Build Platform

function move(direction, count)
  if ( direction == "forward" ) then
    for i=1,count do
      checkFuel()
      while ( not turtle.forward() ) do
        turtle.dig()
        checkInv()
      end
    end
  elseif ( direction == "up" ) then
    for i=1,count do
      checkFuel()
      while ( not turtle.up() ) do
        turtle.digUp()
        checkInv()
      end
    end
  elseif ( direction == "down" ) then
    for i=1,count do
      checkFuel()
      while ( not turtle.down() ) do
        turtle.digDown()
        checkInv()
      end
    end
  else
    io.write("Unknown direction specified: " .. direction .. "\n")
    os.exit()
  end
end

function turn(direction)
  if ( direction == "left" ) then
    turtle.turnLeft()
  elseif ( direction == "right" ) then
    turtle.turnRight()
  else
    io.write("Unknown turn Direction: " .. direction .. "\n")
    os.exit()
  end
end

function checkInv()
  full=true
  for i=freeSlot,16 do
    full=(turtle.getItemCount(i) > 0 and full)
  end
  return full
end

function checkFuel()
  if ( turtle.getFuelLevel() <= 1 ) then
    io.write("The turtle is very low on Fuel. Please place fuel in slot " .. freeSlot .. "\n")
    turtle.select(freeSlot)
    while ( turtle.getFuelLevel() <= 1 ) do
      turtle.refuel()
      sleep(1)
    end
  end
end

function getSlot()
  if ( turtle.getItemCount(currentSlot) > 0 ) then
    return
  else
    for i=1,#subs do
      if ( turtle.getItemCount(subs[i]) > 0 ) then
        currentSlot=i
        return
      end
    end
    io.write("There are no blocks available for building. Please place blocks in one of the following slots\n")
    for i=1,#subs do
      io.write(subs[i] .. "\n")
    end
    while ( true ) do
      for i=1,#subs do
        if ( turtle.getItemCount(subs[i]) > 0 ) then
          currentSlot=i
          return
        end
      end
      sleep(1)
    end
  end
end

function placeBlock()
  getSlot()
  turtle.select(currentSlot)
  if ( not turtle.compareDown() ) then
    turtle.digDown()
    turtle.placeDown()
  end
  turtle.select(freeSlot)
end

function checkBlocks(requiredNumber)
  j=2
  subs={}
  subs[1]=1
  turtle.select(1)
  if ( turtle.getItemCount(1) > 0 ) then
    blockCount=turtle.getItemCount(1)
    for i=2,16 do
      if ( turtle.compareTo(i) ) then
        subs[j]=i
        j=j+1
        blockCount = blockCount + turtle.getItemCount(i)
      else
        if ( freeSlot == 0 ) then
          freeSlot=i
        end
      end
    end
  else
    io.write("There are no blocks in slot 1. Please correct and run again\n")
    os.exit()
  end
  if ( blocksReq > blockCount ) then
    io.write("There are insufficient blocks in subsitute slots, a refill will be required\n")
  end
end


args={ ... }
length=tonumber(args[1])
width=tonumber(args[2])
freeSlot=0
currentSlot=1
blocksReq=length*width
checkBlocks()
turnDirection="right"
for i=1,width do
  for j=1,length do
    placeBlock()
    if ( j ~= length ) then
      move("forward",1)
    end
  end
  turn(turnDirection)
  move("forward", 1)
  turn(turnDirection)
  if ( i % 2 == 1 ) then
    turnDirection="left"
  else
    turnDirection="right"
  end
end