/*******************************************************************************
 * Copyright (c) 2000, 2017 IBM Corporation and others.
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 * 
 * SPDX-License-Identifier: EPL-2.0
 *
 *******************************************************************************/
package org.eclipse.dltk.internal.ui.workingsets;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IResourceDelta;
import org.eclipse.core.resources.ResourcesPlugin;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.dltk.core.DLTKCore;
import org.eclipse.dltk.core.ElementChangedEvent;
import org.eclipse.dltk.core.IElementChangedListener;
import org.eclipse.dltk.core.IModelElement;
import org.eclipse.dltk.core.IModelElementDelta;
import org.eclipse.dltk.core.IScriptProject;
import org.eclipse.ui.IWorkingSet;
import org.eclipse.ui.IWorkingSetUpdater;

public class ScriptWorkingSetUpdater
		implements IWorkingSetUpdater, IElementChangedListener {

	private List<IWorkingSet> fWorkingSets;

	private static class WorkingSetDelta {
		private IWorkingSet fWorkingSet;
		private List<IAdaptable> fElements;
		private boolean fChanged;

		public WorkingSetDelta(IWorkingSet workingSet) {
			fWorkingSet = workingSet;
			fElements = new ArrayList<>(
					Arrays.asList(workingSet.getElements()));
		}

		public int indexOf(Object element) {
			return fElements.indexOf(element);
		}

		public void set(int index, IAdaptable element) {
			fElements.set(index, element);
			fChanged = true;
		}

		public void remove(int index) {
			if (fElements.remove(index) != null) {
				fChanged = true;
			}
		}

		public void process() {
			if (fChanged) {
				fWorkingSet.setElements(
						fElements.toArray(new IAdaptable[fElements.size()]));
			}
		}
	}

	public ScriptWorkingSetUpdater() {
		fWorkingSets = new ArrayList<>();
		DLTKCore.addElementChangedListener(this);
	}

	@Override
	public void add(IWorkingSet workingSet) {
		checkElementExistence(workingSet);
		synchronized (fWorkingSets) {
			fWorkingSets.add(workingSet);
		}
	}

	@Override
	public boolean remove(IWorkingSet workingSet) {
		boolean result;
		synchronized (fWorkingSets) {
			result = fWorkingSets.remove(workingSet);
		}
		return result;
	}

	@Override
	public boolean contains(IWorkingSet workingSet) {
		synchronized (fWorkingSets) {
			return fWorkingSets.contains(workingSet);
		}
	}

	@Override
	public void dispose() {
		synchronized (fWorkingSets) {
			fWorkingSets.clear();
		}
		DLTKCore.removeElementChangedListener(this);
	}

	@Override
	public void elementChanged(ElementChangedEvent event) {
		IWorkingSet[] workingSets;
		synchronized (fWorkingSets) {
			workingSets = fWorkingSets
					.toArray(new IWorkingSet[fWorkingSets.size()]);
		}
		for (int w = 0; w < workingSets.length; w++) {
			WorkingSetDelta workingSetDelta = new WorkingSetDelta(
					workingSets[w]);
			processScriptDelta(workingSetDelta, event.getDelta());
			IResourceDelta[] resourceDeltas = event.getDelta()
					.getResourceDeltas();
			if (resourceDeltas != null) {
				for (int r = 0; r < resourceDeltas.length; r++) {
					processResourceDelta(workingSetDelta, resourceDeltas[r]);
				}
			}
			workingSetDelta.process();
		}
	}

	private void processScriptDelta(WorkingSetDelta result,
			IModelElementDelta delta) {
		IModelElement jElement = delta.getElement();
		int index = result.indexOf(jElement);
		int type = jElement.getElementType();
		int kind = delta.getKind();
		int flags = delta.getFlags();
		if (type == IModelElement.SCRIPT_PROJECT
				&& kind == IModelElementDelta.CHANGED) {
			if (index != -1 && (flags & IModelElementDelta.F_CLOSED) != 0) {
				result.set(index, ((IScriptProject) jElement).getProject());
			} else if ((flags & IModelElementDelta.F_OPENED) != 0) {
				index = result
						.indexOf(((IScriptProject) jElement).getProject());
				if (index != -1)
					result.set(index, jElement);
			}
		}
		if (index != -1) {
			if (kind == IModelElementDelta.REMOVED) {
				if ((flags & IModelElementDelta.F_MOVED_TO) != 0) {
					result.set(index, delta.getMovedToElement());
				} else {
					result.remove(index);
				}
			}
		}
		IResourceDelta[] resourceDeltas = delta.getResourceDeltas();
		if (resourceDeltas != null) {
			for (int i = 0; i < resourceDeltas.length; i++) {
				processResourceDelta(result, resourceDeltas[i]);
			}
		}
		IModelElementDelta[] children = delta.getAffectedChildren();
		for (int i = 0; i < children.length; i++) {
			processScriptDelta(result, children[i]);
		}
	}

	private void processResourceDelta(WorkingSetDelta result,
			IResourceDelta delta) {
		IResource resource = delta.getResource();
		int type = resource.getType();
		int index = result.indexOf(resource);
		int kind = delta.getKind();
		int flags = delta.getFlags();
		if (kind == IResourceDelta.CHANGED && type == IResource.PROJECT
				&& index != -1) {
			if ((flags & IResourceDelta.OPEN) != 0) {
				result.set(index, resource);
			}
		}
		if (index != -1 && kind == IResourceDelta.REMOVED) {
			if ((flags & IResourceDelta.MOVED_TO) != 0) {
				result.set(index, ResourcesPlugin.getWorkspace().getRoot()
						.findMember(delta.getMovedToPath()));
			} else {
				result.remove(index);
			}
		}

		// Don't dive into closed or opened projects
		if (projectGotClosedOrOpened(resource, kind, flags))
			return;

		IResourceDelta[] children = delta.getAffectedChildren();
		for (int i = 0; i < children.length; i++) {
			processResourceDelta(result, children[i]);
		}
	}

	private boolean projectGotClosedOrOpened(IResource resource, int kind,
			int flags) {
		return resource.getType() == IResource.PROJECT
				&& kind == IResourceDelta.CHANGED
				&& (flags & IResourceDelta.OPEN) != 0;
	}

	private void checkElementExistence(IWorkingSet workingSet) {
		List<IAdaptable> elements = new ArrayList<>(
				Arrays.asList(workingSet.getElements()));
		boolean changed = false;
		for (Iterator<IAdaptable> iter = elements.iterator(); iter.hasNext();) {
			IAdaptable element = iter.next();
			boolean remove = false;
			if (element instanceof IModelElement) {
				IModelElement jElement = (IModelElement) element;
				// If we have directly a project then remove it when it
				// doesn't exist anymore. However if we have a sub element
				// under a project only remove the element if the parent
				// project is open. Otherwise we would remove all elements
				// in closed projects.
				if (jElement instanceof IScriptProject) {
					remove = !jElement.exists();
				} else {
					IProject project = jElement.getScriptProject().getProject();
					remove = project.isOpen() && !jElement.exists();
				}
			} else if (element instanceof IResource) {
				IResource resource = (IResource) element;
				// See comments above
				if (resource instanceof IProject) {
					remove = !resource.exists();
				} else {
					IProject project = resource.getProject();
					remove = (project != null ? project.isOpen() : true)
							&& !resource.exists();
				}
			}
			if (remove) {
				iter.remove();
				changed = true;
			}
		}
		if (changed) {
			workingSet.setElements(
					elements.toArray(new IAdaptable[elements.size()]));
		}
	}
}