#!/usr/bin/python3

import math
import sys
import time

icon = ''
interval = 1 / 4

previous_bytes = (0, 0)

def glyphs_for_util(a, b):
    # TODO: Figure out way to make this the correct-width whitespace.
    glyphs = [' ', '▁', '▂', '▃', '▄', '▅', '▆', '▇', '█']

    i = int(min(a, 1.0) * (len(glyphs) - 1))
    j = int(min(b, 1.0) * (len(glyphs) - 1))

    # FIXME: Hack to pad right glyph to correct offset.
    if j != 0:
        i = max(1, i)

    return glyphs[i] + glyphs[j]

def scale(val):
    MAX_RATE = 1 * 1024 * 1024
    # return math.log(val + 1) / math.log(MAX_RATE + 1)
    return val / MAX_RATE

while True:
    with open('/sys/class/net/{}/statistics/rx_bytes'.format(sys.argv[1]), 'r') as rx_file:
        current_rx_bytes = int(rx_file.read())

    with open('/sys/class/net/{}/statistics/tx_bytes'.format(sys.argv[1]), 'r') as tx_file:
        current_tx_bytes = int(tx_file.read())

    #
    previous_rx_bytes = previous_bytes[0]
    previous_tx_bytes = previous_bytes[1]

    rx_rate = (current_rx_bytes - previous_rx_bytes) / interval
    tx_rate = (current_tx_bytes - previous_tx_bytes) / interval

    previous_bytes = (current_rx_bytes, current_tx_bytes)

    rx_ratio = scale(rx_rate)
    tx_ratio = scale(tx_rate)
    print('{} {}'.format(icon, glyphs_for_util(rx_ratio, tx_ratio)), flush=True)

    time.sleep(interval)