package com.temp.client.foundation.pavment;

import com.google.gwt.user.client.ui.*;

public interface Activity {
    /**
     * Called when the user is trying to navigate away from this activity.
     *
     * @return A message to display to the user, e.g. to warn of unsaved work,
     * or null to say nothing
     */
    String mayStop();

    /**
     * Called when {@link #start} has not yet replied to its callback, but the
     * user has lost interest.
     */
    void onCancel();

    /**
     * Called when the Activity's widget has been removed from view.
     */
    void onStop();

    /**
     * Called when the Activity should ready its widget for the user. When the
     * widget is ready (typically after an RPC response has been received),
     * receiver should present it by calling {@link AcceptsOneWidget#setWidget}
     * on the given panel.
     *
     * @param panel the panel to display this activity's widget when it is ready
     */
    void start( AcceptsOneWidget panel );

    /**
     * Called when the Activity should refresh its view's data.
     * <p/>
     * This should result in the same "view" as if 'start' had just been called.
     * <p/>
     * It is called when, for whatever reason, a 'place' change is request that
     * would have resulted in the same activity being instantiated & started
     * with the same data (i.e. with obfuscation, the URL Fragment would have
     * been the same, and hence, the browser is free to NOT dispatch a History
     * Change Event).
     */
    void refresh();
}