import logging
import math
import re

import matplotlib
from django.db import models
from django.utils.safestring import mark_safe

re_hex = re.compile("^([0-9a-f]{3,6})(\W)?", re.IGNORECASE)


def hex2rgb(hexval):
    return matplotlib.colors.to_rgb(hexval)


def light_or_dark(rgbColor, colors: tuple = ('#FFFFFF', '#333333')):
    if isinstance(rgbColor, str):
        rgbColor = hex2rgb(rgbColor)
    [r, g, b] = rgbColor
    val = 0.299 * (r * r) + 0.587 * (g * g) + 0.114 * (b * b)
    hsp = math.sqrt(val)
    # logging.error([rgbColor, val, hsp])
    # if hsp > 127.5:
    if hsp > .5:
        # light
        return colors[1]
    else:
        # dark
        return colors[0]


def invert_hex(hexval: str):
    def _invert(content):

        text = content.group(1).lower()
        code = {}
        l1 = "0123456789abcdef"
        l2 = "fedcba9876543210"
        for i in range(len(l1)):
            code[l1[i]] = l2[i]
        inverted = ""
        for j in text:
            inverted += code[j]
        return inverted

    prepend_hash = ''
    if hexval.startswith('#'):
        hexval = hexval[1:]
        prepend_hash = '#'
    return prepend_hash + re_hex.sub(_invert, hexval)


def color_label(instance: models.Model, value:str=None):
    value = value or instance.color
    return mark_safe(f'<div style="padding:.5em 1em;display:inline-block;background-color:{instance.color};border-radius:5px;'
                     # f'color:{invert_hex(instance.color)};'
                     f'color:{light_or_dark(instance.color)};'
                     f'">{value}</div>')