Tunnel Mk3.02

-- A revised version of the built in tunnelling script that mines a 3x3 tunnel (as opposed to 3x2)
-- Fills in any missing floor blocks with blocks from slot 1 (in theory)
-- returns to start point (buggy won't refuel)
-- Mk III v0.1
-- changes by LN

local tArgs = { ... }
if #tArgs ~= 1 then  -- No length supplied error out with message
  print( "Usage: tunnel <length>" )
  return
end

-- If value supplied check to make sure it's positive
local length = tonumber( tArgs[1] )
if length < 1 then
  print( "Tunnel length must be positive" )
  return
end

-- some more variables (wtf is depth?)
local depth = 0
local collected = 0
local dbg = 0 -- change to 1 if you want test messages to be displayed (LN)

local function collect() -- function works out how much shit you've collected (fails with lapis & redstone iirc)
  collected = collected + 1
  if math.fmod(collected, 25) == 0 then
    print( "Mined "..collected.." items." )
  end
end

local function test(txt) -- function to print test/debug messages, bit spammy but shows what turtle thinks it's doing... even when it isn't... :D (LN)
  if dbg == 1 then
    print("Turtle says: " , txt )
    sleep(5) -- change to shorter/longer to speed up/slow down debug
  end
end

local function reverseTurtle() -- 180 degree turn (LN)
  turtle.turnRight()
  turtle.turnRight()
  test("Reversing Turtle")
end

local function tryDig()
  while turtle.detect() do
    if turtle.dig() then
      collect()
      sleep(0.5)
      test("Dig Fwd")
    else
      test("Dig Fwd Fail")
      return false
    end
  end
  return true

end

local function tryDigUp()
  while turtle.detectUp() do
    if turtle.digUp() then
      collect()
      sleep(0.5)
      test("Dig Up")
    else
      test("Dig Up Fail")
      return false
    end
  end
  return true

end

local function tryDigDown()
  while turtle.detectDown() do
    if turtle.digDown() then
      collect()
      sleep(0.5)
      test("Dig Down")
    else
      test("Dig Down Fail")
      return false
    end
  end
  return true

end

local function refuel()
  local fuelLevel = turtle.getFuelLevel()
  if fuelLevel == "unlimited" or fuelLevel > 0 then
    return
  end

  local function tryRefuel()
    for n=1,16 do
      if turtle.getItemCount(n) > 0 then
        turtle.select(n)
        if turtle.refuel(1) then
          turtle.select(1)
          return true
        end
      end
    end
    turtle.select(1)
    return false
  end

  if not tryRefuel() then
    print( "Add more fuel to continue." )
    while not tryRefuel() do
      sleep(1)
    end
    print( "Resuming Tunnel." )
  end
end

local function tryUp()
  refuel()
  while not turtle.up() do
    if turtle.detectUp() then
      if not tryDigUp() then
        test("Move Up & Dig")
        return false
      end
    elseif turtle.attackUp() then
      collect()
      test("Attacking Up")
    else
      sleep( 0.5 )
    end
  end
  return true

end

local function tryDown()
  refuel()
  while not turtle.down() do
    if turtle.detectDown() then
      if not tryDigDown() then
        test("Move Down & Dig")
        return false
      end
    elseif turtle.attackDown() then
      collect()
      test("Attacking Down")
    else
      sleep( 0.5 )
    end
  end
  return true

end

local function tryForward()
  refuel()
  while not turtle.forward() do
    if turtle.detect() then
      if not tryDig() then
        test("Move Fwd & Dig")
        return false
      end
    elseif turtle.attack() then
      collect()
      test("Attacking Fwd")
    else
      sleep( 0.5 )
    end
  end
  return true

end

print( "Tunnelling..." )

--[[ Tunnel cross section
| 1 | 2 | 3 |
| 4 | 5 | 6 |
| 7 | 8 | 9 |
Turtle starts at 7, digs 4, moves 4, digs 1, moves 1, digs 2, moves 2, digs 5 & 3, moves 3, digs 6, moves 6, 9 -> 9, 8 -> 8... and back to 7. Places blocks below at 7, 9 , 8. (in that order)
]]

for n=1,length do
  turtle.placeDown()
  test("Place A")
  tryDigUp()
  tryUp()
  tryDigUp()
  tryUp()
  turtle.turnRight()
  test("Turning Right")
  tryDig()
  tryForward()
  tryDigDown()
  tryDig()
  tryForward()
  tryDigDown()
  tryDown()
  tryDigDown()
  tryDown()
  reverseTurtle()
  test("Reversing direction faced")
  tryDig()
  turtle.placeDown()
  test("Place Down C")
  tryForward()
  turtle.placeDown()
  test("Place Down B")
  tryForward()
  turtle.turnRight()
  test("Turning Right")

  if n<length then
    tryDig()
    if not tryForward() then
      print( "Aborting Tunnel." )
      break
    end
  else
    print( "Tunnel complete." )
    print( "Returning to start..." )

-- Return to where we started
-- This section is not 100% correct. It should fuel when low on fuel and doesn't, though the tryForward works everywhere else.
-- Does work if the fuel doesn't run out, could just add a manual refuel but that would mean a)in long distances it'd still run out, b)in short dsiatnces I waste fuel... :(

    reverseTurtle()
      while length > 0 do
        if tryForward() then
          length = length - 1
        else
        tryDig()
        end
      end
    reverseTurtle()
  end
end

print( "Tunnel complete." )
print( "Mined "..collected.." items total." )