--CameraShaker.Presets = require(script.CameraShakePresets)


function CameraShaker.new(renderPriority, callback)

	assert(type(renderPriority) == "number", "RenderPriority must be a number (e.g.: Enum.RenderPriority.Camera.Value)")
	assert(type(callback) == "function", "Callback must be a function")

	local self = setmetatable({
		_running = false;
		_renderName = "CameraShaker";
		_renderPriority = renderPriority;
		_posAddShake = v3Zero;
		_rotAddShake = v3Zero;
		_camShakeInstances = {};
		_removeInstances = {};
		_callback = callback;
	}, CameraShaker)

	return self

end


function CameraShaker:Start()
	if (self._running) then return end
	self._running = true
	local callback = self._callback
	game:GetService("RunService"):BindToRenderStep(self._renderName, self._renderPriority, function(dt)
		profileBegin(profileTag)
		local cf = self:Update(dt)
		profileEnd()
		callback(cf)
	end)
end


function CameraShaker:Stop()
	if (not self._running) then return end
	game:GetService("RunService"):UnbindFromRenderStep(self._renderName)
	self._running = false
end


function CameraShaker:StopSustained(duration)
	for _,c in pairs(self._camShakeInstances) do
		if (c.fadeOutDuration == 0) then
			c:StartFadeOut(duration or c.fadeInDuration)
		end
	end
end


function CameraShaker:Update(dt)

	local posAddShake = v3Zero
	local rotAddShake = v3Zero

	local instances = self._camShakeInstances

	-- Update all instances:
	for i = 1,#instances do

		local c = instances[i]
		local state = c:GetState()

		if (state == CameraShakeState.Inactive and c.DeleteOnInactive) then
			self._removeInstances[#self._removeInstances + 1] = i
		elseif (state ~= CameraShakeState.Inactive) then
			local shake = c:UpdateShake(dt)
			posAddShake = posAddShake + (shake * c.PositionInfluence)
			rotAddShake = rotAddShake + (shake * c.RotationInfluence)
		end

	end

	-- Remove dead instances:
	for i = #self._removeInstances,1,-1 do
		local instIndex = self._removeInstances[i]
		table.remove(instances, instIndex)
		self._removeInstances[i] = nil
	end

	return CF(posAddShake) *
		ANG(0, RAD(rotAddShake.Y), 0) *
		ANG(RAD(rotAddShake.X), 0, RAD(rotAddShake.Z))

end


function CameraShaker:Shake(shakeInstance)
	assert(type(shakeInstance) == "table" and shakeInstance._camShakeInstance, "ShakeInstance must be of type CameraShakeInstance")
	self._camShakeInstances[#self._camShakeInstances + 1] = shakeInstance
	return shakeInstance
end


function CameraShaker:ShakeSustain(shakeInstance)
	assert(type(shakeInstance) == "table" and shakeInstance._camShakeInstance, "ShakeInstance must be of type CameraShakeInstance")
	self._camShakeInstances[#self._camShakeInstances + 1] = shakeInstance
	shakeInstance:StartFadeIn(shakeInstance.fadeInDuration)
	return shakeInstance
end


function CameraShaker:ShakeOnce(magnitude, roughness, fadeInTime, fadeOutTime, posInfluence, rotInfluence)
	local shakeInstance = CameraShakeInstance.new(magnitude, roughness, fadeInTime, fadeOutTime)
	shakeInstance.PositionInfluence = (typeof(posInfluence) == "Vector3" and posInfluence or defaultPosInfluence)
	shakeInstance.RotationInfluence = (typeof(rotInfluence) == "Vector3" and rotInfluence or defaultRotInfluence)
	self._camShakeInstances[#self._camShakeInstances + 1] = shakeInstance
	return shakeInstance
end


function CameraShaker:StartShake(magnitude, roughness, fadeInTime, posInfluence, rotInfluence)
	local shakeInstance = CameraShakeInstance.new(magnitude, roughness, fadeInTime)
	shakeInstance.PositionInfluence = (typeof(posInfluence) == "Vector3" and posInfluence or defaultPosInfluence)
	shakeInstance.RotationInfluence = (typeof(rotInfluence) == "Vector3" and rotInfluence or defaultRotInfluence)
	shakeInstance:StartFadeIn(fadeInTime)
	self._camShakeInstances[#self._camShakeInstances + 1] = shakeInstance
	return shakeInstance
end


return CameraShaker