// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Incoprea
// Four-by-four Life board
// Not compiled or tested in-world
// Setup: Enter1-16 to toggle a row-major cell or step to advance. 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. Cells outside the4x4 board are dead, not wrapped. No unbounded automatic generations.
// License: see LICENSE in this distribution.
// Original Incoprea. MIT. Not compiled or tested in-world.
integer channel;
integer handle;
list cells;
integer generation;
close()
{
    if(handle)llListenRemove(handle);
    handle=0;
    llSetTimerEvent(0.0);
}
start()
{
    cells=[0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0];
    generation=0;
}
string view()
{
    string text="Generation "+(string)generation+": ";
    integer i;
    for(i=0;i<16;++i)
    {
        if(llList2Integer(cells,i))text+="X";
        else text+=".";
        if(i%4==3)text+=" / ";
    }
    return text;
}
show()
{
    llOwnerSay(view());
    if(!handle)
    {
        channel=-1000-(integer)llFrand(1000000.0);
        handle=llListen(channel,"",llGetOwner(),"");
    }
    llTextBox(llGetOwner(),"Enter1-16 to toggle a row-major cell or step to advance. 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
        {
            if(s=="step")
            {
                list next=[];
                integer i;
                for(i=0;i<16;++i)
                {
                    integer count=0;
                    integer dx;
                    integer dy;
                    for(dy=-1;dy<=1;++dy)for(dx=-1;dx<=1;++dx)
                    {
                        integer x=i%4+dx;
                        integer y=i/4+dy;
                        if((dx||dy)&&x>=0&&x<4&&y>=0&&y<4)count+=llList2Integer(cells,y*4+x);
                    }
                    integer alive=count==3||(count==2&&llList2Integer(cells,i));
                    next+=[alive];
                }
                cells=next;
                ++generation;
            }
            else
            {
                integer cell=(integer)s-1;
                if(cell>=0&&cell<16&&(string)(cell+1)==s)cells=llListReplaceList(cells,[!llList2Integer(cells,cell)],cell,cell);
            }
        }
        show();
    }
    timer()
    {
        close();
    }
}