/*******************************************************************************
 * Copyright (c) 2000, 2010 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.gef;

import java.beans.PropertyChangeListener;
import java.util.Collection;
import java.util.List;
import java.util.Map;

import org.eclipse.swt.graphics.Cursor;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Control;

import org.eclipse.jface.action.MenuManager;
import org.eclipse.jface.resource.JFaceResources;
import org.eclipse.jface.resource.ResourceManager;
import org.eclipse.jface.util.TransferDragSourceListener;
import org.eclipse.jface.util.TransferDropTargetListener;
import org.eclipse.jface.viewers.ISelection;

import org.eclipse.draw2d.geometry.Point;

/**
 * An adapter on an SWT {@link org.eclipse.swt.widgets.Control} that manages the
 * {@link org.eclipse.gef.EditPart EditParts}. The viewer is responsible for the
 * editpart lifecycle. Editparts have <i>visuals</i>, such as
 * <code>TreeItems</code> or <code>Figures</code>, which are hosted by the
 * viewer and its control. The viewer provides targeting of editparts via their
 * visuals.
 * 
 * <P>
 * A viewer is a {@link org.eclipse.jface.viewers.ISelectionProvider}. It
 * maintains a list of selected editparts. The last member of this list is the
 * <i>primary</i> member of the selection. The list should never be empty; when
 * no editparts are selected, the viewer's contents editpart is used.
 * 
 * <P>
 * A viewer is populated by setting its <i>contents</i>. This can be done by
 * passing the model corresponding to the contents. The viewer's
 * {@link org.eclipse.gef.EditPartFactory EditPartFactory} is then used to
 * create the contents editpart, and add it to the <i>root</i> editpart.
 * Alternatively, the contents editpart itself can be provided. Once the
 * contents editpart is parented, it will populate the rest of the viewer by
 * calling its {@link EditPart#refresh()} method.
 * 
 * <P>
 * The Root editpart does not correspond to anything in the model, it is used to
 * bootstrap the viewer, and to parent the contents. Depending on the type of
 * viewer being used, it may be common to replace the root editpart. See
 * implementations of {@link org.eclipse.gef.RootEditPart}.
 * 
 * <P>
 * An editpart's lifecycle is managed by the viewer. When the Viewer is
 * realized, meaning it has an SWT <code>Control</code>, it activates its root,
 * which in turn activates all editparts. Editparts are deactivated when they
 * are removed from the viewer. When the viewer's control is disposed, all
 * editparts are similarly deactivated by decativating the root.
 * 
 * <P>
 * A Viewer has an arbitrary collection of keyed properties that can be set and
 * queried. A value of <code>null</code> is used to remove a key from the
 * property map. A viewer will fire property change notification whenever these
 * values are updated.
 * 
 * <P>
 * WARNING: This interface is not intended to be implemented. Clients should
 * extend {@link org.eclipse.gef.ui.parts.AbstractEditPartViewer}.
 */
public interface EditPartViewer extends
		org.eclipse.jface.viewers.ISelectionProvider {

	/**
	 * An object which evaluates an EditPart for an arbitrary property.
	 * Conditionals are used when querying a viewer for an editpart.
	 * 
	 * @author hudsonr
	 */
	interface Conditional {
		/**
		 * Returns <code>true</code> if the editpart meets this condition.
		 * 
		 * @param editpart
		 *            the editpart being evaluated
		 * @return <code>true</code> if the editpart meets the condition
		 */
		boolean evaluate(EditPart editpart);
	}

	/**
	 * Provided for compatibility with existing code.
	 * 
	 * @param listener
	 *            a drag source listener
	 * @see #addDragSourceListener(TransferDragSourceListener)
	 */
	void addDragSourceListener(
			org.eclipse.gef.dnd.TransferDragSourceListener listener);

	/**
	 * Adds a <code>TransferDragSourceListener</code> to this viewer. This has
	 * the side-effect of creating a {@link org.eclipse.swt.dnd.DragSource} on
	 * the viewer's Control. A Control can only have a single DragSource.
	 * Clients must not create their own DragSource when using this method.
	 * 
	 * @param listener
	 *            the listener
	 */
	void addDragSourceListener(TransferDragSourceListener listener);

	/**
	 * Provided for compatibility with existing code.
	 * 
	 * @param listener
	 *            the listener
	 * @see #addDropTargetListener(TransferDropTargetListener)
	 */
	void addDropTargetListener(
			org.eclipse.gef.dnd.TransferDropTargetListener listener);

