/*
 * @(#)Connection.java	ver 1.2  6/20/2005
 *
 * Copyright 2005 Weishuai Yang (wyang@cs.binghamton.edu). 
 * All rights reserved.
 * 
 */
 
package gps.network;

import java.util.Iterator;
import java.util.LinkedHashSet;
import java.util.ArrayList;
import java.util.logging.Logger;

import gps.network.graph.Link;
import gps.network.graph.Node;
import gps.protocol.Agent;

/**
 * high level directed connection between nodes
 *
 * @author  Weishuai Yang
 * @version 1.2,  6/20/2005
 */

public class Connection {


	/**
	 * singleton reference to topology
	 */
	protected static Topology mTopology=Topology.getInstance();	
	/**
	 * singleton reference to debug log
	 */
	protected static Logger mDebugLog = Logger.getLogger("Debug");
	
	//public Agent mSource;
	//public Agent mDestination;
	
	/**
	 * source node of the connection, i.e. initiator
	 */
	protected Node mSource;
	/**
	 * destination of the connection
	 */
	protected Node mDestination;
	
	/**
	 * all the links along the connection
	 */
	protected Link[] mLinks=null;
	
	/**
	 * bandwidth consumed by this connection
	 */
	protected double mBandwidth=0;
	/**
	 * bandwidth from source to destination
	 */
	protected double mBandwidthAtoB=0;
	/**
	 * bandwidth from destination to source
	 */
	protected double mBandwidthBtoA=0;
	/**
	 * bandwidth reserved for this connection along links, but not allocated yet
	 */
	protected double mReservedBandwidth=0;
	/**
	 * active connection or not
	 */
	protected boolean mActive=false;
	/**
	 * locked means it is adjusting
	 */
	protected boolean mLocked=false;
	/**
	 * all the connections in the system
	 */
	protected static ArrayList mConnections=new ArrayList();
	
	/**
	 * constructs a connection between agents
	 * @param a source agent
	 * @param b destination agent
	 */
	public Connection(Agent a, Agent b){
		mSource=a.getNode();
		mDestination=b.getNode();
		mLinks=mTopology.getLinksBetween(a.getNode(), b.getNode());
		mConnections.add(this);
		//System.out.println("setting up connection from node "+mSource.getID()+" to node "+mDestination.getID());
	}

	/**
	 * constructs a connection between nodes
	 * @param a source node
	 * @param b destination node
	 */
	public Connection(Node a, Node b){
		mSource=a;
		mDestination=b;
		mLinks=mTopology.getLinksBetween(a, b);
		mConnections.add(this);	
	}
	
	/**
	 * get all the connections in the system, class method
	 * @return connection list
	 */
	public static ArrayList getAllConnections(){
		return mConnections;
	}
	/**
	 * print all connections in system, just for debug purpose
	 */
	public static void printConnections(){
		System.out.println("\n");
		for(int i=0;i<mConnections.size();i++){
			System.out.println((Connection)mConnections.get(i));
		}
		Link[] links=Topology.getInstance().getLinks();
		for(int i=0; i<links.length; i++){
			double d=links[i].getBandwidthManager().getAvailableBandwidth();
			System.out.println(links[i].fromNode()+"->"+links[i].toNode()+":"+d);
		}
	}
	/**
	 * setup this connection along links
	 */
	public void setUp(){
		//always add it to inactive list
		mActive=false;
		mBandwidth=0;
		for(int i=0;i<mLinks.length;i++)
			mLinks[i].getBandwidthManager().addConnection(this);
	}
	/**
	 * reserve bandwidth for this connection along links
	 */
	protected void reserveBandwidth(){
		//after reserve, it's alwasy inactive, even if it is active before reserve
		returnBandwidth();
		negotiateBandwidth();
		for(int i=0;i<mLinks.length;i++)
			mLinks[i].getBandwidthManager().reserveFor(this);
	}
	
	/**
	 * return bandwidth for this connection along links
	 */
	protected void returnBandwidth(){
		for(int i=0;i<mLinks.length;i++)
			mLinks[i].getBandwidthManager().returnBandwidth(this);
		mBandwidth=0;
	}

	protected void negotiateBandwidth(){
		double minimum=mLinks[0].getBandwidthManager().negotiateForConnection(this);
		for(int i=0;i<mLinks.length;i++){
			double tmp=mLinks[i].getBandwidthManager().negotiateForConnection(this);
			if(tmp<minimum){
				minimum=tmp;
			}
		}
		mReservedBandwidth=minimum;
	}
	/**
	 * apply reserved to be real bandwidth
	 */
	protected void applyReservedBandwidth(){
		mBandwidth=mReservedBandwidth;
		mReservedBandwidth=0;
		for(int i=0;i<mLinks.length;i++)
			mLinks[i].getBandwidthManager().activeConnection(this);
	}

	/**
	 * make connection active
	 */
	public void setActive(){
		if(mActive) return;
		reserveBandwidth();
		mActive=true;
		applyReservedBandwidth();
	}
	
	/**
	 * get active status
	 * @return true if active, otherwise false
	 */
	public boolean isActive(){
		return mActive;
	}
	
	/**
	 * maximizes bandwidth for this connection
	 */
	protected void maximize(){
		reserveBandwidth();
		applyReservedBandwidth();
	}

