
    switch (polygonName) {
        case CIRCLE_NAME:
            area = (2 === params.length) ? getTotalCircleArea(params[1]) : getCircleArea(params[0])
            break;
        case RECT_NAME:
            area = getRectArea(...params);
            break;
        case TRAPE_NAME:
            area = getTrapezoidArea(...params);
            break;
        default:
            throw Error(
                "Incorrect Parameters\ngetArea([polygon name], ...params)\npolygon name : circle / rect / trapezoid"
            );
            break;
    }

    return area;
};

console.log(getArea("circle", 1, 3));
console.log(getArea("circle", 3));
console.log(getArea("rect", 3, 4));
console.log(getArea("trapezoid", 1, 2, 8));
printExecutionSequence();