package com.onaro.sanscreen.client.view.topology;

import ilog.views.IlvManagerView;
import ilog.views.IlvManagerViewDecoration;
import ilog.views.swing.IlvJScrollManagerView;

import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.concurrent.atomic.AtomicBoolean;

import com.onaro.sanscreen.client.prefs.GeneralPreferenceManager;

/**
 * Implements a "watermark" in each of the corners of the topology view (formation of 4).<br>
 * 
 * It's possible to set a number of options at run-time that affect the visualization of this watermark.  
 * Because there is no requirement yet only the watermark's text has been implemented to take changes 
 * dynamically by using SANscreen's settings.
 *   
 * <p>  
 * The following static parameters could in the "future" be modified at run-time.
 * <ul>
 * <li> Font size.
 * <li> Font color.
 * <li> Font type.
 * <li> Percentage of Opaqueness.
 * </ul>
 *  
 * @author cohenj
 * @since 8/14/2009 - Everest
 *
 */
public class TopologyWatermark implements IlvManagerViewDecoration, PropertyChangeListener {
	/** Margin value used to provide a space around. 
	 * (Future improvement, make this dynamic by the User.) 
	 */
	private static final int MARGIN = 7;
		
	/** Watermak's font size. 
	 * (Future improvement, make this dynamic by the User.) 
	 */
	private static final int FONT_SIZE = 40;
	
	/** Opaqueness of the text displayed in the watermark. 
	 * (Future improvement, make this dynamic by the User.) 
	 */	
	private static final AlphaComposite alpha = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.25f);

	/** Watermark's font type.
	 * (Future improvement, make this dynamic by the User.) 
	 */
	private static final Font font = new Font(Font.SANS_SERIF, Font.BOLD, FONT_SIZE);
	
	/** Holds the matermark's text going to be displayed. 
	 * (Future improvement, make this dynamic by the User.) 
	 */
	private volatile String watermark;

	/** A panel containing an two scrollbars.*/
	private IlvJScrollManagerView netGraphScrollManager;

	/** Thread safe, If the watermark is enabled then this var holds TRUE, otherwise FALSE */
	private AtomicBoolean isWatermarkEnabled = new AtomicBoolean(false);
	
	/** Encapsulates information about the rendering of a particular font. */
	private FontMetrics fm;


	
	
	/**
	 * Constructor.
	 * 
	 * @param netGraphScrollManager ILog scroll manager.
	 */
	public TopologyWatermark(IlvJScrollManagerView netGraphScrollManager) {
		this.netGraphScrollManager = netGraphScrollManager;
		GeneralPreferenceManager.getInstance().addPropertyChangeListener(this);
		watermark = GeneralPreferenceManager.getInstance().getTopologyWatermarkText();
		isWatermarkEnabled.set(GeneralPreferenceManager.getInstance().isTopologyWatermarkEnabled());
	}

	/**
	 * Logic that take place during the rendering of the <code>netGraphScrollManager</code>
	 */
	public void paint(final Graphics g, final IlvManagerView ilvManagerView) {
		if (!isWatermarkEnabled.get())
			return;

		
		Graphics2D g2 = (Graphics2D) g;

		// Setting for the: geometry, coordinate transformations, color management, and text layout.
		g2.setComposite(alpha);
		g2.setColor(Color.BLACK);
		g2.setRenderingHint(RenderingHints.KEY_TEXT_ANTIALIASING, RenderingHints.VALUE_TEXT_ANTIALIAS_ON);
		g2.setFont(font);
		fm = g.getFontMetrics();

		// useful measurements.
		int height = netGraphScrollManager.getHeight();
		int width = netGraphScrollManager.getWidth();
		int fontHeight = fm.getHeight();
		int stringWidth = fm.stringWidth(watermark);

		// top-left corner
		g.drawString(watermark, MARGIN, fontHeight - MARGIN);

		// bottom-left corner
		g.drawString(watermark, MARGIN, height - fontHeight + MARGIN);

		// top-right corner
		g.drawString(watermark, width - stringWidth - 4 * MARGIN, fontHeight - MARGIN);

		// bottom-left corner
		g.drawString(watermark, width - stringWidth - 4 * MARGIN, height - fontHeight + MARGIN);
	}

	
	/** 
	 * Receive notifications after the "publisher" fires the change events. 
	 * @see  {@link GeneralPreferenceManager#setTopologyWatermarkEnabled} 
	 */
	public void propertyChange(PropertyChangeEvent evt) {
		final String propName = evt.getPropertyName();
		if (GeneralPreferenceManager.SERVER_PREF_TOPOLOGY_WATERMARK_ENABLED.equals(propName)) {
			Boolean newValue = (Boolean) evt.getNewValue();
			if (newValue != null) {
				isWatermarkEnabled.set(newValue);
				netGraphScrollManager.repaint();
			}
		}

		if (GeneralPreferenceManager.SERVER_PREF_TOPOLOGY_WATERMARK_TEXT.equals(propName)) {
			String newValue = (String) evt.getNewValue();
			if (newValue != null) {
				watermark = newValue;
				netGraphScrollManager.repaint();
			}
		}
	}
}