// TreeBrowser.java
// $Id: TreeBrowser.java,v 1.1 2008/09/16 14:13:34 sfwang Exp $ */
// Authors: Jean-Michel.Leon@sophia.inria.fr, 
//          Yves.Lafon@w3.org : 
//          - Lines, insert/remove, awt 1.1 version
//          Thierry.Kormann@sophia.inria.fr
//          - Insert debug, horizontal scrollbar, javadoc, 
//            selection graphic customization, scrollbar policy, 
//            lightweight version.

package org.w3c.tools.widgets ;

import java.awt.Canvas;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Rectangle;
import java.awt.Scrollbar;

import java.awt.event.AdjustmentEvent;
import java.awt.event.AdjustmentListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;

import java.util.Enumeration;
import java.util.EventObject;
import java.util.Stack;
import java.util.Vector;

/**
 * The TreeBrowser class.
 *
 * This class is a generic framework to browser any hierachical structure.
 *
 * <p>Genericity is obtained through the use of 'handlers': the TreeBrowser
 * itself does not perform any action in response to user events, but simply
 * forward them as <b>notifications</b> to <b>handlers</b>. Each item inserted
 * may have its own handler, but handlers may also (this is the most common
 * case) be shared between handlers.
 *
 * <p>Any item added in the Tree is displayed with an icon and a label. When a
 * handler receive a notification on a node, it may change this node, to modify
 * or update its appearance.
 *
 * @author Jean-Michel.Leon@sophia.inria.fr
 * @author Yves.Lafon@w3.org
 * @author Thierry.Kormann@sophia.inria.fr 
 */
public class TreeBrowser extends Canvas implements AdjustmentListener {

    /** 
     * Specifies that the horizontal/vertical scrollbars should always be shown
     * regardless of the respective sizes of the TreeBrowser.  
     */
    public static final int SCROLLBARS_ALWAYS   = 0; 
    /** 
     * Specifies that horizontal/vertical scrollbars should be shown only when
     * the size of the nodes exceeds the size of the TreeBrowser in the
     * horizontal/vertical dimension.  
     */
    public static final int SCROLLBARS_ASNEEDED = 1;
    /** 
     * This policy that lets just one node selected at the same time. 
     */
    public static final int SINGLE = 0;
    /** 
     * The policy that enables a multiple selection of nodes. 
     */
    public static final int MULTIPLE = 1;

    static final int HMARGIN = 5;
    static final int VMARGIN = 5;
    static final int HGAP = 10;
    static final int DXLEVEL = HGAP*2;

    /**
     * The inner mouse listener in charge of all the node expansion
     * selection and execution
     */
    private class BrowserMouseListener extends MouseAdapter {
	
        private void clickAt(TreeNode node, MouseEvent me) {
	    if(node == null) 
		return;
	    int x = me.getX() - HMARGIN;
	    if(node.handler == null)
		return;
	    //	node.handler.notifyExpand(this, node);
	    if((x >= node.level*DXLEVEL) &&
	       (x <= node.level*DXLEVEL + DXLEVEL)) {
		// click on expand/collapse button
		if(node.children != TreeNode.NOCHILD) {
		    node.handler.notifyCollapse(TreeBrowser.this, node);
		}
		else {
		    node.handler.notifyExpand(TreeBrowser.this, node);
		}
	    }
	    else if(x > node.level*DXLEVEL + HGAP) {
		// item selection
		node.handler.notifySelect(TreeBrowser.this, node);
	    }
	}
	
	/**
	 * Handles events and send notifications ot handlers.
	 * is sent, depending on the node's current state.<br>
	 * on MOUSE_DOWN on a label, a <b>Select</b> notificaiton is sent.<br>
	 * on DOUBLE_CLICK on a label, an <b>Execute</b> notification is sent.
	 */
        public void mousePressed(MouseEvent me) {
	    int y = me.getY() - VMARGIN;
	    if(me.getClickCount() == 1) {
		clickAt(itemAt(y), me);
	    }
	}
	
