package com.interview.design.pattern.structural;

/**
 * Created_By: stefanie
 * Date: 14-12-3
 * Time: 上午11:07
 * 装饰模式就是给一个对象增加一些新的功能，而且是动态的，要求装饰对象和被装饰对象实现同一个接口，装饰对象持有被装饰对象的实例
 *
 * Decorator pattern allows to add new functionality an existing object without altering its structure.
 * This pattern creates a decorator class which wraps the original class and provides additional functionality
 * keeping class methods signature intact.
 *
 * 装饰器模式的应用场景：
 * 1、需要扩展一个类的功能。
 * 2、动态的为一个对象增加功能，而且还能动态撤销。（继承不能做到这一点，继承的功能是静态的，不能动态增删。）
 * 缺点：产生过多相似的对象，不易排错！
 */
public class DecoratorPattern {
    static interface Shape {
        void draw();
    }

    static class Rectangle implements Shape {

        @Override
        public void draw() {
            System.out.println("Shape: Rectangle");
        }
    }

    static class Circle implements Shape {

        @Override
        public void draw() {
            System.out.println("Shape: Circle");
        }
    }

    /**
     * use ShapeDecorator to add more logic in draw() for Shape, and it composite a Shape instance
     */
    static abstract class ShapeDecorator implements Shape {
        protected Shape decoratedShape;

        public ShapeDecorator(Shape decoratedShape){
            this.decoratedShape = decoratedShape;
        }

        public void draw(){
            decoratedShape.draw();
        }
    }

    /**
     * Add more logic when call draw()
     */
    static class RedShapeDecorator extends ShapeDecorator {

        public RedShapeDecorator(Shape decoratedShape) {
            super(decoratedShape);
        }

        @Override
        public void draw() {
            decoratedShape.draw();
            setRedBorder(decoratedShape);
        }

        private void setRedBorder(Shape decoratedShape){
            System.out.println("Border Color: Red");
        }
    }

    public static void main(String[] args) {

        Shape circle = new Circle();

        Shape redCircle = new RedShapeDecorator(new Circle());

        Shape redRectangle = new RedShapeDecorator(new Rectangle());
        System.out.println("Circle with normal border");
        circle.draw();

        System.out.println("\nCircle of red border");
        redCircle.draw();

        System.out.println("\nRectangle of red border");
        redRectangle.draw();
    }
}