/*
 * CSB Reserved Slots
 * Copyright (C) 2026 counter-strike-boost.com
 *
 * Keeps a configurable number of slots free for flagged VIPs/admins. When the
 * free-slot count drops below the reserve, the plugin removes the "worst"
 * non-VIP present (bots first, then the highest-ping player) so a reserved slot
 * is available again. Enforced on connect and on a short repeating timer.
 *
 * Inspired by the Reserved Slots plugin shipped with AMX Mod X (AMX Mod X
 * Development Team). Independent GPL re-implementation; no original code reused.
 *
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version. It is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See <https://www.gnu.org/licenses/> for details.
 */

#include <amxmodx>
#include <amxmisc>

new const PLUGIN[] = "CSB Reserved Slots"
new const VERSION[] = "1.0.0"
new const AUTHOR[]  = "counter-strike-boost.com"

new g_pEnabled, g_pReserved, g_pFlag

public plugin_init()
{
    register_plugin(PLUGIN, VERSION, AUTHOR)

    g_pEnabled  = register_cvar("csb_slots_enabled", "1")
    g_pReserved = register_cvar("csb_slots_reserved", "1")
    g_pFlag     = register_cvar("csb_slots_flag", "a")

    set_task(8.0, "taskEnforce", 0, _, _, "b")
}

public client_putinserver(id)
{
    if (is_user_bot(id))
        return

    set_task(1.5, "taskEnforce")
}

hasReserved(id)
{
    new flags[8]
    get_pcvar_string(g_pFlag, flags, charsmax(flags))

    new access = read_flags(flags)

    return (get_user_flags(id) & access) ? 1 : 0
}

pickVictim()
{
    new players[32], num, pid
    get_players(players, num)

    new bestBot = 0
    new worst = 0, worstPing = -1

    for (new i = 0; i < num; i++)
    {
        pid = players[i]

        if (is_user_bot(pid))
        {
            bestBot = pid
            continue
        }

        if (is_user_hltv(pid))
            continue

        /* never kick a VIP or an immune admin to free a reserved slot */
        if (hasReserved(pid))
            continue

        if (get_user_flags(pid) & ADMIN_IMMUNITY)
            continue

        new ping, loss
        get_user_ping(pid, ping, loss)

        if (ping > worstPing)
        {
            worstPing = ping
            worst = pid
        }
    }

    /* prefer removing a bot before a real player */
    if (bestBot)
        return bestBot

    return worst
}

public taskEnforce()
{
    if (!get_pcvar_num(g_pEnabled))
        return

    new reserved = get_pcvar_num(g_pReserved)

    if (reserved < 1)
        return

    new maxSlots = get_maxplayers()

    new players[32], num
    get_players(players, num)

    new free = maxSlots - num

    while (free < reserved)
    {
        new victim = pickVictim()

        if (!victim)
            break

        new name[32]
        get_user_name(victim, name, charsmax(name))

        server_cmd("kick #%d ^"Slot reserved for a VIP - please rejoin later^"", get_user_userid(victim))

        log_amx("[CSB Slots] freed a reserved slot by removing %s", name)

        free++
    }
}