/*******************************************************************************
 * Copyright (c) 2007 VTT Technical Research Centre of Finland and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     VTT Technical Research Centre of Finland - initial API and implementation
 *******************************************************************************/
package org.simantics.proconf.g3d.common;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Iterator;
import java.util.List;

import org.eclipse.jface.viewers.IStructuredSelection;
import org.simantics.db.Resource;


/**
 * StructuredSelection that contains ResourceSelections
 * 
 * @author Marko Luukkainen
 * @author Tuukka Lehtonen
 */
public class StructuredResourceSelection implements IStructuredSelection {
    
    public static final StructuredResourceSelection EMPTY = new StructuredResourceSelection() {
        // Create an empty fixed size List to ensure the list is not modified.
        private List<Resource> empty = Arrays.asList(); 
        
        public void add(Resource rs) {
            throw new UnsupportedOperationException("BUG: attempted to modify StructuredResourceSelection.EMPTY");
        }
        public List<Resource> getSelectionList() {
            return empty;
        }
    };

    private List<Resource> selections;
    
    /**
     * Creates a new selection that doesn't contain any items
     */
    public StructuredResourceSelection() {
    }

    public StructuredResourceSelection(Resource rs) {
        getSelectionList().add(rs);
    }

    public StructuredResourceSelection(Resource... rss) {
        List<Resource> s = getSelectionList();
        for (Resource rs : rss)
            s.add(rs);
    }

    public void add(Resource rs) {
        getSelectionList().add(rs);
    }

    public List<Resource> getSelectionList() {
        if (selections == null) {
            selections = new ArrayList<Resource>();
        }
        return selections;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.eclipse.jface.viewers.ISelection#isEmpty()
     */
    public boolean isEmpty() {
        return selections == null || selections.isEmpty();
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.eclipse.jface.viewers.IStructuredSelection#getFirstElement()
     */
    public Object getFirstElement() {
        if (!isEmpty())
            return selections.get(0);
        return null;
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.eclipse.jface.viewers.IStructuredSelection#iterator()
     */
    public Iterator<Resource> iterator() {
        return getSelectionList().iterator();
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.eclipse.jface.viewers.IStructuredSelection#size()
     */
    public int size() {
        return selections == null ? 0 : selections.size();
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.eclipse.jface.viewers.IStructuredSelection#toArray()
     */
    public Object[] toArray() {
        return selections == null ? new Object[0] : selections.toArray();
    }

    /*
     * (non-Javadoc)
     * 
     * @see org.eclipse.jface.viewers.IStructuredSelection#toList()
     */
    public List<Resource> toList() {
        return selections == null ? Arrays.asList(new Resource[0]) : selections;
    }

    /**
     * Returns whether this structured selection is equal to the given object.
     * Two structured selections are equal iff they contain the same elements
     * in the same order.
     *
     * @param o the other object
     * @return <code>true</code> if they are equal, and <code>false</code> otherwise
     */
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        // null and other classes
        if (!(o instanceof StructuredResourceSelection)) {
            return false;
        }
        StructuredResourceSelection other = (StructuredResourceSelection) o;

        // either or both empty?
        if (isEmpty()) {
            return other.isEmpty();
        }
        if (other.isEmpty()) {
            return false;
        }

        // check size
        if (size() != other.size())
            return false;
        
        // element comparison
        Iterator<Resource> it = iterator();
        Iterator<Resource> otherIt = other.iterator();
        while (it.hasNext()) {
            if (!it.next().equals(otherIt.next()))
                return false;
        }
        
        return true;
    }
    
    @Override
    public String toString() {
    	return Arrays.toString(getSelectionList().toArray());
    }
    
}