【进阶实战】商店周刷：行会商店的每周刷新封装

local CANDIDATES = {
    "强化石礼包", "祝福油礼盒", "沃玛令牌", "金创药箱",
    "魔法药箱", "随机传送卷包", "修理锤", "红名清洗水",
    "双倍经验卡", "宠物口粮", "坐骑饲料", "行会旗",
}
local function weekKey()
    local y = os.date("%Y")
    local yday = tonumber(os.date("%j")) or 1
    return y .. "_W" .. math.floor((yday - 1) / 7)
end
local function weeklyRefresh()
    local wk = weekKey()
    if tostring(getsysvar("GuildShopWeek") or "") == wk then
        return
    end
    local shelf = {}
    local pool = {}
    for i, name in ipairs(CANDIDATES) do
        pool[i] = name
    end
    for slot = 1, 6 do
        local pick = math.random(1, #pool)
        shelf[slot] = pool[pick]
        table.remove(pool, pick)
    end
    setsysvarex("GuildShopWeek", wk, 1)
    setsysvarex("GuildShopShelf", table.concat(shelf, "|"), 1)
    setsysvarex("GuildShopBuyCnt", 0, 1)
    sendmsg(nil, 1, "行会商店本周货架已刷新：" .. table.concat(shelf, "、"))
end

local function buyShelfItem(actor, itemName)
    actor = getplayerbyname(actor)
    local wk = weekKey()
    local cnt = tonumber(getsysvar("GuildShopBuyCnt") or 0)
    if cnt >= 30 then
        sendmsg(actor, 1, "本周该商品已售罄（限购 30 份）。")
        return
    end
    if not takeitem(actor, "金条", 2) then
        sendmsg(actor, 1, "售价 2 根金条。")
        return
    end
    giveitem(actor, itemName, 1, 1)
    setsysvarex("GuildShopBuyCnt", cnt + 1, 1)
    sendmsg(actor, 1, "购得[" .. itemName .. "]，本周剩余 " .. (30 - cnt - 1) .. " 份。")
end