// import things for window
import java.awt.*;
import java.applet.Applet;
import java.awt.event.*;
import javax.swing.border.*;
import javax.swing.*;

public class BinarySearchApplet extends Applet implements ActionListener {

        Panel top;
        Panel bottom;
        Panel grid;
        Button search;
        Button step;
        TextField needle;
        Label needleLabel;
        String found = "Found at index: ";
        String foundStart = "Please enter a search term";
        Label foundLabel;
        String searchText = "Search";
        String contin = "Continue";

        int[] haystack = {1, 2, 4, 7, 9, 10, 16, 22, 27, 32, 58};
        int digits = (haystack[haystack.length - 1] + "").length();
        int thisFirst = 0;
        int thisLast = haystack.length - 1;
        int thisNeedle = 0;

        JLabel[][] boxes = new JLabel[2][haystack.length];

        int[] fontSize = {50, 30};

	public void init() {
		this.setLayout(new BorderLayout());

                grid = new Panel();
		grid.setLayout(new GridLayout(2, 1));

		top = new Panel();
		top.setLayout(new GridLayout(boxes.length, boxes[0].length));

                for (int i = 0; i < boxes.length; i++) {
                    for (int j = 0; j < boxes[i].length; j++) {
                        int labelText = (i == 0)
                                      ? haystack[j]
                                      : j;
                        boxes[i][j] = new JLabel("" + labelText, JLabel.CENTER);
                        if (i == 0) {
                            boxes[i][j].setOpaque(true);
                            boxes[i][j].setBorder(BorderFactory.createLineBorder(Color.black));
                        }
                        else {
                            boxes[i][j].setVerticalAlignment(JLabel.TOP);
                        }
                        boxes[i][j].setFont(new Font("Monospaced", Font.BOLD, fontSize[i]));
                        top.add(boxes[i][j]);
                    }
                }

                bottom = new Panel();
		needleLabel = new Label("Needle:");
                needle = new TextField("", digits);
		search = new Button(searchText);
                search.addActionListener(this);
		step = new Button(contin);
                step.setEnabled(false);
                step.addActionListener(this);
                bottom.add(needleLabel);
                bottom.add(needle);
                bottom.add(search);
                bottom.add(step);

                grid.add(top);
                grid.add(bottom);

                foundLabel = new Label(foundStart);
                foundLabel.setFont(new Font("Monospaced", Font.BOLD, 30));

                this.add(grid, "Center");
                this.add(foundLabel, "South");

                repaint();
        }

        public void binarySearch(int[] haystack, int first, int last, int needle) {
            if (first <= last) {
                int mid = (first + last) / 2;
                if (haystack[mid] == needle) {
                    reset(found + mid);
                    boxes[0][mid].setBackground(Color.PINK);
                    repaint();
                }
                else if (haystack[mid] > needle) {
                    info(first, mid - 1, needle);
                }
                else {
                    info(mid + 1, last, needle);
                }
            }
            else {
                reset(needle + " is not in the array");
            }
        }

        public void reset(String s) {
            foundLabel.setText(s);
            for (int i = 0; i < haystack.length; i++) {
                boxes[0][i].setBackground(Color.GRAY);
            }
            step.setEnabled(false);
            repaint();
        }

        public void info(int first, int last, int needle) {
            thisFirst = first;
            thisLast = last;
            thisNeedle = needle;
            for (int i = first; i <= last; i++) {
                boxes[0][i].setBackground(new Color(255, 255, 151));
            }
            for (int i = 0; i < first; i++) {
                boxes[0][i].setBackground(Color.GRAY);
            }
            for (int i = last + 1; i < haystack.length; i++) {
                boxes[0][i].setBackground(Color.GRAY);
            }
            boxes[0][(first + last) / 2].setBackground(Color.YELLOW);
            repaint();
        }

	public void paint( Graphics g ) {
	}

        public void actionPerformed(ActionEvent e) {

            String c = e.getActionCommand();

            if(c.equals(searchText)) {
                try {
                    thisNeedle = Integer.parseInt(needle.getText());
                    needle.setForeground(Color.BLACK);
                    foundLabel.setForeground(Color.BLACK);
                    foundLabel.setText("Searching for: " + thisNeedle);
                    step.setEnabled(true);
                    info(0, haystack.length - 1, thisNeedle);
                    repaint();
                }
                catch (Exception exc) {
                    needle.setForeground(Color.RED);
                    foundLabel.setForeground(Color.RED);
                    foundLabel.setText("Please enter an integer");
                    repaint();
                }
            }
            else if(c.equals(contin)) {
                binarySearch(haystack, thisFirst, thisLast, thisNeedle);
            }
        }

}