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

/* This listens for all GUI events */
public class MyCanvas extends Canvas 
    implements ActionListener, ItemListener, MouseMotionListener, MouseListener, Runnable	{

    public int WIDTH;
    public int HEIGHT;
    public TwoThreeFourTree T;
    public static final int KEY_WIDTH = 20;
    public static final int NODE_HEIGHT = 17;
    private static final int VERTICAL_SPACING = 70;
    public static final Color gold = new Color(255, 215, 0);
    private static final int OFFSET = 8;        //creates spacing between leaves to prevent overlapping
    private final static int RUN = 0;
    private final static int SINGLE_STEP = 1;
    private final static int STEP_BY_STEP = 2;	
    private int mode;
    public final static int INSERT = 1;
    public final static int DELETE = 2;
    public final static int SEARCH = 3;
    public int OPERATION;
    private Font f;
    private Point currentDragPosition;
    public Thread runner;
    private boolean blockMouseDragging = false;
    public TreeApplet applet;
    private Thread animator;
    private boolean animate = false;

    MyCanvas(TreeApplet applet)	{	
        super();
        this.applet = applet;
        T = new TwoThreeFourTree(this);
        mode = SINGLE_STEP;
        setBackground(Color.white);
        f = new Font("TimesRoman", Font.PLAIN, 14);
        addMouseListener(this);
        addMouseMotionListener(this);
    }


    Image animatedImage;
    String text;

    public void paint(Graphics screen)	{
        WIDTH = getSize().width;
        HEIGHT = getSize().height;

        if (T.root.key[0] != -1)	{	
            if (!animate)	{
                Image bufferImage = createImage(WIDTH, HEIGHT);
                Graphics offscreen = bufferImage.getGraphics();
                offscreen.drawImage(applet.treePicture, 0, 0, 100, 100, null);
                if (runner == null)	setCo_ordinates(T.root, WIDTH/2, 40);
                drawTree(offscreen, T.root);
                screen.drawImage(bufferImage, 0, 0, null);
                String text;
                if (!(text = applet.displayArea.getText()).equals(applet.docp.whatNext))
                    applet.displayArea.setText(applet.docp.whatNext);
                offscreen.dispose();
                applet.keyField.requestFocus();
            }
            else if (animatedImage != null)	{
                screen.drawImage(animatedImage, 0, 0, null);
                applet.displayArea.setText(text);
            }
        }
        else	{
            screen.setColor(Color.white);
            screen.fillRect(0, 0, WIDTH, HEIGHT);
        }	
    }

    public void update(Graphics screen)	{
        paint(screen);
    }

    public void setCo_ordinates(Node node, int x, int y)	{
        if (node == T.root)	T.root.level = 0;
        int level = node.level;
        node.x = x;
        node.y = y; 
        int NODE_WIDTH = KEY_WIDTH*node.n; 

        if (!node.leaf)	{
            for (int j = 0; j < node.n + 1; j++)	{
                int childX, childY;
                if (node.c[j].leaf)	{
                    childX = x - (int)((VERTICAL_SPACING-3)/Math.tan((j+1)*Math.PI/(node.n + 2)));
                    if (level >= 1)	childY = y + VERTICAL_SPACING + OFFSET*(j%2);
                    else	 childY = y + VERTICAL_SPACING;
                }
                else	{
                    childX = 
                        x - (int)((VERTICAL_SPACING+160-50*Math.pow(2,level))/Math.tan((j+1)*Math.PI/(node.n+2)));
                    childY = y + VERTICAL_SPACING;
                }
                node.c[j].level = node.level + 1;
                setCo_ordinates(node.c[j], childX, childY);
            }
        }
    }


    public void drawTree(Graphics offscreen, Node node)	{
        int NODE_WIDTH = KEY_WIDTH*node.n;
        Point corner = new Point(node.x - NODE_WIDTH/2, node.y);

        if (node == T.root)	{
            offscreen.setFont(f);
            offscreen.drawLine(WIDTH/2, 0, T.root.x, T.root.y);
        }

        offscreen.setColor(Color.black);
        offscreen.draw3DRect(corner.x, corner.y, NODE_WIDTH, NODE_HEIGHT, true);
        offscreen.setColor(gold);
        offscreen.fill3DRect(corner.x + 1, corner.y + 1, NODE_WIDTH - 1, NODE_HEIGHT - 1, true);
        offscreen.setColor(Color.black);

