/*******************************************************************************
 * Copyright (c) 2007, 2010 Association for Decentralized Information Management
 * in Industry THTH ry.
 * 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.browsing.ui.graph.impl;

import java.util.Collection;

import org.simantics.browsing.ui.BuiltinKeys;
import org.simantics.browsing.ui.NodeContext;
import org.simantics.browsing.ui.PrimitiveQueryUpdater;
import org.simantics.browsing.ui.BuiltinKeys.ViewpointKey;
import org.simantics.browsing.ui.content.Viewpoint;
import org.simantics.browsing.ui.content.ViewpointFactory;
import org.simantics.db.ReadGraph;
import org.simantics.db.Resource;
import org.simantics.db.exception.DatabaseException;

public abstract class GraphViewpointFactory implements ViewpointFactory {

    @Override
    public Viewpoint create(PrimitiveQueryUpdater updater,
            NodeContext context, ViewpointKey key) {
        assert(updater != null);
        assert(context != null);

        return new LazyViewpoint(updater, context, key) {
            @Override
            public NodeContext[] children(ReadGraph graph) throws DatabaseException {
                return toContextsWithInput(GraphViewpointFactory.this.
                        getChildren(graph, (Resource) context.getConstant(BuiltinKeys.INPUT)));
            }

            @Override
            public Boolean hasChildren(ReadGraph graph) throws DatabaseException {
                return children(graph).length > 0;
            }

            @Override
            public String toString() {
                return GraphViewpointFactory.this.toString();
            }

            @Override
            public Object getIdentity() {
                return GraphViewpointFactory.this.getClass();
            }

        };
    }

    abstract protected Collection<?> getChildren(ReadGraph g, Resource r) throws DatabaseException;
    protected boolean hasChildren(ReadGraph g, Resource r) throws DatabaseException {
        return !getChildren(g, r).isEmpty();
    }

}