drill: ComputerCraft turtle program to drill down or forward through materials until you hit open area, then return to start

drill.lua

--drill: ComputerCraft turtle program to drill down or forward 
--    through materials until you hit open area, then return to start.
--    Arguments are "f" for drill forward, or "d" for drill down.

-- by Alexander "SquidLord" Williams (SaladinVrai)

-- Gist: https://gist.github.com/SquidLord/4757383

-- Requires squidlib and egps
os.loadAPI("squid/squidlib")
os.loadAPI("squid/egps")

ARGS = {...}

function usage()
  squidlib.printTable({
        "SquidOS Drill Program ...",
        "",
        "  Drill down or forward through materials until you hit open area, then return to Start.",
        "",
        "  Arguments:",
        "    f - Drill forward",
        "    d - Drill down"})
  return nil
end

function main()
  if not ARGS[1] then 
    return usage()
  elseif not ((ARGS[1] == "f") or (ARGS[1] == "d")) then
    return usage()
  else -- Everything is groovy
    Loc = {} -- Put starting location in scope
    MoveFunc = false -- Put direction of motion in scope
    DrillFunc = false -- Put direction to drill in scope
    ScanFunc = false -- Put direction to look in scope
    Loc.x, Loc.y, Loc.z, Loc.f = egps.setLocationFromGPS() -- Save the current location to return to
    
    -- Identify
    squidlib.printTable({
        "SquidOS Drill Program ...",
        ""})
    
    if (ARGS[1] == "f") then
      MoveFunc = egps.forward
      DrillFunc = turtle.dig
      ScanFunc = turtle.detect
      print("  Drilling forward")
    else
      MoveFunc = egps.down
      DrillFunc = turtle.digDown
      ScanFunc = turtle.detectDown
      print("  Drilling down")
    end
    
    while ScanFunc() do
      if not DrillFunc() then -- If you're at the bottom of the world or otherwise can't drill
        print("  Cannot drill further")
        break
      elseif not MoveFunc() then -- If you can't move even after drilling
        print("  Cannot move into drilled space")
        break
      end
    end
    
    print("  Nothing more to drill; RTB")
    
    egps.moveTo(Loc.x, Loc.y, Loc.z, Loc.f) -- Returning to start
    
    print("Done")
  end
end


---
--- Main
--- 

main()