<?php
declare(strict_types=1);

namespace Automattic\WooCommerce\Blocks\SharedStores;

use Automattic\WooCommerce\Blocks\Domain\Services\Hydration;
use Automattic\WooCommerce\Blocks\Package;
use InvalidArgumentException;

/**
 * Manages the registration of interactivity state that provides product data
 * to interactive blocks. This is shared store data that is not tied to one
 * specific block.
 *
 * This is an experimental API and may change in future versions.
 */
class ProductsStore {

	/**
	 * The consent statement for using this experimental API.
	 *
	 * @var string
	 */
	private static string $consent_statement = 'I acknowledge that using experimental APIs means my theme or plugin will inevitably break in the next version of WooCommerce';

	/**
	 * The namespace for the store.
	 *
	 * @var string
	 */
	private static string $store_namespace = 'woocommerce/products';

	/**
	 * Products that have been loaded into state.
	 *
	 * @var array
	 */
	private static array $products = array();

	/**
	 * Product variations that have been loaded into state.
	 *
	 * @var array
	 */
	private static array $product_variations = array();

	/**
	 * Check that the consent statement was passed.
	 *
	 * @param string $consent_statement The consent statement string.
	 * @return true
	 * @throws InvalidArgumentException If the statement does not match.
	 */
	private static function check_consent( string $consent_statement ): bool {
		if ( $consent_statement !== self::$consent_statement ) {
			throw new InvalidArgumentException( 'This method cannot be called without consenting that the API may change.' );
		}

		return true;
	}

	/**
	 * Register the interactivity state if products have been loaded.
	 *
	 * @return void
	 */
	private static function register_state(): void {
		$state = array();

		if ( ! empty( self::$products ) ) {
			$state['products'] = self::$products;
		}

		if ( ! empty( self::$product_variations ) ) {
			$state['productVariations'] = self::$product_variations;
		}

		if ( ! empty( $state ) ) {
			wp_interactivity_state( self::$store_namespace, $state );
		}
	}

	/**
	 * Load a product into state.
	 *
	 * @param string $consent_statement The consent statement string.
	 * @param int    $product_id        The product ID.
	 * @return array The product data.
	 * @throws InvalidArgumentException If consent statement doesn't match.
	 */
	public static function load_product( string $consent_statement, int $product_id ): array {
		self::check_consent( $consent_statement );

		// Skip loading if product is already in state.
		if ( isset( self::$products[ $product_id ] ) ) {
			return self::$products[ $product_id ];
		}

		$response = Package::container()->get( Hydration::class )->get_rest_api_response_data( '/wc/store/v1/products/' . $product_id );

		self::$products[ $product_id ] = $response['body'] ?? array();
		self::register_state();

		return self::$products[ $product_id ];
	}

	/**
	 * Load all purchasable child products of a parent product into state.
	 *
	 * @param string $consent_statement The consent statement string.
	 * @param int    $parent_id         The parent product ID.
	 * @return array The purchasable child products keyed by ID.
	 * @throws InvalidArgumentException If consent statement doesn't match.
	 */
	public static function load_purchasable_child_products( string $consent_statement, int $parent_id ): array {
		self::check_consent( $consent_statement );

		// Get the parent product to retrieve child IDs.
		$parent_product = wc_get_product( $parent_id );
		if ( ! $parent_product ) {
			return array();
		}

		// Get child product IDs (for grouped products, these are linked products).
		$child_ids = $parent_product->get_children();
		if ( empty( $child_ids ) ) {
			return array();
		}

		// Query child products using include[] filter.
		// The parent[] filter doesn't work for grouped products because
		// their children are standalone products, not variations.
		$include_params = array_map(
			fn( $id ) => 'include[]=' . $id,
			$child_ids
		);
		$query_string   = implode( '&', $include_params );

		$response = Package::container()->get( Hydration::class )->get_rest_api_response_data( '/wc/store/v1/products?' . $query_string );

		if ( empty( $response['body'] ) ) {
			return array();
		}

		// Filter to only purchasable products.
		$purchasable_products = array_filter(
			$response['body'],
			fn( $product ) => $product['is_purchasable']
		);

		// Re-key array by product ID and merge into state.
		// Use array_replace instead of array_merge to preserve numeric keys.
		$keyed_products = array_column( $purchasable_products, null, 'id' );
		self::$products = array_replace( self::$products, $keyed_products );
		self::register_state();

		return $keyed_products;
	}

	/**
	 * Load all variations of a variable product into state.
	 *
	 * @param string $consent_statement The consent statement string.
	 * @param int    $parent_id         The parent product ID.
	 * @return array The variations keyed by ID.
	 * @throws InvalidArgumentException If consent statement doesn't match.
	 */
	public static function load_variations( string $consent_statement, int $parent_id ): array {
		self::check_consent( $consent_statement );

		$response = Package::container()->get( Hydration::class )->get_rest_api_response_data( '/wc/store/v1/products?parent[]=' . $parent_id . '&type=variation' );

		if ( empty( $response['body'] ) ) {
			return array();
		}

		// Re-key array by variation ID and merge into state.
		// Use array_replace instead of array_merge to preserve numeric keys.
		$keyed_variations         = array_column( $response['body'], null, 'id' );
		self::$product_variations = array_replace( self::$product_variations, $keyed_variations );
		self::register_state();

		return $keyed_variations;
	}
}
