<?php
/**
 * Product JSON-LD.
 *
 * @package CortexCommerce
 */

namespace CortexCommerce\Storefront;

defined( 'ABSPATH' ) || exit;

/**
 * Builds the Product object, field for field with the Shopify theme extension (spec §4.5). Always @type
 * Product (never ProductGroup), one Offer per purchasable variation, prices as '.'-decimal strings.
 */
final class ProductSchema {

	const AVAILABILITY = array(
		'instock'     => 'https://schema.org/InStock',
		'outofstock'  => 'https://schema.org/OutOfStock',
		'onbackorder' => 'https://schema.org/BackOrder',
	);

	/**
	 * @return array<string, mixed>
	 */
	public static function build( \WC_Product $product ): array {
		$url  = (string) get_permalink( $product->get_id() );
		$data = array(
			'@context'    => 'https://schema.org/',
			'@type'       => 'Product',
			'@id'         => $url . '#cortexguard-product',
			'url'         => $url,
			'name'        => self::decode( $product->get_name() ),
			'description' => self::plain( $product->get_description() ),
		);

		$image = self::image_url( $product );
		if ( '' !== $image ) {
			$data['image'] = $image;
		}
		$brand = self::brand( $product );
		if ( '' !== $brand ) {
			$data['brand'] = array(
				'@type' => 'Brand',
				'name'  => $brand,
			);
		}
		if ( '' !== $product->get_sku() ) {
			$data['sku'] = $product->get_sku();
		}
		// @phpstan-ignore-next-line function.alreadyNarrowedType -- the WooCommerce stubs PHPStan scans always declare this (9.2+), but the runtime store may still be older; guard stays for real-world compatibility.
		$gtin = method_exists( $product, 'get_global_unique_id' ) ? (string) $product->get_global_unique_id() : '';
		if ( '' !== $gtin ) {
			$data['gtin'] = $gtin;
		}
		$offers = self::offers( $product );
		if ( array() !== $offers ) {
			$data['offers'] = $offers;
		}
		return $data;
	}

	/**
	 * Tags, shortcodes and entities out; whitespace collapsed (Shopify: strip_html | strip_newlines).
	 */
	public static function plain( string $html ): string {
		$text = wp_strip_all_tags( strip_shortcodes( $html ) );
		$text = self::decode( $text );
		return trim( (string) preg_replace( '/\s+/u', ' ', $text ) );
	}

	/**
	 * WordPress/WooCommerce store term names and (for users without unfiltered_html) post titles with
	 * entities normalised in (e.g. "Marks & Spencer" -> "Marks &amp; Spencer"). JSON-LD is not HTML, so
	 * every plain-text field must come back out decoded to match the Shopify extension's raw values.
	 */
	private static function decode( string $text ): string {
		return html_entity_decode( $text, ENT_QUOTES | ENT_HTML5, 'UTF-8' );
	}

	public static function image_url( \WC_Product $product ): string {
		$image_id = (int) $product->get_image_id();
		if ( 0 === $image_id ) {
			return '';
		}
		$url = wp_get_attachment_image_url( $image_id, 'full' );
		return is_string( $url ) ? $url : '';
	}

	private static function brand( \WC_Product $product ): string {
		if ( ! taxonomy_exists( 'product_brand' ) ) {
			return '';
		}
		$terms = get_the_terms( $product->get_id(), 'product_brand' );
		return is_array( $terms ) && isset( $terms[0] ) ? self::decode( $terms[0]->name ) : '';
	}

	/**
	 * @return array<int, array<string, string>>
	 */
	private static function offers( \WC_Product $product ): array {
		$sources = $product instanceof \WC_Product_Variable
			? array_map( 'wc_get_product', $product->get_children() )
			: array( $product );

		$offers = array();
		foreach ( $sources as $source ) {
			if ( ! $source instanceof \WC_Product || '' === (string) $source->get_price() ) {
				continue;
			}
			if ( $source instanceof \WC_Product_Variation && 'publish' !== $source->get_status() ) {
				continue;
			}
			$offers[] = self::offer( $source );
		}
		return $offers;
	}

	/**
	 * @return array<string, string>
	 */
	private static function offer( \WC_Product $product ): array {
		$offer = array(
			'@type'         => 'Offer',
			// wc_format_decimal() with a precision always uses '.', whatever the store's number format.
			'price'         => wc_format_decimal( wc_get_price_to_display( $product ), wc_get_price_decimals() ),
			'priceCurrency' => get_woocommerce_currency(),
			'availability'  => self::AVAILABILITY[ $product->get_stock_status() ] ?? self::AVAILABILITY['instock'],
			'url'           => (string) $product->get_permalink(),
		);
		if ( '' !== $product->get_sku() ) {
			$offer['sku'] = $product->get_sku();
		}
		return $offer;
	}
}