/*******************************************************************************
 * Copyright (c) 2003, 2008 IBM Corporation 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:
 *     IBM Corporation - initial API and implementation
 * Port to the D programming language:
 *     Frank Benoit <benoit@tionex.de>
 *******************************************************************************/
module dwtx.draw2d.graph.PopulateRanks;

import dwt.dwthelper.utils;
import dwtx.dwtxhelper.Collection;
import dwtx.draw2d.graph.RevertableChange;
import dwtx.draw2d.graph.GraphVisitor;
import dwtx.draw2d.graph.DirectedGraph;
import dwtx.draw2d.graph.RankList;
import dwtx.draw2d.graph.Rank;
import dwtx.draw2d.graph.Node;
import dwtx.draw2d.graph.Edge;
import dwtx.draw2d.graph.VirtualNodeCreation;

/**
 * This class takes a DirectedGraph with an optimal rank assignment and a spanning tree,
 * and populates the ranks of the DirectedGraph. Virtual nodes are inserted for edges that
 * span 1 or more ranks.
 * <P>
 * Ranks are populated using a pre-order depth-first traversal of the spanning tree. For
 * each node, all edges requiring virtual nodes are added to the ranks.
 * @author Randy Hudson
 * @since 2.1.2
 */
class PopulateRanks : GraphVisitor {

private Stack changes;

public this(){
    changes = new Stack();
}
/**
 * @see GraphVisitor#visit(DirectedGraph)
 */
public void visit(DirectedGraph g) {
    if (g.forestRoot !is null) {
        for (int i = g.forestRoot.outgoing.size() - 1; i >= 0; i--)
            g.removeEdge(g.forestRoot.outgoing.getEdge(i));
        g.removeNode(g.forestRoot);
    }
    g.ranks = new RankList();
    for (int i = 0; i < g.nodes.size(); i++) {
        Node node = g.nodes.getNode(i);
        g.ranks.getRank(node.rank).add(node);
    }
    for (int i = 0; i < g.nodes.size(); i++) {
        Node node = g.nodes.getNode(i);
        for (int j = 0; j < node.outgoing.size();) {
            Edge e = node.outgoing.getEdge(j);
            if (e.getLength() > 1)
                changes.push(new VirtualNodeCreation(e, g));
            else
                j++;
        }
    }
}

/**
 * @see GraphVisitor#revisit(DirectedGraph)
 */
public void revisit(DirectedGraph g) {
    for (int r = 0; r < g.ranks.size(); r++) {
        Rank rank = g.ranks.getRank(r);
        Node prev = null, cur;
        for (int n = 0; n < rank.size(); n++) {
            cur = rank.getNode(n);
            cur.left = prev;
            if (prev !is null) {
                prev.right = cur;
            }
            prev = cur;
        }
    }
    for (int i = 0; i < changes.size(); i++) {
        RevertableChange change = cast(RevertableChange)changes.get(i);
        change.revert();
    }
}

}