Computercraft branchmine turtle program

local tArgs = { ... }
if #tArgs ~= 2 then
    print( "Usage: branchmine <tunnellength> <tunnelcount>" )
    return
end

-- Mine in a parallel tunnel pattern until we hit something we can't dig
local length = tonumber( tArgs[1] )
local tunnels= tonumber( tArgs[2] )
if length < 1 then
    print( "Tunnel length must be positive.\n" )
    return
end
if tunnels < 1 then
    print( "# of tunnels must be positive.\n" )
    return
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 collected=0

local function collect()
    collected = collected + 1
    if math.fmod(collected, 25) == 0 then
        print( "Mined "..collected.." items." )
    end
end

local function tryDig()
    while turtle.detect() do
        if turtle.dig() then
            collect()
            sleep(0.3)
        else
            return false
        end
    end
    return true
end

local function tryForward()
    refuel()
    while not turtle.forward() do
        if turtle.detect() then
            if not tryDig() then
                return false
            end
        elseif turtle.attack() then
            collect()
        else
            sleep( 0.3 )
        end
    end
    return true
end

local function tryDigUp()
    while turtle.detectUp() do
        if turtle.digUp() then
            collect()
            sleep(0.3)
        else
            return false
        end
    end
    return true
end

local function tryUp()
    refuel()
    while not turtle.up() do
        if turtle.detectUp() then
            if not tryDigUp() then
                return false
            end
        elseif turtle.attackUp() then
            collect()
        else
            sleep( 0.3 )
        end
    end
    return true
end

local function tryDigDown()
 while turtle.detectDown() do
  if turtle.digDown() then
   collect()
   sleep(0.3)
  else
   return false
  end
 end
 return true
end

local function tryDown()
    refuel()
    while not turtle.down() do
        if turtle.detectDown() then
            if not tryDigDown() then
                return false
            end
        elseif turtle.attackDown() then
            collect()
        else
            sleep( 0.3 )
        end
    end
    return true
end

local function t3x1(iLgth, bInclCurrent)
   if ( type(iLgth) ~= "number" or type(bInclCurrent) ~= "boolean" ) then
      return false
   end
   if (bInclCurrent == false ) then
      tryForward()
   end
   for n=1,iLgth do
         turtle.placeDown()
         tryUp()
         tryDigUp()
         tryDown()

      if n<iLgth then
             tryDig()
              if not tryForward() then
                    print( "Aborting Tunnel." )
                break
           end
         else
           print( "Tunnel complete." )
      end
   end
end

local ht=0
ht=math.floor(tunnels / 2)

for n=1,ht do
    t3x1(length+1, true)
    turtle.turnLeft()
    t3x1(3, false)
    turtle.turnLeft()
    t3x1(length, false)
    turtle.turnRight()
    t3x1(3, false)
    turtle.turnRight()
    sleep(0.5)
end
if (tunnels % 2) ~= 0 then
    t3x1(length, false)
    turtle.turnLeft()
    turtle.turnLeft()
    for rt=1,length do
        tryForward()
    end
    turtle.turnRight()
    turtle.turnRight()
else
   turtle.turnRight()
   for n=1,3 do
      tryForward()
   end
   turtle.turnLeft()
end
-- clear the cross passage
turtle.turnRight()
local t1=tunnels - 1
for n=1,t1 do
    t3x1(3,false)
end
turtle.turnLeft()