Laravel / PHP - Check if a hexidecimal colour is dark

ColorHelper.php

<?php

namespace App\Helpers;

class ColorHelper
{
    // This function tell you if a color is dark or light.
    // It is useful when you want to change the text color to white or black depending on the background color.

    public static function isColorDark($hexColor = '#ffffff') {
        // Remove any hash symbol (#) if present
        $hexColor = str_replace('#', '', $hexColor);

        // Check if color is valid hex color
        if (!preg_match('/^[a-f0-9]{6}$/i', $hexColor))
            return false;

        // Convert hex to RGB
        $r = hexdec(substr($hexColor, 0, 2));
        $g = hexdec(substr($hexColor, 2, 2));
        $b = hexdec(substr($hexColor, 4, 2));

        // Calculate color brightness
        $brightness = (($r * 299) + ($g * 587) + ($b * 114)) / 1000;

        // You can adjust this threshold as needed
        $threshold = 128;

        return $brightness < $threshold;
    }
}