package graph.layout;
import graph.*;
import graph.cluster.*;
import graph.rep.*;
import java.awt.*;
import java.util.*;

/**
 * A force-directed placement algorithm originally implemented
 * by Úlfar Erlingsson at Cornell/RPI and modified to fit into
 * this system.
 *
 * @author Michael Shilman (michaels@eecs.berkeley.edu)
 * @version $Id$
 */
 
 
public class ForceDirect implements Action {
	public void apply(Graph g) {} //XXX
	public void init(Graph g) {} //XXX
	public void step(Graph g) {} //XXX
	public void finish(Graph g) {} //XXX

/*
	protected Blackboard _bb;
	public ForceDirect( Blackboard black ) {
		_bb = black;
	}

	protected double _time;
	protected final double fa(double x) {
		double k = _bb.globals.k();
		double ac = _bb.globals.ac();
		double ae = _bb.globals.ae();
		return ac*Math.pow(x,ae)/k;
	}
	protected final double fr(double x) {
		double k = _bb.globals.k();
		double rc = _bb.globals.rc();
		double re = _bb.globals.re();
		return rc*(k*k)/Math.pow(x,re);
	}
	protected final double temp(double t) {
		return _bb.globals.L()/(2*_bb.globals.D())/(1+Math.exp(t/8-5));
	}

	// Implementation of embedder interface, Init and Embed.
	//
	public final void Init() {
		_bb.removeDummies();
		double L = _bb.globals.L();
		_time = 1.0;
		_bb.setArea( -L/2, -L/2, L/2, L/2 );
	}

	public final void Embed() {
		force_directed_placement();
		_bb.Update();
	}
	private final double __min( double a, double b ) { return (a<b)?a:b; }
	private final double __max( double a, double b ) { return (a>b)?a:b; }

	protected synchronized void force_directed_placement() {
	// Calculate repulsive forces
	//
		double k = _bb.globals.k();
		Vector nodes = _bb.nodes();
		int nodecnt = nodes.size();
		for (int i = 0; i < nodecnt; ++i ) {
			Node u = (Node) nodes.elementAt(i);
			u.stabilize();
			for (int j = 0; j < nodecnt; ++j ) {
				Node v = (Node) nodes.elementAt(j);
				double distance = _bb.Norm( u, v );
				if( distance > 3*k ) 
				continue;
				if( distance == 0.0 ) distance = 0.0001;
				u.forced( v, 1.0/distance*fr(distance) );
			}
		}
		// Calculate attractive forces
		//
		Vector edges = _bb.edges();
		int edgecnt = edges.size();
		for( int i = 0; i < edgecnt; ++i ) {
			Edge e = (Edge) edges.elementAt(i);
			Node from = e.from();
			Node to = e.to();
			double distance = _bb.Norm( to, from );
			if( distance > 0.00001 ) {
				to.forced( from, -1.0/distance*fa(distance) );
				from.forced( to, -1.0/distance*fa(distance) );
			}
		}
		// Displace with regard to temperature
		//
		double Temp = temp(_time)+_bb.globals.minTemp();
		_bb.globals.Temp( Temp );
		for (int j = 0; j < nodecnt; ++j ) {
			Node v = (Node) nodes.elementAt(j);
			double force = v.deltaForce();
			if( force < 0.00001 ) continue;
			if ( !v.fixed() && !v.picked() ) {
				v.moveDelta( 1.0/force * __min(force,Temp) );
			}
		}
		_time += 1.0;
	}
	*/
}