Enchant Turtle

xp = peripheral.wrap("left")
anvil = peripheral.wrap("right")
xp.setAutoCollect(true)
term.clear()
w,h = term.getSize()
elvl = 30
turtle.select(1)

function swrite(str,x,y)
	term.setCursorPos(x,y)
	term.write(str)
end

function swritecenter(str,y)
	term.setCursorPos(w/2 - #str/2,y)
	term.write(str)
end

function cline(y)
	term.setCursorPos(1,y)
	term.clearLine()
end

function drawUI()
	swritecenter("Welcome to Fair's XP Turtle.",1)
	swrite("How to use enchant/repair:",2,3)
	swrite("1. Place item(s) in slot 1/2.",2,4)
	swrite("2. Use Arrowkeys to change level.",2,5)
	swrite("3. Press ENTER to enchant/repair.",2,6)
	swrite("NOTE: Exit, enter turtle to update.",2,13)
end

function updateLVL()
	swrite("Current stored levels: "..xp.getLevels().."  ",2,8)
end

function updateSEL()
	cline(9)
	swrite("Selected enchant level: "..elvl,2,9)
end

function updateREP(str)
	cline(9)
	swrite("Items repair level cost: "..str,2,9)
end

function update(str)
	swrite("Last status:",2,10)
	term.setCursorPos(1,11)
	term.clearLine()
	swrite(str,2,11)
end

drawUI()
updateLVL()
updateSEL()
updateREP("N/A")
update("Startup complete.")

while true do
	event,key = os.pullEvent()
	if turtle.getItemCount(2) == 0 then
		updateSEL()
	else
		if anvil.getRepairCost(1,2) > 0 then
			updateREP(tostring(anvil.getRepairCost(1,2)))
		else
			updateREP("N/A")
		end
	end
	if event == "key" then
		if key == 28 then
			if turtle.getItemCount(2) == 0 then
				if elvl <= xp.getLevels() then
					if xp.enchant(elvl) then
						update("Success enchant of "..elvl.." levels.")
					else
						update("Something went wrong in enchant.")
					end
				else
					update("Turtle level not high enough.")
				end
			else
				if anvil.getRepairCost(1,2) <= xp.getLevels() then
					if anvil.repair(1,2) then
						update("Success repair of items.")
					else
						update("Something went wrong in repair.")
					end
				else
					update("Turtle level not high enough.")
				end
			end
		elseif key == 200 or key == 205 then
			if elvl < 30 then
				elvl = elvl + 1
				updateSEL()
			end
		elseif key == 208 or key == 203 then
			if elvl > 1 then
				elvl = elvl - 1
				updateSEL()
			end
		end
	end
	updateLVL()
	os.sleep(0.1)
end