import java.util.*;

public
class Annealer implements Embedder {

protected Blackboard _bb;
public Annealer( Blackboard black ) {
	_bb = black;
}

protected double _time;
protected final double fa(double x) {
	double k = _bb.globals.k();
	return x*x/k;
}
protected final double fr(double x) {
	double k = _bb.globals.k();
	return k*k/x;
}
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, v.degree()/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 );
		double pullto = (distance/to.degree())*(distance/to.degree())/k;
		double pullfrom = (distance/from.degree())*(distance/from.degree())/k;
		if( distance > 0.00001 ) {
			to.forced( from, -__max(pullto,1.0)/distance*fa(distance) );
			from.forced( to, -__max(pullfrom,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( v.degree()/force * __min(force,Temp) );
		}
	}
	_time += 1.0;
}

} // class Annealer