cellular automaton Fische;

const dimension = 2;
    distance = 1;

type animaltype = (none, exists, accepted);

type celltype = record 
    dir: celladdress;
    animal: animaltype;
    farbe: (lila, gelb, gruen, rot);
end;

global phase : (move, turn, choose);

const cell = (*[0, 0]);
const constantcell = [0,0,none,0];
initial [0,1,exists,random(3)] ~ prob(0.05) and option = 0;
initial [1,0,exists,random(3)] ~ prob(0.05)and option = 0;
initial [0,-1,exists,random(3)] ~ prob(0.05) and option = 0;
initial [-1,0,exists,random(3)] ~ prob(0.05)and option = 0;
initial [0,1,exists,random(3)] ~ prob(0.5) and x < 3*lx/5 and x > 2*lx/5 and y < 4*ly/5 and option = 1;
initial [0,-1,exists,0] ~ (((x+y)mod 2) = 0) and prob(0.8) and x < 2*lx/5 and x > 0 and y < 3*ly/5 and option = 2;
initial [0,1,exists,1] ~(((x+y)mod 2) = 0) and prob(0.8) and x > 3*lx/5 and x <lx-1 and y > 2*ly/5 and option = 2;
initial [1,0,exists,2] ~ (((x+y)mod 2) = 0) and prob(0.8) and y < 2*ly/5 and y > 0 and x > 2*lx/5  and option = 2;
initial [-1,0,exists,3] ~(((x+y)mod 2) = 0) and prob(0.8) and y > 3*ly/5 and y <ly-1 and x < 3*lx/5  and option = 2;
initial [0,0,none,random(3)] ~ true;
color "fische.gif" (0:9,value(cell.farbe):4) ~ (cell.animal = exists and cell.dir = [1,0]);
color "fische.gif" (1:9,value(cell.farbe):4) ~ (cell.animal = exists and cell.dir = [0,1]);
color "fische.gif" (2:9,value(cell.farbe):4) ~ (cell.animal = exists and cell.dir = [0,-1]);
color "fische.gif" (3:9,value(cell.farbe):4) ~ (cell.animal = exists and cell.dir = [-1,0]);
color "fische.gif" (4:9,value(cell.farbe):4) ~ (cell.animal = exists and cell.dir = [0,0]);
color "fische.gif" (5:9,value(cell.farbe):4) ~ (cell.animal = exists and cell.dir = [-1,1]);
color "fische.gif" (6:9,value(cell.farbe):4) ~ (cell.animal = exists and cell.dir = [1,1]);
color "fische.gif" (7:9,value(cell.farbe):4) ~ (cell.animal = exists and cell.dir = [1,-1]);
color "fische.gif" (8:9,value(cell.farbe):4) ~ (cell.animal = exists and cell.dir = [-1,-1]);
color [0, 255, 255] ~ true;

var n : celltype;
var sumx, sumy : -2..2;
var rand: 0..3;

dest : celladdress;

group neighbors = {*[0, 1], *[0, -1], *[1, 0], *[-1, 0]};

rule  begin
    if (phase = move) then begin
    	if cell.animal = exists then begin
    	    dest := cell.dir;
    	    if *dest.animal = accepted and *dest.dir = cell.dir then 
    	    	cell.animal := none
    	    else
    	    	cell.dir := [0,0];
    	end;
    	if cell.animal = accepted then begin
    	    cell.animal := exists;
    	end;  
    end;
	if phase = turn then begin
	    if cell.animal = exists then begin
     	    	sumx := sum(n in neighbors: n.dir.x);
    	    	sumy := sum(n in neighbors: n.dir.y);
    	    	if abs(sumx) > abs(sumy) then begin
    	    	    cell.dir.x := sign(sumx);
    	    	    cell.dir.y := 0;
    	    	end else begin
    	    	    cell.dir.x := 0;
    	    	    cell.dir.y := sign(sumy);
    	    	end;
	    end;
	    if prob(0.01) then begin
		cell.dir.x := cell.dir.y;
		cell.dir.y := -cell.dir.x;
	    end;
	    if cell.dir = [0,0] and prob(0.1) then begin
		rand := random(3);
		case rand of 
			0: cell.dir := [0,1];
			1: cell.dir := [0,-1];
			2: cell.dir := [1,0];
			3: cell.dir := [-1,0];
		end;
	    end;
	end;
 	if (phase = choose ) then begin // phase = choose

    	if cell.animal = none then begin
    	    cell.dir := [0,0];
  	    // Now can accept animal from another cell.
    	    if (*[0, 1].animal=exists and *[0, 1].dir = [0, -1]) then begin
    	    	cell.animal := accepted;
    	    	cell.dir := [0, -1];
    	    	cell.farbe := *[0, 1].farbe;
    	    end;
    	    if (*[0, -1].animal=exists and *[0, -1].dir = [0, 1]) then begin
    	    	cell.animal := accepted;
    	    	cell.dir := [0, 1];
    	    	cell.farbe := *[0, -1].farbe;
    	    end;
    	    if (*[1, 0].animal=exists and *[1, 0].dir = [-1, 0]) then begin
    	    	cell.animal := accepted;
    	    	cell.dir := [-1, 0];
    	    	cell.farbe := *[1, 0].farbe;
    	    end;
    	    if (*[-1, 0].animal=exists and *[-1, 0].dir = [1, 0]) then begin
    	    	cell.animal := accepted;
    	    	cell.dir := [1, 0];
    	    	cell.farbe := *[-1, 0].farbe;
    	    end;
     	end;
    end;
end;

rule global begin
    phase := next(phase);
end;