        public void mouseClicked(MouseEvent me) {
	    if(me.getClickCount() > 1) {
		int y = me.getY() - VMARGIN;
		TreeNode node = itemAt(y);
		if((node != null) && (node.handler != null)) {
		    node.handler.notifyExecute(TreeBrowser.this, node);
		}
	    }
	}
    }

    private Scrollbar vscroll;
    private Scrollbar hscroll;
    private int maxwidth = 0;
    private int startx = 0;
    private Color selectColor = new Color(0, 0, 128);
    private Color selectFontColor = Color.white;
    private int scrollbarDisplayPolicy = SCROLLBARS_ASNEEDED;
    private boolean hierarchyChanged = true;

    protected Vector items;
    protected Vector selection;
    protected int topItem = 0;
    protected int visibleItemCount = 20;
    protected int selectionPolicy = SINGLE;
    protected int fontHeight;

   /**
    * Builds a new browser instance
    *
    * @param root the root node for this hierarchy
    * @param label the label that should be displayed for this item
    * @param handler the handler for this node
    * @param icon the icon that must be displayed for this item
    */    
    public TreeBrowser(Object root, String label,
		       NodeHandler handler, Image icon) {
	this();
	initialize(root, label, handler, icon);
    }

    protected TreeBrowser() {
	selection = new Vector(1, 1);
	items = new Vector();
	topItem = 0;
	addMouseListener(new BrowserMouseListener());
    }

    protected void initialize(Object item,String label,
			      NodeHandler handler, Image icon) {
	items.addElement(new TreeNode(item,label, handler, icon, 0));
    }

    public Dimension getPreferredSize() {
	return new Dimension(200, 400);
    }

    /**
     * Sets the color of a selected node to the specified color.
     * @param color the color used to paint a selected node
     */
    public void setSelectionFontColor(Color color) {
	this.selectFontColor = color;
    }

    /**
     * Sets the background color of a selected node to the specified color.
     * @param color the color used to paint the background of a selected node
     */
    public void setSelectionBackgroudColor(Color color) {
	this.selectColor = color;
    }

    /**
     * Sets the scrollbars display policy to the specified policy. The default
     * is SCROLLBARS_ALWAYS
     * @param scrollbarDisplayPolicy SCROLLBARS_NEVER | SCROLLBARS_ASNEEDED |
     * SCROLLBARS_ALWAYS 
     */
    public void setScrollbarDisplayPolicy(int scrollbarDisplayPolicy) {
	this.scrollbarDisplayPolicy = scrollbarDisplayPolicy;
	hierarchyChanged = false;
    }

    /**
     * repaints the View.
     */
    public void paint(Graphics g) {
	fontHeight = g.getFontMetrics().getHeight();
	int fontAscent = g.getFontMetrics().getAscent();
	int itemCount = items.size();
	
	Dimension dim = getSize();
	int myHeight = dim.height-VMARGIN*2;
	int myWidth = dim.width-HMARGIN*2;
	
 	g.clipRect(HMARGIN, VMARGIN, myWidth, myHeight);
	g.translate(HMARGIN, VMARGIN);
	
	int y = 0;
	int dx, fatherIndex;
	int level;
	
	Stack indexStack = new Stack();
	Graphics bg = g.create();
	bg.setColor(selectColor);
	g.setFont(getFont());
	visibleItemCount = 0;
	TreeNode node;
	level = -1;
	
	int labelwidth;
	if (hierarchyChanged) {
	    maxwidth = 0;
	}
	
	// we push the indexes of the inner levels to speed up things
	for(int i = 0; i < topItem; i++) {
	    node = (TreeNode) items.elementAt(i);
	    // hscroll
	    if (hierarchyChanged) {
		dx = node.level * DXLEVEL;
		labelwidth = g.getFontMetrics().stringWidth(node.label);
		maxwidth = Math.max(maxwidth, dx + DXLEVEL + labelwidth);
	    }
	    
	    if(node.level > level) {
		indexStack.push(new Integer(i-1));
		level = node.level;
	    }
	    if(node.level < level) {
		for(int j=node.level; j<level; j++)
		    indexStack.pop();
		level = node.level;
	    }
	}
	
