narrowtunnel.lua

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

local tArgs = { ... }
if #tArgs ~= 1 then
    local programName = arg[0] or fs.getName(shell.getRunningProgram())
    print("Usage: " .. programName .. " <length>")
    return
end

local length = tonumber(tArgs[1])

local function refuel(amount)
    local fuelLevel = turtle.getFuelLevel()
    if fuelLevel == "unlimited" then
        return true
    end

    turtle.select(16)
    while turtle.getItemCount(16) > 0 and turtle.getFuelLevel() < amount do
        if not turtle.refuel(1) then
            return false
        end
    end

    if turtle.getFuelLevel() < amount then
        return false
    else
        return true
    end
end

local function waitForFuel(amount)
    if not refuel(amount) then
        print("Please put fuel in slot 16")
        while not refuel(amount) do
            sleep(0.5)
        end
        print("Received sufficient fuel. Continuing...")
    end
end

local function selectItem(name)
    for i=15, 1, -1 do
        itemDetail = turtle.getItemDetail(i)
        if itemDetail and itemDetail.name == name then
            turtle.select(i)
            return true
        end
    end
    return false
end

local function countItem(name)
    num = 0
    for i=1, 15 do
        itemDetail = turtle.getItemDetail(i)
        if itemDetail and itemDetail.name == name then
            num = num + itemDetail.count
        end
    end
    return num
end

local function waitForItem(name, amount)
    if countItem(name) < amount then
        print("Please provide more " .. name)
        while countItem(name) < amount do
            sleep(0.5)
        end
        print("Received sufficient " .. name .. ". Continuing...")
    end
    selectItem(name)
end

local function tryForward()
    waitForFuel(1)
    while not turtle.forward() do
        if turtle.detect() then
            if not turtle.dig() then
                return false
            end
        elseif not turtle.attack() then
            sleep(0.5)
        end
    end
    if turtle.detectUp() then
        if not turtle.digUp() then
            return false
        end
    end
    message = true
    while not turtle.detectDown() do
        for i=15, 1, -1 do
            if turtle.getItemCount(i) > 0 then
                turtle.select(i)
                if turtle.placeDown() then
                    if not message then
                        print("Received sufficient building blocks. Continuing...")
                    end
                    return true
                end
            end
        end
        if message then
            message = false
            print("Please provide building blocks")
        end
    end
    return true
end

for i=1, length do
    assert(tryForward())
end