--Charge Program - p3pt3RQM
--Developed by UltraNoobian
local version = "0.04d"

--API_LOAD
--END API_LOAD


--VAR_LOAD
local args = {...}
local targetCharge = 0
--END VAR_LOAD

--FUNC_DEFINE
function Intro()
	print ("--------")
	print ("Charging Program - Developed by UltraNoobian")
	print ("Using version: " .. version)
	print ("--------")
end
function termReset()
	term.clear()
	term.setCursorPos(1,1)
end
-->> termReset() is never called.  Either remove completely or integrate int Intro()

function getVariables()
	if args and #args == 1 then
	-->> Because args is defined as {...} it will always exist as a table.  Remove "args and" as it is redundant.
		if tonumber(args[1]) ~= nil and tonumber(args[1]) >= 1 then
			targetCharge = tonumber(args[1])
			print("Valid Charge: " .. args[1])
		elseif tonumber(args[1]) ~= nil and tonumber(args[1]) < 1 then
			print("That is not a positive charge. Try again.")
			error()
		elseif tonumber(args[1]) == nil then
			print("Not a number, Please enter a valid number next time you run this program~!")
			error()
		end
		-->> Move the handler for tonumber(args[1]) == nil to the top, then you do not need to check for it for the other 2 cases.
	elseif args and #args > 1 then
		print("Invalid number of arguements, We only need the charge level!")
		error()
		-->> use this:  error("Invalid number of arguments.", 0)
		-->> The 2nd parameter, 0, tells Lua to exit with an error, but not provide a line number.
		-->> or do what most Lua programs do; simply ignore the extra parameters.
	else
		print("")
		print("What Charge level would you like to achieve?")
		testCharge = read()
		-->> You never use the string form of testCharge.  Go ahead and use:
		-->> testCharge = tonumber(read())
		-->> This cleans up later code a lot.

		if tonumber(testCharge) ~= nil and tonumber(testCharge) >= 1 then
        -->> Replace with:  if testCharge and testCharge >= 1 then
			targetCharge = tonumber(testCharge)
			print("Valid Charge: " .. targetCharge)
		elseif tonumber(testCharge) ~= nil and tonumber(testCharge) < 1 then
			print("That is not a positive charge. Try again.")
			error()
		elseif tonumber(testCharge) == nil then
			print("Not a number, Please enter a valid number next time you run this program~!")
			error()
		end
		-->> Same concept as above.
	end
end
function printVariables()
	print("")
	print("---NOTICE---")
	print("Your current charge level is " .. turtle.getFuelLevel())
	print("You are charging to " .. targetCharge .. ".")
	print("Press any key to continue...")
	read()
end
function chargeFull()
	if turtle.getFuelLevel() > targetCharge then
		return true
	else
		return false
	end
end
-->> if then else is redundant.  Comparisons return a boolean already.  Use:
-->> return turtle.getFuelLeve() > targetCharge

function tryBurn(slotID)
	while turtle.getItemCount(slotID) > 0 do
		if turtle.refuel(1) == false or chargeFull() then
			break
		end
	end
end
function inventoryBurn()
	print("Inventory burn commencing...")
	print("")

	for slotID = 1,16 do
		turtle.select(slotID)
		lineUpdate("Currently attempting to burn slot " .. slotID .. ".")
		tryBurn(slotID)

		if chargeFull() then
			print("")
			print("Your turtle has reached it's target charge level!!")
			read()
			break
		end
	end
end
function burnCoolDown()
	print("")
	print("Begining idle phase, Now is the time to put in fuel...")
	print("")
	for count = 30,0,-1 do
		lineUpdate("Next Inventory Burn in " .. count .. " seconds")
		sleep(1.0)
	end
	print("")
end
-->> burnCoolDown() calls lineUpdate() before it is declared.  You need to move the lineUpdate() function above burnCoolDown() so it exists when burnCoolDown() is compiled.

function lineUpdate(string)
	local currX,currY = term.getCursorPos()
	term.clearLine()
	term.setCursorPos(1,currY)
	write(string)
end
--END FUNC_DEFINE

--MAIN

Intro()
getVariables()
printVariables()

while not chargeFull() do
	inventoryBurn()
	if not chargeFull() then
		burnCoolDown()
	end
end

print("")
print("This program will now terminate.... Thank you for using UltraNoobian's Programs")