/*******************************************************************************
 * Copyright (c) 2000, 2017 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
 *
 *******************************************************************************/
package org.eclipse.dltk.internal.ui.typehierarchy;

import java.lang.reflect.InvocationTargetException;
import java.util.ArrayList;
import java.util.List;

import org.eclipse.core.runtime.IProgressMonitor;
import org.eclipse.core.runtime.OperationCanceledException;
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.IProjectFragment;
import org.eclipse.dltk.core.IRegion;
import org.eclipse.dltk.core.IScriptFolder;
import org.eclipse.dltk.core.IScriptProject;
import org.eclipse.dltk.core.ISourceModule;
import org.eclipse.dltk.core.IType;
import org.eclipse.dltk.core.ITypeHierarchy;
import org.eclipse.dltk.core.ITypeHierarchyChangedListener;
import org.eclipse.dltk.core.ModelException;
import org.eclipse.dltk.core.ScriptModelUtil;
import org.eclipse.dltk.ui.DLTKUIPlugin;
import org.eclipse.jface.operation.IRunnableContext;
import org.eclipse.jface.operation.IRunnableWithProgress;

/**
 * Manages a type hierarchy, to keep it refreshed, and to allow it to be shared.
 */
public class TypeHierarchyLifeCycle
		implements ITypeHierarchyChangedListener, IElementChangedListener {

	private boolean fHierarchyRefreshNeeded;
	private ITypeHierarchy fHierarchy;
	private IModelElement fInputElement;
	private boolean fIsSuperTypesOnly;

	private List<ITypeHierarchyLifeCycleListener> fChangeListeners;

	public TypeHierarchyLifeCycle() {
		this(false);
	}

	public TypeHierarchyLifeCycle(boolean isSuperTypesOnly) {
		fHierarchy = null;
		fInputElement = null;
		fIsSuperTypesOnly = isSuperTypesOnly;
		fChangeListeners = new ArrayList<>(2);
	}

	public ITypeHierarchy getHierarchy() {
		return fHierarchy;
	}

	public IModelElement getInputElement() {
		return fInputElement;
	}

	public void freeHierarchy() {
		if (fHierarchy != null) {
			fHierarchy.removeTypeHierarchyChangedListener(this);
			DLTKCore.removeElementChangedListener(this);
			fHierarchy = null;
			fInputElement = null;
		}
	}

	public void removeChangedListener(
			ITypeHierarchyLifeCycleListener listener) {
		fChangeListeners.remove(listener);
	}

	public void addChangedListener(ITypeHierarchyLifeCycleListener listener) {
		if (!fChangeListeners.contains(listener)) {
			fChangeListeners.add(listener);
		}
	}

	private void fireChange(IType[] changedTypes) {
		for (int i = fChangeListeners.size() - 1; i >= 0; i--) {
			ITypeHierarchyLifeCycleListener curr = fChangeListeners.get(i);
			curr.typeHierarchyChanged(this, changedTypes);
		}
	}

	public void ensureRefreshedTypeHierarchy(final IModelElement element,
			IRunnableContext context)
			throws InvocationTargetException, InterruptedException {
		if (element == null || !element.exists()) {
			freeHierarchy();
			return;
		}
		boolean hierachyCreationNeeded = (fHierarchy == null
				|| !element.equals(fInputElement));

		if (hierachyCreationNeeded || fHierarchyRefreshNeeded) {

			IRunnableWithProgress op = pm -> {
				try {
					doHierarchyRefresh(element, pm);
				} catch (ModelException e1) {
					throw new InvocationTargetException(e1);
				} catch (OperationCanceledException e2) {
					throw new InterruptedException();
				}
			};
			fHierarchyRefreshNeeded = true;
			context.run(true, true, op);
			fHierarchyRefreshNeeded = false;
		}
	}

