【进阶实战】离线留言：好友留言的时效与已读封装

local function leaveMsg(actor, friendName, text)
    local friend = getplayerbyname(friendName)
    if friend then
        sendmsg(friend, 1, "[留言] " .. text)
        return
    end
    local box = tostring(getsysvar("MsgBox_" .. friendName) or "")
    if #box > 400 then
        sendmsg(actor, 1, "对方留言箱已满。")
        return
    end
    setsysvarex("MsgBox_" .. friendName,
        box .. os.time() .. "|" .. text .. ";", 1)
    sendmsg(actor, 1, "留言已存，对方上线时送达。")
end

local function deliverOnLogin(actor, selfName)
    local box = tostring(getsysvar("MsgBox_" .. selfName) or "")
    if box == "" then
        return
    end
    local n = 0
    for entry in string.gmatch(box, "[^;]+") do
        local ts, text = string.match(entry, "^(%d+)|(.+)$")
        if ts and os.time() - tonumber(ts) < 259200 then
            sendmsg(actor, 1, "[留言] " .. text)
            n = n + 1
        end
    end
    setsysvarex("MsgBox_" .. selfName, "", 1)
    if n > 0 then
        sendmsg(actor, 1, "共 " .. n .. " 条留言送达，3 天内有效。")
    end
end