/*
 * This file is part of JSTUN. 
 * 
 * Copyright (c) 2005 Thomas King <king@t-king.de> - All rights
 * reserved.
 * 
 * This software is licensed under either the GNU Public License (GPL),
 * or the Apache 2.0 license. Copies of both license agreements are
 * included in this distribution.
 */

package de.javawi.jstun.test.demo.ice;

import java.net.InetAddress;
import java.net.NetworkInterface;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Vector;

import de.javawi.jstun.test.DiscoveryInfo;
import de.javawi.jstun.test.DiscoveryTest;
import de.javawi.jstun.test.demo.ice.Candidate.CandidateType;
import de.javawi.jstun.util.Address;

public class ICENegociator {
	// type preference must be an integere from 0 (=lowest) to 126 (=highest) (inclusive)
	private final static int LOCAL_PREFERENCE = 0;
	private final static int SERVER_REFLEXIVE_PREFERENCE = 42;
	private final static int PEER_REFLEXIVE_PREFERENCE = 84;
	private final static int RELAYED_PREFERENCE = 126;
	
	// component id
	private short componentId;
	
	// candidates
	HashSet<Candidate> candidates;
	
	public ICENegociator(short componentId) {
		this.componentId = componentId;
		candidates = new HashSet<Candidate>();
	}

	/*
	 * This method gathers candidate addresses as described in draft-ietf-mmusic-ice-12.txt Chapter 2.1
	 * Unfortunately, only the candidates of the direct attached network interfaces and server reflexive
	 * addreses are gathered. So far, no support for relayed candidates is available (because I am not
	 * aware of any STUN relay server).
	 */
	public void gatherCandidateAddresses() {
		candidates = new HashSet<Candidate>();
		try {
			Enumeration<NetworkInterface> ifaces = NetworkInterface.getNetworkInterfaces();
			while (ifaces.hasMoreElements()) {
				NetworkInterface iface = ifaces.nextElement();
				Enumeration<InetAddress> iaddresses = iface.getInetAddresses();
				while (iaddresses.hasMoreElements()) {
					InetAddress iaddress = iaddresses.nextElement();
					if (!iaddress.isLoopbackAddress() && !iaddress.isLinkLocalAddress()) {
						// add host candidate
						Candidate local = new Candidate(new Address(iaddress.getAddress()), componentId);
						candidates.add(local);
						// add server reflexive address
						DiscoveryTest test = new DiscoveryTest(iaddress, "iphone-stun.freenet.de", 3478);
						DiscoveryInfo di = test.test();
						if (di.getPublicIP() != null) {
							Candidate cand = new Candidate(new Address(di.getPublicIP().getAddress()), CandidateType.ServerReflexive, componentId, local);
							cand.setComponentId(componentId);
							candidates.add(cand);
						}
					}
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}
	
	public void prioritizeCandidates() {
		// count number of candidate types
		int numberLocal = 0;
		int numberServerReflexive = 0;
		int numberPeerReflexive = 0;
		int numberRelayed = 0;
		// count number of candidates of a particular type
		Iterator<Candidate> iterCandidates = candidates.iterator();
		while (iterCandidates.hasNext()) {
			Candidate cand = iterCandidates.next();
			CandidateType type = cand.getCandidateType();
			if (type == CandidateType.Local) numberLocal++;
			else if (type == CandidateType.ServerReflexive) numberServerReflexive++;
			else if (type == CandidateType.PeerReflexive) numberPeerReflexive++;
			else if (type == CandidateType.Relayed) numberRelayed++;
		}
		// assign priorities
		iterCandidates = candidates.iterator();
		while (iterCandidates.hasNext()) {
			int typeValue = 0;
			int localValue = 0;
			int componentValue = 0;
			Candidate cand = iterCandidates.next();
			CandidateType type = cand.getCandidateType();
			if (type == CandidateType.Local) {
				typeValue = LOCAL_PREFERENCE;
				localValue = numberLocal--;
			}
			else if (type == CandidateType.ServerReflexive) {
				typeValue = SERVER_REFLEXIVE_PREFERENCE;
				localValue = numberServerReflexive--;
			}
			else if (type == CandidateType.PeerReflexive) {
				typeValue = PEER_REFLEXIVE_PREFERENCE;
				localValue = numberPeerReflexive--;
			}
			else if (type == CandidateType.Relayed) {
				typeValue = RELAYED_PREFERENCE;
				localValue = numberRelayed--;
			}
			componentValue = cand.getComponentId();
			int priority = ((2 ^ 24) * typeValue) + ((2 ^ 8) * localValue) + componentValue;
			cand.setPriority(priority);
		}
	}
	
	public List<Candidate> getSortedCandidates() {
		Vector<Candidate> sortedCandidates = new Vector<Candidate>(candidates);
		Collections.sort(sortedCandidates);
		return sortedCandidates;
	}

	public static void main(String args[]) {
		ICENegociator cc = new ICENegociator((short) 1);
		// gather candidates
		cc.gatherCandidateAddresses();
		// priorize candidates
		cc.prioritizeCandidates();
		// get SortedCandidates
		List<Candidate> sortedCandidates = cc.getSortedCandidates();
		
		// sent sorted candidate addresses to peer over SDP
		// received sorted candidate addresses of peer over SDP
		
	}
}