//********************************************************************
//  GraphicsStackViewer.java       Author: Sophie Quigley
//
//  Class GraphicsStackViewer shows a transparent stack and its contents
//  in graphical mode.
//  This class is a subclass of StackViewer
//
//********************************************************************

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

public class GraphicsStackViewer extends StackViewer
{
    // Dimensions and colours of stack
    private final int ENTRYHEIGHT = 25;         // Height of each entry
    private final int ENTRYWIDTH = 150;         // Width of each entry
    private final int MAXDISPLAYSIZE = 25;      // Absolute maximum number of entries shown
    private final Color STACKCOLOR = Color.YELLOW;      //Background stack colour
    private final Color STACKENTRYCOLOR = Color.BLUE;   // Colour of stack content
    private final Color BACKCOLOR = Color.LIGHT_GRAY;   // Colour of rest of UI
    private final String MORE = "... More elements ...";

    private int maxdisplaysize;                 // Actual maximum number of entries shown
    // U.I. Components.
    private JFrame frame;
    private JPanel toppanel, leftpanel, mainpanel, rightpanel;
    private JPanel[] cell; 
    private JLabel[] cellentry;
    
    public GraphicsStackViewer (VisibleStack stack, int maxdisplaysize, String title)
    {
        // Associate the viewer with its stack
        super(stack);

        // Set the maximumsize to be displayed
        if (maxdisplaysize > MAXDISPLAYSIZE)
            maxdisplaysize = MAXDISPLAYSIZE;
        if (maxdisplaysize < 1)
            maxdisplaysize = 1;
        this.maxdisplaysize = ++maxdisplaysize; // add 1 entry to show " .. more .."
        
        // Initialize the frame and panels in which the stack will be displayed.
        frame = new JFrame(title);
        toppanel = new JPanel();
        leftpanel = new JPanel();
        mainpanel = new JPanel();
        rightpanel = new JPanel();
        
        // Put together the frame and panels.  
        // Frame contains toppanel.
        // Toppanel contains 3 panels: 2 borders + a central panel for the stack.
        frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);
        frame.getContentPane().add (toppanel);
        toppanel.setLayout(new BoxLayout(toppanel,BoxLayout.X_AXIS));
        toppanel.add(leftpanel);
        toppanel.add(mainpanel);
        toppanel.add(rightpanel);
        
        // Set panel sizes and backgrounds
        int panelheight = (maxdisplaysize+2)*ENTRYHEIGHT;
        toppanel.setPreferredSize(new Dimension(2*ENTRYWIDTH,panelheight));
        leftpanel.setPreferredSize(new Dimension(ENTRYWIDTH/4,panelheight));
        mainpanel.setPreferredSize(new Dimension(ENTRYWIDTH*3/2,panelheight));
        rightpanel.setPreferredSize(new Dimension(ENTRYWIDTH/4,panelheight));
        toppanel.setBackground(BACKCOLOR);
        leftpanel.setBackground(BACKCOLOR);
        mainpanel.setBackground(BACKCOLOR);
        rightpanel.setBackground(BACKCOLOR);
        
        // Prepare all the elements to be displayed in the panel.
        mainpanel.setLayout(new BoxLayout(mainpanel,BoxLayout.Y_AXIS));
        // First the "Top" label.
        JLabel templabel = new JLabel("Top of Stack");
        templabel.setAlignmentX(JLabel.CENTER_ALIGNMENT);
        mainpanel.add(templabel);
        // Then the stack entries.
        cell = new JPanel[maxdisplaysize];
        cellentry = new JLabel[maxdisplaysize];
        for (int i=maxdisplaysize-1; i>=0; i--)
        {
            cell[i] = new JPanel();
            cell[i].setPreferredSize(new Dimension(ENTRYWIDTH, ENTRYHEIGHT));
            mainpanel.add(cell[i]);
            cellentry[i] = new JLabel();
            cellentry[i].setForeground(STACKENTRYCOLOR);
            cell[i].add(cellentry[i]);
        }
        // Finally the "Bottom" label.
        templabel = new JLabel("Bottom of Stack");
        templabel.setAlignmentX(JLabel.CENTER_ALIGNMENT);
        mainpanel.add(templabel);
        
        // Display the result
        frame.pack();
        frame.show();

    }
    
    // The Display method overriddes the Display method in StackViewer.
    public void display()
    {
        int i;
        int size = super.stack.currentSize();
       
        // If there is more display room than needed,
        // leave the top slots of the display blank
        if (size <= maxdisplaysize)
        {
            for (i=0; i<size; i++)            {
                cellentry[i].setText(super.stack.element(i).toString());
                cell[i].setBackground(STACKCOLOR);
                cell[i].setBorder(BorderFactory.createLineBorder(STACKENTRYCOLOR));
            }
            for (i=size; i<maxdisplaysize; i++)
            {
                cellentry[i].setText("");
                cell[i].setBackground(BACKCOLOR);
                cell[i].setBorder(BorderFactory.createEmptyBorder());
            } 
        }
        // If there is not enough space to display the whole stack,
        // show the top elements
        else
        {
            cellentry[0].setText(MORE);
            cell[0].setBackground(STACKCOLOR);
            cell[0].setBorder(BorderFactory.createLineBorder(STACKENTRYCOLOR));
            for (i=1; i<maxdisplaysize; i++)
            {
                cell[i].setBackground(STACKCOLOR);
                cell[i].setBorder(BorderFactory.createLineBorder(STACKENTRYCOLOR));
                cellentry[i].setText(super.stack.element(i+size-maxdisplaysize).toString());
            }
       }
    }

}