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local ObjectShakeAddedEvent = Instance.new("BindableEvent")
local ObjectShakeRemovedEvent = Instance.new("BindableEvent")
local ObjectShakeUpdatedEvent = Instance.new("BindableEvent")
local PausedEvent = Instance.new("BindableEvent")
local ResumedEvent = Instance.new("BindableEvent")

local WindShake = {
	UpdateHz = 1 / 45,
	ComputeHz = 1 / 30,
	Radius = 120,

	ObjectMetadata = {},
	Octree = Octree.new(),

	Handled = 0,
	Active = 0,
	LastUpdate = os.clock(),

	ObjectShakeAdded = ObjectShakeAddedEvent.Event,
	ObjectShakeRemoved = ObjectShakeRemovedEvent.Event,
	ObjectShakeUpdated = ObjectShakeUpdatedEvent.Event,
	Paused = PausedEvent.Event,
	Resumed = ResumedEvent.Event,
}

export type WindShakeSettings = {
	WindDirection: Vector3?,
	WindSpeed: number?,
	WindPower: number?,
}

function WindShake:Connect(funcName: string, event: RBXScriptSignal): RBXScriptConnection
	local callback = self[funcName]
	assert(typeof(callback) == "function", "Unknown function: " .. funcName)

	return event:Connect(function(...)
		return callback(self, ...)
	end)
end

function WindShake:AddObjectShake(object: BasePart, settingsTable: WindShakeSettings?)
	if typeof(object) ~= "Instance" then
		return
	end

	if not object:IsA("BasePart") then
		return
	end

	local metadata = self.ObjectMetadata

	if metadata[object] then
		return
	else
		self.Handled += 1
	end

	metadata[object] = {
		Node = self.Octree:CreateNode(object.Position, object),
		Settings = Settings.new(object, DEFAULT_SETTINGS),

		Seed = math.random(1000) * 0.1,
		Origin = object.CFrame,
	}

	if settingsTable then
		self:UpdateObjectSettings(object, settingsTable)
	end

	ObjectShakeAddedEvent:Fire(object)
end

function WindShake:RemoveObjectShake(object: BasePart)
	if typeof(object) ~= "Instance" then
		return
	end

	local metadata = self.ObjectMetadata
	local objMeta = metadata[object]

	if objMeta then
		self.Handled -= 1
		metadata[object] = nil
		objMeta.Settings:Destroy()
		objMeta.Node:Destroy()

		if object:IsA("BasePart") then
			object.CFrame = objMeta.Origin
		end
	end

	ObjectShakeRemovedEvent:Fire(object)
end

function WindShake:Update()
	local now = os.clock()
	local dt = now - self.LastUpdate

	if dt < self.UpdateHz then
		return
	end

	self.LastUpdate = now

	debug.profilebegin("WindShake")

	local camera = workspace.CurrentCamera
	local cameraCF = camera and camera.CFrame

	debug.profilebegin("Octree Search")
	local updateObjects =
		self.Octree:RadiusSearch(cameraCF.Position + (cameraCF.LookVector * (self.Radius * 0.95)), self.Radius)
	debug.profileend()

	local activeCount = #updateObjects

	self.Active = activeCount

	if activeCount < 1 then
		return
	end

	local step = math.min(1, dt * 8)
	local cfTable = table.create(activeCount)
	local objectMetadata = self.ObjectMetadata

	debug.profilebegin("Calc")
	for i, object in ipairs(updateObjects) do
		local objMeta = objectMetadata[object]
		local lastComp = objMeta.LastCompute or 0

		local origin = objMeta.Origin
		local current = objMeta.CFrame or origin

		if (now - lastComp) > self.ComputeHz then
			local objSettings = objMeta.Settings

			local seed = objMeta.Seed
			local amp = objSettings.WindPower * 0.1

			local freq = now * (objSettings.WindSpeed * 0.08)
			local rotX = math.noise(freq, 0, seed) * amp
			local rotY = math.noise(freq, 0, -seed) * amp
			local rotZ = math.noise(freq, 0, seed + seed) * amp
			local offset = object.PivotOffset
			local worldpivot = origin * offset

