calculate-average-hex-color.php

<?php

class Solution
{
    protected Converter $converter;

    public function __construct(
        protected string $hexColorOne,
        protected string $hexColorTwo
    ){
        $this->converter = new Converter();
    }

    public function averageColor(): string
    {
        $colorOne = $this->converter->hex2Rgb($this->hexColorOne);
        $colorTwo = $this->converter->hex2Rgb($this->hexColorTwo);

        $rgbMean = [];

        for ($i = 0; $i < 3; $i++) {
            $rgbMean[] = ($colorOne[$i] + $colorTwo[$i]) / 2;
        }

        return $this->converter->rgbToHex($rgbMean);
    }
}

class Converter
{
    public function hex2Rgb(string $hexColorCode): array
    {
        return sscanf($hexColorCode, '%02x%02x%02x');
    }

    public function rgbToHex(array $rgb): string
    {
        $hex = [];

        foreach ($rgb as $value) {
            $hex[] = str_pad(dechex($value), 2,'0', STR_PAD_LEFT);
        }

        return implode('', $hex);
    }
}

echo (new Solution('ffffff', 'ff00ff00'))->averageColor() . PHP_EOL;