        for (int i = 1; i <= node.n - 1; i++)
            offscreen.drawLine(corner.x+NODE_WIDTH/node.n*i, corner.y, corner.x+NODE_WIDTH/node.n*i, 
                    corner.y+NODE_HEIGHT);
        for (int i = 1; i <= node.n; i++)	{
            String key = Integer.toString(node.key[i-1]);
            if (key.length() == 1)	key = ' ' + key;
            offscreen.drawString(key, corner.x + NODE_WIDTH/node.n*(i-1) + 3, corner.y + 13);
        }

        if (!node.leaf)	{
            for (int j = 0; j < node.n + 1; j++)	{
                drawTree(offscreen, node.c[j]);
                drawLineToChild(offscreen, node, j);
            }
        }
    }


    public void drawLineToChild(Graphics offscreen, Node parent, int j)	{
        Node child = parent.c[j];
        int x1 = parent.x - parent.n*KEY_WIDTH/2 + j*KEY_WIDTH;
        int y1 = parent.y + NODE_HEIGHT;
        int x2 = child.x;
        int y2 = child.y;
        offscreen.drawLine(x1, y1, x2, y2);
    }


    public void run()	{			//Thread which runs whenever the mouse is being dragged
        boolean vicinity = false;
        Node node = null;
        Point previousPosition = null;

        while (runner != null)	{
            Node[] nodearray = T.toArray();
            if (!vicinity )	{
                int i = 0;
                for (i = 0; i < nodearray.length; i++)	{
                    node = nodearray[i];
                    if (Math.abs(currentDragPosition.x - node.x) < KEY_WIDTH*node.n/2 
                            && currentDragPosition.y - node.y < NODE_HEIGHT && currentDragPosition.y - node.y > 0) break;
                }
                if (i != nodearray.length)	vicinity = true;
                else vicinity = false;
            }
            if (vicinity && (previousPosition != null) && !currentDragPosition.equals(previousPosition))	{
                setCo_ordinates(node, currentDragPosition.x, currentDragPosition.y);
                repaint();
            }
            previousPosition = currentDragPosition;
        }
    }


    public void itemStateChanged(ItemEvent ie)	{
        if (((JRadioButton)(ie.getItem())).getText().equals("Step by step"))	mode = STEP_BY_STEP;
        else if (((JRadioButton)ie.getItem()).getText().equals("Run"))	mode = RUN;
        else if (((JRadioButton)ie.getItem()).getText().equals("Single step"))	mode = SINGLE_STEP;
    }


