/*
 * Authro: CHEN Yongyuan (Walter) 1930006025 from OOP(1007)
 * Date: 2022/03/09
 * Description: This is the main class of AutoRobot.
 */

public class AutoRobot {
    /**
     * current speed of the robot.
     */
    private double currentSpeed;

    /**
     * name of the robot
     */
    private String name;

    /**
     * Constructor for objects of class AutoRobot. Default name is "xyz".
     * Initial speed is 0.
     */
    public AutoRobot() {
        // initialise instance variables
        this.currentSpeed = 0;
        this.name = "xyz";
    }

    /**
     * Getter method for name.
     *
     * @return name of the robot.
     */
    public String getName() {
        return this.name;
    }

    /**
     * Getter method for current speed.
     *
     * @return current speed of the robot.
     */
    public double getCurrentSpeed() {
        return this.currentSpeed;
    }

    /**
     * Increase the speed of the robot by 5. The speed exceed 20 will
     * print "Dangerous" message and do nothing.
     *
     * @return current speed of the robot.
     */
    public void accelerate() {
        if (this.currentSpeed >= 20) {
            System.out.println("Dangerous! Please stay within speed limit.");
            return;
        }

        this.currentSpeed += 5;
    }

    /**
     * Decrase the speed of the robot by 5. The speed can not be less than 0.
     *
     * @return current speed of the robot.
     */
    public void brake() {
        if (this.currentSpeed - 5 <= 0) {
            this.currentSpeed = 0;
            return;
        }

        this.currentSpeed -= 5;
    }

    /**
     * Print out current status.
     *
     * @return void.
     */
    public void printStatus() {
        System.out.println(String.format("Hello there, my name is %s and my current speed is %.1f",
                this.name, this.currentSpeed));
    }

    /**
     * Setter method for name.
     *
     * @param name name of the robot.
     * @return void.
     */
    public void setName(String name) {
        this.name = name;
    }
    
    /**
     * Static test the class AutoRobot.
     *
     * @return void.
     */
    public static void testAutoRobot() {
        AutoRobot robot = new AutoRobot();

        // print current status
        robot.printStatus();

        // print true for default value
        System.out.println(robot.getName().equals("xyz"));
        System.out.println(doubleEquals(robot.getCurrentSpeed(), 0));
        System.out.println(robot.getCurrentSpeed() == 0);

        // change name and print current status
        robot.setName("ABC");

        // print true for name
        System.out.println(robot.getName().equals("ABC"));

        // accelerate and print true for current speed
        robot.accelerate();
        System.out.println(doubleEquals(robot.getCurrentSpeed(), 5));

        // accelerate and print true for current speed
        robot.accelerate();
        System.out.println(doubleEquals(robot.getCurrentSpeed(), 10));

        // brake and print true for current speed
        robot.brake();
        System.out.println(doubleEquals(robot.getCurrentSpeed(), 5));

        // accelerate and print true for current speed
        robot.accelerate();
        System.out.println(doubleEquals(robot.getCurrentSpeed(), 10));

        // accelerate and print true for current speed
        robot.accelerate();
        System.out.println(doubleEquals(robot.getCurrentSpeed(), 15));

        // accelerate and print true for current speed
        robot.accelerate();
        System.out.println(doubleEquals(robot.getCurrentSpeed(), 20));

        // accelerate and print true for current speed
        robot.accelerate();
        System.out.println(doubleEquals(robot.getCurrentSpeed(), 20));

        // break and print true for current speed
        robot.brake();
        System.out.println(doubleEquals(robot.getCurrentSpeed(), 15));

        // brake and print true for current speed
        robot.brake();
        System.out.println(doubleEquals(robot.getCurrentSpeed(), 10));

        // brake and print true for current speed
        robot.brake();
        System.out.println(doubleEquals(robot.getCurrentSpeed(), 5));

        // brake and print true for current speed
        robot.brake();
        System.out.println(doubleEquals(robot.getCurrentSpeed(), 0));

        // brake and print true for current speed
        robot.brake();
        System.out.println(doubleEquals(robot.getCurrentSpeed(), 0));

        // print current status
        robot.printStatus();
    }

    public static void main(String[] args) {
        testAutoRobot();
    }

    /**
     * Compare double value.
     *
     * @param a double value.
     * @param b double value.
     * @return true if a and b are equal.
     */
    public static boolean doubleEquals(double a, double b) {
        return Math.abs(a - b) < 0.00001;
    }
}