/* *************************************************************************
 
 IT Mill Toolkit 

 Development of Browser User Interfaces Made Easy

 Copyright (C) 2000-2006 IT Mill Ltd
 
 *************************************************************************

 This product is distributed under commercial license that can be found
 from the product package on license.pdf. Use of this product might 
 require purchasing a commercial license from IT Mill Ltd. For guidelines 
 on usage, see licensing-guidelines.html

 *************************************************************************
 
 For more information, contact:
 
 IT Mill Ltd                           phone: +358 2 4802 7180
 Ruukinkatu 2-4                        fax:   +358 2 4802 7181
 20540, Turku                          email:  info@itmill.com
 Finland                               company www: www.itmill.com
 
 Primary source for information and releases: www.itmill.com

 ********************************************************************** */

package com.itmill.toolkit.terminal;

import java.util.Map;
import java.util.Set;

/**
 * <p>
 * Listener interface for UI variable changes. The user communicates with the
 * application using the so-called <i>variables</i>. When the user makes a
 * change using the UI the terminal trasmits the changed variables to the
 * application, and the components owning those variables may then process those
 * changes.
 * </p>
 * 
 * <p>
 * The variable-owning components can be linked with <i>dependency relationships</i>.
 * A dependency between two components means that all variable change events to
 * the depended component will be handled before any such events to the
 * depending component.
 * </p>
 * 
 * <p>
 * For example, the commit button for a text field will depend on that text
 * field. This is because we want to handle any pending changes the user makes
 * to the contents on the text field before we accept the click of the commit
 * button which starts processing the text field contents.
 * </p>
 * 
 * @author IT Mill Ltd.
 * @version
 * @VERSION@
 * @since 3.0
 */
public interface VariableOwner {

    /**
     * Dependencies are not needed anymore as HTML-mode is deprecated in Toolkit
     * 5. *
     * 
     * @return Set of <code>VariableOwners</code> this component directly
     *         depend on, <code>null</code> if this component does not depend
     *         on anybody.
     * @deprecated
     */
    public Set getDirectDependencies();

    /**
     * Called when one or more variables handled by the implementing class are
     * changed.
     * 
     * @param source
     *                the Source of the variable change. This is the origin of
     *                the event. For example in Web Adapter this is the request.
     * @param variables
     *                the Mapping from variable names to new variable values.
     */
    public void changeVariables(Object source, Map variables);

    /**
     * Dependencies are not needed anymore as HTML-mode is deprecated in Toolkit
     * 5.
     * 
     * @param depended
     *                the <code>VariableOwner</code> component who this
     *                component depends on.
     * @deprecated
     */
    public void dependsOn(VariableOwner depended);

    /**
     * Dependencies are not needed anymore as HTML-mode is deprecated in Toolkit
     * 5.
     * 
     * @param depended
     *                the component to be removed from this component's
     *                dependency list.
     * @deprecated
     */
    public void removeDirectDependency(VariableOwner depended);

    /**
     * <p>
     * Tests if the variable owner is enabled or not. The terminal should not
     * send any variable changes to disabled variable owners.
     * </p>
     * 
     * @return <code>true</code> if the variable owner is enabled,
     *         <code>false</code> if not
     */
    public boolean isEnabled();

    /**
     * <p>
     * Tests if the variable owner is in immediate mode or not. Being in
     * immediate mode means that all variable changes are required to be sent
     * back from the terminal immediately when they occur.
     * </p>
     * 
     * <p>
     * <strong>Note:</strong> <code>VariableOwner</code> does not include a
     * set- method for the immediateness property. This is because not all
     * VariableOwners wish to offer the functionality. Such VariableOwners are
     * never in the immediate mode, thus they always return <code>false</code>
     * in {@link #isImmediate()}.
     * </p>
     * 
     * @return <code>true</code> if the component is in immediate mode,
     *         <code>false</code> if not.
     */
    public boolean isImmediate();

    /**
     * VariableOwner error event.
     */
    public interface ErrorEvent extends Terminal.ErrorEvent {

        /**
         * Gets the source VariableOwner.
         * 
         * @return the variable owner.
         */
        public VariableOwner getVariableOwner();

    }
}