YATP

-- Created by: pastebin.com/u/clintwk

local function progHelp()
    print( "Usage: " )
    print( shell.getRunningProgram().." <length> (branches) (L or R)" )
    print( "Place path blocks in slot 1!" )
end
local tArgs = { ... }
if #tArgs <= 3 and #tArgs > 0 then
    if #tArgs == 2 then
        print( "Must put argument for branch direction (L) or (R)" )
        progHelp()
        return
    end
else
    progHelp()
    return
end

-- Mine in a quarry pattern until we hit something we can't dig
if not tonumber( tArgs[1] ) then
    print( "Tunnel length must be a positive number" )
    progHelp()
    return
end
local length = tonumber( tArgs[1] )
local branches = 1
local direction = "L"
if length < 1 then
    print( "Tunnel length must be a positive number" )
    progHelp()
    return
end

if #tArgs == 3 then
    if not tonumber( tArgs[2] ) then
            print( "Branches must be a positive number" )
        progHelp()
        return
    end
    branches = tonumber( tArgs[2] )
    if branches < 1 then
        print( "Number of branches must be a positive number" )
        progHelp()
        return
    end
    direction = tArgs[3]
    if direction ~= "L" and direction ~= "l" and direction ~= "R" and direction ~= "r" then
        print( "Please enter the direction you would like your branches to go (either L or R)" )
        progHelp()
        return
    end
    if direction == "L" or direction == "l" then
        direction = "L"
    else
        direction = "R"
    end
end

local depth = 0
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(0.2)
        else
            return false
        end
    end
    return true
end

local function tryDigUp()
    while turtle.detectUp() do
        if turtle.digUp() then
            collect()
            sleep(0.2)
        else
            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
                return false
            end
        elseif turtle.attackUp() then
            collect()
        else
            sleep( 0.2 )
        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( 0.2 )
        end
    end
    return true
end

print( "Tunnelling..." )

local function tunnel(tunStart, tunEnd)
    for n=tunStart,tunEnd do
        turtle.placeDown()
        tryDigUp()
        turtle.suck()

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

    end
end
local function newBranch()
    tunnel(1, 3)
    if direction == "L" then
        turtle.turnLeft()
        direction = "R"
    else
        turtle.turnRight()
        direction = "L"
    end
end

local function connectBranch()
    if direction == "L" then
        turtle.turnRight()
    else
        turtle.turnLeft()
    end
    tunnel(1, 2)
    turtle.turnRight()
    turtle.turnRight()
    tunnel(1, 2)
end

for b=1,branches do
    tunnel(1, length)
    if b ~= 1 then
        connectBranch()
    end
    if b ~= branches then
        if b == 1 then
            if direction == "L" then
                turtle.turnLeft()
            else
                turtle.turnRight()
            end
        end
        newBranch()
    end
end
--[[
print( "Returning to start..." )

-- Return to where we started
turtle.turnLeft()
turtle.turnLeft()
while depth > 0 do
    if turtle.forward() then
        depth = depth - 1
    else
        turtle.dig()
    end
end
turtle.turnRight()
turtle.turnRight()
]]

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