<?php
/**
 * Complete, immutable catalog generations stored in private database tables.
 *
 * @package Selectika
 */

defined( 'ABSPATH' ) || exit;

/** Selectika Catalog integration. */
final class Selectika_Catalog {
	const PAGE_SIZE  = 100;
	const BATCH_SIZE = 20;

	/**
	 * Register WordPress and WooCommerce integration hooks.
	 */
	public function __construct() {
		add_action( 'selectika_catalog_tick', array( $this, 'tick' ) );
		add_action( 'save_post_product', array( __CLASS__, 'changed' ) );
		add_action( 'save_post_product_variation', array( __CLASS__, 'changed' ) );
		add_action( 'woocommerce_update_product', array( __CLASS__, 'changed' ) );
		add_action( 'woocommerce_update_product_variation', array( __CLASS__, 'changed' ) );
		add_action( 'woocommerce_product_set_stock', array( __CLASS__, 'changed' ) );
		add_action( 'woocommerce_variation_set_stock', array( __CLASS__, 'changed' ) );
		add_action( 'before_delete_post', array( __CLASS__, 'deleted' ) );
		add_action( 'rest_api_init', array( $this, 'routes' ) );
	}

	/**
	 * Create the private plugin table through WordPress schema migration.
	 */
	public static function install() {
		global $wpdb;
		require_once ABSPATH . 'wp-admin/includes/upgrade.php';
		$table   = $wpdb->prefix . 'selectika_catalog';
		$charset = $wpdb->get_charset_collate();
		dbDelta( "CREATE TABLE $table (generation varchar(36) NOT NULL, row_id bigint unsigned NOT NULL, payload longtext NOT NULL, digest char(64) NOT NULL, PRIMARY KEY  (generation,row_id)) $charset;" );
	}

	/**
	 * Invalidate in-progress catalog generations after product mutations.
	 */
	public static function changed() {
		update_option( 'selectika_catalog_revision', wp_generate_uuid4(), false );
	}

	/**
	 * Invalidate the catalog when a product or variation is removed.
	 *
	 * @param int $id Native object ID.
	 */
	public static function deleted( $id ) {
		if ( in_array( get_post_type( $id ), array( 'product', 'product_variation' ), true ) ) {
			self::changed();
		}
	}

	/**
	 * Report the most recent complete catalog and build state.
	 */
	public static function status() {
		$m = get_option( 'selectika_catalog_manifest', array() );
		return array(
			'generation'   => $m['generation'] ?? null,
			'completed_at' => $m['completed_at'] ?? null,
			'rows'         => $m['rows'] ?? 0,
			'error'        => get_option( 'selectika_catalog_error', '' ),
			'building'     => (bool) get_option( 'selectika_catalog_job', false ),
		);
	}

	/**
	 * Ensure a recurring catalog refresh is scheduled.
	 */
	public static function schedule() {
		if ( ! wp_next_scheduled( 'selectika_catalog_tick' ) ) {
			wp_schedule_event( time() + 5, 'hourly', 'selectika_catalog_tick' );
		}
	}

	/**
	 * Register authenticated read-only connection and catalog routes.
	 */
	public function routes() {
		register_rest_route(
			'selectika/v1',
			'/connection',
			array(
				'methods'             => 'GET',
				'callback'            => array( $this, 'connection' ),
				'permission_callback' => array( 'Selectika_Connection', 'authorize' ),
			)
		);
		register_rest_route(
			'selectika/v1',
			'/catalog',
			array(
				'methods'             => 'GET',
				'callback'            => array( $this, 'page' ),
				'permission_callback' => array( 'Selectika_Connection', 'authorize' ),
			)
		);
	}

	/**
	 * Return private connection diagnostics.
	 */
	public function connection() {
		$response = new WP_REST_Response( Selectika_Connection::descriptor() );
		$response->header( 'Cache-Control', 'private, no-store' );
		return $response;
	}

	/**
	 * Schedule a fresh build without deleting an active worker's state.
	 */
	public static function request_build() {
		self::changed();
		if ( ! wp_next_scheduled( 'selectika_catalog_continue' ) ) {
			wp_schedule_single_event( time() + 1, 'selectika_catalog_continue' );
		}
	}

