#!/usr/bin/env python3

import json
import os
import sys
import time


billion = 10 ** 9
per_level = 10 ** 3
interval = 2
state_filename = "state.json"


def level(i, n):
    return (i % (per_level ** n)) / (per_level ** (n - 1))


def pathname(i):
    fullname = "{:09d}".format(i)
    dir1 = fullname[-9:-6]
    dir2 = fullname[-6:-3]
    dirname = "{}/{}".format(dir1, dir2)
    basename = fullname[-3:]
    return dirname, basename


def create_dir(root, dirname):
    try:
        os.makedirs(os.path.join(root, dirname))
    except OSError:
        pass


def create_file(root, dirname, basename):
    try:
        open(os.path.join(root, dirname, basename), "w")
    except OSError:
        return


def load_state():
    try:
        return json.load(open(state_filename))
    except IOError:
        return {}


def save_state(i):
    state = {"current": i}
    with open(state_filename, "w") as f:
        json.dump(state, f)


root = sys.argv[1]
start = int(sys.argv[2])
end = int(sys.argv[3])

start = load_state().get("current", start)

curdir = None
last_checkpoint = time.time()

i = start
while i < end:
    dirname, basename = pathname(i)
    if dirname != curdir:
        create_dir(root, dirname)
        curdir = dirname
    create_file(root, dirname, basename)
    now = time.time()
    if now > last_checkpoint + interval:
        save_state(i)
        last_checkpoint = now
    i += 1

save_state(i)