/*
Wotonomy: OpenStep design patterns for pure Java applications.
Copyright (C) 2000 Intersect Software Corporation

This library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.

This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public
License along with this library; if not, see http://www.gnu.org
*/

package net.wotonomy.ui;

import net.wotonomy.control.EOClassDescription;
import net.wotonomy.control.EODataSource;
import net.wotonomy.control.EOEditingContext;
import net.wotonomy.control.EOObserverCenter;
import net.wotonomy.control.PropertyDataSource;
import net.wotonomy.foundation.NSArray;
import net.wotonomy.foundation.NSMutableArray;

/**
 * MasterDetailAssociation binds a display group to a property on the selected
 * object of another display group. Bindings are:
 * <ul>
 * <li>parent: The property on the selected object of the bound display group
 * that is expected to be an indexed property.</li>
 * </ul>
 *
 * @author michael@mpowers.net
 * @author $Author: cgruber $
 * @version $Revision: 904 $
 */
public class MasterDetailAssociation extends EOAssociation {
	static final NSArray aspects = new NSArray(new Object[] { ParentAspect });
	static final NSArray aspectSignatures = new NSArray(new Object[] { AttributeToOneAspectSignature });
	static final NSArray objectKeysTaken = new NSArray(new Object[] { "allObjects" });

	/**
	 * Used to be notified of changes to objects in the controlled display group.
	 * requalify() should place all objects fetched into the controlled group into
	 * this array. Otherwise, the parent object is only marked as changed for
	 * inserts and deletes.
	 */
	protected NSMutableArray observableArray;

	/**
	 * Constructor expecting an EODisplayGroup. If the controlled display group does
	 * not have a data source, a new PropertyDataSource will be used.
	 */
	public MasterDetailAssociation(Object anObject) {
		super(anObject);
		observableArray = new ObservableArray(this);
	}

	/**
	 * Returns a List of aspect signatures whose contents correspond with the
	 * aspects list. Each element is a string whose characters represent a
	 * capability of the corresponding aspect.
	 * <ul>
	 * <li>"A" attribute: the aspect can be bound to an attribute.</li>
	 * <li>"1" to-one: the aspect can be bound to a property that returns a single
	 * object.</li>
	 * <li>"M" to-one: the aspect can be bound to a property that returns multiple
	 * objects.</li>
	 * </ul>
	 * An empty signature "" means that the aspect can bind without needing a key.
	 * This implementation returns "A1M" for each element in the aspects array.
	 */
	public static NSArray aspectSignatures() {
		return aspectSignatures;
	}

	/**
	 * Returns a List that describes the aspects supported by this class. Each
	 * element in the list is the string name of the aspect. This implementation
	 * returns an empty list.
	 */
	public static NSArray aspects() {
		return aspects;
	}

	/**
	 * Returns a List of EOAssociation subclasses that, for the objects that are
	 * usable for this association, are less suitable than this association.
	 */
	public static NSArray associationClassesSuperseded() {
		return new NSArray();
	}

	/**
	 * Returns whether this class can control the specified object.
	 */
	public static boolean isUsableWithObject(Object anObject) {
		return (anObject instanceof EODisplayGroup);
	}

	/**
	 * Returns a List of properties of the controlled object that are controlled by
	 * this class. For example, "stringValue", or "selected".
	 */
	public static NSArray objectKeysTaken() {
		return objectKeysTaken;
	}

	/**
	 * Returns the aspect that is considered primary or default. This is typically
	 * "value" or somesuch.
	 */
	public static String primaryAspect() {
		return ParentAspect;
	}

	/**
	 * Returns whether this association can bind to the specified display group on
	 * the specified key for the specified aspect.
	 */
	public boolean canBindAspect(String anAspect, EODisplayGroup aDisplayGroup, String aKey) {
		return (aspects.containsObject(anAspect));
	}

	/**
	 * Establishes a connection between this association and the controlled object.
	 * Subclasses should begin listening for events from their controlled object
	 * here.
	 */
	public void establishConnection() {
		// NOTE: if nothing refers to this assocation, it gets gc'd.
		// otherwise, this is not needed.
		component().addObserver(this);

		EODisplayGroup displayGroup = displayGroupForAspect(ParentAspect);
		String key = displayGroupKeyForAspect(ParentAspect);

		// obtain and qualify new data source from existing source if necessary
		if (component().dataSource() == null) {
			if ((displayGroup != null) && (displayGroup.dataSource() != null)) {
				component().setDataSource(displayGroup.dataSource().dataSourceQualifiedByKey(key));
			}
		}

		// set up proxy data source if necessary
		if (component().dataSource() == null) {
			// get context and class desc from master group
			EOEditingContext editingContext = null;
			EOClassDescription classDesc = null;
			if (displayGroup != null) {
				EODataSource dataSource = displayGroup.dataSource();
				if (dataSource != null) {
					editingContext = dataSource.editingContext();
					EOClassDescription parentDesc = dataSource.classDescriptionForObjects();
					if (parentDesc != null) {
						classDesc = parentDesc.classDescriptionForDestinationKey(key);
					}
				}
			}