    int stepCount = 0;
    Display [] buffer = new Display[10];
    public void actionPerformed(ActionEvent ae)	{
        try{
            if (applet.keyField.getText().length() > 2)	throw new NumberFormatException();
            if (ae.getActionCommand().equals("Insert") && !animate)	{
                if (mode == SINGLE_STEP)	{
                    T.INSERT(Integer.parseInt(applet.keyField.getText()));
                    applet.keyField.setText("");
                    repaint();
                }
                else {
                    OPERATION = INSERT;
                    animate = true;
                    if (mode == RUN)	new RunAnimator(Integer.parseInt(applet.keyField.getText()), this);
                    else	 {
                        buffer = T.INSERT_ANIMATED(Integer.parseInt(applet.keyField.getText()));
                        stepCount = 0;
                        applet.nextButton.setEnabled(true);
                        animate = true;
                        animatedImage = buffer[0].im;
                        text = buffer[0].text;
                        if (buffer[stepCount + 1] == null)	applet.nextButton.setLabel("Finish");
                        repaint();
                    }
                    applet.keyField.setText("");
                }
            }
            else if (ae.getActionCommand().equals("Delete") && !animate)	{
                if (mode == SINGLE_STEP)	{
                    T.DELETE(T.root, Integer.parseInt(applet.keyField.getText()));
                    applet.keyField.setText("");
                    repaint();
                }
                else {
                    OPERATION = DELETE;
                    animate = true;
                    if (mode == RUN)	new RunAnimator(Integer.parseInt(applet.keyField.getText()), this);
                    else	 {
                        buffer = T.DELETE_ANIMATED(T.root, Integer.parseInt(applet.keyField.getText()));
                        stepCount = 0;
                        applet.nextButton.setEnabled(true);
                        animate = true;
                        animatedImage = buffer[0].im;
                        text = buffer[0].text;
                        if (buffer[stepCount + 1] == null)	applet.nextButton.setLabel("Finish");
                        repaint();
                    }
                    applet.keyField.setText("");
                }				 
            }
            else if (ae.getActionCommand().equals("Search"))	{
                if (mode == SINGLE_STEP)	{
                    Pair result;
                    result = T.SEARCH(T.root, Integer.parseInt(applet.keyField.getText()));
                    if (result != null) {
                        applet.displayArea.setText("Key "+((Node)result.obj).key[result.value-1]+ " found!");
                    }else{
                        applet.displayArea.setText("Search failed: key "+((Node)result.obj).key[result.value-1]+" not found!");
                    }
                    applet.keyField.setText("");
                }
                else{
                    OPERATION = SEARCH;
                    animate = true;
                    if (mode == RUN)
                        animator = new RunAnimator(Integer.parseInt(applet.keyField.getText()), this);
                    else	 {
                        buffer = T.SEARCH_ANIMATED(T.root, Integer.parseInt(applet.keyField.getText()));
                        stepCount = 0;
                        applet.nextButton.setEnabled(true);
                        animate = true;
                        animatedImage = buffer[0].im;
                        text = buffer[0].text;
                        if (buffer[stepCount + 1] == null)	applet.nextButton.setLabel("Finish");
                        repaint();
                    }
                    applet.keyField.setText("");
                }
            }else if (ae.getActionCommand().equals("Prev step"))	{
                if (stepCount == 1)	applet.prevButton.setEnabled(false);
                animatedImage = buffer[--stepCount].im;
                text = buffer[stepCount].text;
                if (applet.nextButton.getLabel().equals("Finish"))	applet.nextButton.setLabel("Next step");
                repaint();
            }
            else if (ae.getActionCommand().equals("Next step"))	{
                animatedImage = buffer[++stepCount].im;
                text = buffer[stepCount].text;
                if (stepCount == 1) applet.prevButton.setEnabled(true);
                repaint();
                if (buffer[stepCount+1] == null)	applet.nextButton.setLabel("Finish");
            }
            else if (ae.getActionCommand().equals("Finish"))	{
                animate = false;
                applet.prevButton.setEnabled(false);
                applet.nextButton.setEnabled(false);
                applet.nextButton.setLabel("Next step");
                repaint();
                applet.keyField.requestFocus();
                stepCount = 0;
            }else if (ae.getActionCommand().equals("Reset"))	{
                animate = false;
                if (animator != null && animator.isAlive())	{
                    animate = false;
                    animator.destroy();
                }
                System.runFinalization();
                T = new TwoThreeFourTree(this);
                applet.keyField.setText("");
                applet.keyField.requestFocus();
                repaint();
            }
        } catch (NumberFormatException e)	{
            applet.displayArea.setText(applet.docp.invalid);
            applet.keyField.setText("");
            return;
        }
    }


    class RunAnimator extends Thread	{
        MyCanvas canvas;
        Display[] buffer;

        RunAnimator(int key, MyCanvas canvas)	{
            this.canvas = canvas;
            switch (OPERATION){
                case INSERT:
                    buffer = T.INSERT_ANIMATED(key);
                    break;
                case DELETE:
                    buffer = T.DELETE_ANIMATED(T.root, key);
                    break;
                case SEARCH:
                    buffer = T.SEARCH_ANIMATED(T.root, key);
                    break;
            }
            start();
        }

        public void run()	 {
            try{
                for (int i = 0; buffer[i] != null; i++)	{
                    animatedImage = buffer[i].im;
                    text = buffer[i].text;
                    repaint();
                    Thread.sleep(1000); 
                }
                animate = false;
                repaint();
            } catch (InterruptedException e)	{}
        }

    }


    int i = 0;
    public void mouseDragged(MouseEvent e)	{
        currentDragPosition = e.getPoint();
        if (i == 0 && !blockMouseDragging)	{
            runner = new Thread(this);
            runner.start();
        }
        i++;
    }		

    public void mouseReleased(MouseEvent e)	{
        runner = null;
        i = 0;
    }

    public void mouseMoved(MouseEvent e)	{}
    public void mouseClicked(MouseEvent e)	{}
    public void mouseEntered(MouseEvent e)	{}
    public void mouseExited(MouseEvent e)	{}
    public void mousePressed(MouseEvent e)	{}

}