       int nitems = myHeight/fontHeight;
       int ditems = itemCount - topItem;
       if (ditems < nitems) {
           topItem = Math.max(0, topItem-(nitems-ditems));
       }
       if (myWidth >= maxwidth) {
	   startx = 0;
       } else if (startx+myWidth > maxwidth) {
	   startx = (maxwidth - myWidth);
       }

       for(int i = topItem; i < itemCount ; i++) {
	   node = (TreeNode) items.elementAt(i);
	   if(node.level > level) {
	       indexStack.push(new Integer(i-1));
	       level = node.level;
	   }
	   if(node.level < level) {
	       for(int j=node.level; j<level; j++)
		   indexStack.pop();
	       level = node.level;
	   }
	    
	   dx = (node.level * DXLEVEL)-startx;
	   if(y <= myHeight) {
	       if(node.selected) {
		   bg.fillRect(dx, y-1,
			       Math.max(myWidth-1, maxwidth-1), fontHeight);
		   g.setColor(selectFontColor);
		   g.drawImage(node.icon, dx, y, this);
		   g.drawString(node.label, dx + DXLEVEL, y+fontAscent);
		   g.setColor(getForeground());
	       } else {
		   g.setColor(getForeground());
		   g.drawImage(node.icon, dx, y, this);
		   g.drawString(node.label, dx + DXLEVEL, y+fontAscent);
	       }
		
	       fatherIndex = ((Integer) indexStack.peek()).intValue();
	       if( fatherIndex != -1) { // draw fancy lines
		   int fi = fatherIndex - topItem;
		   g.drawLine(dx - HGAP/2 , y + fontHeight/2,
			      dx - DXLEVEL + HGAP/2, y + fontHeight/2);
		    
		   if(node.handler.isDirectory(this, node)) {
		       g.drawRect(dx - DXLEVEL + HGAP/2 -2,
				  y + fontHeight/2 - 2,
				  4, 4);
		   }
		   g.drawLine(dx-DXLEVEL + HGAP/2, y + fontHeight/2, 
			      dx-DXLEVEL + HGAP/2, (fi+1)*fontHeight - 1);
	       }
	       visibleItemCount++;
	   } else { // draw the lines for invisible nodes.
	       fatherIndex = ((Integer)indexStack.peek()).intValue();
	       if(fatherIndex != -1) {
		   int fi = fatherIndex - topItem;
		   if((fi+1)*fontHeight -1 < myHeight)
		       g.drawLine(dx - DXLEVEL + HGAP/2, myHeight-1,
				  dx - DXLEVEL + HGAP/2, (fi+1)*fontHeight-1);
	       }
	   }
	   // hscroll
	   if (hierarchyChanged) {
	       dx = (node.level * DXLEVEL);
	       labelwidth = g.getFontMetrics().stringWidth(node.label);
	       maxwidth = Math.max(maxwidth, dx + DXLEVEL + labelwidth);
	   }
	   y += fontHeight;
       }
	
       // hscroll
       if (hierarchyChanged) {
	   for (int i=itemCount; i < items.size(); ++i) {
	       node = (TreeNode) items.elementAt(i);
	       dx = (node.level * DXLEVEL);
	       labelwidth = g.getFontMetrics().stringWidth(node.label);
	       maxwidth = Math.max(maxwidth, dx + DXLEVEL + labelwidth);
	   }
       }
       hierarchyChanged = false;
       updateScrollbars();
    }

    /**
     * this should be private. having it protected is a present
     * for dummy VM that doesn't know that an inner class can access
     * private method of its parent class
     */

    protected TreeNode itemAt(int y) {
	for(int i = topItem; ((i < items.size()) && (y >0)); i++) {
	    if(y < fontHeight) {
		return (TreeNode) items.elementAt(i);
	    }
	    y -= fontHeight;
	}
	return null;
    }

    public void update(Graphics pg) {
        Rectangle r = pg.getClipBounds();
        Graphics offgc;
        Image offscreen = null;
        Dimension d = getSize();
	
