tree

-- Move up for given amount and check for every move if there is enough fuel for this opreation
function moveUp(amount)
    for n = 1, amount, 1 do
      checkFuel(0)
      turtle.up()
    end
end

-- Move down for given amount and check for every move if there is enough fuel for this opreation
function moveDown(amount)
    for n = 1, amount, 1 do
      checkFuel(0)
      turtle.down()
    end
end

-- if there is more fuel then requested, otherweise refuel from slot 5
-- if this fails then wait for userinput
function checkFuel(value)
  fuel = turtle.getFuelLevel()
  if fuel <= value then
    print("Need FUEL!, press any key when ready")
    -- move wood to refuel slot and refuel (we could refuel from 5 but this is logically cleaner ;) )
    turtle.select(5)
    turtle.transferTo(16 ,32)
    turtle.select(16)
    turtle.refuel()
    fuel = turtle.getFuelLevel()
    print("Refueled - Fuel Level"..fuel)

    -- refuel failed for some reason? wait for player to refuel
    if fuel == 0 then
       print("Refuel failed, please refuel manually!!")
       local event, param1 = os.pullEvent("char")
       turtle.select(16)
       turtle.refuel()
    end
  end
end

-- checks if there is something in front of turtel
-- if yes : it must be a tree and turtel will chop it down
-- maybe there are just leaves but we think of them as a tree and clear the way ;)
function detectAndCutTree()
  -- is something in front of turtel?
  if turtle.detect() then
    -- dig block in front place it in slot 5 and move to digged pos, chop 1 below and chop everything above
    turtle.select(5)
    turtle.dig()
    moveForward(1)
    turtle.digDown()
    while turtle.detectUp() do
      turtle.digUp()
      moveUp(1)
    end

    -- move down to ground
    while not turtle.detectDown() do
      moveDown(1)
    end

    -- move to original postion, pre chopping
    moveUp(1)
    turtle.back()
  end
end


-- moves turtel forwar for given amount, check for fuel and possible tree on every move
function moveForward(amount)
    for n = 1, amount, 1 do
      checkFuel(0)
      detectAndCutTree()
      turtle.forward()
    end
end

-- plant a sappling, checks for saps in slot 1 and 2. if empty waits for player input
function plantSap()
  gotSap = 1

  turtle.select(1)
  sapLevel = turtle.getItemCount(1)
  -- if slot 1 is empty try slot 2
  if sapLevel == 0 then
     turtle.select(2)
     sapLevel2 = turtle.getItemCount(2)
     -- if slot 2 is empty try slot 3
     if sapLevel2 == 0 then
       turtle.select(3)
       sapLevel3 = turtle.getItemCount(3)
       -- if slot 3 is empty try slot 4
       if sapLevel3 == 0 then
         turtle.select(4)
         sapLevel4 = turtle.getItemCount(4)
         -- if slot 4 is empty just continue in felling mode
         if sapLevel4 == 0 then
           gotSap = 0
           print("No Saplings! just felling now")
        end
      end
    end
  end
  -- if gotSap == 1 we cant plant something and have the right slot selected
  if gotSap == 1 then
    turtle.placeDown()
  end

end

-- move in straight line and planting a sappling on every second field
function plantOrCut(dist)
    plant = 0
    while dist > 0 do
        dist = dist - 1
        if plant == 0 then
          -- just move and cut no plating
          moveForward(1)
          plant = 1
        else
          -- try planting then move and cut
          plantSap()
          moveForward(1)
          plant = 0
        end
    end
end

-- method for moving the turtel through the grid
function moveTurtel()
  dist = 10
  turn = 0
  moveUp(1)
  turtle.select(1)

  for n = 1, dist, 1 do
    -- move turtel
    plantOrCut(dist)
    -- turn right
    if turn == 0 then
      turtle.turnRight()
      moveForward(2)
      turtle.turnRight()
      turn = 1
    -- turn left
    else
      turtle.turnLeft()
      moveForward(2)
      turtle.turnLeft()
      turn = 0
    end
  end
end


-- returns back to chest, refuels and drops loot
function goHome()
  turtle.turnLeft()
  moveForward(20)
  turtle.turnRight()
  --sit on chest
  moveDown(1)
  -- move one wood to another place to make sure the slot will be filled with wood again
  turtle.select(5)
  turtle.transferTo(15 ,4)
  checkFuel(800)

  -- drop loot to chest
  turtle.select(5)
  turtle.dropDown()
  turtle.select(6)
  turtle.dropDown()
  turtle.select(7)
  turtle.dropDown()
  turtle.select(8)
  turtle.dropDown()

  -- move one wood back to 5 to ensure we have wood there to refuel from
  -- reserves slot
  turtle.select(15)
  turtle.transferTo(5 ,1)
  turtle.transferTo(6 ,1)
  turtle.transferTo(7 ,1)
  turtle.transferTo(8 ,1)
end

-- Main Routine, endless repeating
-- fuels itself than starts
function gogoTurtel()
  turtle.select(16)
  turtle.refuel()

  while 1 > 0 do
    fuel = turtle.getFuelLevel()
    print("Going with Fuel Level"..fuel)
    moveTurtel()
    goHome()
  end

end

gogoTurtel()