// SPDX-License-Identifier: MIT
// Copyright (c) 2026 Incoprea
// Four-pair memory board
// Not compiled or tested in-world
// Setup: Owner-touch. Enter card numbers 1–8. Remember revealed symbols while matching four pairs.
// Stop / restore: Stop responding and the listener closes after 90 seconds, or remove/disable the script. Owner-touch restarts the exercise.
// Notes: Owner-only local exercise; no prizes, visitor records, network service, or persistent scores. Symbols are shown in private prompts and owner chat; no textures or inventory cards are required.
// License: see LICENSE in this distribution.
// Original Incoprea. MIT. Not compiled or tested in-world.
integer channel;
integer handle;
close()
{
    if(handle)llListenRemove(handle);
    handle=0;
    llSetTimerEvent(0.0);
}
ask(string prompt)
{
    if(!handle)
    {
        channel=-1000-(integer)llFrand(1000000.0);
        handle=llListen(channel,"",llGetOwner(),"");
    }
    llTextBox(llGetOwner(),prompt,channel);
    llSetTimerEvent(90.0);
}
integer digit(string text,integer min,integer max)
{
    if(llStringLength(text)!=1)return -1;
    integer n=llSubStringIndex("0123456789",text);
    if(n<min||n>max)return -1;
    return n;
}
list cards;
list found;
integer first=-1;
integer pairs;
string view()
{
    string out="";
    integer i;
    for(i=0;i<8;++i)
    {
        if(llListFindList(found,[i])>=0)out+=llList2String(cards,i);
        else out+=(string)(i+1);
        out+=" ";
    }
    return out;
}
start()
{
    cards=llListRandomize(["A","A","B","B","C","C","D","D"],1);
    found=[];
    pairs=0;
    first=-1;
    ask(view()+"\nChoose a card.");
}
answer(string s)
{
    integer p=digit(s,1,8)-1;
    if(p<0||llListFindList(found,[p])>=0||p==first)
    {
        ask(view()+"\nChoose a different hidden card.");
        return;
    }
    string symbol=llList2String(cards,p);
    if(first<0)
    {
        first=p;
        ask("Card "+s+" is "+symbol+". Choose its partner.");
        return;
    }
    string old=llList2String(cards,first);
    string result="No match: "+old+" and "+symbol;
    if(old==symbol)
    {
        found+=[first,p];
        ++pairs;
        result="Pair found: "+symbol;
    }
    first=-1;
    if(pairs==4)
    {
        close();
        llOwnerSay("All four pairs found.");
    }
    else ask(result+"\n"+view()+"\nChoose another card.");
}
default
{
    touch_start(integer count)
    {
        if(llDetectedKey(0)!=llGetOwner())return;
        close();
        start();
    }
    listen(integer ch,string name,key id,string message)
    {
        if(!handle||ch!=channel||id!=llGetOwner())return;
        answer(llStringTrim(message,STRING_TRIM));
    }
    timer()
    {
        close();
        llOwnerSay("Exercise paused. Touch to restart.");
    }
    changed(integer change)
    {
        if(change&CHANGED_OWNER)llResetScript();
    }
}