Tunnel2021

local args = {...}
local distance = tonumber(args[1])
local fuel = 1
local torches = 2
local place_block = 3
local max_slot = 16

local function refuel()
    if turtle.getFuelLevel() == 0 then
        local prev = turtle.getSelectedSlot()
        turtle.select(fuel)
        if not turtle.refuel(1) then
            print('Need more fuel')
            while not turtle.refuel(1) do
                sleep(1)
            end
        end
        turtle.select(prev)
    end
end

local function smart_dig_forward()
    if turtle.detect() then
        turtle.dig()
    else
        return
    end

    local slot = turtle.getSelectedSlot()
    local i = 0

    if (slot != max_slot) then
        while (turtle.getItemCount() > 0 and slot != max_slot)
        do
            turtle.select(slot + i)
            i = i + 1
        end
    end
end

local function smart_dig_up()
    if turtle.detectUp() then
        turtle.digUp()
    else
        return
    end

    local slot = turtle.getSelectedSlot()
    local i = 0

    if (slot != max_slot) then
        while (turtle.getItemCount() > 0 and slot != max_slot)
        do
            turtle.select(slot + i)
            i = i + 1
        end
    end
end

local function smart_dig_down()
    if turtle.detectDown() then
        turtle.digDown()
    else
        return
    end

    local slot = turtle.getSelectedSlot()
    local i = 0

    if (slot != max_slot) then
        while (turtle.getItemCount() > 0 and slot != max_slot)
        do
            turtle.select(slot + i)
            i = i + 1
        end
    end
end


local function tryForwards()
    refuel()
    while not turtle.forward() do
        if turtle.detect() then
            smart_dig_forward()
        end
        sleep(0.5)
    end
end

local function tryDown()
    refuel()
    while not turtle.down() do
        if turtle.detectDown() then
            smart_dig_down()
        end
        sleep(0.5)
    end
end

local function tryUp()
    refuel()
    while not turtle.up() do
        if turtle.detectUp() then
            smart_dig_up()
        end
        sleep(0.5)
    end
end

local function dig_block_gravel()
    smart_dig_forward()
    sleep(.5)
    while turtle.detect() do
        smart_dig_forward()
    end
end

local function placeTorch()
    local prev = turtle.getSelectedSlot()
    turtle.select(torches)
    turtle.place()
    turtle.select(prev)
end

local function placeBlock()
    local prev = turtle.getSelectedSlot()
    turtle.select(place_block)
    turtle.placeDown()
    turtle.select(prev)
end

local function clearSection(currDistance)
    tryUp()
    tryUp()

    tryForwards()

    turtle.turnLeft()
    dig_block_gravel()

    turtle.turnRight()
    turtle.turnRight()
    dig_block_gravel()


    turtle.turnLeft()
    tryDown()

    turtle.turnLeft()
    smart_dig_forward()
    if currDistance % 6 == 0 then
        turtle.turnRight()
        turtle.turnRight()
        placeTorch()
        turtle.turnRight()
        turtle.turnRight()
    end

    turtle.turnRight()
    turtle.turnRight()
    smart_dig_forward()
    if currDistance % 6 == 0 then
        turtle.turnRight()
        turtle.turnRight()
        placeTorch()
        turtle.turnRight()
        turtle.turnRight()
    end

    turtle.turnLeft()
    tryDown()

    if not turtle.detectDown() then
        placeBlock()
    end

    turtle.turnLeft()
    tryForwards()

    if not turtle.detectDown() then
        placeBlock()
    end


    turtle.turnRight()
    turtle.turnRight()
    tryForwards()
    tryForwards()

    if not turtle.detectDown() then
        placeBlock()
    end

    turtle.turnLeft()
    turtle.turnLeft()
    tryForwards()

    turtle.turnRight()

end

turtle.select(1)

local curr_distance = 1

while(curr_distance <= distance)
do
    for i = curr_distance, distance, 1 do
        clearSection(i)
        if (turtle.getSelectedSlot() == 16) then
            break
        end
    end

    turtle.turnRight()
    turtle.turnRight()

    for i = 1, curr_distance, 1 do
        tryForwards()
    end

    for i = 3, 16, 1 do
        turtle.select(i)
        turtle.drop()
    end

    if (curr_distance == distance) then
        break
    end

    for i = 1, curr_distance, 1 do
        tryForwards()
    end
end