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

/**
 * A class that implements an Observer object that displays a barchart view of
 * a data model.
 */
public class BarFrame extends JFrame implements ChangeListener {
    /**
     * Constructs a BarFrame object
     *
     * @param dataModel the data that is displayed in the barchart
     */
    public BarFrame(DataModel dataModel) {
        this.dataModel = dataModel;
        a = dataModel.getData();

        setLocation(0, 200);
        setLayout(new BorderLayout());

        JLabel barLabel = new JLabel();
        barLabel.setIcon(new BarIcon());
        barLabel.addMouseListener(new MouseAdapter() {
            @Override
            public void mousePressed(MouseEvent e) {
                int mouseX = e.getX();
                int mouseY = e.getY();

                double max = a.stream().max(Double::compare).orElse(1.0);
                double barHeight = ICON_HEIGHT / (double) a.size();

                // Find the nearest bar to the mouse click
                int index = (int) (mouseY / barHeight);
                if (index >= 0 && index < a.size()) {
                    double newValue = max * mouseX / ICON_WIDTH;
                    dataModel.update(index, newValue);
                }
            }
        });

        add(barLabel);

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
        setVisible(true);
    }

    /**
     * Called when the data in the model is changed.
     *
     * @param e the event representing the change
     */
    public void stateChanged(ChangeEvent e) {
        a = dataModel.getData();
        repaint();
    }

    private class BarIcon implements Icon {
        public int getIconWidth() {
            return ICON_WIDTH;
        }

        public int getIconHeight() {
            return ICON_HEIGHT;
        }

        public void paintIcon(Component c, Graphics g, int x, int y) {
            Graphics2D g2 = (Graphics2D) g;

            g2.setColor(Color.red);

            double max = a.stream().max(Double::compare).orElse(1.0);
            double barHeight = getIconHeight() / (double) a.size();

            int i = 0;
            for (Double value : a) {
                double barLength = getIconWidth() * value / max;

                Rectangle2D.Double rectangle = new Rectangle2D.Double(
                        0, barHeight * i, barLength, barHeight);
                i++;
                g2.fill(rectangle);
            }
        }
    }

    private ArrayList<Double> a;
    private DataModel dataModel;

    private static final int ICON_WIDTH = 200;
    private static final int ICON_HEIGHT = 200;
}