Mine

-- Tunnel Mining Turtle (with return)
-- Mines, places torches, builds floor
-- Variables
turtle.select(1)
local tArgs = { ... }
local togo = tonumber(tArgs[1])
togo = togo or 1
local torch = 0
local cobble = 0
term.clear()
term.setCursorPos(1,1)
print(os.getComputerLabel() .. " at your service!")
print()
print("Please place blocks as follows:")
print("Slot 1 - Fuel (coal or lava)")
print("Slot 2 - Torches (optional)")
print("Slot 3 - Cobble (optional)")
print()
print("Press [ENTER] when ready.")
read(input)

-- Starting Out
if turtle.getItemCount(1) < 1 then
  print("No fuel! Abort!")
  quit()
end
torch = 0
if turtle.getItemCount(2) > 0 then
  torch = 1
end
if turtle.getItemCount(3) > 0 then
  cobble = 1
end
local i = 0

-- Functions
function tfuel(amount)
 if turtle.getFuelLevel() < 16 then
  turtle.select(1)
  turtle.refuel(amount)
 end
end

function turnaround()
  turtle.turnRight()
  turtle.turnRight()
end

function uandd()
  if turtle.detectUp() then
   repeat
    turtle.digUp()
        sleep(0.5)
   until turtle.detectUp() == false
  end
  if turtle.detectDown() then
   repeat
    turtle.digDown()
   until turtle.detectDown() == false
  end
  if cobble > 0 then
    turtle.down()
        if turtle.detectDown() == false then
      turtle.select(3)
      turtle.placeDown()
          turtle.select(1)
        end
    turtle.up()
  end
end

function mydig()
  tfuel(1)
  if turtle.detect() then
   repeat
    turtle.dig()
    sleep(0.5)
   until turtle.detect() == false
   turtle.forward()
   uandd()
  else
   turtle.forward()
   uandd()
  end
end

function discard() -- run back to start and drop off items
  turnaround()
  for f = 1,i do
    tfuel(1)
    while turtle.forward() == false do
      turtle.dig()
    end
  end
  for x = 2+torch+cobble,16 do
    turtle.select(x)
        turtle.dropDown()
  end
  turnaround()
  for f = 1,i do
    tfuel(1)
    while turtle.forward() == false do
      turtle.dig()
    end
  end
  turtle.select(1)
end

-- Main Loop
repeat
  i = i + 1
  term.clear()
  term.setCursorPos(1,1)
  local pct = (i/togo)*100
  print("Mining "..i.." of "..togo.." ("..pct.."%)")
  print("Fuel: "..turtle.getFuelLevel())
  mydig()
  turtle.turnRight()
  mydig()
  turnaround()
  turtle.forward()
  mydig()
  turnaround()
  turtle.forward()
  turtle.turnLeft()
  if togo >= 8 and torch > 0 then
   if (i % 8 == 0) then
    turtle.select(2)
    turtle.placeDown()
        turtle.select(1)
   end
  end
  -- check to see if turtle is full
  if turtle.getItemCount(16) > 0 then
    discard()
  end
  turtle.select(1)
until i >= togo

--Lets assume that worked and he made it
turnaround()
for r = 1, togo do
  tfuel(1)
  while turtle.forward() == false do
    turtle.dig()
  end
end
for x = 1,16 do
  turtle.select(x)
  turtle.dropDown()
end
turtle.select(1)