--!strict

--[[
	Given a `tweenInfo` and `currentTime`, returns a ratio which can be used to
	tween between two values over time.
]]

-- local TweenService = game:GetService "TweenService"
local easing = require "../../../Modules/Polyfill/easing"

local function getTweenRatio(tweenInfo: TweenInfo, currentTime: number): number
	local delay = tweenInfo.DelayTime
	local duration = tweenInfo.Time
	local reverses = tweenInfo.Reverses
	local numCycles = 1 + tweenInfo.RepeatCount
	local easeStyle = tweenInfo.EasingStyle
	local easeDirection = tweenInfo.EasingDirection

	local cycleDuration = delay + duration
	if reverses then
		cycleDuration += duration
	end

	if
		currentTime >= cycleDuration * numCycles
		and tweenInfo.RepeatCount > -1
	then
		return 1
	end

	local cycleTime = currentTime % cycleDuration

	if cycleTime <= delay then
		return 0
	end

	local tweenProgress = (cycleTime - delay) / duration
	if tweenProgress > 1 then
		tweenProgress = 2 - tweenProgress
	end

	-- return TweenService:GetValue(tweenProgress, easeStyle, easeDirection)
	return easing[easeStyle][easeDirection](tweenProgress, 0, 1)
end

return getTweenRatio