/*=============================================================================#
 # Copyright (c) 2008, 2020 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.ltk.ui.sourceediting;

import static org.eclipse.statet.ecommons.ui.actions.UIActions.VIEW_GROUP_ID;

import java.util.HashMap;
import java.util.Map;

import org.eclipse.core.commands.IHandler2;
import org.eclipse.jface.action.Action;
import org.eclipse.jface.action.GroupMarker;
import org.eclipse.jface.action.IMenuListener;
import org.eclipse.jface.action.IMenuManager;
import org.eclipse.jface.action.MenuManager;
import org.eclipse.jface.action.Separator;
import org.eclipse.jface.commands.ActionHandler;
import org.eclipse.jface.text.Document;
import org.eclipse.jface.text.DocumentEvent;
import org.eclipse.jface.text.IDocumentListener;
import org.eclipse.jface.text.source.SourceViewer;
import org.eclipse.jface.viewers.ISelectionChangedListener;
import org.eclipse.jface.viewers.SelectionChangedEvent;
import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.StyledText;
import org.eclipse.swt.events.DisposeEvent;
import org.eclipse.swt.graphics.Color;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Menu;
import org.eclipse.ui.services.IServiceLocator;
import org.eclipse.ui.texteditor.ITextEditorActionConstants;
import org.eclipse.ui.texteditor.IUpdate;

import org.eclipse.statet.ecommons.preferences.ui.SettingsUpdater;
import org.eclipse.statet.ecommons.text.ui.TextViewerAction;
import org.eclipse.statet.ecommons.text.ui.TextViewerEditorColorUpdater;
import org.eclipse.statet.ecommons.text.ui.TextViewerJFaceUpdater;
import org.eclipse.statet.ecommons.ui.actions.ControlServicesUtil;
import org.eclipse.statet.ecommons.ui.actions.HandlerCollection;
import org.eclipse.statet.ecommons.ui.components.WidgetToolsButton;
import org.eclipse.statet.ecommons.ui.util.LayoutUtils;
import org.eclipse.statet.ecommons.ui.util.UIAccess;


/**
 * Text snippet editor (no Eclipse editor) supporting {@link SourceEditorViewerConfigurator}.
 */
public class SnippetEditor extends Object {
	
	public static final int DEFAULT_SINGLE_LINE_STYLE= SWT.BORDER | SWT.SINGLE | SWT.LEFT_TO_RIGHT;
	public static final int DEFAULT_MULTI_LINE_STYLE= SWT.BORDER | SWT.V_SCROLL | SWT.H_SCROLL | SWT.MULTI | SWT.LEFT_TO_RIGHT;
	
	
	private static class ExtStyledText extends StyledText {
		
		
		private Color savedColor;
		
		
		public ExtStyledText(final Composite parent, final int style) {
			super(parent, style);
		}
		
		
		@Override
		public void setBackground(final Color color) {
			this.savedColor= color;
			if (isEnabled()) {
				super.setBackground(color);
			}
		}
		
		@Override
		public void setEnabled(final boolean enabled) {
			super.setEnabled(enabled);
			if (enabled) {
				super.setBackground(this.savedColor);
			}
			else {
				super.setBackground(getDisplay().getSystemColor(SWT.COLOR_WIDGET_BACKGROUND));
			}
		}
		
	}
	
	
	private class Updater implements ISelectionChangedListener, IDocumentListener, Runnable {
		
		private boolean actionUpdateScheduled= false;
		
		
		@Override
		public void selectionChanged(final SelectionChangedEvent event) {
			schedule();
		}
		
		@Override
		public void documentAboutToBeChanged(final DocumentEvent event) {
		}
		@Override
		public void documentChanged(final DocumentEvent event) {
			schedule();
		}
		
		
		public void schedule() {
			if (this.actionUpdateScheduled) {
				return;
			}
			Display.getCurrent().asyncExec(this);
			this.actionUpdateScheduled= true;
		}
		
