【后端接口】竞技场挑战：挑战匹配与战斗结果接口

-- 竞技场：匹配与队列
local player = class(actor)
local matchPool = {}
local function joinMatch(player, rating, name)
    matchPool[#matchPool + 1] = {rating = rating, name = name}
    for i = 1, #matchPool - 1 do
        local other = matchPool[i]
        if other.name ~= name and math.abs(other.rating - rating) <= 100 then
            -- 匹配成功，移除双方
            table.remove(matchPool, i)
            for j = #matchPool, 1, -1 do
                if matchPool[j].name == name then table.remove(matchPool, j) end
            end
            return other.name
        end
    end
    return nil
end

-- 竞技场：结算与段位
local player = class(actor)
local function updateRating(player, winnerName, loserName)
    local winRating = tonumber(getplayvar(class(winnerName), "HUMAN", "ArenaRating") or 1000)
    local loseRating = tonumber(getplayvar(class(loserName), "HUMAN", "ArenaRating") or 1000)
    local k = 32
    local expected = 1 / (1 + math.pow(10, (loseRating - winRating) / 400))
    local delta = math.floor(k * (1 - expected))
    setplayvar(class(winnerName), "HUMAN", "ArenaRating", winRating + delta, true)
    setplayvar(class(loserName), "HUMAN", "ArenaRating", math.max(0, loseRating - delta), true)
    sendmsg(class(winnerName), 1, 0, "胜利！段位分 +" .. delta)
    sendmsg(class(loserName), 1, 0, "失败，段位分 -" .. delta)
end