	/**
	 * Build one bounded product batch and publish only complete generations.
	 *
	 * @throws RuntimeException Internally caught to retain the previous completed generation.
	 */
	public function tick() {
		global $wpdb;
		if ( ! Selectika_Connection::active( 'catalog' ) || ! function_exists( 'wc_get_products' ) ) {
			return;
		}
		$now  = time();
		$lock = Selectika_Connection::acquire_lock( 'selectika_catalog_lock', 300 );
		if ( ! $lock ) {
			return;
		}
		$job = get_option( 'selectika_catalog_job', false );
		try {
			$c = Selectika_Connection::get();
			if ( ! $job ) {
				$job = array(
					'generation' => wp_generate_uuid4(),
					'connection' => $c['generation'],
					'page'       => 1,
					'rows'       => 0,
					'revision'   => Selectika_Connection::fresh_option( 'selectika_catalog_revision', '' ),
					'started'    => $now,
				);
			}
			if ( $c['generation'] !== $job['connection'] || Selectika_Connection::fresh_option( 'selectika_catalog_revision', '' ) !== $job['revision'] || $now - $job['started'] > 3600 ) {
				throw new RuntimeException( 'catalog_changed_retry' );
			}
			$products = wc_get_products(
				array(
					'status'  => 'publish',
					'limit'   => self::BATCH_SIZE,
					'page'    => $job['page'],
					'orderby' => 'ID',
					'order'   => 'ASC',
				)
			);
			foreach ( $products as $product ) {
				foreach ( self::rows( $product ) as $row ) {
					$json = wp_json_encode( $row, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES );
					// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery -- Append to a private immutable generation; no WordPress object/cache exists for these rows.
					if ( false === $json || false === $wpdb->insert(
						$wpdb->prefix . 'selectika_catalog',
						array(
							'generation' => $job['generation'],
							'row_id'     => $job['rows'],
							'payload'    => $json,
							'digest'     => hash( 'sha256', $json ),
						)
					) ) {
						throw new RuntimeException( 'catalog_storage_failed' );
					}
					++$job['rows'];
				}
			}
			$current = Selectika_Connection::refresh();
			if ( Selectika_Connection::fresh_option( 'selectika_catalog_revision', '' ) !== $job['revision'] || ! Selectika_Connection::active( 'catalog' ) || $current['generation'] !== $c['generation'] ) {
				throw new RuntimeException( 'catalog_changed_retry' );
			}
			if ( count( $products ) < self::BATCH_SIZE ) {
				$manifest = array(
					'generation'   => $job['generation'],
					'connection'   => $c['generation'],
					'rows'         => $job['rows'],
					'completed_at' => gmdate( 'c' ),
					'expires'      => $now + DAY_IN_SECONDS,
				);
				update_option( 'selectika_catalog_manifest_' . $job['generation'], $manifest, false );
				update_option( 'selectika_catalog_manifest', $manifest, false );
				delete_option( 'selectika_catalog_job' );
				delete_option( 'selectika_catalog_error' );
				self::cleanup();
			} else {
				++$job['page'];
				update_option( 'selectika_catalog_job', $job, false );
				wp_schedule_single_event( time() + 2, 'selectika_catalog_continue' );
			}
		} catch ( Throwable $error ) {
			delete_option( 'selectika_catalog_job' );
			$known = array( 'catalog_changed_retry', 'catalog_storage_failed', 'unsupported_product_type', 'too_many_variations', 'invalid_catalog_product' );
			update_option( 'selectika_catalog_error', in_array( $error->getMessage(), $known, true ) ? $error->getMessage() : 'catalog_export_failed', false );
			if ( 'catalog_changed_retry' === $error->getMessage() && ! wp_next_scheduled( 'selectika_catalog_continue' ) ) {
				wp_schedule_single_event( time() + 10, 'selectika_catalog_continue' ); }
			if ( is_array( $job ) ) {
				// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching -- Delete only a failed or expired private generation; rows are deliberately not cached.
				$wpdb->delete( $wpdb->prefix . 'selectika_catalog', array( 'generation' => $job['generation'] ) );
			}
		} finally {
			Selectika_Connection::release_lock( 'selectika_catalog_lock', $lock );
		}
	}