		@Override
		public void run() {
			this.actionUpdateScheduled= false;
			if (UIAccess.isOkToUse(SnippetEditor.this.sourceViewer)) {
				SnippetEditor.this.handlers.update(null);
				for (final Action action : SnippetEditor.this.globalActions.values()) {
					if (action instanceof IUpdate) {
						((IUpdate) action).update();
					}
				}
			}
		}
	}
	
	
	private Composite composite;
	
	private final Document document;
	private SourceViewer sourceViewer;
	
	private final boolean withToolButton;
	private WidgetToolsButton toolButton;
	
	private final SourceEditorViewerConfigurator configurator;
	private Map<String, Action> globalActions;
	private Updater updater;
	
	private final HandlerCollection handlers;
	private final IServiceLocator serviceLocator;
	private ControlServicesUtil serviceUtil;
	
	
	/**
	 * Creates snippet editor with initial content.
	 */
	public SnippetEditor(final SourceEditorViewerConfigurator configurator, final String initialContent,
			final IServiceLocator serviceParent, final boolean withToolButton) {
		this.configurator= configurator;
		this.document= (initialContent != null) ? new Document(initialContent) : new Document();
		this.configurator.getDocumentSetupParticipant().setup(this.document);
		this.handlers= new HandlerCollection();
		this.serviceLocator= serviceParent;
		this.withToolButton= withToolButton;
	}
	
	/**
	 * Creates snippet editor with initial content.
	 */
	public SnippetEditor(final SourceEditorViewerConfigurator configurator, final String initialContent,
			final IServiceLocator serviceParent) {
		this(configurator, initialContent, serviceParent, false);
	}
	
	/**
	 * Creates snippet editor with empty document.
	 */
	public SnippetEditor(final SourceEditorViewerConfigurator configurator) {
		this(configurator, null, null, false);
	}
	
	
	protected final IServiceLocator getServiceLocator() {
		return this.serviceLocator;
	}
	
	public void create(final Composite parent, final int style) {
		if (this.withToolButton) {
			this.composite= new Composite(parent, SWT.NONE) {
				@Override
				public boolean setFocus() {
					return SnippetEditor.this.sourceViewer.getTextWidget().setFocus();
				}
			};
			this.composite.setLayout(LayoutUtils.newSashGrid(2));
			
			createSourceViewer(this.composite, style);
			this.sourceViewer.getControl().setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
			
			final WidgetToolsButton button= new WidgetToolsButton(this.sourceViewer.getTextWidget()) {
				@Override
				protected void fillMenu(final Menu menu) {
					SnippetEditor.this.fillToolMenu(menu);
				}
			}; 
			button.setLayoutData(new GridData(SWT.LEFT, SWT.TOP, false, false));
			this.toolButton= button;
		}
		else {
			createSourceViewer(parent, style);
			this.composite= this.sourceViewer.getTextWidget();
		}
		
		initActions();
		this.sourceViewer.activatePlugins();
		this.updater= new Updater();
		this.sourceViewer.addSelectionChangedListener(this.updater);
		this.sourceViewer.getDocument().addDocumentListener(this.updater);
		
		this.composite.addDisposeListener(this::dispose);
	}
	
	private void createSourceViewer(final Composite composite, final int style) {
		this.sourceViewer= new SourceViewer(composite, null, style) {
			
			@Override
			protected StyledText createTextWidget(final Composite parent, final int styles) {
				final StyledText styledText= new ExtStyledText(parent, styles);
				styledText.setLeftMargin(Math.max(styledText.getLeftMargin(), 2));
				return styledText;
			}
			
		};
		this.sourceViewer.setEditable(true);
		
		this.sourceViewer.setDocument(this.document);
		
		final ViewerSourceEditorAdapter adapter= new ViewerSourceEditorAdapter(this.sourceViewer, this.configurator);
		this.configurator.setTarget(adapter);
		new TextViewerJFaceUpdater(this.sourceViewer,
				this.configurator.getSourceViewerConfiguration().getPreferences() );
		new TextViewerEditorColorUpdater(this.sourceViewer,
				this.configurator.getSourceViewerConfiguration().getPreferences() );
		new SettingsUpdater(this.configurator, this.sourceViewer.getControl());
	}
	
