api_location

x, y, z = 0, 0, 0
direction = 0

function safeDig(side)
  if not (peripheral.getType(side) == "turtle") then
     if side == "front" then
       return turtle.dig()
     elseif side == "top" then
       return turtle.digUp()
     elseif side == "bottom" then
       return turtle.digDown()
     end
  end

  return false
end

function forward(steps)
  steps = steps or 1

  for i = 1, steps do

    while not turtle.forward() do
      safeDig("front")
      sleep(0.6)
    end

    if direction == 0 then
      z = z - 1
    elseif direction == 2 then
      z = z + 1
    elseif direction == 1 then
      x = x + 1
    elseif direction == 3 then
      x = x - 1
    end
  end
end

function up()
  while not turtle.up() do
    safeDig("top")
  end
  y = y + 1
end

function down()
  while not turtle.down() do
    safeDig("bottom")
  end
  y = y - 1
end

function turnTo(newDirection)
  local turns = newDirection - direction

  if turns <= -3 then
    turns = turns + 4
  elseif turns >= 3 then
    turns = turns - 4
  end

  while turns ~= 0 do
    if turns < 0 then
      turns = turns + 1
      turtle.turnLeft()
    else
      turns = turns - 1
      turtle.turnRight()
    end
  end

  direction = newDirection
end

function deploy(to)
  forward()
  if to < 0 then
    turnTo(3)
  elseif to > 0 then
    turnTo(1)
  end

  while x ~= to do
    forward()
  end

  turnTo(0)
  forward()
end

function dock()
  turnTo(2)
  while z < -1 do
    forward()
  end

  while y ~= -1 do
    if y < -1 then
      up()
    else
      down()
    end
  end

  if x < 0 then
    while x < -1 do
      turnTo(1)
      forward()
    end

    turnTo(2)
    forward()
    forward()
    turnTo(1)
    forward()
  else
    if x == 0 then
      turnTo(1)
      forward()
    end

    while x > 1 do
      turnTo(3)
      forward()
    end

    turnTo(2)
    forward()
    forward()
    turnTo(3)
    forward()
  end

  up()
  turnTo(0)
  forward()
end