	/**
	 * Adds a <code>TransferDropTargetListener</code> to this viewer. This has
	 * the side-effect of creating a {@link org.eclipse.swt.dnd.DropTarget} on
	 * the viewer's Control. A Control can only have a single DropTarget.
	 * Clients must not create their own DropTarget when using this method.
	 * 
	 * @param listener
	 *            the listener
	 */
	void addDropTargetListener(TransferDropTargetListener listener);

	/**
	 * Adds a listener to be notified of viewer property changes.
	 * 
	 * @param listener
	 *            the listener
	 */
	void addPropertyChangeListener(PropertyChangeListener listener);

	/**
	 * Appends the specified <code>EditPart</code> to the viewer's
	 * <i>selection</i>. The EditPart becomes the new primary selection. Fires
	 * selection changed to all
	 * {@link org.eclipse.jface.viewers.ISelectionChangedListener}s.
	 * 
	 * @param editpart
	 *            the EditPart to append
	 */
	void appendSelection(EditPart editpart);

	/**
	 * Optionally creates the default {@link org.eclipse.swt.widgets.Control
	 * Control} using the default style. The Control can also be created
	 * externally and then set into the Viewer.
	 * 
	 * @param composite
	 *            the parent in which create the SWT <code>Control</code>
	 * @see #setControl(Control)
	 * @return the created Control for convenience
	 */
	Control createControl(Composite composite);

	/**
	 * Removes the specified <code>EditPart</code> from the current selection.
	 * If the selection becomes empty, the viewer's {@link #getContents()
	 * contents} becomes the current selected part. The last EditPart in the new
	 * selection is made {@link EditPart#SELECTED_PRIMARY primary}.
	 * <P>
	 * Fires selection changed to
	 * {@link org.eclipse.jface.viewers.ISelectionChangedListener}s.
	 * 
	 * @param editpart
	 *            the <code>EditPart</code> to deselect
	 */
	void deselect(EditPart editpart);

	/**
	 * Deselects all EditParts. The viewer's {@link #getContents() contents}
	 * becomes the current selection. Fires selection changed to
	 * {@link org.eclipse.jface.viewers.ISelectionChangedListener}s.
	 */
	void deselectAll();

	/**
	 * Returns <code>null</code> or the <code>EditPart</code> associated with
	 * the specified location. The location is relative to the client area of
	 * the Viewer's <code>Control</code>. An EditPart is not directly visible.
	 * It is targeted using its <i>visual part</i> which it registered using the
	 * {@link #getVisualPartMap() visual part map}. What constitutes a <i>visual
	 * part</i> is viewer-specific. Examples include Figures and TreeItems.
	 * 
	 * @param location
	 *            The location
	 * @return <code>null</code> or an EditPart
	 */
	EditPart findObjectAt(Point location);

	/**
	 * Returns <code>null</code> or the <code>EditPart</code> at the specified
	 * location, excluding the specified set. This method behaves similarly to
	 * {@link #findObjectAt(Point)}.
	 * 
	 * @param location
	 *            The mouse location
	 * @param exclusionSet
	 *            The set of EditParts to be excluded
	 * @return <code>null</code> or an EditPart
	 */
	EditPart findObjectAtExcluding(Point location, Collection exclusionSet);

	/**
	 * Returns <code>null</code> or the <code>EditPart</code> at the specified
	 * location, using the given exclusion set and conditional. This method
	 * behaves similarly to {@link #findObjectAt(Point)}.
	 * 
	 * @param location
	 *            The mouse location
	 * @param exclusionSet
	 *            The set of EditParts to be excluded
	 * @param conditional
	 *            the Conditional used to evaluate a potential hit
	 * @return <code>null</code> or an EditPart
	 */
	EditPart findObjectAtExcluding(Point location, Collection exclusionSet,
			Conditional conditional);

	/**
	 * Flushes all pending updates to the Viewer.
	 */
	void flush();

	/**
	 * Returns the <i>contents</i> of this Viewer. The contents is the EditPart
	 * associated with the top-level model object. It is considered to be
	 * "The Diagram". If the user has nothing selected, the <i>contents</i> is
	 * implicitly the selected object.
	 * <P>
	 * The <i>Root</i> of the Viewer is different. By constrast, the root is
	 * never selected or targeted, and does not correspond to something in the
	 * model.
	 * 
	 * @see #getRootEditPart()
	 * @return the <i>contents</i> <code>EditPart</code>
	 */
	EditPart getContents();

