GPS Tree Farm

local x = 0
local y = 0
local z = 0
local facing = 0

local homex = -21
local homey = 17
local homez = 253

local yupper = 45
local xupper = 3

local fuelSlot = 1
local sapSlot = 2

local success = false
local data = nil

waitTimer = 0

local ready = true
local loopCheck = true

---------------------------------------
-- BASIC FUNCTIONS FOR TURTLE CONTROL -
---------------------------------------
local function gf(n)
  if n==nil then
    n=1
  end
  for i=1,n,1 do
    turtle.forward()
  end
end
local function gb(n)
  if n==nil then
    n=1
  end
  for i=1,n,1 do
    turtle.back()
  end
end
local function gu(n)
  if n==nil then
    n=1
  end
  for i=1,n,1 do
    turtle.up()
  end
end
local function gd(n)
  if n==nil then
    n=1
  end
  for i=1,n,1 do
    turtle.down()
  end
end
local function tl()
  turtle.turnLeft()
  if facing == 1 then
    facing = 4
  else
    facing = facing - 1
  end
end
local function tr()
  turtle.turnRight()
  if facing == 4 then
    facing = 1
  else
    facing = facing + 1
  end
end
local function pf()  turtle.place()       end
local function pu()  turtle.placeUp()     end
local function pd()  turtle.placeDown()   end
local function df()  return turtle.dig()  end
local function du()  turtle.digUp()       end
local function dd()  turtle.digDown()     end
local function sf()  turtle.suck()        end
local function su(n)
  if n==nil then
    while turtle.suckUp() do end
  else
    for i=1,n do
      turtle.suckUp()
    end
  end
end
local function sd(n)
  if n==nil then
    while turtle.suckDown() do end
  else
    for i=1,n do
      turtle.suckDown()
    end
  end
end
local function Df()  turtle.drop()       end
local function Du()  turtle.dropUp()     end
local function Dd(n)
  if n==nil then n=64 end
  turtle.dropDown(n)
end
local function ss(s) turtle.select(s)    end
local function cf() turtle.compare()     end
local function cu() turtle.compareUp()   end

---------------------------------------
--          Building Blocks          --
---------------------------------------

local function locate()
  x,y,z = gps.locate(5)
  if not x then
    print("Failed to get my location!")
  else
    print("I am at (" .. x .. ", " .. y .. ", " .. z .. ")")
  end
end

local function refuel()
  if turtle.getFuelLevel()<80 then
    ss(fuelSlot)
    turtle.refuel(1)
  end
end

local function changeFacing(goal)
  while facing ~= goal do
    tl()
  end
end

local function calibrate()
  locate()
  local tempx = x
  local tempy = y
  gf()
  locate()
  if (x - tempx) == 1 then
    facing = 2
  elseif (x - tempx) == -1 then
    facing = 4
  else
    if (y - tempy) == 1 then
      facing = 1
    else
      facing = 3
    end
  end
  gb()
  changeFacing(1)
end

local function mx(n)
  if n > 0 then
    changeFacing(2)
  elseif n < 0 then
    changeFacing(4)
    n = n*-1
  end
  for i=1,n do
    --if turtle.detect() then
      --df()
    --end
    gf()
  end
end

local function my(n)
  if n > 0 then
    changeFacing(1)
  elseif n < 0 then
    changeFacing(3)
    n = n*-1
  end
  for i=1,n do
    --if turtle.detect() then
      --df()
    --end
    gf()
  end
end

local function mz(n)
  if n > 0 then
    for i=1,n do
      if turtle.detectUp() then
        du()
      end
      gu()
    end
  elseif n < 0 then
    for i=1,-n do
      if turtle.detectDown() then
        dd()
      end
      gd()
    end
  end
end

local function home()
  mz(10)
  locate()
  if x > homex then
    mx(-math.abs(homex-x))
  elseif x < homex then
    mx(math.abs(homex-x))
  end
  if y > homey then
    my(-math.abs(homey-y))
  elseif y < homey then
    my(math.abs(homey-y))
  end
  if z > homez then
    mz(-math.abs(homez-z))
  elseif z < homez then
    mz(math.abs(homez-z))
  end
  locate()
  ready = true
  changeFacing(1)
  loopCheck = false
end

local function refuel()
  if turtle.getFuelLevel()<500 then
    print("Fuck")
  end
end

local function checkFull()
  --TODO:Drop off when full
end

local function checkSaps()
  --TODO:Go back for saplings
end

local function tempReload()
  --TODO: Write a reload function
end

local function calibrate2()
  success, data = turtle.inspect()
  if success then
    if data.name == "minecraft:log" then
      chopTree()
    end
  end
  calibrate()
end

local function chopTree()
  waitTimer = 0
  success,data = turtle.inspect()
  while data.name ~= "minecraft:log" do
    os.sleep(5)
    if data.name == "minecraft:sapling" then
      waitTimer = waitTimer + 1
      if waitTimer > 4 then
        break
      end
    end
    success,data = turtle.inspect()
    print(waitTimer)
  end
  if data.name == "minecraft:log" then
    df()
    gf()
    while success do
      success,data = turtle.inspectUp()
      if data.name == "minecraft:log" then
        du()
        gu()
        z = z + 1
      else
        break
      end
    end
    for i=z,homez+2,-1 do
      gd()
    end
    ss(sapSlot)
    pd()
  else
    gu()
    gf()
  end
    z = homez
end

local function nextTree()
  locate()
  if y == yupper then
    if  x == xupper then
      home()
    else
      tr()
    end
  elseif y == (homey + 4) then
    if x ~= homex then
      tl()
    end
  end
  if turtle.detect() then
    df()
  end
  gf()
  gd()
  gf()
  gf()
end

---------------------------------------
---------         MAIN        ---------
---------------------------------------

calibrate2()

while loopCheck do
  nextTree()
  chopTree()
  refuel()
  checkFull()
  checkSaps()
end

gb()
gb()
gb()
gb()