App

-- https://turtleappstore.com/u/Skeemer/a/tunnel1
--tunnel2

--digs all gravel ar sand forward
function digUntilClear()
  while turtle.detect() do
    if not turtle.dig() then
      return false
    end
  end
  return true
end

--advance function
function advance()
  digUntilClear()
  turtle.forward() 
  turtle.digUp()                 
  turtle.digDown()
end

--2 sections
for k = 1,2 do

--digs 5 blocks ahead of 4x4 size
local success, data = turtle.inspectDown()
if success then
  turtle.up()
end

for i = 1,5 do
  advance()
  if i % 2 == 0 then
    turtle.turnLeft()
  else
    turtle.turnRight()
  end
  advance()
  advance()
  if i % 2 == 0 then
    turtle.turnRight()
  else
    turtle.turnLeft()
  end
end

--places torches
turtle.turnLeft()
turtle.forward()
turtle.place() -- 1stTorch
turtle.turnLeft()
turtle.forward()
turtle.turnLeft()
turtle.place() -- 2ndTorch
turtle.turnRight()
turtle.forward()
turtle.forward()
turtle.turnRight()
turtle.place() -- 3rdTorch
turtle.turnLeft()
turtle.forward()
turtle.turnLeft()
turtle.place() -- 4thTorch
turtle.turnRight()
turtle.turnRight()
turtle.forward()

--digs branches
for i = 1,107 do
  --change arc
  if i == 54 then
    turtle.forward()
    turtle.turnLeft()
    turtle.forward()
    turtle.turnRight()
    turtle.forward()
  end

  if i == 26 or i == 83 then
    turtle.turnRight()
  end
  -- Leaves 2 blocks digged to connect next branch
  if i == 29 or i == 80 then
    if i == 80 then
      turtle.turnLeft()
    end
    advance()
    advance()
    turtle.turnRight()
    turtle.turnRight()
    turtle.forward()
    turtle.forward()
    if i == 29 then
      turtle.turnLeft()
    end
  end

  advance()
  if i == 11 or i == 23 or i == 30 or i == 42 then
    turtle.placeDown()
  elseif i == 65 or i == 77 or i == 84 or i == 96 then
    turtle.placeDown()
  end
end

--prepares for the next section
turtle.forward()
turtle.turnRight()
turtle.down()
turtle.forward()
turtle.forward()
turtle.forward()
turtle.up()
advance()
turtle.turnLeft()
advance()
advance()
turtle.turnRight()

end