	/**
	 * Returns <code>null</code> or the MenuManager for this viewer. The menu
	 * manager is set using {@link #setContextMenu(MenuManager)}.
	 * 
	 * @return <code>null</code> or a MenuManager
	 */
	MenuManager getContextMenu();

	/**
	 * Returns <code>null</code> or the SWT <code>Control</code> for this
	 * viewer. The control is either set explicitly or can be created by the
	 * viewer.
	 * 
	 * @see #setControl(Control)
	 * @see #createControl(Composite)
	 * @return the SWT <code>Control</code>
	 */
	Control getControl();

	/**
	 * Returns the {@link EditDomain EditDomain} to which this viewer belongs.
	 * 
	 * @return the viewer's EditDomain
	 */
	EditDomain getEditDomain();

	/**
	 * Returns the <code>EditPartFactory</code> for this viewer. The
	 * EditPartFactory is used to create the <i>contents</i> EditPart when
	 * {@link #setContents(Object)} is called. It is made available so that
	 * other EditParts can use it to create their children or connection
	 * editparts.
	 * 
	 * @return EditPartFactory
	 */
	EditPartFactory getEditPartFactory();

	/**
	 * Returns the {@link Map} for registering <code>EditParts</code> by
	 * <i>Keys</i>. EditParts may register themselves using any method, and may
	 * register themselves with multiple keys. The purpose of such registration
	 * is to allow an EditPart to be found by other EditParts, or by listeners
	 * of domain notifiers. By default, EditParts are registered by their model.
	 * <P>
	 * Some models use a "domain" notification system, in which all changes are
	 * dispatched to a single listener. Such a listener might use this map to
	 * lookup editparts for a given model, and then ask the editpart to update.
	 * 
	 * @return the registry map
	 */
	Map getEditPartRegistry();

	/**
	 * Returns the <i>focus</i> <code>EditPart</code>. Focus refers to keyboard
	 * focus. This is the same concept as focus in a native Tree or Table. The
	 * User can change focus using the keyboard without affecting the currently
	 * selected objects. Never returns <code>null</code>.
	 * 
	 * @return the <i>focus</i> <code>EditPart</code>
	 */
	EditPart getFocusEditPart();

	/**
	 * Returns the <code>KeyHandler</code> for this viewer. The KeyHandler is
	 * sent KeyEvents by the currently active <code>Tool</code>. This is
	 * important, because only the current tool knows if it is in a state in
	 * which keys should be ignored, such as during a drag. By default, only the
	 * {@link org.eclipse.gef.tools.SelectionTool} forwards keysrokes. It does
	 * not do so during a drag.
	 * 
	 * @return <code>null</code> or a KeyHandler
	 */
	KeyHandler getKeyHandler();

	/**
	 * Returns the value of the given property. Returns <code>null</code> if the
	 * property has not been set, or has been set to null.
	 * 
	 * @param key
	 *            the property's key
	 * @return the given properties value or <code>null</code>.
	 */
	Object getProperty(String key);

	/**
	 * Returns <code>null</code>, or the ResourceManager for this Viewer. Once a
	 * viewer has a Control, clients may access the viewer's resource manager.
	 * Any resources constructed using this manager, but not freed, will be
	 * freed when the viewer's control is disposed. This does not mean that
	 * clients should be lazy about deallocating resources. If a resource is no
	 * longer needed but the viewer is still in use, the client must deallocate
	 * the resource.
	 * <P>
	 * Typical usage is by EditParts contained inside the viewer. EditParts
	 * which are removed from the viewer should free their resources during
	 * {@link EditPart#removeNotify()}. When the viewer is disposed,
	 * <code>removeNotify()</code> is not called, but the viewer's resource
	 * manager will be disposed anyway.
	 * <P>
	 * The viewer's default resource manager is linked to JFace's
	 * {@link JFaceResources#getResources() global shared resources}.
	 * 
	 * @return the ResourceManager associated with this viewer
	 * @since 3.3
	 */
	ResourceManager getResourceManager();

