Change colors in a css file.

css_color.py

import re
import sys
from colorsys import hls_to_rgb, rgb_to_hls
from itertools import chain


def hex2rgb(x):
    x = x.lstrip("#")
    if len(x) == 3:
        x = "".join(chain(*zip(x, x)))
    assert len(x) == 6
    return tuple(int(x[i : i + 2], 16) for i in (0, 2, 4))


def rgb2hex(r, g, b):
    return f"#{r:02x}{g:02x}{b:02x}"


def rgb2hls(r, g, b):
    return rgb_to_hls(r / 255, g / 255, b / 255)


def hls2rgb(h, l, s):
    return tuple(int(x * 255) for x in hls_to_rgb(h, l, s))


def change_hls(h, l, s):
    return h, (l + 1) / 2, s  # increase lightness

    # return h, 1 - l, s  # reverse lightness


def change_hex(x):
    r, g, b = hex2rgb(x)
    h, l, s = rgb2hls(r, g, b)
    h, l, s = change_hls(h, l, s)
    r, g, b = hls2rgb(h, l, s)
    x = rgb2hex(r, g, b)
    return x


def repl(m: re.Match):
    return change_hex(m.group())


if __name__ == "__main__":
    if len(sys.argv) == 2:
        file = sys.argv[1]
    else:
        file = input("filename:")

    with open(file, "r") as f:
        content = f.read()
        content = re.sub(r"#[0-9a-f]+(?=[^0-9a-f])", repl, content, flags=re.I)
    with open(file, "w") as f:
        f.write(content)