/*=============================================================================#
 # Copyright (c) 2010, 2021 Stephan Wahlbrink and others.
 # 
 # This program and the accompanying materials are made available under the
 # terms of the Eclipse Public License 2.0 which is available at
 # https://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
 # which is available at https://www.apache.org/licenses/LICENSE-2.0.
 # 
 # SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
 # 
 # Contributors:
 #     Stephan Wahlbrink <sw@wahlbrink.eu> - initial API and implementation
 #=============================================================================*/

package org.eclipse.statet.internal.r.ui.rhelp;

import java.net.URI;
import java.net.URISyntaxException;

import org.eclipse.core.commands.AbstractHandler;
import org.eclipse.core.commands.ExecutionEvent;
import org.eclipse.core.commands.ExecutionException;
import org.eclipse.core.commands.IHandler2;
import org.eclipse.core.runtime.IAdaptable;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.Status;
import org.eclipse.jface.resource.ImageDescriptor;
import org.eclipse.jface.viewers.ILabelProvider;
import org.eclipse.swt.browser.TitleEvent;
import org.eclipse.swt.graphics.Image;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;
import org.eclipse.ui.contexts.IContextService;
import org.eclipse.ui.handlers.IHandlerService;
import org.eclipse.ui.services.IServiceLocator;
import org.eclipse.ui.statushandlers.StatusManager;

import org.eclipse.statet.jcommons.lang.NonNullByDefault;
import org.eclipse.statet.jcommons.lang.Nullable;

import org.eclipse.statet.ecommons.ui.mpbv.BrowserSession;
import org.eclipse.statet.ecommons.ui.mpbv.PageBookBrowserPage;
import org.eclipse.statet.ecommons.ui.mpbv.PageBookBrowserView;
import org.eclipse.statet.ecommons.ui.viewers.breadcrumb.IBreadcrumb;
import org.eclipse.statet.ecommons.ui.workbench.ContextHandlers;

import org.eclipse.statet.r.core.RCore;
import org.eclipse.statet.r.ui.RUI;
import org.eclipse.statet.rhelp.core.RHelpUtils;
import org.eclipse.statet.rhelp.core.http.RHelpHttpService;
import org.eclipse.statet.rj.renv.core.REnv;


@NonNullByDefault
public class RHelpViewPage extends PageBookBrowserPage implements IAdaptable {
	
	
	private IBreadcrumb breadcrumb;
	private Control breadcrumbControl;
	
	private @Nullable Object helpObject;
	
	private final ILabelProvider labelProvider= new RHelpLabelProvider();
	
	
	public RHelpViewPage(final PageBookBrowserView view, final BrowserSession session) {
		super(view, session);
	}
	
	@Override
	public void dispose() {
		super.dispose();
		
		this.labelProvider.dispose();
	}
	
	
	public Object getHelpObject() {
		return this.helpObject;
	}
	
	@Override
	public void setUrl(final @Nullable String url) {
		if (url != null && url.startsWith(RHelpHttpService.PORTABLE_URI_SCHEME + ':')) {
			try {
				URI uri= new URI(url);
				uri= RCore.getRHelpHttpService().toHttpUrl(uri);
				super.setUrl(uri);
				return;
			}
			catch (final URISyntaxException e) {
				// ?
				return;
			}
		}
		super.setUrl(url);
	}
	
	@Override
	public void setUrl(@Nullable URI url) {
		if (url != null && url.getScheme().equals(RHelpHttpService.PORTABLE_URI_SCHEME)) {
			try {
				url= RCore.getRHelpHttpService().toHttpUrl(url);
			}
			catch (final URISyntaxException e) {
				return;
			}
		}
		super.setUrl(url);
	}
	
	@Override
	protected Control createAddressBar(final Composite parent) {
		this.breadcrumb= new RHelpBreadcrumb(this);
		if (this.breadcrumb != null) {
			this.breadcrumbControl= this.breadcrumb.createContent(parent);
			updateBreadcrumbInput();
		}
		return this.breadcrumbControl;
	}
	