	/**
	 * Returns the <code>RootEditPart</code>. The RootEditPart is a special
	 * EditPart that serves as the parent to the contents editpart. The
	 * <i>root</i> is never selected. The root does not correspond to anything
	 * in the model. The User does not interact with the root.
	 * <P>
	 * The RootEditPart has a single child: the {@link #getContents() contents}.
	 * <P>
	 * By defining the concept of "root", GEF allows the application's "real"
	 * EditParts to be more homogeneous. For example, all non-root EditParts
	 * have a parent. Also, it allows applications to change the type of root
	 * being used without affecting their own editpart implementation hierarchy.
	 * 
	 * @see #getContents()
	 * @see #setRootEditPart(RootEditPart)
	 * @return the RootEditPart
	 */
	RootEditPart getRootEditPart();

	/**
	 * Returns an unmodifiable <code>List</code> containing zero or more
	 * selected editparts. This list may be empty. In contrast, the inherited
	 * method
	 * {@link org.eclipse.jface.viewers.ISelectionProvider#getSelection()}
	 * should not return an empty selection. When no editparts are selected,
	 * generally the contents editpart is considered to be selected. This list
	 * can be modified indirectly by calling other methods on the viewer.
	 * 
	 * @return a list containing zero or more editparts
	 */
	List getSelectedEditParts();

	/**
	 * This method is inherited from
	 * {@link org.eclipse.jface.viewers.ISelectionProvider ISelectionProvider}.
	 * This method should return a
	 * {@link org.eclipse.jface.viewers.StructuredSelection} containing one or
	 * more of the viewer's EditParts. If no editparts are selected, the
	 * {@link #getContents() contents} editpart is returned.
	 * 
	 * @see org.eclipse.jface.viewers.ISelectionProvider#getSelection()
	 */
	ISelection getSelection();

	/**
	 * Returns the viewer's selection manager. The selection manager has
	 * complete control over the viewer's representation of selection. It
	 * provides the {@link ISelection} for the viewer, and manages all changes
	 * to the current selection.
	 * 
	 * @return the selection manager
	 * @since 3.2
	 */
	SelectionManager getSelectionManager();

	/**
	 * Returns the {@link Map} for associating <i>visual parts</i> with their
	 * <code>EditParts</code>. This map is used for hit-testing. Hit testing is
	 * performed by first determining which visual part is hit, and then mapping
	 * that part to an <code>EditPart</code>. What consistutes a <i>visual
	 * part</i> is viewer-specific. Examples include <code>Figures</code> and
	 * <code>TreeItems</code>.
	 * 
	 * @return the visual part map
	 */
	Map getVisualPartMap();

	/**
	 * Used for accessibility purposes.
	 * 
	 * @param acc
	 *            the AccessibleEditPart
	 */
	void registerAccessibleEditPart(AccessibleEditPart acc);

	/**
	 * Removes the specified drag source listener. If all listeners are removed,
	 * the DragSource that was created will be disposed.
	 * 
	 * @see #addDragSourceListener(TransferDragSourceListener)
	 * @param listener
	 *            the listener
	 * @deprecated
	 */
	void removeDragSourceListener(
			org.eclipse.gef.dnd.TransferDragSourceListener listener);

	/**
	 * Removes the specified drag source listener. If all listeners are removed,
	 * the DragSource that was created will be disposed.
	 * 
	 * @see #addDragSourceListener(TransferDragSourceListener)
	 * @param listener
	 *            the listener
	 */
	void removeDragSourceListener(TransferDragSourceListener listener);

	/**
	 * Removes the specified drop target listener. If all listeners are removed,
	 * the DropTarget that was created will be disposed.
	 * 
	 * @see #addDropTargetListener(TransferDropTargetListener)
	 * @param listener
	 * @deprecated
	 */
	void removeDropTargetListener(
			org.eclipse.gef.dnd.TransferDropTargetListener listener);

	/**
	 * Removes the specified drop target listener. If all listeners are removed,
	 * the DropTarget that was created will be disposed.
	 * 
	 * @see #addDropTargetListener(TransferDropTargetListener)
	 * @param listener
	 *            the listener
	 */
	void removeDropTargetListener(TransferDropTargetListener listener);

	/**
	 * removes the first instance of the specified property listener.
	 * 
	 * @param listener
	 *            the listener to remove
	 */
	void removePropertyChangeListener(PropertyChangeListener listener);

	/**
	 * Reveals the given EditPart if it is not visible.
	 * 
	 * @param editpart
	 *            the EditPart to reveal
	 */
	void reveal(EditPart editpart);

