/*
 * Copyright 2009 Wishnu Prasetya.
 *
 * You can redistribute and/or modify this class under
 * the terms of the GNU General Public License (GPL) as published by the
 * Free Software Foundation; either version 3 of the License, or any
 * later version.
 */

package Sequenic.Graph;

import java.io.Serializable;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.Map.Entry;


/**
 * Representing a node in a graph.
 * 
 * @author Wishnu Prasetya
 *
 */
public class Vertex implements Serializable {
	
	private static final long serialVersionUID = 1L;
	
	/**
	 * The node's id.
	 */
	private int id;
	
	public Vertex(){ super() ; } 
	
//	public List<Vertex> parents  = new LinkedList<Vertex>() ; 
//	public List<Vertex> children = new LinkedList<Vertex>() ;
	
	private Map<String,Vertex> childEdges = new HashMap<String,Vertex>();
	private Set<Vertex> childVertices = new HashSet<Vertex>();
	
	private Set<Vertex> parentVertices = new HashSet<Vertex>();

	public static final String LABEL_DEFAULT = "_";

	public static final String LABEL_TRUE = "T";

	public static final String LABEL_FALSE = "F";
	
	public int outDegree(){ return childVertices.size();}
	public int inDegree(){ return parentVertices.size();}

	public Map<String,Vertex> childEdges(){
		return childEdges;
	}
	
	public Collection<Vertex> children(){
		return childVertices;
	}
	
	public Collection<Vertex> parents(){
		return parentVertices;
	}
	
	public void addChild(Vertex v, String label){
		if(childEdges.containsKey(label)){
			if(!childEdges.get(label).equals(v))
				throw new IllegalArgumentException("A single outgoing label can not point to two different vertices: label =" + label);
		} else {
			childEdges.put(label, v);
			childVertices.add(v);
			v.parentVertices.add(this);
		}
	}
	
	/**
	 * Unlink this node: remove links to it from all of its parents and remove the links to its parents.
	 * 
	 */
	public void unlink(){
		Iterator<Vertex> iter;
		for(Vertex parent : parentVertices){
			parent.childVertices.remove(this);
			iter = parent.childEdges.values().iterator();
			while(iter.hasNext()){
				if(iter.next()==this)
					iter.remove();
			}
		}
		parentVertices.clear();
	}
	
	/** True if child is a child of this vertex.
	 * 
	 * @param child
	 * @return
	 */
	public boolean isChild(Vertex child){
		return childVertices.contains(child);
	}
	
	/**
	 * Returns the child that is reached when following label l from this node.
	 * Returns null if there is no outgoing edge with label l.
	 * 
	 * @param label
	 * @return
	 */
	public Vertex getChild(String label){
		return childEdges.get(label);
	}
	
	
	@Override
	public String toString() {
		return Integer.toString(getId()) ;
	}
	
	public void printEdges(StringBuffer out){
		out.append(toString()).append(" --> ");
		String s = "";
		for(Entry<String, Vertex> kv : childEdges.entrySet()){
			out.append(s).append(kv.getKey().toString()).append(":").append(kv.getValue().toString());
			s = ", ";
		}
		if(s=="")
			out.append(" no-children");
	}
	
	/** Note id's are restricted to be in the range [0..65535].
	 * I.e. only the lower 16 bits may be set.
	 * 
	 * TODO: Restrict further to the range [0..Short.MAX]
	 * Also, make id a final field, that is set in the constructor.
	 * Finally, modify CFG so that startNodes are required to have id==0.
	 * 
	 */
	public void setId(int id)
	{
		if(id >>> 16 != 0)
			throw new IllegalArgumentException("id must be in the range [0..65535].");
		this.id = id;
	}
	public int getId()
	{
		return id;
	}
	public static String labelForSwitchCase(int i){
		return Integer.toString(i);
	}
	
}