Tree Logger

local paces = 0
local facing = 0

function backTrack()
   while (paces > -1) do
       refuel()
       turtle.back()
       paces = paces - 1
    end
end

function goTree()
    while (not turtle.detect()) do
        refuel()
        turtle.forward()
        paces = paces + 1
    end
end

local function comeDown()
  while (turtle.detectDown() == false)
  do
    turtle.down()
  end
end

function refuel()
  if turtle.getFuelLevel() < 5 then
    turtle.select(16)
    while (turtle.getItemCount(16) == 0)
    do
      print("Waiting for fuel..")
      sleep(2)
    end
    turtle.refuel(1)
    turtle.select(1)
  end
end

local function checkTree()
    turtle.dig()
    turtle.forward()
    if (turtle.detect()) then
        log2x2()
    else
        log1x1()
    end
end

function log1x1()
    turtle.select(1)
    while (turtle.compareUp()) do
        refuel()
        turtle.digUp()
        turtle.up()
    end
end

function log2x2()
    turtle.select(1)
    turtle.dig()
    turtle.forward()
    turtle.turnLeft()
    if (turtle.detect()) then
        for chop = 0, 2, 1 do
            turtle.dig()
            turtle.forward()
            turtle.turnLeft()
        end

        while (turtle.compareUp()) do
            for chop = 0, 3, 1 do
                refuel()
                turtle.dig()
                turtle.forward()
                turtle.turnLeft()
                facing = facing + 1
                if (facing == 4) then
                  facing = 0
                end
            end
            refuel()
            turtle.digUp()
            turtle.up()
        end
    else
        turtle.turnRight()
        turtle.turnRight()

        for chop = 0, 2, 1 do
            turtle.dig()
            turtle.forward()
            turtle.turnRight()
        end

        while (turtle.compareUp()) do
            for chop = 0, 3, 1 do
                refuel()
                turtle.dig()
                turtle.forward()
                turtle.turnRight()
                facing = facing - 1
                if (facing == -1) then
                  facing = 3
                end
            end
            refuel()
            turtle.digUp()
            turtle.up()
        end
    end
end

--[[Main Function]]--

function main()
    refuel()
    goTree()
    checkTree()
    comeDown()
    backTrack()
end

--[[Program entry]]--

main()