	/**
	 * Replaces the current selection with the specified <code>EditPart</code>.
	 * That part becomes the primary selection. Fires selection changed to
	 * {@link org.eclipse.jface.viewers.ISelectionChangedListener}s.
	 * 
	 * @param editpart
	 *            the new selection
	 */
	void select(EditPart editpart);

	/**
	 * Sets the contents for this Viewer. The contents can also be set using
	 * {@link #setContents(Object)}.
	 * 
	 * @param editpart
	 *            the contents
	 * @see #getRootEditPart()
	 */
	void setContents(EditPart editpart);

	/**
	 * Creates an <code>EditPart</code> for the provided model object using the
	 * <code>EditPartFactory</code>. That EditPart is then added to the
	 * {@link #getRootEditPart() RootEditPart}, and becomes the viewer's
	 * contents editpart.
	 * 
	 * @param contents
	 *            the contents model object
	 */
	void setContents(Object contents);

	/**
	 * Sets the context <code>MenuManager</code> for this viewer. The
	 * MenuManager will be asked to create a Menu, which will be used as the
	 * context menu for this viewer's Control.
	 * 
	 * @param contextMenu
	 *            the <code>ContextMenuProvider</code>
	 */
	void setContextMenu(MenuManager contextMenu);

	/**
	 * Sets the <code>Control</code> for this viewer. The viewer's control is
	 * also set automatically if {@link #createControl(Composite)} is called.
	 * 
	 * @param control
	 *            the Control
	 */
	void setControl(Control control);

	/**
	 * Sets the cursor for the viewer's <code>Control</code>. This method should
	 * only be called by {@link Tool Tools}. <code>null</code> can be used to
	 * indicate that the default cursor should be restored.
	 * 
	 * @param cursor
	 *            <code>null</code> or a Cursor
	 * @see #getControl()
	 */
	void setCursor(Cursor cursor);

	/**
	 * Sets the <code>EditDomain</code> for this viewer. The Viewer will route
	 * all mouse and keyboard events to the EditDomain.
	 * 
	 * @param domain
	 *            The EditDomain
	 */
	void setEditDomain(EditDomain domain);

	/**
	 * Sets the EditPartFactory.
	 * 
	 * @param factory
	 *            the factory
	 * @see #getEditPartFactory()
	 */
	void setEditPartFactory(EditPartFactory factory);

	/**
	 * Sets the <i>focus</i> EditPart.
	 * 
	 * @see #getFocusEditPart()
	 * @param focus
	 *            the FocusPart.
	 */
	void setFocus(EditPart focus);

	/**
	 * Sets the <code>KeyHandler</code>.
	 * 
	 * @param keyHandler
	 *            the KeyHandler
	 * @see #getKeyHandler()
	 */
	void setKeyHandler(KeyHandler keyHandler);

	/**
	 * Sets a property on this viewer. A viewer property is an arbitrary
	 * key-value pair that can be observed via
	 * {@link #addPropertyChangeListener(PropertyChangeListener)}. A
	 * <code>null</code> value will remove the property from the viewer.
	 * 
	 * @param propertyName
	 *            a unique string identifying the property
	 * @param value
	 *            the properties new value or <code>null</code> to remove
	 * @since 3.0
	 */
	void setProperty(String propertyName, Object value);

	/**
	 * Sets the <i>root</i> of this viewer. The root should not be confused with
	 * the <i>contents</i>.
	 * 
	 * @param root
	 *            the RootEditPart
	 * @see #getRootEditPart()
	 * @see #getContents()
	 */
	void setRootEditPart(RootEditPart root);

	/**
	 * Turns on/off the routing of events directly to the Editor. If supported
	 * by the viewer implementation, all Events should be routed to the
	 * <code>EditDomain</code> rather than handled in the default way.
	 * 
	 * @param value
	 *            true if the viewer should route events to the EditDomain
	 */
	void setRouteEventsToEditDomain(boolean value);

	/**
	 * Sets the selection manager for this viewer.
	 * 
	 * @param manager
	 *            the new selection manager
	 * @since 3.2
	 */
	void setSelectionManager(SelectionManager manager);

	/**
	 * Used for accessibility purposes.
	 * 
	 * @param acc
	 *            the accessible part
	 */
	void unregisterAccessibleEditPart(AccessibleEditPart acc);

}