<?php

declare(strict_types=1);

namespace CrocoAI\DataBridge\Domain;

/**
 * What identifies a product attribute, on the wire and in this store.
 *
 * WooCommerce keeps a global attribute as the taxonomy `pa_<slug>` and shows a
 * label over it. The slug is the identity: it never changes, it is what a
 * product's terms are attached to, and it is what a storefront filter URL is
 * built from. The label is free text a merchant may edit at any time.
 *
 * So an attribute travels as `{key, name, values}`: the key is the slug, the
 * optional name is the label to show. Omitting the name preserves an existing
 * merchant label; creating a new attribute still requires one. Bridge protocol
 * 2 sent a label-to-values map and left the slug to be derived from the label,
 * which made a renamed attribute a second attribute and a long label an upload
 * this store had to refuse. Both shapes are read here, so a client and this
 * plugin can be deployed in either order.
 */
final class AttributeIdentity
{
    /**
     * WooCommerce refuses a slug of this length or more, because "pa_" plus the
     * slug has to fit the 32-character taxonomy column.
     */
    public const MAX_KEY_LENGTH = 28;

    /**
     * Read an attribute payload into rows, whichever shape it arrived in.
     *
     * @param array<mixed> $attributes
     * @return array<int,array{key:string,label:string,values:array<int,mixed>}>
     */
    public static function rows(array $attributes): array
    {
        $rows = [];
        foreach ($attributes as $index => $entry) {
            if (is_array($entry) && (isset($entry['key']) || isset($entry['name']))) {
                $label = trim((string) ($entry['name'] ?? ''));
                $key = trim((string) ($entry['key'] ?? ''));
                $values = (array) ($entry['values'] ?? []);
            } else {
                $label = trim((string) $index);
                $key = '';
                $values = (array) $entry;
            }
            if ($label === '' && $key === '') {
                continue;
            }
            $rows[] = [
                'key' => $key !== '' ? self::slug($key) : self::slug($label),
                'label' => $label,
                'values' => $values,
            ];
        }
        return $rows;
    }

    /**
     * The keys an attribute payload states, in order.
     *
     * @param array<mixed> $attributes
     * @return array<int,string>
     */
    public static function keys(array $attributes): array
    {
        return array_column(self::rows($attributes), 'key');
    }

    /**
     * The slug WordPress would register for this name.
     *
     * A name that is already a slug comes back unchanged, so this is safe to
     * apply to a key as well as to a label.
     */
    public static function slug(string $name): string
    {
        $slug = wc_sanitize_taxonomy_name($name);
        if (str_starts_with($slug, 'pa_')) {
            $slug = (string) substr($slug, 3);
        }
        if (function_exists('wc_check_if_attribute_name_is_reserved') && wc_check_if_attribute_name_is_reserved($slug)) {
            $slug = 'product-' . $slug;
        }
        return $slug;
    }

    /**
     * The identity this store keeps one attribute on a product under.
     *
     * A global attribute is a `pa_` taxonomy and the slug is the identity. A
     * per-product attribute has no taxonomy, so its own name is all there is;
     * it is reduced the same way so both sides compare alike.
     */
    public static function fromProductAttribute(string $name): string
    {
        if (str_starts_with($name, 'pa_')) {
            return (string) substr($name, 3);
        }
        return self::slug($name);
    }
}