import java.awt.*;     // Needed for window and graphics (explained in COMP1406)
import javax.swing.*;  // Needed for window and graphics (explained in COMP1406)

// This application simulates robots attracted to beacons in a window
public class RobotSimulation {
    // This variable stores the panel that displays the robots and beacons
    // (This is a topic discussed in COMP1406 course)
    public static RobotEnvironmentPanel   envPanel;
    public static Robot[]                 robots;      // an array to hold the robots

    public static void startSimulation() {
        while(true) {
            for (int i=0; i<robots.length; i++) 
                move(robots[i]);
            envPanel.repaint();
            try{ Thread.sleep(10); } catch(Exception e){};
        }
    }

    // Code for moving a robot towards its beacon
    public static void move(Robot r) {
        float nextX, nextY, crossProduct;
        
        nextX = r.x + (int)(r.speed*Math.cos(r.direction)); 
        nextY = r.y + (int)(r.speed*Math.sin(r.direction));
        
        crossProduct = (nextX - r.x)*(r.beacon.y - r.y)-(nextY - r.y)*(r.beacon.x - r.x);
        r.x = (int)nextX; 
        r.y = (int)nextY;
        if (crossProduct < 0)   // try changing to:  if((crossProduct<0)&&(random(1)<0.6))
            r.direction -= (Robot.TURN_ANGLE + Math.random()*Robot.TURN_ANGLE/4 - (Robot.TURN_ANGLE/8))/180*Math.PI;
        else
            r.direction += (Robot.TURN_ANGLE + Math.random()*Robot.TURN_ANGLE/4 - (Robot.TURN_ANGLE/8))/180*Math.PI;
    }

    // Create a window, add beacons and robots, then start simulating
    public static void main(String args[]) {
        // Make some robots with unique beacons
        robots = new Robot[10];      // an array to hold the robots
        for (int i=0; i<robots.length; i++) {
            robots[i] = new Robot(RobotEnvironmentPanel.WIDTH/2, RobotEnvironmentPanel.HEIGHT/2);
            robots[i].beacon = new Beacon((int)(Math.random()*RobotEnvironmentPanel.WIDTH), (int)(Math.random()*RobotEnvironmentPanel.HEIGHT));
        }
        
        JFrame frame = new JFrame("Robot Simulation");
        frame.add(envPanel = new RobotEnvironmentPanel(robots));
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.pack(); // Makes size according to panel's preference
        frame.setVisible(true);
        
        startSimulation();
    }
}