/*******************************************************************************
 * Copyright (c) 2003, 2006 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.ui.internal.navigator.resources.workbench;

import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;

import org.eclipse.core.resources.IContainer;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IResourceDelta;
import org.eclipse.jface.viewers.AbstractTreeViewer;
import org.eclipse.jface.viewers.StructuredViewer;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.swt.widgets.Control;
import org.eclipse.ui.model.WorkbenchContentProvider;

/**
 * <p>
 * <strong>EXPERIMENTAL</strong>. This class or interface has been added as
 * part of a work in progress. There is a guarantee neither that this API will
 * work nor that it will remain the same. Please do not use this API without
 * consulting with the Platform/UI team.
 * </p>
 * @since 3.2
 */
public class ResourceExtensionContentProvider extends WorkbenchContentProvider {
 
	private static final Object[] NO_CHILDREN = new Object[0];
	private Viewer viewer;
	
	/**
	 *  
	 */
	public ResourceExtensionContentProvider() {
		super();
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.ui.model.BaseWorkbenchContentProvider#getElements(java.lang.Object)
	 */
	public Object[] getElements(Object element) {
		return super.getChildren(element);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.ui.model.BaseWorkbenchContentProvider#getChildren(java.lang.Object)
	 */
	public Object[] getChildren(Object element) {
		if(element instanceof IResource)
			return super.getChildren(element);
		return NO_CHILDREN;
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.ui.model.BaseWorkbenchContentProvider#hasChildren(java.lang.Object)
	 */
	public boolean hasChildren(Object element) {
		return element instanceof IContainer && super.hasChildren(element);
	}
	
	/* (non-Javadoc)
	 * @see org.eclipse.ui.model.WorkbenchContentProvider#inputChanged(org.eclipse.jface.viewers.Viewer, java.lang.Object, java.lang.Object)
	 */
	public void inputChanged(Viewer viewer, Object oldInput, Object newInput) { 
		super.inputChanged(viewer, oldInput, newInput);
		this.viewer = viewer;
	}


	/**
	 * Process the resource delta.
	 * 
	 * @param delta
	 */
	protected void processDelta(IResourceDelta delta) {		

		Control ctrl = viewer.getControl();
		if (ctrl == null || ctrl.isDisposed()) {
			return;
		}
		
		
		final Collection runnables = new ArrayList();
		processDelta(delta, runnables);

		if (runnables.isEmpty()) {
			return;
		}

		//Are we in the UIThread? If so spin it until we are done
		if (ctrl.getDisplay().getThread() == Thread.currentThread()) {
			runUpdates(runnables);
		} else {
			ctrl.getDisplay().asyncExec(new Runnable(){
				/* (non-Javadoc)
				 * @see java.lang.Runnable#run()
				 */
				public void run() {
					//Abort if this happens after disposes
					Control ctrl = viewer.getControl();
					if (ctrl == null || ctrl.isDisposed()) {
						return;
					}
					
					runUpdates(runnables);
				}
			});
		}

	}
	
	/**
	 * Process a resource delta. Add any runnables
	 */
	private void processDelta(IResourceDelta delta, Collection runnables) {
		//he widget may have been destroyed
		// by the time this is run. Check for this and do nothing if so.
		Control ctrl = viewer.getControl();
		if (ctrl == null || ctrl.isDisposed()) {
			return;
		}

		// Get the affected resource
		final IResource resource = delta.getResource();
	
		// If any children have changed type, just do a full refresh of this
		// parent,
		// since a simple update on such children won't work,
		// and trying to map the change to a remove and add is too dicey.
		// The case is: folder A renamed to existing file B, answering yes to
		// overwrite B.
		IResourceDelta[] affectedChildren = delta
				.getAffectedChildren(IResourceDelta.CHANGED);
		for (int i = 0; i < affectedChildren.length; i++) {
			if ((affectedChildren[i].getFlags() & IResourceDelta.TYPE) != 0) {
				runnables.add(getRefreshRunnable(resource));
				return;
			}
		}

		// Check the flags for changes the Navigator cares about.
		// See ResourceLabelProvider for the aspects it cares about.
		// Notice we don't care about F_CONTENT or F_MARKERS currently.
		int changeFlags = delta.getFlags();
		if ((changeFlags & (IResourceDelta.OPEN | IResourceDelta.SYNC
				| IResourceDelta.TYPE | IResourceDelta.DESCRIPTION)) != 0) {
//			Runnable updateRunnable =  new Runnable(){
//				public void run() {
//					((StructuredViewer) viewer).update(resource, null);
//				}
//			};
//			runnables.add(updateRunnable);
			