        // create the offscreen buffer and associated Graphics
        offscreen = ImageCache.getImage(this, d.width, d.height);
        offgc = offscreen.getGraphics();
        if(r != null) {
            offgc.clipRect(r.x, r.y, r.width, r.height);
        }
        // clear the exposed area
        offgc.setColor(getBackground());
        offgc.fillRect(0, 0, d.width, d.height);
        offgc.setColor(getForeground());
        // do normal redraw
        paint(offgc);
        // transfer offscreen to window
        pg.drawImage(offscreen, 0, 0, this);

    }

    /**
     * Inserts new node.
     *
     * @param parent the parent node.
     * @item the abstract object this node refers to. may be null.
     * @handler the node handler, that will receive notifications for this node
     * @label the label displayed in the list.
     * @icon the icon displayed in the list.
     */    
    public void insert(TreeNode parent, Object item, NodeHandler handler,
		       String label, Image icon) {
	boolean done;
	int j;
	if(parent == null) throw new IllegalArgumentException("null parent");
	if((handler == null) && (label == null)) {
	    throw new IllegalArgumentException("non-null item required");
	}
	if(handler == null) {
	    handler = parent.handler;
	}
	if(label == null) {
	    label = handler.toString();
	}
	if(parent.children == TreeNode.NOCHILD) {
	    parent.children = 1;
	} else {
	    parent.children += 1;
	}
	done = false;
	TreeNode node = null;

	int i = items.indexOf(parent)+parent.children;
	for (; (i < items.size() && 
		((TreeNode) items.elementAt(i)).level > parent.level); 
	    i++) {}
	items.insertElementAt(node=new TreeNode(item, label, handler, icon,
						parent.level+1), i);
	// hscroll
	hierarchyChanged = true;
	return;
    }

   
    /**
     * Removes the specified node.
     * This simply removes a node, without modifying its children if any. USE
     * WITH CAUTION.
     * @param node the node to remove
     */
    public void remove(TreeNode node) {
	int ind = items.indexOf(node);
	TreeNode t = null;

	while (ind>=0) {
	    t = (TreeNode) items.elementAt(ind);
	    if (t.level >= node.level)
		ind--;
	    else {
		t.children--;
		break;
	    }
	}
	items.removeElement(node);
	
	if(node.selected) {
	    unselect(node);
	}
	// hscroll
	hierarchyChanged = true;
    }

    /**
     * Removes the specified node and its children.
     * NOTE: if two threads are doing adds and removes,
     * this can lead to IndexOutOfBound exception.
     * You will probably have to use locks to get rid of that problem
     * @param node the node to remove
     */
    public void removeBranch(TreeNode node) {
	int ist, iend;
	
	ist  = items.indexOf(node)+1;
	iend = items.size()-1;
	
	for(int i = ist; i< iend; i++) {
	    if(((TreeNode)items.elementAt(ist)).level > node.level) {
		remove((TreeNode)items.elementAt(ist));
	    } else
		break;
	}
	remove(node);
	// hscroll
	hierarchyChanged = true;
    }

    /**
     * Contracts the representation of the specified node.
     * removes all the children nodes of 'item'. It is caller's
     * responsibility to call repaint() afterwards.
     * @param item the node to contracts
     */
    public synchronized void collapse(TreeNode item) {
	TreeNode node = (TreeNode)item;
	if(node.children != TreeNode.NOCHILD) {
	    node.children = TreeNode.NOCHILD;
	    for(int j = items.indexOf(item)+1; j <items.size(); /*nothing*/) {
		TreeNode child = (TreeNode)items.elementAt(j);
		if(child.level > node.level) {
		    items.removeElementAt(j);
		    if(child.selected) {
			unselect(child);
		    }
		}
		else {
		    // hscroll
		    hierarchyChanged = true;
		    // last children reached, exit
		    return;
		}
	    }
	}
    }

    /**
     * Sets the selection policy.
     * @param policy: SINGLE or MULTIPLE
     */    
    public void setSelectionPolicy(int policy) {
	selectionPolicy = policy;
    }

    /**
     * Gets the selection policy.
     */
    public int getSelectionPolicy() {
	return selectionPolicy;
    }

