// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Incoprea
// Undo and redo a local setting
// Not compiled or tested in-world
// Setup: Put in a spare prim you own. Touch through a five-step repeating sequence. The setting exists only in script memory.
// Stop / restore: Disable or remove the script. It only reports to its owner and does not change prim properties. Reset clears its temporary state.
// Notes: History is capped at eight values. A new edit after undo truncates the old forward branch.
// License: see LICENSE in this distribution.
// Original Incoprea example. MIT. Owner-only calculation; no scene changes.
list history = [0];
integer at;
integer step;
setValue(integer value)
{
    history = llList2List(history,0,at) + [value];
    ++at;
    if (llGetListLength(history) > 8)
    {
        history = llDeleteSubList(history,0,0);
        --at;
    }
}
default
{
    touch_start(integer detectedCount)
    {
        if (llDetectedKey(0) != llGetOwner()) return;
        integer action = step % 5;
        ++step;
        if (action == 0) setValue(step*10);
        else if (action == 1) setValue(step*10);
        else if (action == 2 && at > 0) --at;
        else if (action == 3 && at < llGetListLength(history)-1) ++at;
        else setValue(step*10);
        llOwnerSay("Current=" + (string)llList2Integer(history,at) + "; history=" + llDumpList2String(history,",") + "; cursor=" + (string)at);
    }
    changed(integer change)
    {
        if (change & CHANGED_OWNER) llResetScript();
    }
}