// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Incoprea
// Five-by-five Langton ant
// Not compiled or tested in-world
// Setup: Enter step or ten. Board wraps at edges; ant starts in center facing north. Owner-touch initializes; enter reset to restart. Text input closes after90seconds.
// Stop / restore: Close or ignore the text box, or remove the script. It changes no world objects, avatar state or inventory.
// Notes: Original bounded, manually stepped educational toy. Not a calibrated simulator, real-world control system, or live scientific measurement. White cells turn right; black cells left. The finite torus differs from the usual infinite-plane ant.
// License: see LICENSE in this distribution.
// Original Incoprea. MIT. Not compiled or tested in-world.
integer channel;
integer handle;
list cells;
integer pos;
integer direction;
integer steps;
close()
{
    if(handle)llListenRemove(handle);
    handle=0;
    llSetTimerEvent(0.0);
}
start()
{
    cells=[];
    integer i;
    for(i=0;i<25;++i)cells+=[0];
    pos=12;
    direction=0;
    steps=0;
}
string view()
{
    string text="Step "+(string)steps+" direction "+(string)direction+": ";
    integer i;
    for(i=0;i<25;++i)
    {
        if(i==pos)text+="A";
        else if(llList2Integer(cells,i))text+="#";
        else text+=".";
        if(i%5==4)text+=" / ";
    }
    return text;
}
show()
{
    llOwnerSay(view());
    if(!handle)
    {
        channel=-1000-(integer)llFrand(1000000.0);
        handle=llListen(channel,"",llGetOwner(),"");
    }
    llTextBox(llGetOwner(),"Enter step or ten. Board wraps at edges; ant starts in center facing north. Type reset to restart.",channel);
    llSetTimerEvent(90.0);
}
default
{
    touch_start(integer n)
    {
        if(llDetectedKey(0)!=llGetOwner())return;
        close();
        start();
        show();
    }
    listen(integer incomingChannel,string name,key id,string s)
    {
        if(!handle||incomingChannel!=channel||id!=llGetOwner())return;
        s=llToLower(llStringTrim(s,STRING_TRIM));
        if(s=="reset")start();
        else
        {
            integer count=0;
            if(s=="step")count=1;
            else if(s=="ten")count=10;
            integer i;
            for(i=0;i<count;++i)
            {
                integer old=llList2Integer(cells,pos);
                if(old)direction=(direction+3)%4;
                else direction=(direction+1)%4;
                cells=llListReplaceList(cells,[!old],pos,pos);
                integer x=pos%5;
                integer y=pos/5;
                if(direction==0)y=(y+4)%5;
                else if(direction==1)x=(x+1)%5;
                else if(direction==2)y=(y+1)%5;
                else x=(x+4)%5;
                pos=y*5+x;
                ++steps;
            }
        }
        show();
    }
    timer()
    {
        close();
    }
}