package com.onaro.sanscreen.client.view.selection;

import java.util.ArrayList;
import java.util.List;

import javax.swing.ListSelectionModel;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;

import org.eclipse.core.runtime.IAdaptable;

/**
 * A <code>ObjectSelectionModel</code> backed by a <code>ListSelectionModel</code>.
 */
public class ListObjectSelectionModel extends ObjectSelectionModel {

	/**
	 * The backing list selection model.
	 */
	final ListSelectionModel listSelectionModel;

	/**
	 * Translates list indices to objects.
	 */
	final ListToObjectTranslator translator;

	/**
	 * Construct an object selection model from the given list selection model. The selection mode is set to match the
	 * list's mode and the current selection is copied into the object selection model.
	 * 
	 * @param listSelectionModel
	 *            the list selection model
	 */
	public ListObjectSelectionModel(ListSelectionModel listSelectionModel, ListToObjectTranslator translator) {

		if (listSelectionModel == null) throw new IllegalArgumentException("listSelectionModel"); //$NON-NLS-1$
		if (translator == null) throw new IllegalArgumentException("translator"); //$NON-NLS-1$

		this.listSelectionModel = listSelectionModel;
		this.translator = translator;

		this.listSelectionModel.addListSelectionListener(new MyListSelectionListener());
	}

	public static abstract class ListToObjectTranslator {

		protected ListToObjectTranslator() {
			//do nothing
		}
		
		public abstract IAdaptable getAdaptable(int index);

        public abstract SelectedObject getSelectedObject(int index);
	}

	class MyListSelectionListener implements ListSelectionListener {

		public void valueChanged(ListSelectionEvent event) {

			List<SelectedObject> newSelection = new ArrayList<SelectedObject>();

			if (event.getValueIsAdjusting()) return;

			int minSelectionIndex = listSelectionModel.getMinSelectionIndex();
			int maxSelectionIndex = listSelectionModel.getMaxSelectionIndex();

			if (minSelectionIndex >= 0 && maxSelectionIndex >= 0) {
				for (int index = minSelectionIndex; index <= maxSelectionIndex; index++) {
					if (listSelectionModel.isSelectedIndex(index)) {
						SelectedObject selectedObject = translator.getSelectedObject(index);

						if (selectedObject != null) {
							newSelection.add(selectedObject);
						}
					}
				}
			}

			setSelectedAdaptables(newSelection);
		}
	}
}