// Before: Duplicate code
function calculateArea(shape) {
  if (shape.type === 'circle') {
    return Math.PI * shape.radius * shape.radius;
  } else if (shape.type === 'rectangle') {
    return shape.width * shape.height;
  }
}

function calculatePerimeter(shape) {
  if (shape.type === 'circle') {
    return 2 * Math.PI * shape.radius;
  } else if (shape.type === 'rectangle') {
    return 2 * (shape.width + shape.height);
  }
}

// After: Extracted logic
class Circle {
  constructor(radius) {
    this.radius = radius;
  }
  area() {
    return Math.PI * this.radius * this.radius;
  }
  perimeter() {
    return 2 * Math.PI * this.radius;
  }
}

class Rectangle {
  constructor(width, height) {
    this.width = width;
    this.height = height;
  }
  area() {
    return this.width * this.height;
  }
  perimeter() {
    return 2 * (this.width + this.height);
  }
}