【进阶实战】商店回购：回购列表容量与过期淘汰

local function sellToShop(actor, itemName, priceGold)
    actor = getplayerbyname(actor)
    if not takeitem(actor, itemName, 1) then
        sendmsg(actor, 1, "背包里没有" .. itemName .. "。")
        return
    end
    giveitem(actor, "金条", math.max(1, math.floor(priceGold / 10000)))
    local list = getplayvar(actor, "HUMAN", "BuyBack") or ""
    local entries = {}
    for e in string.gmatch(list, "[^|]+") do
        entries[#entries + 1] = e
    end
    entries[#entries + 1] = os.time() .. ":" .. itemName .. ":" .. priceGold
    while #entries > 20 do
        table.remove(entries, 1)
    end
    setplayvar(actor, "HUMAN", "BuyBack", table.concat(entries, "|"), 1)
end

local function buyBack(actor, stamp)
    actor = getplayerbyname(actor)
    local list = getplayvar(actor, "HUMAN", "BuyBack") or ""
    local kept, found = {}, false
    for e in string.gmatch(list, "[^|]+") do
        local t, name, price = string.match(e, "(%d+):([^:]+):(%d+)")
        if tonumber(t) == stamp then
            found = true
            if os.time() - tonumber(t) > 1800 then
                kept[#kept + 1] = e
                sendmsg(actor, 1, "该物品已超 30 分钟，无法回购。")
            elseif takeitem(actor, "金条", math.max(1, math.floor(tonumber(price) / 10000))) then
                giveitem(actor, name, 1)
                sendmsg(actor, 1, "回购成功：" .. name .. "。")
            else
                kept[#kept + 1] = e
                sendmsg(actor, 1, "金条不足，无法回购。")
            end
        else
            kept[#kept + 1] = e
        end
    end
    if not found then
        sendmsg(actor, 1, "未找到该笔回购记录。")
        return
    end
    setplayvar(actor, "HUMAN", "BuyBack", table.concat(kept, "|"), 1)
end