	protected void dispose(final DisposeEvent e) {
		this.handlers.dispose();
	}
	
	
	public void registerCommandHandler(final String commandId, final IHandler2 handler) {
		this.handlers.add(commandId, handler);
		if (this.serviceUtil != null) {
			this.serviceUtil.activateHandler(commandId, handler);
		}
	}
	
	public HandlerCollection getCommandHandlers() {
		return this.handlers;
	}
	
	public void addAction(final Action action) {
		this.globalActions.put(action.getId(), action);
		final String commandId= action.getActionDefinitionId();
		if (this.serviceUtil != null && commandId != null) {
			this.serviceUtil.activateHandler(commandId, new ActionHandler(action));
		}
	}
	
	public Action getAction(final String id) {
		return this.globalActions.get(id);
	}
	
	protected void initActions() {
		this.globalActions= new HashMap<>(10);
		
		if (this.serviceLocator != null) {
			this.serviceUtil= new ControlServicesUtil(this.serviceLocator, getClass().getName()+'#'+hashCode(), getSourceViewer().getControl());
			this.serviceUtil.addControl(getSourceViewer().getControl());
			if (this.toolButton != null) {
				this.serviceUtil.addControl(this.toolButton.getButton());
			}
		}
		
		// default actions
		addAction(TextViewerAction.createUndoAction(this.sourceViewer));
		addAction(TextViewerAction.createRedoAction(this.sourceViewer));
		addAction(TextViewerAction.createCutAction(this.sourceViewer));
		addAction(TextViewerAction.createCopyAction(this.sourceViewer));
		addAction(TextViewerAction.createPasteAction(this.sourceViewer));
		addAction(TextViewerAction.createSelectAllAction(this.sourceViewer));
		
		// create context menu
		final MenuManager manager= new MenuManager(null, null);
		manager.setRemoveAllWhenShown(true);
		manager.addMenuListener(new IMenuListener() {
			@Override
			public void menuAboutToShow(final IMenuManager mgr) {
				fillContextMenu(mgr);
			}
		});
		
		final StyledText text= this.sourceViewer.getTextWidget();
		final Menu menu= manager.createContextMenu(text);
		text.setMenu(menu);
	}
	
	protected void fillContextMenu(final IMenuManager menu) {
		menu.add(new GroupMarker(ITextEditorActionConstants.GROUP_UNDO));
		menu.appendToGroup(ITextEditorActionConstants.GROUP_UNDO, getAction(ITextEditorActionConstants.UNDO));
		menu.appendToGroup(ITextEditorActionConstants.GROUP_UNDO, getAction(ITextEditorActionConstants.REDO));
		
		menu.add(new Separator(ITextEditorActionConstants.GROUP_EDIT));
		menu.appendToGroup(ITextEditorActionConstants.GROUP_EDIT, getAction(ITextEditorActionConstants.CUT));
		menu.appendToGroup(ITextEditorActionConstants.GROUP_EDIT, getAction(ITextEditorActionConstants.COPY));
		menu.appendToGroup(ITextEditorActionConstants.GROUP_EDIT, getAction(ITextEditorActionConstants.PASTE));
		menu.appendToGroup(ITextEditorActionConstants.GROUP_EDIT, getAction(ITextEditorActionConstants.SELECT_ALL));
		
		menu.add(new Separator(ITextEditorActionConstants.GROUP_ASSIST));
		final Action action= this.globalActions.get("ContentAssistProposal"); //$NON-NLS-1$
		if (action != null && action.getText() != null) {
			menu.appendToGroup(ITextEditorActionConstants.GROUP_ASSIST, action);
		}
		
		menu.add(new Separator(VIEW_GROUP_ID));
	}
	
	protected void fillToolMenu(final Menu menu) {
	}
	
	
	public Document getDocument() {
		return this.document;
	}
	
	public SourceViewer getSourceViewer() {
		return this.sourceViewer;
	}
	
	public Composite getControl() {
		return this.composite;
	}
	
	public StyledText getTextControl() {
		return this.sourceViewer.getTextWidget();
	}
	
	public void reset() {
		this.sourceViewer.resetPlugins();
		this.updater.run();
	}
	
}