public class BouncyBall
{


   public static void main(String [] args){

       FakeGravity earth = new FakeGravity("Earth", 32, -0.5);
       FakeGravity discWorld = new FakeGravity("DiscWorld",6, -3);
       FakeGravity krypton = new FakeGravity("Krypton",74,-0.22);
       // intance of FakeGravity



       //call menu method to display menu to user
       menu();


       Scanner input = new Scanner(System.in);
       //local variable option assigned to values entered by user
       int option;
       double velocity;
       double height;

       // Prompts user to enter number choice from menu
       System.out.println("Enter your option: ");
       option = input.nextInt();   // reads number from user


       //error checking
       // If user selects an option other than 0-3 the user is taken back to the menu and prompted to re enter valid number choice.
     while(option < 0  || option > 3){
        menu();
         System.out.println("ERROR, please enter a valid number from the choices above: ");
         option = input.nextInt();

         if (option == 0){

             System.out.println("The program has ended");
             System.exit(0);

            }

        }

        while (option == 1 || option == 2 || option ==3)
        {

        // If user enter option 1, user is prompted to enter velocity, which is then stored in local variable called velocity.
         while (option == 1){

             System.out.println("You have selected Earth");
             System.out.println("Initial Velocity: ");
             velocity = input.nextDouble();
             // Error check to see if velocity entered by user is negative. If it is negative the user will receive an error message and be prompted to enter a positive velocity
              while (velocity < 0){

                    System.out.println("ERROR you have entered a negative number, Please enter a poitive velocity: ");

                    menu();

                   velocity = input.nextDouble();

                }

             compute(earth, velocity);  // pass earth and velocity as an argument to compute method
             earth.getVelocityDecay(); // retrieve value of earths velocity decay for use in calculation
             menu();      // calls menu method againt



                // once calculations are returned to user, prompt user again
             while (option == 1){
                 System.out.println("Enter your option: ");
                 option = input.nextInt();
                 if (option ==1){
                 System.out.println("You have selected Earth");

                }
                 if (option == 0){

                     System.out.println("The program has ended");
                     System.exit(0);

                    }

                 System.out.println("Initial Velocity: ");
                 velocity = input.nextDouble();

                 while (velocity < 0){

                     System.out.println("ERROR, you have entered a negative number, Please enter a positive velocity: ");
                     menu();
                     velocity = input.nextDouble();


                    }

                 compute(earth, velocity);
                 earth.getVelocityDecay();
                 menu();



                }


            }
            // if user chooses option 2, user is informed of planet choice and asked to enter initial velocity
            while (option == 2){

                System.out.println("You have selected Disc World");
                System.out.println("Initial Velocity: ");
                velocity = input.nextDouble();

                while (velocity < 0){

                    System.out.println("ERROR, you have entered a negative number, Please enter a positive velocity: ");
                    menu();
                    velocity = input.nextDouble();

                }
                compute(discWorld, velocity);
                discWorld.getVelocityDecay();
                menu();

                if (option == 2){

                    System.out.println("Enter your option: ");
                    option = input.nextInt();
                    System.out.println("You have selected DiscWorld");

                    if (option == 0){

                        System.out.println("The program has ended");
                        System.exit(0);
                    }

                    System.out.println("Initial Velocity: ");
                    velocity = input.nextDouble();

                    while (velocity < 0){

                        System.out.println("ERROR, you have entered a negative number, Please enter a positive velocity: ");
                        velocity = input.nextDouble();

                    }
                    compute(discWorld, velocity);
                    discWorld.getVelocityDecay();
                    menu();
                // if user enters a negative velocity, user is returned to method menu which displays meny again and prompts user to enter choices again.

            }
        }
        // if user selects option 3, user is informed of planet name and prompted to enter intial velocity
            while (option == 3){

                System.out.println("You have selected Krypton, please enter an initial velocity: ");
                velocity = input.nextDouble();

                while (velocity < 0){

                    System.out.println("ERROR, you have entered a negative number, Please enter a positive velocity: ");
                    menu();
                    velocity = input.nextDouble();

                }
                compute(krypton, velocity);
                krypton.getVelocityDecay();
                menu();

                if (option == 3){
                    System.out.println("Enter your option: ");
                    option = input.nextInt();

                    while (option == 0){

                        System.out.println("The program has ended");
                        System.exit(0);

                    }
                    System.out.println("Initial Velocity: ");
                    velocity = input.nextDouble();


                // anytime user enters negative velocity, user is returned to method menu and asked to enter value
                compute(krypton, velocity);
                krypton.getVelocityDecay();
                menu();
            }







        }
        }
    }
    // Static method menu
    // This menu simply prints out the menu so the user can see the choices
        public static void menu(){

        System.out.println("*** Gravity Menu ***");
        System.out.println("1.) Earth");
        System.out.println("2.) Disc World");
        System.out.println("3.) Krypton ");
        System.out.println("0.) Quit");
        System.out.println("**********************");
    }

    // Static method compute
    public static void compute(FakeGravity planet, double velocity){
        Scanner input = new Scanner(System.in);
       double height;
       int time;

       height = velocity;  // initial height is zero
       time = 0;    // inital time is zero
       double newHeight;  // new height variable to remember new height

      while (time <= 20)
      {
          newHeight = height;



          height = (height + velocity) - planet.getVelocityDecay();
          velocity -= planet.getVelocityDecay();
          time = time +1;
           // newHeight is equal to the height

            if (newHeight < 0){    // everytime the new height is less than 0, BOUNCE! is printed
                   velocity = (velocity * planet.getBouncinessFactor());
                   height = (height * planet.getBouncinessFactor());
                   System.out.println(" " +"BOUNCE!"+ " ");

                }

                if (newHeight > 0){

                    System.out.println("time: "+time +" " + " "+"Height: "+newHeight + " "+ "");

                }


        }




    }
}