			// FIXME: should this be called DetailDataSource?
			component().setDataSource(new PropertyDataSource(editingContext, classDesc));
		}

		super.establishConnection();
		requalify();
	}

	/**
	 * Breaks the connection between this association and its object. Override to
	 * stop listening for events from the object.
	 */
	public void breakConnection() {
		// NOTE: if nothing refers to this assocation, it gets gc'd.
		// otherwise, this is not needed.
		component().deleteObserver(this);

		super.breakConnection();
	}

	/**
	 * Called when either the selection or the contents of an associated display
	 * group have changed.
	 */
	public void subjectChanged() {
		EODisplayGroup displayGroup;

		// parent aspect
		displayGroup = displayGroupForAspect(ParentAspect);
		if (displayGroup != null) {
			if (displayGroup.selectionChanged()) {
				requalify();
			} else if (displayGroup.contentsChanged()) {
				requalify();
			}
		}
	}

	/**
	 * Overridden to intercept notifications of changes to objects in the controlled
	 * display group and broadcast a change on the parent group's selected object.
	 * All other notifications are passed to the super implementation.
	 */
	public void objectWillChange(Object anObject) {
		// if child display group is notifying
		if (!(anObject instanceof EODisplayGroup)) {
			// mark parent group's object as changed
			EODisplayGroup displayGroup = displayGroupForAspect(ParentAspect);
			if (displayGroup != null) {
				Object selected = displayGroup.selectedObject();
				if (selected != null) {
					// only notify if childrenKey is an attribute of parentDesc
					// (and therefore not a toOne or toMany relationship)
					EOClassDescription parentDesc = EOClassDescription.classDescriptionForClass(selected.getClass());
					String key = displayGroupKeyForAspect(ParentAspect);
					if (key != null) {
						int idx = key.indexOf('.');
						if (idx != -1)
							key = key.substring(0, idx);
						if (parentDesc.attributeKeys().contains(key)) {
							// only notify if we are an attribute key
							EOObserverCenter.notifyObserversObjectWillChange(selected);
						}
					}
				}
			}
		} else // display group is notifying
		{
			// call super so subjectChanged will be called
			super.objectWillChange(anObject);
		}
	}

	/**
	 * Called by subjectChanged() to requalify the controlled display group with the
	 * selected object and the bound key.
	 */
	protected void requalify() {
		EODisplayGroup component = component();
		EODisplayGroup displayGroup = displayGroupForAspect(ParentAspect);
		String key = displayGroupKeyForAspect(ParentAspect);

		if ((displayGroup.selectedObject() != null) && (component.dataSource() != null)) {
			component.dataSource().qualifyWithRelationshipKey(key, displayGroup.selectedObject());
			component.fetch();
			observableArray.setArray(component.allObjects());
		} else // no selection or no data source, clear
		{
			component.setObjectArray(null);
			observableArray.removeAllObjects();
		}
		component.updateDisplayedObjects();
	}

	/**
	 * This implementation returns ObserverPrioritySecond so that master detail
	 * assocations are notified before other associations.
	 */
	public int priority() {
		return ObserverPrioritySecond;
	}

	// convenience

	private EODisplayGroup component() {
		return (EODisplayGroup) object();
	}

}

/*
 * $Log$ Revision 1.2 2006/02/18 23:14:35 cgruber Update imports and maven
 * dependencies.
 *
 * Revision 1.1 2006/02/16 13:22:22 cgruber Check in all sources in
 * eclipse-friendly maven-enabled packages.
 *
 * Revision 1.14 2004/02/04 20:00:49 mpowers Improved change notification for
 * dotted key paths.
 *
 * Revision 1.13 2003/08/06 23:07:52 chochos general code cleanup (mostly,
 * removing unused imports)
 *
 * Revision 1.12 2001/10/26 18:39:05 mpowers Now a delayed observer with a
 * higher priority, so that it is processed before other associations.
 *
 * Revision 1.11 2001/06/26 21:39:33 mpowers Added check for null component data
 * source before requalifying.
 *
 * Revision 1.10 2001/05/21 14:04:15 mpowers No longer changing a detail group's
 * data source if it's already specified.
 *
 * Revision 1.9 2001/05/18 21:08:46 mpowers Now calling updateDisplayedObjects
 * on detail after master changes.
 *
 * Revision 1.8 2001/05/14 15:26:42 mpowers Modified logic for controlled groups
 * that have no data source already set.
 *
 * Revision 1.7 2001/05/04 14:42:58 mpowers Now getting stored values in
 * KeyValueCoding. MasterDetail now marks dirty based on whether it's an
 * attribute or relation. Implemented editing context marker.
 *
 * Revision 1.6 2001/04/29 02:29:31 mpowers Debugging relationship faulting.
 *
 * Revision 1.4 2001/02/20 16:38:55 mpowers MasterDetailAssociations now observe
 * their controlled display group's objects for changes to that the parent
 * object will be marked as updated. Before, only inserts and deletes to an
 * object's items are registered. Also, moved ObservableArray to package access.
 *
 * Revision 1.3 2001/01/18 16:57:18 mpowers Fixed problem with losing
 * connection: the association was getting garbage collected because nothing
 * referred to it. All other associations make themselves listeners of their
 * controlled object, and that has been the only thing keeping them from getting
 * gc'd. This will need to be fixed.
 *
 * Revision 1.2 2001/01/17 23:06:09 mpowers TreeAssociation now modifies the
 * contents of the children display group rather than adding items to the titles
 * display group.
 *
 * Revision 1.1.1.1 2000/12/21 15:48:23 mpowers Contributing wotonomy.
 *
 * Revision 1.5 2000/12/20 16:25:40 michael Added log to all files.
 *
 *
 */