/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2011 by Rapid-I and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapid-i.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.gui.tools.actions;

import java.awt.event.ActionEvent;

import com.rapidminer.gui.tools.ResourceAction;

/**
 * This action is meant for actions that depend on a selection but are present
 * all the time.
 * Subclasses will get the currently selected object automatically and can perform
 * their action depending on it.
 * Additionally if included somewhere these actions can be enabled or disabled depending
 * on the current selection. GUI classes using this kind of action need to call {@link #selectionChanged()}
 * whenever the selection changes to update the state of the action.
 * 
 * @author Sebastian Land
 */
public abstract class SelectionDependentAction extends ResourceAction {

    /**
     * Interface for all selection dependencies. These actions can
     * for example be dependent on a Tree selection, or list selection.
     *
     * @author Sebastian Land
     */
    public static interface SelectionDependency {
        /**
         * This method has to return the currently selected object or null if
         * nothing is selected.
         */
        public Object getSelectedObject();
    }

    private static final long serialVersionUID = 1L;

    private SelectionDependency dependency = null;

    public SelectionDependentAction(boolean smallIcon, String i18nKey, Object...i18nArgs) {
        super(smallIcon, i18nKey, i18nArgs);
    }

    @Override
    public final void actionPerformed(ActionEvent e) {
        if (dependency != null)
            actionPerformed(e, dependency.getSelectedObject());
    }

    /**
     * Subclasses need to implement this method in order to be able to perform the action on
     * the given object. The selectedObject might be null, since some actions might be
     * performable without a selection.
     */
    protected abstract void actionPerformed(ActionEvent e, Object selectedObject);

    /**
     * This might be called whenever the selection of the given {@link SelectionDependency} changes.
     * The state of this action will then be adapted automatically.
     */
    public void selectionChanged() {
        setEnabled(dependency != null && isEnabledForSelection(dependency.getSelectedObject()));
    }

    /**
     * This sets the dependency of this action. This method has to be called before the first
     * action can be performed.
     */
    public void setDependency(SelectionDependency dependency) {
        this.dependency = dependency;
    }
    /**
     * This method must be implemented by subclasses to indicate if this action is available
     * for this kind of object.
     * The selected object might be null since some actions might be possible even without selection.
     */
    protected abstract boolean isEnabledForSelection(Object selectedObject);

    /**
     * Creates a clone of this action.
     */
    @Override
    public Object clone() {
        try {
            SelectionDependentAction clone = (SelectionDependentAction) super.clone();
            clone.setDependency(dependency);
            return clone;
        } catch (CloneNotSupportedException e) {
            // can't happen
            return null;
        }
    }
}