	@Override
	protected void initActions(final IServiceLocator serviceLocator, final ContextHandlers handlers) {
		super.initActions(serviceLocator, handlers);
		final IHandlerService handlerService= serviceLocator.getService(IHandlerService.class);
		final IContextService contextService= serviceLocator.getService(IContextService.class);
		
		final IHandler2 breadcrumbHandler= new AbstractHandler() {
			@Override
			public Object execute(final ExecutionEvent event) throws ExecutionException {
				if (RHelpViewPage.this.breadcrumb != null) {
					RHelpViewPage.this.breadcrumb.activate();
				}
				return null;
			}
		};
		handlers.add(IBreadcrumb.SHOW_BREADCRUMB_COMMAND_ID, breadcrumbHandler);
		handlerService.activateHandler(IBreadcrumb.SHOW_BREADCRUMB_COMMAND_ID, breadcrumbHandler);
		contextService.activateContext(IBreadcrumb.WITH_BREADCRUMB_CONTEXT_ID);
	}
	
	@Override
	protected void onPageChanged() {
		super.onPageChanged();
		
		try {
			final BrowserSession session= getSession();
			final Object input= RCore.getRHelpHttpService().getContentOfUrl(session.getUrl());
			this.helpObject= input;
			
			final Image image= this.labelProvider.getImage(input);
			if (image != null) {
				setIcon(session, ImageDescriptor.createFromImage(image));
			}
			updateBreadcrumbInput();
		}
		catch (final Exception e) {
			StatusManager.getManager().handle(new Status(IStatus.ERROR, RUI.BUNDLE_ID, 0,
					"An error occurred when updating the R help view address bar/breadcrumbs.", e));
		}
	}
	
	@Override
	public void changed(final TitleEvent event) {
		super.changed(event);
		if (this.helpObject == null) {
			updateBreadcrumbInput();
		}
	}
	
	/**
	 * Makes the breadcrumb visible.
	 */
	private void showBreadcrumb() {
		if (this.breadcrumb == null || this.breadcrumbControl.isVisible()) {
			return;
		}
//		((GridData) fBreadcrumbControl.getLayoutData()).exclude= false;
		this.breadcrumbControl.setVisible(true);
		this.breadcrumbControl.getParent().layout(true, true);
	}
	
	/**
	 * Hides the breadcrumb
	 */
	private void hideBreadcrumb() {
		if (this.breadcrumb == null || !this.breadcrumbControl.isVisible()) {
			return;
		}
//		((GridData) fBreadcrumbControl.getLayoutData()).exclude= true;
		this.breadcrumbControl.setVisible(false);
		this.breadcrumbControl.getParent().layout(true, true);
	}
	
	/**
	 * Sets the breadcrumb input to the given element.
	 * @param content the element to use as input for the breadcrumb
	 * @since 3.4
	 */
	private void updateBreadcrumbInput() {
		if (this.breadcrumb == null) {
			return;
		}
		Object input= this.helpObject;
		if (input == null) {
			if (getCurrentUrl().length() > 0) {
				input= getCurrentTitle();
			}
		}
		else if (input instanceof Object[]) {
			final Object[] array= (Object[]) input;
			if (array.length >= 2) {
				array[array.length-1]= getCurrentTitle();
			}
			else {
				input= null;
			}
		}
		this.breadcrumb.setInput(input);
	}
	
	
	@Override
	@SuppressWarnings("unchecked")
	public <T> @Nullable T getAdapter(final Class<T> adapterType) {
		if (adapterType == REnv.class) {
			final Object input= this.helpObject;
			if (input != null) {
				if (input instanceof REnv) {
					return (T) input;
				}
				return (T) RHelpUtils.getREnv(input);
			}
			return null;
		}
		return null;
	}
	
}