	private ITypeHierarchy createTypeHierarchy(IModelElement element,
			IProgressMonitor pm) throws ModelException {
		if (element.getElementType() == IModelElement.TYPE) {
			IType type = (IType) element;
			if (fIsSuperTypesOnly) {
				return type.newSupertypeHierarchy(pm);
			} else {
				return type.newTypeHierarchy(pm);
			}
		} else {
			IRegion region = DLTKCore.newRegion();
			if (element.getElementType() == IModelElement.SCRIPT_PROJECT) {
				// for projects only add the contained source folders
				IProjectFragment[] roots = ((IScriptProject) element)
						.getProjectFragments();
				for (int i = 0; i < roots.length; i++) {
					if (!roots[i].isExternal()) {
						region.add(roots[i]);
					}
				}
			} else if (element
					.getElementType() == IModelElement.PROJECT_FRAGMENT) {
				IProjectFragment[] roots = element.getScriptProject()
						.getProjectFragments();
				String name = element.getElementName();
				for (int i = 0; i < roots.length; i++) {
					IScriptFolder pack = roots[i].getScriptFolder(name);
					if (pack.exists()) {
						region.add(pack);
					}
				}
			} else {
				region.add(element);
			}
			IScriptProject jproject = element.getScriptProject();
			return jproject.newTypeHierarchy(region, pm);
		}
	}

	public synchronized void doHierarchyRefresh(IModelElement element,
			IProgressMonitor pm) throws ModelException {
		boolean hierachyCreationNeeded = (fHierarchy == null
				|| !element.equals(fInputElement));
		// to ensure the order of the two listeners always remove / add
		// listeners on operations
		// on type hierarchies
		if (fHierarchy != null) {
			fHierarchy.removeTypeHierarchyChangedListener(this);
			DLTKCore.removeElementChangedListener(this);
		}
		if (hierachyCreationNeeded) {
			fHierarchy = createTypeHierarchy(element, pm);
			if (pm != null && pm.isCanceled()) {
				throw new OperationCanceledException();
			}
			fInputElement = element;
		} else {
			fHierarchy.refresh(pm);
		}
		fHierarchy.addTypeHierarchyChangedListener(this);
		DLTKCore.addElementChangedListener(this);
		fHierarchyRefreshNeeded = false;
	}

	@Override
	public void typeHierarchyChanged(ITypeHierarchy typeHierarchy) {
		fHierarchyRefreshNeeded = true;
		fireChange(null);
	}

	@Override
	public void elementChanged(ElementChangedEvent event) {
		if (fChangeListeners.isEmpty()) {
			return;
		}

		if (fHierarchyRefreshNeeded) {
			return;
		} else {
			ArrayList<IType> changedTypes = new ArrayList<>();
			processDelta(event.getDelta(), changedTypes);
			if (changedTypes.size() > 0) {
				fireChange(
						changedTypes.toArray(new IType[changedTypes.size()]));
			}
		}
	}

	/*
	 * Assume that the hierarchy is intact (no refresh needed)
	 */
	private void processDelta(IModelElementDelta delta,
			ArrayList<IType> changedTypes) {
		IModelElement element = delta.getElement();
		switch (element.getElementType()) {
		case IModelElement.TYPE:
			processTypeDelta((IType) element, changedTypes);
			processChildrenDelta(delta, changedTypes); // (inner types)
			break;
		case IModelElement.SCRIPT_MODEL:
		case IModelElement.SCRIPT_PROJECT:
		case IModelElement.PROJECT_FRAGMENT:
			processChildrenDelta(delta, changedTypes);
			break;
		case IModelElement.SOURCE_MODULE:
			ISourceModule cu = (ISourceModule) element;
			if (!ScriptModelUtil.isPrimary(cu)) {
				return;
			}

			if (delta.getKind() == IModelElementDelta.CHANGED
					&& isPossibleStructuralChange(delta.getFlags())) {
				try {
					if (cu.exists()) {
						IType[] types = cu.getAllTypes();
						for (int i = 0; i < types.length; i++) {
							processTypeDelta(types[i], changedTypes);
						}
					}
				} catch (ModelException e) {
					DLTKUIPlugin.log(e);
				}
			} else {
				processChildrenDelta(delta, changedTypes);
			}
			break;
		}
	}

	private boolean isPossibleStructuralChange(int flags) {
		return (flags & (IModelElementDelta.F_CONTENT
				| IModelElementDelta.F_FINE_GRAINED)) == IModelElementDelta.F_CONTENT;
	}

	private void processTypeDelta(IType type, ArrayList<IType> changedTypes) {
		if (getHierarchy().contains(type)) {
			changedTypes.add(type);
		}
	}

	private void processChildrenDelta(IModelElementDelta delta,
			ArrayList<IType> changedTypes) {
		IModelElementDelta[] children = delta.getAffectedChildren();
		for (int i = 0; i < children.length; i++) {
			processDelta(children[i], changedTypes); // recursive
		}
	}

}