// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Incoprea
// Three-by-three sandpile
// Not compiled or tested in-world
// Setup: Enter1-9 to add a grain, or step to topple each eligible cell once. 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. Sequential toppling pass; repeat step until stable. Grains leaving the finite boundary are counted and lost.
// License: see LICENSE in this distribution.
// Original Incoprea. MIT. Not compiled or tested in-world.
integer channel;
integer handle;
list piles;
integer lost;
close()
{
    if(handle)llListenRemove(handle);
    handle=0;
    llSetTimerEvent(0.0);
}
start()
{
    piles=[0,0,0,0,0,0,0,0,0];
    lost=0;
}
string view()
{
    return "Rows: "+llList2CSV(llList2List(piles,0,2))+" / "+llList2CSV(llList2List(piles,3,5))+" / "+llList2CSV(llList2List(piles,6,8))+" | boundary loss "+(string)lost;
}
show()
{
    llOwnerSay(view());
    if(!handle)
    {
        channel=-1000-(integer)llFrand(1000000.0);
        handle=llListen(channel,"",llGetOwner(),"");
    }
    llTextBox(llGetOwner(),"Enter1-9 to add a grain, or step to topple each eligible cell once. 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")
            {
                integer i;
                for(i=0;i<9;++i)if(llList2Integer(piles,i)>=4)
                {
                    piles=llListReplaceList(piles,[llList2Integer(piles,i)-4],i,i);
                    list neighbors=[];
                    if(i%3>0)neighbors+=[i-1];
                    else ++lost;
                    if(i%3<2)neighbors+=[i+1];
                    else ++lost;
                    if(i/3>0)neighbors+=[i-3];
                    else ++lost;
                    if(i/3<2)neighbors+=[i+3];
                    else ++lost;
                    integer j;
                    for(j=0;j<llGetListLength(neighbors);++j)
                    {
                        integer p=llList2Integer(neighbors,j);
                        piles=llListReplaceList(piles,[llList2Integer(piles,p)+1],p,p);
                    }
                }
            }
            else
            {
                integer cell=(integer)s-1;
                if(cell>=0&&cell<9&&(string)(cell+1)==s&&llList2Integer(piles,cell)<99)piles=llListReplaceList(piles,[llList2Integer(piles,cell)+1],cell,cell);
            }
        }
        show();
    }
    timer()
    {
        close();
    }
}