/*******************************************************************************
 * Copyright (c) 2000, 2005 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.ltk.internal.ui.refactoring;

import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Item;
import org.eclipse.swt.widgets.TreeItem;
import org.eclipse.swt.widgets.Widget;

import org.eclipse.jface.viewers.CheckStateChangedEvent;
import org.eclipse.jface.viewers.CheckboxTreeViewer;
import org.eclipse.jface.viewers.ICheckStateListener;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.StructuredSelection;

class ChangeElementTreeViewer extends CheckboxTreeViewer {
	
	public ChangeElementTreeViewer(Composite parentComposite) {
		super(parentComposite, SWT.NONE);
		addCheckStateListener(new ICheckStateListener() {
			public void checkStateChanged(CheckStateChangedEvent event){
				ChangeElement element= (ChangeElement)event.getElement();
				boolean checked= event.getChecked();
				
				element.setEnabled(checked);
				setSubtreeChecked(element, checked);
				setSubtreeGrayed(element, false);
				ChangeElement parent= element.getParent();
				while(parent != null) {
					int active= parent.getActive();
					parent.setEnabledShallow(active == ChangeElement.PARTLY_ACTIVE || active == ChangeElement.ACTIVE);
					boolean grayed= (active == ChangeElement.PARTLY_ACTIVE);
					setChecked(parent, checked ? true : grayed);
					setGrayed(parent, grayed);
					parent= parent.getParent();
				}
			}
		});
	}
	
	protected void inputChanged(Object input, Object oldInput) {
		super.inputChanged(input, oldInput);
		// XXX workaround for http://bugs.eclipse.org/bugs/show_bug.cgi?id=9390
		initializeChildren((ChangeElement)input);
	}
	
	protected void doUpdateItem(Item item, Object element) {
		super.doUpdateItem(item, element);
		TreeItem treeItem= (TreeItem)item;
		ChangeElement ce= (ChangeElement)element;
		int state= ce.getActive();
		boolean checked= state == ChangeElement.INACTIVE ? false : true;
		treeItem.setChecked(checked);
		boolean grayed= state == ChangeElement.PARTLY_ACTIVE ? true : false;
		treeItem.setGrayed(grayed);
	}
	
	protected void revealNext() {
		revealElement(true);
	}
	
	protected void revealPrevious() {
		revealElement(false);
	}
	
	private void initializeChildren(ChangeElement element) {
		if (element == null)
			return;
		ChangeElement[] children= element.getChildren();
		if (children == null)
			return;
		for (int i= 0; i < children.length; i++) {
			ChangeElement child= children[i];
			int state= child.getActive();
			boolean checked= state == ChangeElement.INACTIVE ? false : true;
			if (checked)
				setChecked(child, checked);
			boolean grayed= state == ChangeElement.PARTLY_ACTIVE ? true : false;
			if (grayed)
				setGrayed(child, grayed);
		}
	}
	
	private void setSubtreeGrayed(Object element, boolean grayed) {
		Widget widget= findItem(element);
		if (widget instanceof TreeItem) {
			TreeItem item= (TreeItem)widget;
			if (item.getGrayed() != grayed) {
				item.setGrayed(grayed);
				grayChildren(getChildren(item), grayed);
			}
		}
	}
	
	private void grayChildren(Item[] items, boolean grayed) {
		for (int i= 0; i < items.length; i++) {
			Item element= items[i];
			if (element instanceof TreeItem) {
				TreeItem item= (TreeItem)element;
				if (item.getGrayed() != grayed) {
					item.setGrayed(grayed);
					grayChildren(getChildren(item), grayed);
				}
			}
		}
	}
	
	private void revealElement(boolean next) {
		ChangeElement current= (ChangeElement)getInput();
		IStructuredSelection selection= (IStructuredSelection)getSelection();
		if (!selection.isEmpty())
			current= (ChangeElement)selection.iterator().next();
			
		ChangeElement candidate= getLeaf(current, next);
		if (candidate == null) {
			candidate= getElement(current, next);
			if (candidate != null) {
				ChangeElement leaf= getLeaf(candidate, next);
				if (leaf != null)
					candidate= leaf;
			}
		}
		if (candidate != null)
			setSelection(new StructuredSelection(candidate), true);
		else
			getControl().getDisplay().beep();
	}
	
	private ChangeElement getLeaf(ChangeElement element, boolean first) {
		ChangeElement result= null;
		ChangeElement[] children= element.getChildren();
		while(children != null && children.length > 0) {
			result= children[first ? 0 : children.length - 1];
			children= result.getChildren();
		}
		return result;
	}
	
	private ChangeElement getElement(ChangeElement element, boolean next) {
		while(true) {
			ChangeElement parent= element.getParent();
			if (parent == null)
				return null;
			ChangeElement candidate= getSibling(parent.getChildren(), element, next);
			if (candidate != null)
				return candidate;
			element= parent;
		}
	}
	
	private ChangeElement getSibling(ChangeElement[] children, ChangeElement element, boolean next) {
		for (int i= 0; i < children.length; i++) {
			if (children[i] == element) {
				if (next)
	 				if (i < children.length - 1)
	 					return children[i + 1];
	 				else
	 					return null;
	 			else 
					if (i > 0)
	 					return children[i - 1];
	 				else
	 					return null;
			}
		}
		return null;
	}
}