d

m = "minecraft:"

function stuck()
 while not turtle.forward() do
  if turtle.detect() then
   turtle.dig()
  else
   sleep(1)
  end
 end
end

function turnR()
 turtle.turnRight()
 stuck()
 turtle.turnRight()
 turtle.digDown()
end

function turnL()
 turtle.turnLeft()
 stuck()
 turtle.turnLeft()
 turtle.digDown()
end

function torch()
 local tcnt = 0
 for i = 1,16 do
  local blk = turtle.getItemDetail(i)
  if blk and
     blk.name == m.."torch" then
      tcnt = tcnt + blk.count
  else
   i = i + 1
  end
 end

 return tcnt
end
----------
local arg = {...}
local dir = tostring(arg[1])
local pass = 1
local l = 1

turtle.digDown()
while turtle.forward() do
 turtle.digDown()
 l = l + 1
end


while not turtle.forward() do
local y,blk = turtle.inspect()
 if blk.name == m.."torch" then
  turtle.dig()
  turtle.forward()
  turtle.digDown()
  l = l + 1
  print("Length: "..l)
  --? start on left or right
  if dir == "l" then
   turnR()
  else
   turnL()
  end

  pass = pass + 1
  while torch() ~= 2 do
   for i = 1,l do
    if i == l then
     turtle.digDown()
    elseif i == l-1
           and pass%2 == 1 then
     local s,data = turtle.inspect()
     if s and
        data.name == m.."torch" then
      turtle.digDown()
      turtle.dig()
      turtle.forward()
      turtle.digDown()

      return
     else
      turtle.digDown()
      turtle.dig()
      turtle.forward()
     end
    else
     turtle.digDown()
     stuck()
    end
   end
   if dir == "l" then
    if pass%2 == 0 then
     turnL()
     pass = pass + 1
    else
     turnR()
     pass = pass + 1
    end
   else
    if pass%2 == 0 then
     turnR()
     pass = pass + 1
    else
     turnL()
     pass = pass + 1
    end
   end
  end
 else
  turtle.dig()
  turtle.forward()
  l = l + 1
  turtle.digDown()
 end
end

if pass%2 == 0 then
 for j = 1,l-1 do
  if j == l-1 then
   turtle.digDown()
  else
   turtle.digDown()
   stuck()
  end
 end
end