【后端接口】灵珠合成：低阶灵珠合成高阶的接口实现

local COMBINE_COST = 50000
local SUCCESS_RATE = { [1] = 80, [2] = 60, [3] = 40 }
function combinePearl(actor, pearlType)
    local matName = pearlType .. "灵珠"
    if not checkitemw(actor, matName, 3) then
        sendmsg(actor, 0, "需要 3 颗 " .. matName)
        return
    end
    if not checkitemw(actor, "金币", COMBINE_COST) then
        sendmsg(actor, 0, "金币不足，需要 " .. COMBINE_COST)
        return
    end
    takeitem(actor, matName, 3)
    takeitem(actor, "金币", COMBINE_COST)
    local roll = math.random(1, 100)
    if roll <= SUCCESS_RATE[pearlType] then
        giveitem(actor, pearlType + 1 .. "级灵珠", 1)
        sendmsg(actor, 0, "合成成功")
    else
        giveitem(actor, matName, 1)
        sendmsg(actor, 0, "合成失败，返还一颗材料")
    end
end

local function checkPity(actor)
    local fail = tonumber(getplayvar(actor, "HUMAN", "PEARL_FAIL") or "0") + 1
    setplayvar(actor, "HUMAN", "PEARL_FAIL", fail, 1)
    if fail >= 5 then
        setplayvar(actor, "HUMAN", "PEARL_FAIL", 0, 1)
        setplayvar(actor, "HUMAN", "PEARL_PITY", 1, 1)
        sendmsg(actor, 0, "保底触发，下次合成必定成功")
    end
end