MenuByGrimReaper

local bRunning = true
local nScreenWidth, nScreenHeight = term.getSize()
local nSelection = 1
local tMainMenu = {
[1] = { sTitle = "First Option", fAssociatedFunction = FirstOption },
[2] = { sTitle = "Second Option", fAssociatedFunction = SecondOption },
[3] = { sTitle = "Exit", fAssociatedFunction = function() bRunning = false end }
}
function PrintCentered( nHeight, sString )
	term.setCursorPos( nScreenWidth/2 - string.len( sString )/2, nHeight )
	term.write( sString )
end
function ClearScreen()
	term.clear()
	term.setCursorPos( 1, 1 )
end
function PrintMenu( tMenu, nStartHeight )
	for index = 1, #tMenu do
		if index == nSelection then
			PrintCentered( nStartHeight + ( index - 1 ), "[" .. tMenu[index].sTitle .. "]" )
		else
			PrintCentered( nStartHeight + ( index - 1 ), " " .. tMenu[index].sTitle .. " " )
		end
	end
end
function HandleKeyPress( nKey, tMenu )
	if nKey == 28 then
		tMenu[nSelection].fAssociatedFunction()
	elseif nKey == 200 and nSelection > 1 then
		nSelection = nSelection - 1
	elseif nKey == 208 and nSelection < 3 then
		nSelection = nSelection + 1
	end
end
function FirstOption()
	ClearScreen()
	PrintCentered( 5, "First option selected." )
	sleep( 2 )
end
function SecondOption()
	ClearScreen()
	PrintCentered( 5, "Second option selected." )
	sleep( 2 )
end

while bRunning do
	ClearScreen()
	PrintMenu( tMainMenu, 5, nSelect )

	local sEvent, nKey = os.pullEvent( "key" )
	HandleKeyPress( nKey, tMainMenu )
end