package util;

// Java imports
import java.awt.*;
import java.util.*;
import javax.swing.*;

// Wrapper around JPanel to work around a bug in GridBagLayout
public class UPanel extends JPanel {

    // Instance fields
    private HashSet<PaintListener> paintListeners;



    ///////////////////////////////////////////////////////////////////////////
    //                                Classes                                //
    ///////////////////////////////////////////////////////////////////////////

    // Functional interface for paint events
    public interface PaintListener {
        void paint(Graphics2D g, int width, int height);
    }



    ///////////////////////////////////////////////////////////////////////////
    //                             Constructors                              //
    ///////////////////////////////////////////////////////////////////////////

    // Default constructor
    public UPanel() {
        this(null);
    }

    // Layout manager constructor
    public UPanel(LayoutManager layout) {
        super(layout);
        paintListeners = new HashSet<PaintListener>();
    }



    ///////////////////////////////////////////////////////////////////////////
    //                            Public Methods                             //
    ///////////////////////////////////////////////////////////////////////////

    // Add a listener to receive paint events
    public void addPaintListener(PaintListener l) {
        if (l != null)
            paintListeners.add(l);
    }

    // Retrieve a list of the current paint listeners
    public PaintListener[] getPaintListeners() {
        return paintListeners.toArray(
            new PaintListener[paintListeners.size()]);
    }

    // Retrieve the maximum size of the component
    public Dimension getMaximumSize() {
        var ret = super.getMaximumSize();
        return ret != null ? ret : new Dimension();
    }

    // Retrieve the minimum size of the component
    public Dimension getMinimumSize() {
        var ret = super.getMinimumSize();
        return ret != null ? ret : new Dimension();
    }

    // Retrieve the preferred size of the component
    public Dimension getPreferredSize() {
        var ret = super.getPreferredSize();
        return ret != null ? ret : new Dimension();
    }

    // Draw the component
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        var G      = (Graphics2D) g;
        int width  = getWidth();
        int height = getHeight();
        for (var lst : paintListeners)
            lst.paint(G, width, height);
    }

    // Remove a paint listener from the collection
    public void removePaintListener(PaintListener l) {
        paintListeners.remove(l);
    }

}