/*
 * (c) 1999 The Brookings Institution All Rights Reserved
 *
 * Permission to use this software and its documentation for non-commercial
 * purposes and without fee is hereby granted, provided this copyright statement
 * is included. Please contact us for permission for redistribution and other uses.
 * 
 * BROOKINGS MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
 * THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
 * TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, 
 * OR NON-INFRINGEMENT. BROOKINGS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY
 * LICENSEE AS A RESULT OF USING THIS SOFTWARE OR ITS DERIVATIVES.
 *
 * _Sugarscape_
 * See _Growing Artificial Societies: Social Science from the Ground Up_
 * Brookings Institution Press, The MIT Press
 * Joshua Epstein
 * jepstein@brook.edu
 * Robert Axtell
 * raxtell@brook.edu
 *
 * Miles Parker
 * mparker@brook.edu

 * http://www.brook.edu/es/dynamics/models/ascape
 * The Brookings Institution
 * Washington, D.C.
 * 
 * Alan Lockard
 * alockard@gmu.edu
 */

package edu.brook.sugarscape;

import java.lang.*;

import edu.brook.ascape.model.*;
import edu.brook.ascape.rule.*;
import edu.brook.ascape.util.*;


/**
 * This trade rule solicits offers from all partners, takes best 
 * offer, and counteroffers remaining partners the chance to
 * trade on those same, most favorable terms
 *
 * @author Alan Lockard
 * @version 1.0
 */ 
public class TradeT3 extends TradeT2 {

    Exchange2 exchanges[] = new Exchange2[4]; // max number Von Neuman neighbors
    Exchange2 exchange;

    public void execute(Agent agent) {
        Cell[] neighbors = ((CellOccupant) agent).getNeighborsOnHost();
        // If only 1 neighbor, life is easy
        if (neighbors.length == 1) {
	    exchange = new Exchange2(((SpiceAgent) agent), ((SpiceAgent) neighbors[0]));
	    if (((SpiceAgent) neighbors[0]).acceptOffer ((Exchange) exchange)) {
		executeTrade((Exchange) exchange);
            }
	}
	else { // Find best offer. Note that order is irrelevant, needn't be randomized.
	    int imax = -1;
	    float maxDif = 0;
	    float transDif;
	    for (int i = 0; i < neighbors.length; i++) {
		exchanges[i] = new Exchange2(((SpiceAgent) agent), ((SpiceAgent) neighbors[i]));
		transDif = (float) Math.abs((exchanges[i]).logPrice - Math.log((exchanges[i]).selfExAnteMRS));
		if (transDif > maxDif) {
		    maxDif = transDif;
		    imax = i;
		}
	    }
	    if (imax >= 0) { // At least one beneficial trade found
                // Deal with trading partner offering best price
	        if (((SpiceAgent) neighbors[imax]).acceptOffer ((Exchange) exchanges[imax])) {
		    executeTrade((Exchange) exchanges[imax]);
                }
	        // give trading partners a chance to match the best price
	        for (int i = 0; i < neighbors.length; i++) {
		    if (i == imax) continue;
		    exchange = new Exchange2((SpiceAgent) agent, (SpiceAgent) neighbors[i], (exchanges[imax]).price);
	            if (((SpiceAgent) neighbors[i]).acceptOffer ((Exchange) exchange)) {
		        executeTrade((Exchange) exchange);
		    }
                }
	    }
	}
    }   	   
}