os.loadAPI("apis/tortoise.lua")


local id,x,z=...

id=tonumber(id)
x=tonumber(x)
z=tonumber(z)

local position = {x=0,y=0,z=0}
local turns = 0

local fuelChestPos = {x=1,y=0,z=4}
local oreChestPos  = {x=1,y=0,z=1}


local function moveX(dist)
  local relTurns = turns%4
  if relTurns == 0 then
    tortoise.forceForward(dist)
  elseif relTurns == 1 then
    tortoise.turnLeft()
    tortoise.forceForward(dist)
    tortoise.turnRight()
  elseif relTurns == 2 then
    tortoise.forceBack(dist)
  else
     tortoise.turnRight()
     tortoise.forceForward(dist)
     tortoise.turnLeft()
  end
  position.x = position.x + dist
end

local function moveY(dist)
  tortoise.forceDown(dist)
  position.y = position.y + dist
end

local function moveZ(dist)
  tortoise.turnRight()
  moveX(dist)
  tortoise.turnLeft()
  position.x = position.x - dist
  position.z = position.z + dist
end

if id==1 then
  moveX(1)
elseif id==2 then
  moveX(1)
  moveZ(z*0.5)
  moveY(1)
  position.y=0
elseif id==3 then
    moveX(x*0.5)
    moveY(2)
    position.y=0
elseif id==4 then
    moveX(x*0.5)
    moveZ(z*0.5)
    moveY(3)
    position.y=0
else
    print("no ID specified. quitting")
    return
end

local function turnLeft(times)
  if times == 0 then return end
  tortoise.turnLeft(times)
  turns = turns - times
end

local function turnRight(times)
  if times == 0 then return end
  tortoise.turnRight(times)
  turns = turns + times
end

local function distanceFromHome()
  return position.x + position.y + position.z
end

local function checkFuel()
  if turtle.getFuelLevel() + (80 * turtle.getItemCount()) < distanceFromHome()+10 then
    local oldPos = position

    moveY(-position.y)
    moveX(fuelChestPos.x-position.x)
    moveZ(fuelChestPos.z-position.z)

    turnLeft(turns)
    turnLeft(2)
    turtle.suck(64)
    moveZ(-2)

    for i=2,16 do
      turtle.select(i)
      turtle.drop()
    end
    turtle.select(1)

    turnRight(2)


    moveY(oldPos.y)
    moveX(oldPos.x-position.x)
    moveZ(oldPos.z-position.z)

  end
end

local function checkInv()
  for i=2,16 do
     if turtle.getItemCount(i) == 0 then
       return
     end
  end

  local oldPos = position
  moveY(-position.y)
  moveX(oreChestPos.x - position.x)
  moveZ(oreChestPos.z - position.z)
  turnLeft(turns)
  turnLeft(2)
  for i=2,16 do
    turtle.select(i)
    turtle.drop()
  end

  moveZ(3)
  turtle.select(1)
  turtle.suck(64-turtle.getItemCount())

  turnRight(2)

  moveX(oldPos.x - position.x)
  moveZ(oldPos.z - position.z)
  moveY(position.y)
end


while true do
  for i=1,x/2 do
    for _=1,z/2 do
      turnLeft(turns)
      checkFuel()
      checkInv()
      turtle.digDown()
      if turtle.detectDown() then
        moveY(-position.y - id)
        moveX(x)
        print("finished.")
        return
      end
      if i%2==1 then moveZ(1)
      else moveZ(-1) end
    end
    if position.y%2==1 then moveX(1)
    else moveX(-1) end
  end
  moveY(1)
end