Program arguments

local usage = {
  "multiple different args are accepted",
  "if multiple of the same arg are given then the last one will be used - this is redundent don't do it",
  "we will tell you the arg number which caused any errors",
  "  -h | print this usage information",
  "  -f <filePath> | where filePath points to a file which contains the quadProgram",
  "  -n <interger/number> | numOfQuads",
  "  -d <float/number> | delayMult",
  "  -r <side/'ignore'> | redstoneSide or ignoreRedstone = true",
  "  -b <side> | baseSide",
  "  -t <bool> | anyKeyTerminate",
}


--# there is more code here, but not related to arg processing

local arg = {...}
--# set vaiables to default, we will overide these with the arg later
local quadProgram = defaults.quadProgram
local numOfQuads = defaults.numOfQuads
local delayMult = defaults.delayMult
local ignoreRedstone = defaults.ignoreRedstone
local anyKeyTerminate = defaults.anyKeyTerminate
local bSide = defaults.bSide
local rSide = defaults.rSide

if #arg > 0 then
  --# lower case everything
  for i = 1, #arg do
	if not tonumber(arg[i]) then
	  arg[i] = string.lower(arg[i])
	end
  end
  --# process arg
  local i = 1
  while i <= #arg do
	local doubleInc = false
	if arg[i] == "-h" then
	  printUsage()
	elseif arg[i] == "-f" then --# quadProgram
	  do --# make my editor look clearer
	  if not (fs.exists(tostring(arg[i+1])) and (not fs.isDir(tostring(arg[i+1])))) then
		myError("arg "..i.." Can't load file, either doesn't exist or is a directory", 2)
	  else
		local f = fs.open(arg[i+1], "r")
		local p = f.readAll()
		f.close()
		quadProgram = textutils.unserialize(p)
		if quadProgram == nil then error("unable to understand file: "..tostring(arg[i+1]))
	  end
	  doubleInc = true
	  end --# make my editor look clearer
	elseif arg[i] == "-n" then --# numOfQuads
	  do --# make my editor look clearer
	  local n = tonumber(arg[i+1])
	  if n == nil or n < 1 then
		myError("arg "..i.." -n arg must be followed by a whole number greater than 0 (1 or greater are valid)", 2)
	  else
		local a,b = math.modf(n)
		if b ~= 0 then
		  myError("arg "..i.." -n arg must be followed by a whole number greater than 0 (1 or greater are valid)", 2)
		end
	  end
	  if n > 64 then
		print("arg "..i.." Warning: numOfQuads is larger than one stack(64). Did the max per base change or are you piping them in?")
	  end
	  numOfQuads = n
	  doubleInc = true
	  end --# make my editor look clearer
	elseif arg[i] == "-d" then --# delayMult
	  do --# make my editor look clearer
	  local d = tonumber(arg[i+1])
	  if d == nil then
		myError("arg "..i.." -d arg must be followed by a number", 2)
	  end
	  delayMult = d
	  doubleInc = true
	  end --# make my editor look clearer
	elseif arg[i] == "-r" then --# redstoneSide
	  do --# make my editor look clearer
	  local r = tostring(arg[i+1])
	  if r == nil then
	   myError("arg "..i.." -r arg must be followed by a string representing a side or equal to 'ignore'", 2)
	  end
	  if r == "ignore" then
		ignoreRedstone = true
	  elseif r == "left" or r == "right" or r == "front" or r == "back" then
		rSide = r
		ignoreRedstone  = false
	  else
		myError("arg "..i.." -r arg must be followed by a string representing a side or equal to 'ignore'", 2)
	  end
	  doubleInc = true
	  end --# make my editor look clearer
	elseif arg[i] == "-b" then --# baseSide
	  do --# make my editor look clearer
	  local b = tostring(arg[i+1])
	  if b == nil then
		myError("arg "..i.." -b arg must be followed by a string representing a side", 2)
	  end
	  if b == "left" or b == "right" or b == "front" or b == "back" then
		bSide = b
	  else
		myError("arg "..i.." -b arg must be followed by a string representing a side", 2)
	  end
	  doubleInc = true
	  end --# make my editor look clearer
	elseif arg[i] == "-t" then --# anyKeyTerminate
	  do --# make my editor look clearer
	  local t = tostring(arg[i+1])
	  if t == nil then
		myError("arg "..i.." -t arg must be followed by a string equal to 'true' or 'false'", 2)
	  end
	  if t == "true" then
		anyKeyTerminate = true
	  elseif t == "false" then
		anyKeyTerminate = false
	  else
		myError("arg "..i.." -t arg must be followed by a string equal to 'true' or 'false'", 2)
	  end
	  doubleInc = true
	  end --# make my editor look clearer
	else
	  myError("arg "..i.." unprocessed arg",2)
	end
	if doubleInc then
	  i = i +2
	else
	  i = i +1
	end
  end
end