			objMeta.Target = (
				worldpivot * CFrame.Angles(rotX, rotY, rotZ)
				+ objSettings.WindDirection * ((0.5 + math.noise(freq, seed, seed)) * amp)
			) * offset:Inverse()

			objMeta.LastCompute = now
		end

		current = current:Lerp(objMeta.Target, step)
		objMeta.CFrame = current
		cfTable[i] = current
	end
	debug.profileend()

	workspace:BulkMoveTo(updateObjects, cfTable, Enum.BulkMoveMode.FireCFrameChanged)
	debug.profileend()
end

function WindShake:Pause()
	if self.UpdateConnection then
		self.UpdateConnection:Disconnect()
		self.UpdateConnection = nil
	end

	self.Active = 0
	self.Running = false

	PausedEvent:Fire()
end

function WindShake:Resume()
	if self.Running then
		return
	else
		self.Running = true
	end

	-- Connect updater
	self.UpdateConnection = self:Connect("Update", RunService.Heartbeat)

	ResumedEvent:Fire()
end

function WindShake:Init()
	if self.Initialized then
		return
	else
		self.Initialized = true
	end

	-- Define attributes if they're undefined.
	local power = script:GetAttribute("WindPower")
	local speed = script:GetAttribute("WindSpeed")
	local direction = script:GetAttribute("WindDirection")

	if typeof(power) ~= "number" then
		script:SetAttribute("WindPower", DEFAULT_SETTINGS.WindPower)
	end

	if typeof(speed) ~= "number" then
		script:SetAttribute("WindSpeed", DEFAULT_SETTINGS.WindSpeed)
	end

	if typeof(direction) ~= "Vector3" then
		script:SetAttribute("WindDirection", DEFAULT_SETTINGS.WindDirection)
	end

	-- Clear any old stuff.
	self:Cleanup()

	-- Wire up tag listeners.
	local windShakeAdded = CollectionService:GetInstanceAddedSignal(COLLECTION_TAG)
	self.AddedConnection = self:Connect("AddObjectShake", windShakeAdded)

	local windShakeRemoved = CollectionService:GetInstanceRemovedSignal(COLLECTION_TAG)
	self.RemovedConnection = self:Connect("RemoveObjectShake", windShakeRemoved)

	for _, object in pairs(CollectionService:GetTagged(COLLECTION_TAG)) do
		self:AddObjectShake(object)
	end

	-- Automatically start.
	self:Resume()
end

function WindShake:Cleanup()
	if not self.Initialized then
		return
	end

	self:Pause()

	if self.AddedConnection then
		self.AddedConnection:Disconnect()
		self.AddedConnection = nil
	end

	if self.RemovedConnection then
		self.RemovedConnection:Disconnect()
		self.RemovedConnection = nil
	end

	table.clear(self.ObjectMetadata)
	self.Octree:ClearNodes()

	self.Handled = 0
	self.Active = 0
	self.Initialized = false
end

function WindShake:UpdateObjectSettings(object: Instance, settingsTable: WindShakeSettings)
	if typeof(object) ~= "Instance" then
		return
	end

	if typeof(settingsTable) ~= "table" then
		return
	end

	if not self.ObjectMetadata[object] and (object ~= script) then
		return
	end

	for key, value in pairs(settingsTable) do
		object:SetAttribute(key, value)
	end

	ObjectShakeUpdatedEvent:Fire(object)
end

function WindShake:UpdateAllObjectSettings(settingsTable: WindShakeSettings)
	if typeof(settingsTable) ~= "table" then
		return
	end

	for obj, objMeta in pairs(self.ObjectMetadata) do
		for key, value in pairs(settingsTable) do
			obj:SetAttribute(key, value)
		end
		ObjectShakeUpdatedEvent:Fire(obj)
	end
end

function WindShake:SetDefaultSettings(settingsTable: WindShakeSettings)
	self:UpdateObjectSettings(script, settingsTable)
end

return WindShake