<?php

declare(strict_types=1);

namespace CrocoAI\DataBridge\Domain;

/** Shared projection for publication and metadata-only change detection. */
final class ProductMetadata
{
    public const SEO_KEYS = [
        'meta_title' => ['_yoast_wpseo_title', 'rank_math_title'],
        'meta_description' => ['_yoast_wpseo_metadesc', 'rank_math_description'],
    ];

    /** @return array<string,mixed> Only supplied, source-owned metadata is written. */
    public static function values(array $canonical, array $ownership = [], bool $existing = true): array
    {
        $values = [];
        if (!$existing || ($ownership['meta_data'] ?? 'source') !== 'merchant') {
            foreach ((array) ($canonical['meta_data'] ?? []) as $key => $value) {
                $key = sanitize_key((string) $key);
                if ($key !== '') {
                    $values[$key] = $value;
                }
            }
        }
        foreach (self::SEO_KEYS as $field => $keys) {
            $owner = $ownership[$field] ?? $ownership['meta_data'] ?? 'source';
            foreach ($keys as $key) {
                if ($existing && $owner === 'merchant') {
                    unset($values[$key]);
                } elseif (array_key_exists($field, $canonical)) {
                    $values[$key] = sanitize_text_field($canonical[$field]);
                } elseif (array_key_exists($key, $values)) {
                    $values[$key] = sanitize_text_field($values[$key]);
                }
            }
        }
        return $values;
    }

    /** Identify the upload field to retain when the publisher filters unchanged fields. */
    public static function field(string $key, array $canonical): string
    {
        foreach (self::SEO_KEYS as $field => $keys) {
            if (array_key_exists($field, $canonical) && in_array($key, $keys, true)) {
                return $field;
            }
        }
        return 'meta_data';
    }

    /** @return list<string> */
    public static function errors(array $canonical): array
    {
        $errors = [];
        foreach (self::SEO_KEYS as $field => $keys) {
            if (array_key_exists($field, $canonical) && !is_string($canonical[$field])) {
                $errors[] = $field . ' must be a string; use an empty string to clear it';
            }
            foreach ($keys as $key) {
                if (
                    is_array($canonical['meta_data'] ?? null)
                    && array_key_exists($key, $canonical['meta_data'])
                    && !is_string($canonical['meta_data'][$key])
                ) {
                    $errors[] = 'meta_data.' . $key . ' must be a string';
                }
            }
        }
        if (array_key_exists('meta_data', $canonical) && !is_array($canonical['meta_data'])) {
            $errors[] = 'meta_data must be an object keyed by metadata name';
        }
        return $errors;
    }
}