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package org.valkyriercp.widget;

import org.valkyriercp.application.PageComponentContext;
import org.valkyriercp.command.support.AbstractCommand;

import javax.swing.*;
import java.util.List;

/**
 * Widget specifies the interface for Swing component factories
 *
 * General usage of implementations:
 * 
 * Instantiate the widget
 * Set specific parameters for the widget or use overloaded constructors
 * to combine this step and the previous one
 * Get the component using {@link #getComponent()}
 * 
 */
public interface Widget
{
    static Widget EMPTY_WIDGET = new AbstractWidget(){

        public JComponent getComponent()
        {
            return new JPanel();
        }

        @Override
        public String getId() {
            return "emptyWidget";
        }
    };

    static WidgetProvider EMPTY_WIDGET_PROVIDER = new WidgetProvider(){

        @Override
        public Widget getWidget() {
            return EMPTY_WIDGET;
        }
    };


    /**
     * @return A not null graphical component built using the
     * parameters held in the widget instance.
     */
    public JComponent getComponent();

    /**
     * Hook method called before showing the component on screen.
     */
    public void onAboutToShow();

    /**
     * Hook method called before moving the component to the background (=hiding)
     */
    public void onAboutToHide();

    /**
     * Encompasses the status of the widget between onAboutToShow() and onAboutToHide().
     * A component does not know when it's active, even if there is an isShowing() method
     * in it's API (due to tab panels or scroll panes).
     *
     * @return true if the widget is shown in the foreground.
     */
    public boolean isShowing();

    /**
     * Checks whether this component can be closed visually, for example when there
     * are no unsaved changes.
     *
     * @return true if the widget can be closed without problems.
     */
    public boolean canClose();

    /**
     * Returns a list of commands for this widget.
     */
    public List getCommands();

    public String getId();

    public void registerLocalCommandExecutors(PageComponentContext context);
}