/*******************************************************************************
 * Copyright (c) 2000, 2004 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
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.snippets;

/*
 *
 * For a list of all SWT example snippets see
 * http://www.eclipse.org/swt/snippets/
 */
import org.eclipse.core.databinding.Binding;
import org.eclipse.core.databinding.DataBindingContext;
import org.eclipse.core.databinding.UpdateValueStrategy;
import org.eclipse.core.databinding.beans.PojoObservables;
import org.eclipse.core.databinding.conversion.Converter;
import org.eclipse.core.databinding.observable.Realm;
import org.eclipse.core.databinding.observable.value.IObservableValue;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.jface.databinding.swt.SWTObservables;
import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.FormAttachment;
import org.eclipse.swt.layout.FormData;
import org.eclipse.swt.layout.FormLayout;
import org.eclipse.swt.widgets.Button;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;

public class SnippetUpdtStrategEx {

	/**
	 * the model bound to the UI.
	 * 
	 */
	private static class MyModel {

		private String myText;

		public String getMyText() {
			return myText;
		}

		public void setMyText(String myText) {
			this.myText = myText;
		}
	}

	/**
	 * 
	 * Represents the updatevaluestrategy that will be used to manually update
	 * the target
	 * 
	 */
	private static class UpdateValueStrategyEx extends UpdateValueStrategy {
		private Binding binding;

		/**
		 * 
		 * @param policy
		 */
		public UpdateValueStrategyEx(int policy) {
			super(policy);
		}

		public void setBinding(Binding binding) {
			this.binding = binding;
		}

		@Override
		protected IStatus doSet(IObservableValue observableValue, Object value) {
			IStatus status = super.doSet(observableValue, value);
			if (binding != null)
				binding.updateModelToTarget();
			return status;
		}

	}

	/**
	 * 
	 * A composite that will contains a text to validate.
	 * 
	 */
	private static class MainCompo extends Composite {
		private final MyModel model = new MyModel();

		private Text text;

		private Button button;

		/**
		 * 
		 * @param parent
		 * @param style
		 */
		public MainCompo(Composite parent, int style) {
			super(parent, style);
			doLayout();
		}

		private void doLayout() {
			setLayout(new FormLayout());

			Label lbl = new Label(this, SWT.NONE);
			lbl.setText("Enter a text without 'aa' :");

			text = new Text(this, SWT.BORDER);

			button = new Button(this, SWT.NONE);
			button.setText("Hello");

			FormData data = new FormData();
			data.left = new FormAttachment(0, 100, 5);
			data.top = new FormAttachment(text, 0, SWT.CENTER);
			lbl.setLayoutData(data);

			data = new FormData();
			data.left = new FormAttachment(lbl, 5, SWT.RIGHT);
			data.top = new FormAttachment(0, 100, 5);
			data.right = new FormAttachment(100, 100, -5);
			text.setLayoutData(data);

			data = new FormData();
			data.left = new FormAttachment(lbl, 5, SWT.RIGHT);
			data.top = new FormAttachment(text, 5);
			button.setLayoutData(data);

		}

		/**
		 * we bind text to MyModel.myText
		 */
		public void binding(final DataBindingContext dbc) {
			// let's go binding text to MyModel.myText
			// we will do validation
			// In case the string typed by the user contains 'aa', we do the
			// roundtrip to go
			// back to the last correct value.
			// Unfortunately, this solution does not work if we type two times
			//the same bad text
			

			final UpdateValueStrategyEx strgTargetToModel = new UpdateValueStrategyEx(
					UpdateValueStrategy.POLICY_UPDATE);
			final UpdateValueStrategy strgModelToTarget = new UpdateValueStrategy(
					UpdateValueStrategy.POLICY_UPDATE);
			Binding b = dbc.bindValue(SWTObservables.observeText(text,
					SWT.FocusOut), PojoObservables
					.observeValue(model, "myText"), strgTargetToModel,
					strgModelToTarget);

			//don't forget to set the binding
			strgTargetToModel.setBinding(b);
			strgTargetToModel.setConverter(new Converter(String.class, String.class) {
				
				@Override
				public Object convert(Object fromObject) {
					if (fromObject == null) {
						
						return "";
					}
					String strVal = (String) fromObject;
					// error, contains 'aa'
					if (strVal.indexOf("aa") != -1) {
						//force the update with the last valid value
						return model.getMyText();
					}
					return strVal;
				}
			});
			

		}

	}

	/**
	 * Main entry point
	 * 
	 * @param args
	 */
	public static void main(String[] args) {
		final Display display = new Display();

		Realm.runWithDefault(SWTObservables.getRealm(display), new Runnable() {
			public void run() {
				Shell shell = new Shell(display);
				shell.setBounds(0, 0, 400, 200);
				shell.setLayout(new FormLayout());
				MainCompo compo = new MainCompo(shell, SWT.NONE);
				FormData data = new FormData();
				data.left = new FormAttachment(0, 100, 0);
				data.right = new FormAttachment(100, 100, 0);
				data.top = new FormAttachment(0, 100, 0);
				data.bottom = new FormAttachment(100, 100, 0);
				compo.setLayoutData(data);

				final DataBindingContext dbc = new DataBindingContext();
				compo.binding(dbc);
				shell.open();

				while (!shell.isDisposed()) {
					if (!display.readAndDispatch())
						display.sleep();
				}
			}
		});
		display.dispose();
	}
}