	/**
	 * finds bottle neck along links
	 * @param forward true means search forward, otherwise backward
	 */
	public Link findBottleNeck(boolean forward){
		double minimum=mLinks[0].getBandwidthManager().getAvailableBandwidth();
		Link bottleNeck=mLinks[0];
		if(forward)
			for(int i=0;i<mLinks.length;i++){
				if(mLinks[i].getBandwidthManager().getAvailableBandwidth()<minimum){
					minimum=mLinks[i].getBandwidthManager().negotiateForConnection(this);
					bottleNeck=mLinks[i];
				}
			}
		else
			for(int i=mLinks.length-1;i>=0;i--){
				if(mLinks[i].getBandwidthManager().getAvailableBandwidth()<minimum){
					minimum=mLinks[i].getBandwidthManager().negotiateForConnection(this);
					bottleNeck=mLinks[i];
				}
			}
		return bottleNeck;
	}
	/**
	 * gets bandwidth allocated for this connection
	 * @return allocated bandwidth
	 */
	public double getBandwidth(){
		return mBandwidth;
	}
	
	/**
	 * gets one way bandwidth
	 * @param n source
	 * @return bandwidth from source
	 */
	public double getBandwidthFrom(Node n){
		if(n==mSource)
			return mBandwidthAtoB;
		else if(n==mDestination)
			return mBandwidthBtoA;
		return 0;
	}
	
	/**
	 * sets one way bandwidth
	 * @param n source
	 * @param b new bandwidth value
	 */
	public void setBandwidthFrom(Node n, double b){
		if(n==mSource)
			mBandwidthAtoB=b;
		else if(n==mDestination)
			mBandwidthBtoA=b;
	}
	
	/**
	 * makes connection inactive
	 */
	public void setInActive(){
		if(!mActive) return;
		mActive=false;
		for(int i=0;i<mLinks.length;i++)
			mLinks[i].getBandwidthManager().inActiveConnection(this);
		relaxBandwidthAlongTheWay();
		mBandwidth=0;
	}


	public void relaxBandwidthAlongTheWay(){
		
		//find bottleneck first 
		Link bottleNeck1=findBottleNeck(true);
		Link bottleNeck2=null;

		int count=0;
		while(bottleNeck1!=bottleNeck2){
			count++;
			
			LinkedHashSet connections=bottleNeck1.getBandwidthManager().getActiveConnectionList();
		
			ArrayList connlist=new ArrayList(connections);
	    	Iterator it=connlist.iterator();
	    	while(it.hasNext()){
	    		Connection c=(Connection)it.next();
	    		if(c==this){
	    			mDebugLog.warning("relaxing self!");
	    			return;
	    		}
	    		if(c.mActive){
	    			if(c.getBandwidth()==0) return;
	    			c.maximize();
	    		}
	    		else
	    			mDebugLog.warning("connection get from active connection list is not active!");
	    	}
			bottleNeck2=bottleNeck1;
			bottleNeck1=findBottleNeck(true);
			
			if(count>100){
				mDebugLog.warning("Finding bottleneck forward more than 100 times!");
			}
		}



		//find bottleneck first 
		bottleNeck1=findBottleNeck(false);
		bottleNeck2=null;

		count=0;
		while(bottleNeck1!=bottleNeck2){
			count++;
			
			LinkedHashSet connections=bottleNeck1.getBandwidthManager().getActiveConnectionList();
		
			ArrayList connlist=new ArrayList(connections);
	    	Iterator it=connlist.iterator();
	    	while(it.hasNext()){
	    		Connection c=(Connection)it.next();
	    		if(c==this){
	    			mDebugLog.warning("relaxing self!");
	    			return;
	    		}
	    		if(c.mActive){
	    			if(c.getBandwidth()==0) return;
	    			c.maximize();
	    		}
	    		else
	    			mDebugLog.warning("connection get from active connection list is not active!");
	    	}
			bottleNeck2=bottleNeck1;
			bottleNeck1=findBottleNeck(false);
			
			if(count>100){
				mDebugLog.warning("Finding bottleneck reverse more than 100 times!");
			}
		}
		
	}

	/**
	 * tear down the connection
	 */
	public void tearDown(){
		if(mActive)
			setInActive();
		for(int i=0;i<mLinks.length;i++)
			mLinks[i].getBandwidthManager().removeConnection(this);
		//System.out.println("tearing down connection from node "+mSource.getID()+" to node "+mDestination.getID());
		mConnections.remove(this);
		
	}

	/**
	 * adjust bandwidth for provided amount
	 * @param adj adjust amount
	 */	
	public void adjustBandwidth(double adj){
		//request more or less bandwidth

	    if(!mActive)
			mDebugLog.warning("Trying to adjust bandwidth for inactive connection "+ this);
	    mBandwidth+=adj;
		for(int i=0;i<mLinks.length;i++)
			mLinks[i].getBandwidthManager().adjustBandwidthForConnection(this, adj);

	}
	
	/**
	 * gets string description
	 * 
	 * @return string description
	 */
	public String toString() {
		String ret = "Connection("+mSource.getID()+"->"+mDestination.getID()+")";
		if (mActive) 
			ret += ": Active, Bandwidth: "+mBandwidth;
		else 
			ret += ": InActive";
		if(mReservedBandwidth!=0)
			ret +=" ReservedBandwidth: "+mReservedBandwidth;
		ret+=" ";
		return ret;
	}
	
}