/*******************************************************************************
 * Copyright (c) 2000, 2016 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.jdt.internal.ui.viewsupport;


import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.IPath;

import org.eclipse.core.resources.IContainer;
import org.eclipse.core.resources.IResource;

import org.eclipse.jface.action.IStatusLineManager;
import org.eclipse.jface.viewers.ISelection;
import org.eclipse.jface.viewers.ISelectionChangedListener;
import org.eclipse.jface.viewers.IStructuredSelection;
import org.eclipse.jface.viewers.SelectionChangedEvent;

import org.eclipse.ui.model.IWorkbenchAdapter;

import org.eclipse.jdt.core.IJarEntryResource;
import org.eclipse.jdt.core.IJavaElement;

import org.eclipse.jdt.internal.corext.util.Messages;

import org.eclipse.jdt.ui.JavaElementLabels;

import org.eclipse.jdt.internal.ui.JavaUIMessages;
import org.eclipse.jdt.internal.ui.packageview.PackageFragmentRootContainer;

import org.eclipse.jdt.internal.core.manipulation.util.BasicElementLabels;

/**
 * Add the <code>StatusBarUpdater</code> to your ViewPart to have the statusbar
 * describing the selected elements.
 */
public class StatusBarUpdater implements ISelectionChangedListener {

	private final long LABEL_FLAGS= JavaElementLabels.DEFAULT_QUALIFIED | JavaElementLabels.ROOT_POST_QUALIFIED | JavaElementLabels.APPEND_ROOT_PATH |
			JavaElementLabels.M_PARAMETER_TYPES | JavaElementLabels.M_PARAMETER_NAMES | JavaElementLabels.M_APP_RETURNTYPE | JavaElementLabels.M_EXCEPTIONS |
		 	JavaElementLabels.F_APP_TYPE_SIGNATURE | JavaElementLabels.T_TYPE_PARAMETERS;

	private IStatusLineManager fStatusLineManager;

	public StatusBarUpdater(IStatusLineManager statusLineManager) {
		fStatusLineManager= statusLineManager;
	}

	/*
	 * @see ISelectionChangedListener#selectionChanged
	 */
	@Override
	public void selectionChanged(SelectionChangedEvent event) {
		String statusBarMessage= formatMessage(event.getSelection());
		fStatusLineManager.setMessage(statusBarMessage);
	}


	protected String formatMessage(ISelection sel) {
		if (sel instanceof IStructuredSelection && !sel.isEmpty()) {
			IStructuredSelection selection= (IStructuredSelection) sel;

			int nElements= selection.size();
			if (nElements > 1) {
				return Messages.format(JavaUIMessages.StatusBarUpdater_num_elements_selected, String.valueOf(nElements));
			} else {
				Object elem= selection.getFirstElement();
				if (elem instanceof IJavaElement) {
					return formatJavaElementMessage((IJavaElement) elem);
				} else if (elem instanceof IResource) {
					return formatResourceMessage((IResource) elem);
				} else if (elem instanceof PackageFragmentRootContainer) {
					PackageFragmentRootContainer container= (PackageFragmentRootContainer) elem;
					return container.getLabel() + JavaElementLabels.CONCAT_STRING + container.getJavaProject().getElementName();
				} else if (elem instanceof IJarEntryResource) {
					IJarEntryResource jarEntryResource= (IJarEntryResource) elem;
					StringBuilder buf= new StringBuilder(BasicElementLabels.getResourceName(jarEntryResource.getName()));
					buf.append(JavaElementLabels.CONCAT_STRING);
					IPath fullPath= jarEntryResource.getFullPath();
					if (fullPath.segmentCount() > 1) {
						buf.append(BasicElementLabels.getPathLabel(fullPath.removeLastSegments(1), false));
						buf.append(JavaElementLabels.CONCAT_STRING);
					}
					buf.append(JavaElementLabels.getElementLabel(jarEntryResource.getPackageFragmentRoot(), JavaElementLabels.ROOT_POST_QUALIFIED));
					return buf.toString();
				} else if (elem instanceof IAdaptable) {
					IWorkbenchAdapter wbadapter= ((IAdaptable)elem).getAdapter(IWorkbenchAdapter.class);
					if (wbadapter != null) {
						return wbadapter.getLabel(elem);
					}
				}
			}
		}
		return "";  //$NON-NLS-1$
	}

	private String formatJavaElementMessage(IJavaElement element) {
		return JavaElementLabels.getElementLabel(element, LABEL_FLAGS);
	}

	private String formatResourceMessage(IResource element) {
		IContainer parent= element.getParent();
		if (parent != null && parent.getType() != IResource.ROOT)
			return BasicElementLabels.getResourceName(element.getName()) + JavaElementLabels.CONCAT_STRING + BasicElementLabels.getPathLabel(parent.getFullPath(), false);
		else
			return BasicElementLabels.getResourceName(element.getName());
	}

}
