【进阶实战】邮件经济学：邮箱容量的分级管理封装

local CAPS = { sys = 40, player = 40, auction = 20 }
local mailboxes = {}
local function countMails(actorName, source)
    local box = mailboxes[actorName]
    if box == nil then
        return 0
    end
    local n = 0
    for _, m in ipairs(box) do
        if m.source == source then
            n = n + 1
        end
    end
    return n
end
local function canReceive(actorName, source)
    local used = countMails(actorName, source)
    return used < (CAPS[source] or 100)
end

local EXPIRE = { sys = 0, player = 15, auction = 30 }
local function purgeExpired(actorName)
    local box = mailboxes[actorName]
    if box == nil then
        return
    end
    local now = os.time()
    local kept = {}
    for _, m in ipairs(box) do
        local days = EXPIRE[m.source] or 30
        if now - m.ts < days * 86400 then
            kept[#kept + 1] = m
        end
    end
    mailboxes[actorName] = kept
end