<?php

namespace App\Support\Qr;

class QrStyleNormalizer
{
    /**
     * Silently tune styles so more phone cameras (including Samsung) can read the code.
     *
     * @param  array<string, mixed>  $style
     * @return array<string, mixed>
     */
    public static function normalize(array $style): array
    {
        $style = self::ensureContrast($style);
        $style = self::ensureQuietZone($style);
        $style = self::ensureRenderScale($style);

        $style['error_correction'] = QrStyleDefaults::recommendedEcc($style);

        return $style;
    }

    /** @param  array<string, mixed>  $style */
    private static function ensureContrast(array $style): array
    {
        $target = 4.5;
        $attempts = 0;

        while (QrScanReliability::contrastRatio($style) < $target && $attempts < 16) {
            $fg = self::hexToRgb((string) $style['foreground']);
            $bg = self::hexToRgb((string) $style['background']);

            if (self::relativeLuminance($fg) > self::relativeLuminance($bg)) {
                $style['foreground'] = self::rgbToHex(self::darkenToward($fg, 0.18));
            } else {
                $style['foreground'] = self::rgbToHex(self::darkenToward($fg, 0.15));
                $style['background'] = self::rgbToHex(self::lightenToward($bg, 0.15));
            }

            $attempts++;
        }

        if (QrScanReliability::contrastRatio($style) < $target) {
            $style['foreground'] = '#000000';
            $style['background'] = '#ffffff';
        }

        return $style;
    }

    /** @param  array<string, mixed>  $style */
    private static function ensureQuietZone(array $style): array
    {
        $margin = (int) ($style['margin'] ?? 4);
        $moduleStyle = (string) ($style['module_style'] ?? 'square');

        if (QrModuleStyleCatalog::isDecorative($moduleStyle)) {
            $margin = max($margin, 5);
        }

        $style['margin'] = max(4, min(10, $margin));

        return $style;
    }

    /** @param  array<string, mixed>  $style */
    private static function ensureRenderScale(array $style): array
    {
        $scale = (int) ($style['scale'] ?? 8);
        $module = QrModuleStyleCatalog::optionsFor((string) ($style['module_style'] ?? 'square'));

        if ($module['circular'] ?? false) {
            $scale = max($scale, 10);
        }

        if (! empty($style['logo_path'])) {
            $scale = max($scale, 10);
        }

        $style['scale'] = max(6, min(16, $scale));

        return $style;
    }

    /** @return array{0: int, 1: int, 2: int} */
    private static function hexToRgb(string $hex): array
    {
        $hex = ltrim(trim($hex), '#');
        if (strlen($hex) === 3) {
            $hex = $hex[0] . $hex[0] . $hex[1] . $hex[1] . $hex[2] . $hex[2];
        }

        if (strlen($hex) !== 6 || ! ctype_xdigit($hex)) {
            return [0, 0, 0];
        }

        return [hexdec(substr($hex, 0, 2)), hexdec(substr($hex, 2, 2)), hexdec(substr($hex, 4, 2))];
    }

    /** @param  array{0: int, 1: int, 2: int}  $rgb */
    private static function rgbToHex(array $rgb): string
    {
        return sprintf('#%02x%02x%02x', $rgb[0], $rgb[1], $rgb[2]);
    }

    /** @param  array{0: int, 1: int, 2: int}  $rgb */
    private static function darkenToward(array $rgb, float $amount): array
    {
        return [
            (int) max(0, $rgb[0] * (1 - $amount)),
            (int) max(0, $rgb[1] * (1 - $amount)),
            (int) max(0, $rgb[2] * (1 - $amount)),
        ];
    }

    /** @param  array{0: int, 1: int, 2: int}  $rgb */
    private static function lightenToward(array $rgb, float $amount): array
    {
        return [
            (int) min(255, $rgb[0] + ((255 - $rgb[0]) * $amount)),
            (int) min(255, $rgb[1] + ((255 - $rgb[1]) * $amount)),
            (int) min(255, $rgb[2] + ((255 - $rgb[2]) * $amount)),
        ];
    }

    /** @param  array{0: int, 1: int, 2: int}  $rgb */
    private static function relativeLuminance(array $rgb): float
    {
        $channels = [];
        foreach ($rgb as $value) {
            $v = $value / 255;
            $channels[] = $v <= 0.03928 ? $v / 12.92 : (($v + 0.055) / 1.055) ** 2.4;
        }

        return (0.2126 * $channels[0]) + (0.7152 * $channels[1]) + (0.0722 * $channels[2]);
    }
}