			/* support the Closed Projects filter; 
			 * when a project is closed, it may need to be removed from the view.
			 */
			runnables.add(getRefreshRunnable(resource.getParent()));
		}
		// Replacing a resource may affect its label and its children
		if ((changeFlags & IResourceDelta.REPLACED) != 0) {
			runnables.add(getRefreshRunnable(resource));
			return;
		}


		// Handle changed children .
		for (int i = 0; i < affectedChildren.length; i++) {
			processDelta(affectedChildren[i], runnables);
		}

		// @issue several problems here:
		//  - should process removals before additions, to avoid multiple equal
		// elements in viewer
		//   - Kim: processing removals before additions was the indirect cause of
		// 44081 and its varients
		//   - Nick: no delta should have an add and a remove on the same element,
		// so processing adds first is probably OK
		//  - using setRedraw will cause extra flashiness
		//  - setRedraw is used even for simple changes
		//  - to avoid seeing a rename in two stages, should turn redraw on/off
		// around combined removal and addition
		//   - Kim: done, and only in the case of a rename (both remove and add
		// changes in one delta).

		IResourceDelta[] addedChildren = delta
				.getAffectedChildren(IResourceDelta.ADDED);
		IResourceDelta[] removedChildren = delta
				.getAffectedChildren(IResourceDelta.REMOVED);

		if (addedChildren.length == 0 && removedChildren.length == 0) {
			return;
		}

		final Object[] addedObjects;
		final Object[] removedObjects;

		// Process additions before removals as to not cause selection
		// preservation prior to new objects being added
		// Handle added children. Issue one update for all insertions.
		int numMovedFrom = 0;
		int numMovedTo = 0;
		if (addedChildren.length > 0) {
			addedObjects = new Object[addedChildren.length];
			for (int i = 0; i < addedChildren.length; i++) {
				addedObjects[i] = addedChildren[i].getResource();
				if ((addedChildren[i].getFlags() & IResourceDelta.MOVED_FROM) != 0) {
					++numMovedFrom;
				}
			}
		} else {
			addedObjects = new Object[0];
		}

		// Handle removed children. Issue one update for all removals.
		if (removedChildren.length > 0) {
			removedObjects = new Object[removedChildren.length];
			for (int i = 0; i < removedChildren.length; i++) {
				removedObjects[i] = removedChildren[i].getResource();
				if ((removedChildren[i].getFlags() & IResourceDelta.MOVED_TO) != 0) {
					++numMovedTo;
				}
			}
		} else {
			removedObjects = new Object[0];
		}
		// heuristic test for items moving within same folder (i.e. renames)
		final boolean hasRename = numMovedFrom > 0 && numMovedTo > 0;
		
		Runnable addAndRemove = new Runnable(){
			public void run() {
				if (viewer instanceof AbstractTreeViewer) {
					AbstractTreeViewer treeViewer = (AbstractTreeViewer) viewer;
					// Disable redraw until the operation is finished so we don't
					// get a flash of both the new and old item (in the case of
					// rename)
					// Only do this if we're both adding and removing files (the
					// rename case)
					if (hasRename) {
						treeViewer.getControl().setRedraw(false);
					}
					try {
						if (addedObjects.length > 0) {
							treeViewer.add(resource, addedObjects);
						}
						if (removedObjects.length > 0) {
							treeViewer.remove(removedObjects);
						}
					}
					finally {
						if (hasRename) {
							treeViewer.getControl().setRedraw(true);
						}
					}
				} else {
					((StructuredViewer) viewer).refresh(resource);
				}
			}
		};
		runnables.add(addAndRemove);
	}
	
	/**
	 * Return a runnable for refreshing a resource.
	 * @param resource
	 * @return Runnable
	 */
	private Runnable getRefreshRunnable(final IResource resource) {
		return new Runnable(){
			public void run() {
				((StructuredViewer) viewer).refresh(resource);
			}
		};
	}
	
	/**
	 * Run all of the runnables that are the widget updates
	 * @param runnables
	 */
	private void runUpdates(Collection runnables) {
		Iterator runnableIterator = runnables.iterator();
		while(runnableIterator.hasNext()){
			((Runnable)runnableIterator.next()).run();
		}
		
	}
	
}