/*
 * 
 * HEATBUGS in MAML
 * (c) 1998, CEU Systems Laboratory
 * 
 * This simulation is based on the following model:
 * 
 * Heatbugs application. Copyright (C) 1996 Santa Fe Institute.
 * This library is distributed without any warranty; without even the
 * implied warranty of merchantability or fitness for a particular purpose.
 * See file LICENSE for details and terms of copying.
 * 
 */

// The HeatSpace is a simple object to represent the heat in the
// world: a spatial variable. HeatSpace inherits most of its behaviour
// from the "Diffuse" space Object. It is basically a rectangular grid. 
// Heat values are stored in each cell.
// The heat diffuses to the neighbouring cells as time goes by.

@agent HeatSpace : Diffuse2d {
@uses <space.h>;			// We need this Swarm package as
					// Discrete2d is there.

  // Shorthands borrowed from the Swarm implementeation
  $define HeatValue : "int";
  $define maxHeat: "0x7fff";

  $define HeatExtremeType : "int";
  $define hot : "42", cold : "24";

  // Increase the heat in a cell. The maximum is limited to "maxHeat".
  @sub: (void) addHeat: (HeatValue) moreHeat X: (int) x Y: (int) y {

    HeatValue heatHere = [self getValueAtX: x Y: y];
    heatHere = ( (moreHeat <= maxHeat-heatHere) ? heatHere + moreHeat : 
						  maxHeat );
    [self putValue: heatHere atX: x Y: y];
  }

  // Try to find a better place in the neighbourhood.
  // Better means colder or warmer according to "type".
  // Sets "px" and "py" to the best position and returns the heat there. 
  // The % (modulo) treatment of the indeces results in a thoric behavior.
  @sub: (HeatValue) findExtremeType: (HeatExtremeType) type 
				  X: ([] int) px Y: ([] int) py { 
    HeatValue bestHeat;
    int x, y;
    int bestX, bestY;
    bestX = *px;
    bestY = *py;
    bestHeat = [self getValueAtX: bestX Y: bestY];
    for (x = *px - 1; x <= *px + 1; x++) {      // search all neighbours
      for (y = *py - 1; y <= *py + 1; y++) {
        HeatValue heatHere;
        boolean hereIsBetter;

        heatHere = [self getValueAtX: (x+xsize)%xsize Y: (y+ysize)%ysize];
        hereIsBetter = (type == cold) ? (heatHere < bestHeat)
	                              : (heatHere > bestHeat);
        if (hereIsBetter) {                         
	  bestHeat = heatHere;
	  bestX = x;
	  bestY = y;
        }
      }
    }
    *px = (bestX + xsize) % xsize;
    *py = (bestY + ysize) % ysize;
    return bestHeat;
  } 
}