package gvps.gui;

import java.awt.*;
import javax.swing.*;
import java.util.*;

/**
 *	<p>The VehicleAnimator class provides an automatically updating canvas on 
 *	which to display moving vehicles.</p>
 *	<p>In order to animate the vehicles "nicely" (without flickering) it uses 
 *	a concept called "double buffering" to render the display off-screen (thus
 *	in memory) before transferring it over to the screen. This results in 
 *	potentially larger memory usage... however, this should be negligable.</p>
 */
public class VehicleAnimator extends Component implements Runnable {
	/* for additional functionality (e.g. collisions, etc), extend the Vector 
	 * class with a "VehicleManager", which checks for additional vehicle 
	 * placement parameters and use it in place of 'vehicles' */
	private Vector<MappedVehicle> vehicles;
	private int state;
	private Image carImage;
	private int animationSpeed = 83; // animation speed: ~12fps
	private Graphics offScreenGraphics;
	private Image offScreenImage;
	
	/** Creates an animated canvas that displays movements of various vehicles 
	 * based on their position and speed */
	public VehicleAnimator(){
		carImage = Toolkit.getDefaultToolkit().getImage("car_icon.png");
		vehicles = new Vector<MappedVehicle>();
	}

	public void addVehicle(String vehicleId, Vector<Point> path, int speed){
		MappedVehicle vehicle = new MappedVehicle(vehicleId, path, speed);
		vehicles.add(vehicle);
		Thread vehicleThread = new Thread(vehicle);
		vehicleThread.start();
	}
	
	/**
	 *	Forces the current location of a vehicle with the specified vehicleID
	 *	@param vehicleId	the unique identifier of the desired vehicle
	 *	@param location		the new location of the vehicle
	 */
	public void forceVehicleLocation(String vehicleId, Point location){
		try {
			getMappedVehicle(vehicleId).setLocation(location);
		}
		catch (VehicleNotFoundException e) {
			System.out.println(e);
		}
	}
	
	/**
	 *	Changes the predictive speed of a vehicle with the specified vehicleID.
	 *	Warning: No mutexes are used to validate the size of vehicles Vector, 
	 *	resulting in possibly incorrect vehicle counts.
	 *	@param vehicleID	the id of the vehicle
	 *	@param speed		the new speed of the chosen vehicle
	 */
	public void setVehicleSpeed(String vehicleId, int speed) {
		try {
			getMappedVehicle(vehicleId).setSpeed(speed);
		}
		catch (VehicleNotFoundException e) {
			System.out.println(e);
		}
	}
	
	/**
	 *	Pauses a selected vehicles movements.
	 */
	public void pauseVehicle(String vehicleId){
		
	
	/**
	 *	Gets a MappedVehicle object based on it's vehicleId.
	 *	@param id	the unique identifier of a vehicle
	 *	@throws VehicleNotFoundException	if a vehicle does not exist with this id
	 */
	public MappedVehicle getMappedVehicle(String id) throws VehicleNotFoundException {
		boolean vehicleFound = false;
		int totalVehicles = vehicles.size();
		int count = 0;
		// loop through each vehicle looking for one with the right ID
		while ( !vehicleFound || count < totalVehicles ){
			if ( vehicles.get(count).getId().equals(id) ){
				vehicleFound = true;
			}
			else {
				count++;
			}
		}
		if ( !vehicleFound ){
			throw new VehicleNotFoundException("A vehicle does not exist "+
					"with the id \"" + id + "\"" );
		}
		else {
			return vehicles.get(count);
		}
	}

	public void run(){
		while (true){
			repaint();
			try { 
				Thread.sleep(animationSpeed);
			}
			catch (InterruptedException e){
				System.out.println("This thread has been broken... "+
						"I have NO idea what that means");
			}
		}
	}
	
	/**
	 *	Redraws the positions of the vehicles on screen.
	 */
	public void update(Graphics g){
		// clears the offscreen graphics image, places a "car" image at every point
		// on the map where a car is supposed to be
		// then draws that to the component
		int totalVehicles = vehicles.size();
		
		if (offScreenGraphics == null) {
			//System.out.println("Creating buffer");
			offScreenImage = createImage(getWidth(), getHeight());
			offScreenGraphics = offScreenImage.getGraphics();
		}
		
		// clear the screen
		offScreenGraphics.clearRect(0,0, this.getWidth(),this.getHeight());
		
		// if we have vehicles, loop through them, get their position, and draw them
		if ( totalVehicles > 0 ){
			for ( int i = 0; i < totalVehicles; i++ ){
				MappedVehicle currentVehicle = vehicles.get(i);
				// check if the current vehicle hasn't actually reached its 
				// destination, if it hasn't, draw it
				if ( !currentVehicle.isFinished() ){
					//System.out.println("Drawing to buffer");
					offScreenGraphics.drawImage(
								carImage, 
								(int)currentVehicle.getLocation().getX(),
								(int)currentVehicle.getLocation().getY(),
								this);
				}
				// else, remove it from the list of vehicles
				else {
					vehicles.remove(i);
					// compensate for removed vehicle
					i--;
					totalVehicles = vehicles.size();
				}
			}
			if ( offScreenGraphics != null ) {
				//System.out.println("Drawing to screen");
				g.drawImage(offScreenImage, 0, 0, this);
			}
		}
	}
	
	public void paint(Graphics g){
		
	}
	
}