    /**
     * Selects the specified node.
     * Selects the given node. If selectionPolicy is SINGLE any previously
     * selected node is unselected first.  It is caller's responsibility to
     * call repaint() 
     * @param node the node to select
     */
    public void select(TreeNode node) {
	if(node == null) return;
	if(selectionPolicy == SINGLE) {
	    unselectAll();
	}
	selection.addElement(node);
	node.selected = true;
    }

    /**
     * Unselects the specified node.
     * It is caller's responsibility to call repaint()
     * @param node the node to unselect
     */  
    public void unselect(TreeNode node) {
	if(node == null) return;
	selection.removeElement(node);
	node.selected = false;
    }

    /**
     * Unselects all selected items.
     */    
    public void unselectAll() {
	for(Enumeration e = selection.elements(); e.hasMoreElements(); ) {
	    TreeNode node = (TreeNode)e.nextElement();
	    node.selected = false;
	}
    }

    /**
     * Returns an Enumeraiton of selected items.
     */
    public Enumeration selection() {
	return selection.elements();
    }

    private void updateScrollbars() {
	int max = items.size()+1;
        if(items.size() > visibleItemCount) {
	    vscroll.setMaximum(max);
	    vscroll.setVisibleAmount(visibleItemCount);
	    vscroll.setVisible(true);
        } else {
	    vscroll.setValue(0);
	    vscroll.setMaximum(max);
	    vscroll.setVisibleAmount(max);
	    if (scrollbarDisplayPolicy == SCROLLBARS_ASNEEDED) {
		vscroll.setVisible(false);
	    }
	}

	int myWidth = getSize().width-HMARGIN*2;
	hscroll.setMaximum(maxwidth);
	hscroll.setVisibleAmount(myWidth);
	if (maxwidth > myWidth) {
	    hscroll.setVisible(true);
	} else {
	    if (scrollbarDisplayPolicy == SCROLLBARS_ASNEEDED) {
		hscroll.setVisible(false);
	    }
	}
    }

    /**
     * Sets 'a' as vertical Scrollbar.
     * The Browser becomes an AdjustmentListener of this scrollbar.
     */
    public void setVerticalScrollbar(Scrollbar a) {
	vscroll = a;
	vscroll.addAdjustmentListener(this);
	vscroll.setMaximum(visibleItemCount);
	vscroll.setVisibleAmount(visibleItemCount);
	vscroll.setBlockIncrement(visibleItemCount);
    }

    /**
     * Sets 'a' as horizontal Scrollbar.
     * The Browser becomes an AdjustmentListener of this scrollbar.
     */
    public void setHorizontalScrollbar(Scrollbar a) {
	hscroll = a;
	hscroll.addAdjustmentListener(this);
	int myWidth = getSize().width-HMARGIN*2;
	hscroll.setMaximum(myWidth);
	hscroll.setVisibleAmount(myWidth);
	hscroll.setBlockIncrement(20);
    }

    /**
     * Updates graphical appearance in response to a scroll.
     */    
    public void adjustmentValueChanged(AdjustmentEvent evt) {
	if (evt.getSource() == vscroll) {
	    topItem = evt.getValue();
	} else {
	    startx = evt.getValue();
	}
	repaint();
    }

    /**
     * Returns the parent node of the specified node.
     * If 'child' is a valid node belonging to the Tree and has a parent node,
     * returns its parent. Returns null otherwise.
     * @param child the child node you want to get its parent
     */
    public TreeNode getParent(TreeNode child) {
	int n = items.indexOf(child);
	for(int i = n-1; i >= 0; i--) {
	    TreeNode node = (TreeNode)(items.elementAt(i));
	    if(node.level < child.level) {
		return node;
	    }
	}
	return null;
    }

    /**
     * Gets the node associated to the specified object, or null if any.
     * @param obj the object related to a node
     */
    public TreeNode getNode(Object obj) {
	int imax = items.size();
	for(int i=0; i < imax; i++) {
	    if(obj.equals(((TreeNode)(items.elementAt(i))).getItem())) 
		return (TreeNode)(items.elementAt(i));
	}
	return null;
    }
}


