------------------------------------------------------------------------------
-- Invert Animation Curve
-- This script inverts a bezier spline by swapping time and value of each
-- key frame. So for example a key at 10 with a value of 44 will end up as
-- a key at frame 44 with a value of 10.
-- It's your task to make sure that a spline is strictly monotonic so it can
-- actually be inverted. Also, bezier handles won't be converted.
-- Just the time/value pairs of keyframes.
--
-- This is a tool script!
-- written by Stefan Ihringer, stefan@bildfehler.de
--
-- Version 1.0 - 2011-10-23
------------------------------------------------------------------------------

if not tool then
	tool = composition:GetAttrs().COMPH_ActiveTool
	if not tool then
		print("This is a tool script, you must select a tool in the flow to run this script")
		composition:GetFrameList()[1]:SwitchMainView('ConsoleView') 
		exit()
	end
end

controlNames = {}   -- saves the names of animated number inputs

for key,inp in tool:GetInputList() do
	local attrs = inp:GetAttrs()
	if attrs.INPB_Connected then
		if inp:GetConnectedOutput():GetTool().ID == "BezierSpline" then
			table.insert(controlNames, attrs.INPS_ID)
		end
	end
end

if table.getn(controlNames) == 0 then
	print("No input of this tool is animated with a BezierSpline :-(")
	return
end

-- display user dialog
ret = composition:AskUser("Invert this bezier spline:", {
	{ "input", "Dropdown", Name = "Input", Options = controlNames },
})

------------------------------------------------------------------------------
-- MAIN ----------------------------------------------------------------------
------------------------------------------------------------------------------

if ret then
	inpname = controlNames[ret.input+1]
	inp = tool[inpname]

	comp:StartUndo("Invert Animation on "..tool.Name..":"..inpname)
	comp:Lock()
	
	-- get key frames of BezierSpline object (not from the input object)
	keys = inp:GetConnectedOutput():GetTool():GetKeyFrames()

	-- connect fresh spline
	tool[inpname] = BezierSpline()
	
	-- remember current time because a default keyframe has already been
	-- created on the spline and we need to remove it later
	currenttime = comp.CurrentTime

	-- iterate over keyframe table
	for f, k in keys do
		local value = k[1]
		inp[value] = f
		-- once the first new key has been set, delete the one that came
		-- with our BezierSpline object
		if currenttime ~= nil then
			if currenttime ~= value then
				inp[currenttime] = nil
			end
			currenttime = nil
		end
	end	

	comp:Unlock()
	comp:EndUndo(true)
end