	/**
	 * Yield stable variant rows using native WooCommerce CRUD objects.
	 *
	 * @param WC_Product $parent_product Native parent product.
	 * @throws RuntimeException When a product cannot be represented without data loss.
	 */
	public static function rows( $parent_product ) {
		if ( ! $parent_product->is_type( array( 'simple', 'variable' ) ) ) {
			throw new RuntimeException( 'unsupported_product_type' );
		}
		$children = $parent_product->is_type( 'variable' ) ? $parent_product->get_children() : array( $parent_product->get_id() );
		if ( count( $children ) > 1000 ) {
			throw new RuntimeException( 'too_many_variations' );
		}
		$categories = wp_get_post_terms( $parent_product->get_id(), 'product_cat', array( 'fields' => 'names' ) );
		foreach ( $children as $id ) {
			$child = wc_get_product( $id );
			if ( ! $child || 'publish' !== $child->get_status() ) {
				continue;
			}
			$price = $child->get_regular_price();
			if ( '' === $price ) {
				$price = $child->get_price();
			}
			if ( '' === $price || ! is_numeric( $price ) || '' === self::identity( $parent_product ) ) {
				throw new RuntimeException( 'invalid_catalog_product' );
			}
			$attributes   = $child->is_type( 'variation' ) ? $child->get_variation_attributes() : array();
			$images       = array_unique( array_filter( array_merge( array( $child->get_image_id(), $parent_product->get_image_id() ), $parent_product->get_gallery_image_ids() ) ) );
			$image_urls   = array_values( array_filter( array_map( 'wp_get_attachment_url', $images ) ) );
			$variation_id = $child->is_type( 'variation' ) ? $child->get_id() : 0;
			yield array(
				'schema_version'    => 1,
				'item_id'           => self::identity( $parent_product ),
				'product_id'        => $parent_product->get_id(),
				'parent_id'         => $parent_product->get_id(),
				'variation_id'      => $variation_id,
				'variant_id'        => $parent_product->get_id() . '#' . $variation_id,
				'slug'              => $parent_product->get_slug(),
				'parent_sku'        => $parent_product->get_sku(),
				'sku'               => $child->get_sku(),
				'title'             => $parent_product->get_name(),
				'description'       => $parent_product->get_description(),
				'short_description' => $parent_product->get_short_description(),
				'link'              => $child->get_permalink(),
				'image_urls'        => $image_urls,
				'category_path'     => is_wp_error( $categories ) ? '' : implode( ' > ', $categories ),
				'price'             => wc_format_decimal( wc_get_price_to_display( $child, array( 'price' => (float) $price ) ), wc_get_price_decimals() ),
				'sale_price'        => $child->is_on_sale() ? wc_format_decimal( wc_get_price_to_display( $child ), wc_get_price_decimals() ) : '',
				'currency'          => get_woocommerce_currency(),
				'price_tax_display' => get_option( 'woocommerce_tax_display_shop' ),
				'availability'      => $child->is_in_stock() && $child->is_purchasable() ? 'in' : 'out',
				'stock_status'      => $child->get_stock_status(),
				'backorders'        => $child->get_backorders(),
				'attributes'        => $attributes,
				'color'             => 'parent-' . $parent_product->get_id(),
				'variant_color'     => self::attribute( $attributes, 'color' ),
				'size'              => self::attribute( $attributes, 'size' ),
				'sale_from'         => $child->get_date_on_sale_from() ? $child->get_date_on_sale_from()->date( DATE_ATOM ) : null,
				'sale_to'           => $child->get_date_on_sale_to() ? $child->get_date_on_sale_to()->date( DATE_ATOM ) : null,
			);
		}
	}

	/**
	 * Resolve parent identity without conflating native writeback IDs.
	 *
	 * @param WC_Product $parent_product Native parent product.
	 */
	private static function identity( $parent_product ) {
		return Selectika_Connection::item_id( $parent_product ); }
	/**
	 * Read an attribute by its canonical suffix.
	 *
	 * @param array  $attributes Configured attributes.
	 * @param string $name Event or attribute name.
	 */
	private static function attribute( $attributes, $name ) {
		foreach ( $attributes as $key => $value ) {
			if ( preg_match( '/(?:^|_)' . preg_quote( $name, '/' ) . '$/i', $key ) ) {
				return $value; }
		}
		return '';
	}

