turtle.tunnel with return

if not turtle then
    printError("Requires a Turtle")
    return
end

local tArgs = { ... }
if #tArgs ~= 2 then
    local programName = arg[0] or fs.getName(shell.getRunningProgram())
    print("Usage: " .. programName .. " <length> <return>")
    return
end

-- Mine in a quarry pattern until we hit something we can't dig
-- return to start
local returnToStart = tArgs[2]
if not returnToStart == "true" then
    print("return must be true or false")
    return

elseif not returnToStart == "false" then
    print("return must be true or false")
    return
end

-- length
local length = tonumber(tArgs[1])
local length1 = length
if length < 1 then
    print("Tunnel length must be positive")
    return
end
local collected = 0

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

-- Dig
local function tryDig()
    while turtle.detect() do
        if turtle.dig() then
            collect()

        else
            return false
        end
    end
    return turtle
end
-- Dig up
local function tryDigUp()
    while turtle.detectUp() do
        if turtle.digUp() then
            collect()

        else
            return false
        end
    end
    return true
end
-- Dig down
local function tryDigDown()
    while turtle.detectDown() do
        if turtle.digDown() then
            collect()

        else
            return false
        end
    end
    return true
end


--refuel
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 conrinue (Coal)")
        while not tryRefuel() do
            os.pullEvent("turtle_inventory")
        end
        print("Resuming Tunnel")
    end
end



--try move Up
local function tryUp()
    refuel()
    while not turtle.up() do
        if turtle.detectUp() then
            if not turtle.tryDigUp() then
                return false
            end
        elseif turtle.attackUp() then
            collect()
        else

        end
    end
    return true
end

--try move Down
local function tryDown()
    refuel()
    while not turtle.down() do
        if turtle.detectDown() then
            if not turtle.tryDigDown() then
                return false
            end
        elseif turtle.attackDown() then
            collect()
        else

        end
    end
    return true
end

--try move Forward
local function tryForward()
    refuel()
    while not turtle.forward() do
        if turtle.detect() then
            if not turtle.tryDig() then
                return false
            end
        elseif turtle.attack() then
            collect()
        else

        end
    end
    return true
end

print("Tunneling...")

-- Tunnel
for n = 1, length do
    turtle.placeDown()
    tryDigUp()
    tryDig()
    tryUp()
    tryDig()
    tryDig()
    tryDown()
    tryDig()


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


turtle.turnRight()
turtle.turnRight()
for n = 1, length1 do
    turtle.placeDown()

    if returnToStart == "true" then
        tryDig()
        if not tryForward() then
            print("Aborting Tunnel.")
            break
        end
    else
        turtle.Stop()
    end
end

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