--[[
    Optimize_Controller 模块：
    1、提供了检测帧率，调整LOD自适应的策略
        帧率检测方法：检测当前帧之前一定数量(CheckTotalCount)的游戏帧中，deltaTime超过某一阈值(DeltaTimeThreshold)的帧数。
                    若此帧数超过设定帧数(CheckFrameCount)的次数在一定时间内(TotalCheckTick)高于可容忍的次数(JankTolerateCount), 则进行档位自适应调整。
        自适应方法：若当前LOD档位为非自定义档位，则自动下降一档；否则直接调整到Lod0档位。
]]--

local LuaUpdater = require("Main/LuaUpdater")
local EventSystem = require("Event/EventSystem")

local DeltaTimeThreshold = 0.05 --检测达成降档的DT阈值
local CheckTotalCount = 30 -- 当前帧之前，需要统计DT状态的帧数
local CheckFrameCount = 20 -- 需要统计的帧数中，DT高于阈值的数量
local JankTolerateCount = 3   -- 帧率检测到不达标的容忍次数
local TotalCheckTick = 2000 -- 连续检测帧率的最大次数

local Optimize_Controller = {}
local private = 
{
    _accumulateReachQueue = 
    {
        head = 1,
        tail = 1,
        size = 0,
        capacity = CheckTotalCount,
        array = LuaExt.CreateTable(CheckTotalCount),
    },
    
    _frFailTickQueue = 
    {
        head = 1,
        tail = 1,
        size = 0,
        capacity = JankTolerateCount,
        array = LuaExt.CreateTable(JankTolerateCount),
    },
    
    _enableAutoDownLOD = true,
    _accumulateReachCount = 0,
    _frameCheckTick = 0,
}

function Optimize_Controller.OnStartup()
    if MDL.Setting.HasKey(LuaConst.SettingKeyEnum.Adaptive) then
        private._enableAutoDownLOD = MDL.Setting.GetKeyValue(LuaConst.SettingKeyEnum.Adaptive)
    end
    Optimize_Controller.StartFrameCheck()
end

function Optimize_Controller.OnShutdown()
    Optimize_Controller.StopFrameCheck()
end

function Optimize_Controller.GetAdaptiveLODState()
    return private._enableAutoDownLOD
end

function Optimize_Controller.EnableAdaptiveLOD(enable)
    private._enableAutoDownLOD = enable
    MDL.Setting.SetKeyValue(LuaConst.SettingKeyEnum.Adaptive, enable)
    if enable then
        private.StartFrameCheck()
    else
        private.StopFrameCheck()
    end
end

-- 开启帧率检测 外部接口
function Optimize_Controller.StartFrameCheck()
    if private._enableAutoDownLOD then
        private.StartFrameCheck()
    end
end

-- 关闭帧率检测的 外部接口
function Optimize_Controller.StopFrameCheck()
    if private._enableAutoDownLOD then
        private.StopFrameCheck()
    end
end


function Optimize_Controller.OnRealTimeUpdate(deltaTime, timeSinceUpdate)
    private._frameCheckTick = private._frameCheckTick + 1
    local reachQueue = private._accumulateReachQueue
    if reachQueue.size == CheckTotalCount then
        if private.Dequeue(reachQueue) then
            private._accumulateReachCount = private._accumulateReachCount - 1
        end
    end

    local reach = deltaTime >= DeltaTimeThreshold
    private.Enqueue(reachQueue, reach)
    if not reach then
        --当前帧如果没有出现未达标的情况，可以跳出
        return
    end

    private._accumulateReachCount = private._accumulateReachCount + 1
    if private._accumulateReachCount < CheckFrameCount then
        --还未达到帧率不达标的情况，可以跳出
        return
    end
    
    private.ClearQueue(reachQueue)
    private._accumulateReachCount = 0

    local tickQueue = private._frFailTickQueue
    if tickQueue.size == JankTolerateCount and private._frameCheckTick - private.Dequeue(tickQueue) < TotalCheckTick then
        private.ClearQueue(tickQueue)
        private._frameCheckTick = 0
        EventSystem.Dispatch(EventID.Setting_OnAdaptiveQualityTrigger, true)
    else
        private.Enqueue(tickQueue, private._frameCheckTick)
    end
end

function Optimize_Controller.AdjustFrameCheckSensitivity(dtThreshold, totalCount, frameCount, tolerateTimes)
    Optimize_Controller.StopFrameCheck()
    
    DeltaTimeThreshold = dtThreshold
    CheckTotalCount = totalCount
    CheckFrameCount = frameCount
    JankTolerateCount = tolerateTimes

    private._accumulateReachQueue.capacity = CheckTotalCount
    private._accumulateReachQueue.array = LuaExt.CreateTable(CheckTotalCount)

    private._frFailTickQueue.capacity = JankTolerateCount
    private._frFailTickQueue.array = LuaExt.CreateTable(JankTolerateCount)
    
    Optimize_Controller.StartFrameCheck()
end

function private.StartFrameCheck()
    LuaUpdater.StartRealTimeUpdate(Optimize_Controller.OnRealTimeUpdate)
    private.ClearQueue(private._accumulateReachQueue)
    private.ClearQueue(private._frFailTickQueue)
    private._accumulateReachCount = 0
    private._frameCheckTick = 0
end

function private.StopFrameCheck()
    LuaUpdater.StopRealTimeUpdate(Optimize_Controller.OnRealTimeUpdate)
end

function private.Enqueue(queue,item)
    if queue.size == queue.capacity then
        logging.error(LTAG.ERROR,"fail: push a full queue")
        return
    end
    queue.array[queue.tail] = item
    queue.tail = queue.tail % queue.capacity  + 1
    queue.size = queue.size + 1
end

function private.Dequeue(queue)
    if queue.size <= 0 then
        return nil
    end
    local item = queue.array[queue.head]
    queue.array[queue.head] = nil
    queue.head = queue.head % queue.capacity + 1
    queue.size = queue.size - 1
    return item
end

function private.ClearQueue(queue)
    table.clearArray(queue.array)
    queue.head = 1
    queue.tail = 1
    queue.size = 0
end

return Optimize_Controller