	/**
	 * Read and integrity-check one page of an immutable generation.
	 *
	 * @param WP_REST_Request $request Authenticated REST request.
	 */
	public function page( $request ) {
		global $wpdb;
		if ( ! Selectika_Connection::active( 'catalog' ) ) {
			return new WP_Error( 'selectika_catalog_disabled', __( 'Catalog export is disabled.', 'selectika' ), array( 'status' => 403 ) );
		}
		$generation = $request->get_param( 'snapshot' );
		if ( null !== $generation && ( ! is_string( $generation ) || ! preg_match( '/^[a-f0-9-]{36}$/D', $generation ) ) ) {
			return new WP_Error( 'selectika_snapshot_invalid', __( 'Invalid catalog generation.', 'selectika' ), array( 'status' => 400 ) );
		}
		$m = get_option( $generation ? 'selectika_catalog_manifest_' . $generation : 'selectika_catalog_manifest', false );
		$c = Selectika_Connection::get();
		if ( ! $m || $m['expires'] < time() || $m['connection'] !== $c['generation'] ) {
			return new WP_Error( 'selectika_snapshot_unavailable', __( 'A complete catalog generation is not available. Rebuild the feed.', 'selectika' ), array( 'status' => 503 ) );
		}
		$page = $request->get_param( 'page' );
		if ( null !== $page && ( ! is_scalar( $page ) || ! ctype_digit( (string) $page ) || (int) $page < 1 ) ) {
			return new WP_Error( 'selectika_page_invalid', __( 'Invalid catalog page.', 'selectika' ), array( 'status' => 400 ) );
		}
		$page     = max( 1, (int) $page );
		$start    = ( $page - 1 ) * self::PAGE_SIZE;
		$expected = min( self::PAGE_SIZE, max( 0, $m['rows'] - $start ) );
		if ( $start >= $m['rows'] && ( $page > 1 || $m['rows'] > 0 ) ) {
			return new WP_Error( 'selectika_page_invalid', __( 'Catalog page is outside the generation.', 'selectika' ), array( 'status' => 400 ) );
		}
		$table = $wpdb->prefix . 'selectika_catalog';
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching -- Read private snapshot rows directly to validate count and checksums; all identifiers and values are prepared.
		$rows    = $wpdb->get_results( $wpdb->prepare( 'SELECT row_id,payload,digest FROM %i WHERE generation=%s AND row_id >= %d AND row_id < %d ORDER BY row_id', $table, $m['generation'], $start, $start + self::PAGE_SIZE ), ARRAY_A );
		$results = array();
		foreach ( $rows as $index => $row ) {
			if ( (int) $row['row_id'] !== $start + $index || ! hash_equals( $row['digest'], hash( 'sha256', $row['payload'] ) ) ) {
				return new WP_Error( 'selectika_catalog_corrupt', __( 'Catalog integrity check failed.', 'selectika' ), array( 'status' => 503 ) );
			}
			$decoded = json_decode( $row['payload'], true );
			if ( ! is_array( $decoded ) ) {
				return new WP_Error( 'selectika_catalog_corrupt', __( 'Catalog integrity check failed.', 'selectika' ), array( 'status' => 503 ) ); }
			$results[] = $decoded;
		}
		if ( count( $results ) !== $expected ) {
			return new WP_Error( 'selectika_catalog_corrupt', __( 'Catalog integrity check failed.', 'selectika' ), array( 'status' => 503 ) ); }
		$next     = $start + count( $results ) < $m['rows'] ? add_query_arg(
			array(
				'snapshot' => $m['generation'],
				'page'     => $page + 1,
			),
			rest_url( 'selectika/v1/catalog' )
		) : null;
		$response = new WP_REST_Response(
			array(
				'schema_version' => 1,
				'snapshot'       => $m['generation'],
				'total'          => $m['rows'],
				'results'        => $results,
				'next'           => $next,
			)
		);
		$response->header( 'Cache-Control', 'private, no-store' );
		return $response;
	}

	/**
	 * Remove expired generations from private storage.
	 */
	private static function cleanup() {
		global $wpdb;
		$prefix = 'selectika_catalog_manifest_';
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching -- Enumerate plugin-owned manifests for expiry; WordPress has no option-prefix listing API.
		$names = $wpdb->get_col( $wpdb->prepare( "SELECT option_name FROM {$wpdb->options} WHERE option_name LIKE %s", $wpdb->esc_like( $prefix ) . '%' ) );
		foreach ( $names as $name ) {
			$m = get_option( $name );
			if ( is_array( $m ) && $m['expires'] < time() ) {
				// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching -- Delete only a failed or expired private generation; rows are deliberately not cached.
				$wpdb->delete( $wpdb->prefix . 'selectika_catalog', array( 'generation' => $m['generation'] ) );
				delete_option( $name );
			}
		}
	}
}