GPI

_G["gpi"] = {}
North,South,West,East,Invalid = 0,1,2,3,-1
gpi.direction = -1
gpi.location = {0,0,0}
function gpi.locate(x,y,z)
  if x == nil then
    x2, y2, z2 = gps.locate(5)
    if x2 then
      oldTForward()
      local x3, y3, z3 = gps.locate(5)
      if x3 then
        if x3 ~= x2 then
          if x3 > x2 then
            gpi.direction = 3
          else
            gpi.direction = 2
          end
        else
          if z3 ~= z2 then
            if z3 > z2 then
              gpi.direction = 1
            else
              gpi.direction = -1
            end
          else
            gpi.direction = -1
          end
        end
      end
    end
  elseif y == nil then
    error("Error: 3 or 0 Coordinates required.")
  end
  turtle.back()
  gpi.location[1] = x2
  gpi.location[2] = y2
  gpi.location[3] = z2
  return x2, y2, z2, gpi.direction
end
oldTForward = turtle.forward
gpi.locate()
function gpi.forward()
  if turtle.getFuelLevel() == "unlimited" or turtle.getFuelLevel <= 1 then
  if gpi.direction > -1 and gpi.direction < 4 then
  if oldTForward() then
    if gpi.direction == 0 then
      gpi.location[3] = gpi.location[3] - 1
      oldTForward()
    elseif gpi.direction == 1 then
      gpi.location[3] = gpi.location[3] + 1
      oldTForward()
    elseif gpi.direction == 2 then
      gpi.location[1] = gpi.location[1] - 1
      oldTForward()
    elseif gpi.direction == 3 then
      gpi.location[1] = gpi.location[1] + 1
      oldTForward()
    end
    return gpi.location[1], gpi.location[2], gpi.location[3]
  else
    return false
  end
  else
    return false
  end
  else
    return false
  end
end
turtle.forward = gpi.forward

function gpi.restore()
  turtle.forward = oldTForward
  turtle.back = oldTBack
  turtle.turnLeft = oldTLeft
  turtle.turnRight = oldTRight
  turtle.up = oldTUp
  turtle.down = oldTDown
end

oldTLeft = turtle.turnLeft
function gpi.turnLeft()
  if gpi.direction > -1 and gpi.direction < 4 then
    if gpi.direction == 0 then
      gpi.direction = 2
      oldTLeft()
    elseif gpi.direction == 1 then
      gpi.direction = 3
      oldTLeft()
    elseif gpi.direction == 2 then
      gpi.direction = 1
      oldTLeft()
    elseif gpi.direction == 3 then
      gpi.direction = 0
      oldTLeft()
    end
    return gpi.direction
  else
    return false
  end
end
turtle.turnLeft = gpi.turnLeft
oldTRight = turtle.turnRight()
function gpi.turnRight()
  if gpi.direction > -1 and gpi.direction < 4 then
    if gpi.direction == 0 then
      gpi.direction = 3
      oldTRight()
    elseif gpi.direction == 1 then
      gpi.direction = 2
      oldTRight()
    elseif gpi.direction == 2 then
      gpi.direction = 0
      oldTRight()
    elseif gpi.direciton == 3 then
      gpi.direction = 1
      oldTRight()
    end
    return gpi.direction
  else
    return false
  end
end
turtle.turnRight = gpi.turnRight
oldTBack = turtle.back
function gpi.back()
  if turtle.getFuelLevel() == "unlimited" or turtle.getFuelLevel() >= 1 then
  if gpi.direction > -1 and gpi.direction < 4 then
  if oldTBack() then
    oldTBack()
    if gpi.direction == 0 then
      gpi.location[3] = gpi.location[3] + 1
    elseif gpi.direction == 1 then
      gpi.location[3] = gpi.location[3] - 1
    elseif gpi.direction == 2 then
      gpi.location[1] = gpi.location[1] + 1
    elseif gpi.direction == 3 then
      gpi.location[1] = gpi.location[1] - 1
    end
    return gpi.location[1], gpi.location[2], gpi.location[3]
  else
    return false
  end
  else
    return false
  end
  else
    return false
  end
end
turtle.back = gpi.back
oldTUp = turtle.up
function gpi.up()
  if turtle.getFuelLevel() == "unlimited" or turtle.getFuelLevel >= 1 then
  if gpi.direction > -1 and gpi.direction < 4 then
  if oldTUp() then
    oldTUp()
    gpi.location[2] = gpi.location[2] + 1
    return gpi.location[1], gpi.location[2], gpi.location[3]
  else
    return false
  end
  else
    return false
  end
  else
    return false
  end
end
turtle.up = gpi.up
oldTDown = turtle.down
function gpi.down()
  if turtle.getFuelLevel() == "unlimited" or turtle.getFuelLevel >= 1 then
  if gpi.direction > -1 and gpi.direction < 4 then
  if oldTDown() then
    oldTDown()
    gpi.location[2] = gpi.location[2] - 1
    return gpi.location[1], gpi.location[2], gpi.location[3]
  else
    return false
  end
  else
    return false
  end
  else
    return false
  end
end
turtle.down = gpi.down
function gpi.getDirection()
  return gpi.direction
end
function gpi.setDirection(dire)
  if not tonumber(dire) then
    error("Error: Got "..type(dire)..". Number Or Compass Expected.")
  end
  if dire > -1 and dire < 4 then
  if gpi.direction > -1 and gpi.direction < 4 then
  while gpi.direction ~= dire do
    gpi.turnLeft()
  end
  return direction
  else
    return false
  end
  else
    return false
  end
end