common/plugins/org.eclipse.jpt.common.utility/src/org/eclipse/jpt/common/utility/internal/model/value/swing/DateSpinnerModelAdapter.java

/*******************************************************************************
 * Copyright (c) 2007, 2012 Oracle. 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:
 *     Oracle - initial API and implementation
 ******************************************************************************/
package org.eclipse.jpt.common.utility.internal.model.value.swing;

import java.util.Calendar;
import java.util.Date;
import javax.swing.SpinnerDateModel;
import javax.swing.event.ChangeListener;
import org.eclipse.jpt.common.utility.internal.StringTools;
import org.eclipse.jpt.common.utility.internal.model.listener.awt.AWTPropertyChangeListenerWrapper;
import org.eclipse.jpt.common.utility.model.event.PropertyChangeEvent;
import org.eclipse.jpt.common.utility.model.listener.PropertyChangeListener;
import org.eclipse.jpt.common.utility.model.value.PropertyValueModel;
import org.eclipse.jpt.common.utility.model.value.ModifiablePropertyValueModel;

/**
 * This javax.swing.SpinnerDateModel can be used to keep a ChangeListener
 * (e.g. a JSpinner) in synch with a PropertyValueModel that holds a date.
 * 
 * This class must be a sub-class of SpinnerDateModel because of some
 * crappy jdk code....  ~bjv
 * @see javax.swing.JSpinner#createEditor(javax.swing.SpinnerModel)
 * 
 * If this class needs to be modified, it would behoove us to review the
 * other, similar classes:
 * @see ListSpinnerModelAdapter
 * @see NumberSpinnerModelAdapter
 */
public class DateSpinnerModelAdapter
	extends SpinnerDateModel
{

	/**
	 * The default spinner value; used when the underlying model date value is null.
	 * The default is the current date.
	 */
	private final Date defaultValue;

	/** A value model on the underlying date. */
	private final ModifiablePropertyValueModel<Object> dateHolder;

	/** A listener that allows us to synchronize with changes made to the underlying date. */
	private final PropertyChangeListener dateChangeListener;


	// ********** constructors **********

	/**
	 * Constructor - the date holder is required.
	 * The default spinner value is the current date.
	 */
	public DateSpinnerModelAdapter(ModifiablePropertyValueModel<Object> dateHolder) {
		this(dateHolder, new Date());
	}

	/**
	 * Constructor - the date holder and default value are required.
	 */
	public DateSpinnerModelAdapter(ModifiablePropertyValueModel<Object> dateHolder, Date defaultValue) {
		this(dateHolder, null, null, Calendar.DAY_OF_MONTH, defaultValue);
	}

	/**
	 * Constructor - the date holder is required.
	 * The default spinner value is the current date.
	 */
	public DateSpinnerModelAdapter(ModifiablePropertyValueModel<Object> dateHolder, Comparable<?> start, Comparable<?> end, int calendarField) {
		this(dateHolder, start, end, calendarField, new Date());
	}

	/**
	 * Constructor - the date holder is required.
	 */
	public DateSpinnerModelAdapter(ModifiablePropertyValueModel<Object> dateHolder, Comparable<?> start, Comparable<?> end, int calendarField, Date defaultValue) {
		super(dateHolder.getValue() == null ? defaultValue : (Date) dateHolder.getValue(), start, end, calendarField);
		this.dateHolder = dateHolder;
		this.dateChangeListener = this.buildDateChangeListener();
		// postpone listening to the underlying date
		// until we have listeners ourselves...
		this.defaultValue = defaultValue;
	}


	// ********** initialization **********

	protected PropertyChangeListener buildDateChangeListener() {
		return new AWTPropertyChangeListenerWrapper(this.buildDateChangeListener_());
	}

	protected PropertyChangeListener buildDateChangeListener_() {
		return new PropertyChangeListener() {
			public void propertyChanged(PropertyChangeEvent event) {
				DateSpinnerModelAdapter.this.synchronize(event.getNewValue());
			}
			@Override
			public String toString() {
				return "date listener"; //$NON-NLS-1$
			}
		};
	}


	// ********** SpinnerModel implementation **********

	/**
	 * Extend to check whether this method is being called before we 
	 * have any listeners.
	 * This is necessary because some crappy jdk code gets the value
	 * from the model *before* listening to the model.  ~bjv
	 * @see javax.swing.JSpinner.DefaultEditor(javax.swing.JSpinner)
	 */
    @Override
	public Object getValue() {
		if (this.getChangeListeners().length == 0) {
			// sorry about this "lateral" call to super  ~bjv
			super.setValue(this.spinnerValueOf(this.dateHolder.getValue()));
		}
		return super.getValue();
	}

	/**
	 * Extend to update the underlying date directly.
	 * The resulting event will be ignored: @see #synchronize(Object).
	 */
	@Override
	public void setValue(Object value) {
		super.setValue(value);
		this.dateHolder.setValue(value);
	}

	/**
	 * Extend to start listening to the underlying date if necessary.
	 */
	@Override
	public void addChangeListener(ChangeListener listener) {
		if (this.getChangeListeners().length == 0) {
			this.dateHolder.addPropertyChangeListener(PropertyValueModel.VALUE, this.dateChangeListener);
			this.synchronize(this.dateHolder.getValue());
		}
		super.addChangeListener(listener);
	}

	/**
	 * Extend to stop listening to the underlying date if appropriate.
	 */
    @Override
	public void removeChangeListener(ChangeListener listener) {
		super.removeChangeListener(listener);
		if (this.getChangeListeners().length == 0) {
			this.dateHolder.removePropertyChangeListener(PropertyValueModel.VALUE, this.dateChangeListener);
		}
	}


	// ********** queries **********

	protected Date getDefaultValue() {
		return this.defaultValue;
	}

	/**
	 * Convert to a non-null value.
	 */
	protected Object spinnerValueOf(Object value) {
		return (value == null) ? this.getDefaultValue() : value;
	}


	// ********** behavior **********

	/**
	 * Set the spinner value if it has changed.
	 */
	void synchronize(Object value) {
		Object newValue = this.spinnerValueOf(value);
		// check to see whether the spinner date has already been synchronized
		// (via #setValue())
		if ( ! this.getValue().equals(newValue)) {
			this.setValue(newValue);
		}
	}


	// ********** standard methods **********

	@Override
	public String toString() {
		return StringTools.buildToStringFor(this, this.dateHolder);
	}

}