Move

function DemandLocation()
 local pos = nil
 while (pos == nil) do
  pos = vector.new(gps.locate())
 end
 return pos
end

function DirString()
 if (Move.Dir == Move.DIR_NORTH) then
  return "north"
 elseif (Move.Dir == Move.DIR_EAST) then
  return "east"
 elseif (Move.Dir == Move.DIR_SOUTH) then
  return "south"
 elseif (Move.Dir == Move.DIR_WEST) then
  return "west"
 else
  return nil
 end
end

function Face(direction)
 while (Move.Dir ~= direction) do
  TurnRight()
 end
end

function ForceDown()
 while (TryDown() ~= true) do
  turtle.digDown()
 end
end

function ForceForward()
 while (TryForward() ~= true) do
  turtle.dig()
 end
end

function ForceUp()
 while (TryUp() ~= true) do
  turtle.digUp()
 end
end

function Initialize()
 Move.DIR_NORTH = 0
 Move.DIR_EAST = 1
 Move.DIR_SOUTH = 2
 Move.DIR_WEST = 3

 local pos1 = DemandLocation()
 ForceForward()
 local pos2 = DemandLocation()
 local delta = pos2 - pos1

 if (delta.z == -1) then
  Move.Dir = Move.DIR_NORTH
 elseif (delta.x == 1) then
  Move.Dir = Move.DIR_EAST
 elseif (delta.z == 1) then
  Move.Dir = Move.DIR_SOUTH
 elseif (delta.x == -1) then
  Move.Dir = Move.DIR_WEST
 end

 MoveTo(pos1)
end

function MoveTo(newPos)
 local currPos = DemandLocation()
 local delta = newPos - currPos

 alignEastWest(delta)
 alignNorthSouth(delta)
 alignUpDown(delta)
end

function TryDown()
 return turtle.down()
end

function TryForward()
 return turtle.forward()
end

function TryUp()
 return turtle.up()
end

function TurnLeft()
 turtle.turnLeft()
 Move.Dir = (Move.Dir + 3) % 4
end

function TurnRight()
 turtle.turnRight()
 Move.Dir = (Move.Dir + 1) % 4
end

function alignEastWest(delta)
 if (delta.x < 0) then
  Face(Move.DIR_WEST)
  doMultiple(ForceForward, 0 - delta.x)
 elseif (delta.x > 0) then
  Face(Move.DIR_EAST)
  doMultiple(ForceForward, delta.x)
 end
end

function alignNorthSouth(delta)
 if (delta.z < 0) then
  Face(Move.DIR_NORTH)
  doMultiple(ForceForward, 0 - delta.z)
 elseif (delta.z > 0) then
  Face(Move.DIR_SOUTH)
  doMultiple(ForceForward, delta.z)
 end
end

function alignUpDown(delta)
 if (delta.y < 0) then
  doMultiple(ForceDown, 0 - delta.y)
 elseif (delta.y > 0) then
  doMultiple(ForceUp, delta.y)
 end
end

function doMultiple(func, count)
 for i = 1, count do
  func()
 end
end