/*******************************************************************************
 * Copyright (c) 2000, 2004 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.views.bookmarkexplorer;

import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.resources.IMarker;
import org.eclipse.core.resources.IMarkerDelta;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IResourceChangeEvent;
import org.eclipse.core.resources.IResourceChangeListener;
import org.eclipse.core.resources.IResourceDelta;
import org.eclipse.core.resources.IWorkspace;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.jface.viewers.IBasicPropertyConstants;
import org.eclipse.jface.viewers.IStructuredContentProvider;
import org.eclipse.jface.viewers.Viewer;
import org.eclipse.swt.widgets.Control;

/**
 * Provides content for the bookmark navigator
 */
class BookmarkContentProvider implements IStructuredContentProvider,
        IResourceChangeListener, IBasicPropertyConstants {

    private IResource input;

    private Viewer viewer;

    /**
     * The constructor.
     */
    public BookmarkContentProvider(BookmarkNavigator bookmarksView) {
        super();
    }

    /**
     * The visual part that is using this content provider is about
     * to be disposed. Deallocate all allocated SWT resources.
     */
    public void dispose() {
        IResource resource = (IResource) viewer.getInput();
        if (resource != null) {
            resource.getWorkspace().removeResourceChangeListener(this);
        }
    }

    /**
     * Returns all the bookmarks that should be shown for
     * the current settings.
     */
    Object[] getBookmarks(IResource resource) {
        try {
            return resource.findMarkers(IMarker.BOOKMARK, true,
                    IResource.DEPTH_INFINITE);
        } catch (CoreException e) {
            return new Object[0];
        }
    }

    public Object[] getChildren(Object element) {
        // If the input element is a workbench return a list
        // of the existing bookmarks.  Otherwise, return an empty list.
        if (element instanceof IResource)
            return getBookmarks((IResource) element);
        else
            return new Object[0];
    }

    public Object[] getElements(Object element) {
        return getChildren(element);
    }

    /**
     * Recursively walks over the resource delta and gathers all marker deltas.  Marker
     * deltas are placed into one of the three given vectors depending on
     * the type of delta (add, remove, or change).
     */
    void getMarkerDeltas(IResourceDelta delta, List additions, List removals,
            List changes) {
        IMarkerDelta[] markerDeltas = delta.getMarkerDeltas();
        for (int i = 0; i < markerDeltas.length; i++) {
            IMarkerDelta markerDelta = markerDeltas[i];
            IMarker marker = markerDelta.getMarker();
            switch (markerDelta.getKind()) {
            case IResourceDelta.ADDED:
                if (markerDelta.isSubtypeOf(IMarker.BOOKMARK)) {
                    additions.add(marker);
                }
                break;
            case IResourceDelta.REMOVED:
                if (markerDelta.isSubtypeOf(IMarker.BOOKMARK)) {
                    removals.add(marker);
                }
                break;
            case IResourceDelta.CHANGED:
                if (markerDelta.isSubtypeOf(IMarker.BOOKMARK)) {
                    changes.add(marker);
                }
                break;
            }
        }

        //recurse on child deltas
        IResourceDelta[] children = delta.getAffectedChildren();
        for (int i = 0; i < children.length; i++) {
            getMarkerDeltas(children[i], additions, removals, changes);
        }
    }

    /* (non-Javadoc)
     * Method declared on ITreeContentProvider,
     */
    public Object getParent(Object element) {
        return input;
    }

    /**
     * hasChildren method comment.
     */
    public boolean hasChildren(Object element) {
        if (element instanceof IWorkspace)
            return true;
        else
            return false;
    }

    public void inputChanged(Viewer newViewer, Object oldInput, Object newInput) {
        if (oldInput == null) {
            IResource resource = (IResource) newInput;
            resource.getWorkspace().addResourceChangeListener(this);
        }
        this.viewer = newViewer;
        this.input = (IResource) newInput;
    }

    /**
     * The workbench has changed.  Process the delta and provide updates to the viewer,
     * inside the UI thread.
     *
     * @see IResourceChangeListener#resourceChanged
     */
    public void resourceChanged(final IResourceChangeEvent event) {

        // gather all marker changes from the delta.
        // be sure to do this in the calling thread, 
        // as the delta is destroyed when this method returns
        final List additions = new ArrayList();
        final List removals = new ArrayList();
        final List changes = new ArrayList();

        IResourceDelta delta = event.getDelta();
        if (delta == null)
            return;
        getMarkerDeltas(delta, additions, removals, changes);

        // update the viewer based on the marker changes, in the UI thread
        if (additions.size() + removals.size() + changes.size() > 0) {
            viewer.getControl().getDisplay().asyncExec(new Runnable() {
                public void run() {
                    // This method runs inside an asyncExec.  The 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;

                    viewer.refresh();
                }
            });
        }
    }
}