帮会烽火台：敌袭烽火的逐台传递

local function lightBeacon(actor, tower)
    if getsysvar("beacon_" .. tower) == 1 then
        return   -- 已燃不重复
    end
    setsysvarex("beacon_" .. tower, 1)
    sendcentermsg(0, tower .. " 号烽火燃起！")
    local nextTower = ({1, 2, 3})[tower + 1]
    if nextTower then
        lightBeacon(actor, nextTower)
    end
end

local function resetBeacons()
    for i = 1, 3 do
        setsysvarex("beacon_" .. i, 0)
    end
    sendcentermsg(0, "烽火已熄，警戒解除")
end