package org.openslx.graph;

import java.awt.Color;

import org.apache.commons.math3.util.FastMath;

public class Edge implements java.io.Serializable
{
	private static final long serialVersionUID = 4401455477347084262L;
	private Node _source;
	private Node _target;
	private double _weight;
	private String _id = null;
	private int _age = 0;
	private static final Color[] COLORS = new Color[ 20 ];
	private final int _maxHealth;
	private int _health;

	static
	{
		for ( int i = 0; i < COLORS.length; ++i ) {
			int r = blend( 255, 100, i, COLORS.length - 1 );
			int g = blend( 0, 100, i, COLORS.length - 1 );
			int b = blend( 0, 255, i, COLORS.length - 1 );
			COLORS[i] = new Color( r, g, b );
		}
	}

	private static int blend( int a, int b, int current, int max )
	{
		a *= a;
		b *= b;
		return (int)FastMath.sqrt( ( ( b * current ) + ( a * ( max - current ) ) ) / max );
	}

	public Edge( Node source, Node target )
	{
		// Note that this graph is actually undirected.
		_source = source;
		_target = target;
		_weight = 0;
		_maxHealth = Math.max( source.getMaxHealth(), target.getMaxHealth() );
		_health = _maxHealth;
	}

	public void resetWeight()
	{
		if ( _health == _maxHealth && _maxHealth != 1 && _source.wasActivated() && _target.wasActivated() ) {
			_health = 1;
		} else {
			_health--;
		}
		_age++;
	}

	public boolean isAlive()
	{
		return _health > 0;
	}

	public void setWeight( double weight )
	{
		_weight = weight;
		_health = _maxHealth;
	}

	public double getWeight()
	{
		return _weight;
	}

	public Node getSource()
	{
		return _source;
	}

	public Node getTarget()
	{
		return _target;
	}

	public boolean equals( Object o )
	{
		if ( o instanceof Edge ) {
			Edge other = (Edge)o;
			return ( _source.equals( other._source ) && _target.equals( other._target ) ) || ( _source.equals( other._target ) && _target.equals( other._source ) );
		}
		return false;
	}

	public boolean hasNode( Node node )
	{
		return _source.equals( node ) || _target.equals( node );
	}

	public double getLengthSquared()
	{
		final double dx = _source.getX() - _target.getX();
		final double dy = _source.getY() - _target.getY();
		return dx * dx + dy * dy;
	}

	public int hashCode()
	{
		return _source.hashCode() ^ _target.hashCode();
	}

	public String toString()
	{
		return _source + " " + _target + " w(" + _weight + ")";
	}

	public String getId()
	{
		if ( _id == null ) {
			if ( _source.getId().compareTo( _target.getId() ) > 0 )
				_id = _target.getId() + "==" + _source.getId();
			_id = _source.getId() + "==" + _target.getId();
		}
		return _id;
	}

	public Color getColor()
	{
		return COLORS[_age >= COLORS.length ? COLORS.length - 1 : _age];
	}

}