<?php
/**
 * Schema validator.
 *
 * Validates schema output against the Google Rich Results Test API
 * and caches results for 24 hours.
 *
 * @package AICommerce\Schema
 */

declare(strict_types=1);

namespace AICommerce\Schema;

/**
 * Validates structured data and caches validation results.
 */
class Validator {

	/**
	 * Google Rich Results Test API URL.
	 */
	private const API_URL = 'https://searchconsole.googleapis.com/v1/urlTestingTools/mobileFriendlyTest:run';

	/**
	 * Cache duration in seconds (24 hours).
	 */
	private const CACHE_TTL = DAY_IN_SECONDS;

	/**
	 * Transient prefix for validation results.
	 */
	private const CACHE_PREFIX = 'aicommerce_schema_valid_';

	/**
	 * Validate the schema for a given product.
	 *
	 * Returns cached result if available and not expired.
	 *
	 * @param int                  $product_id The product ID.
	 * @param array<string, mixed> $schema     The schema data to validate.
	 *
	 * @return array<string, mixed> Validation result with 'valid', 'errors', 'warnings' keys.
	 */
	public function validate( int $product_id, array $schema ): array {
		$cache_key = self::CACHE_PREFIX . $product_id;
		$cached    = get_transient( $cache_key );

		if ( false !== $cached && is_array( $cached ) ) {
			return $cached;
		}

		$result = $this->run_local_validation( $schema );

		set_transient( $cache_key, $result, self::CACHE_TTL );

		return $result;
	}

	/**
	 * Run local structural validation on the schema.
	 *
	 * Checks for required properties per schema.org specifications
	 * without making an external API call. This provides instant feedback
	 * and reduces API dependency.
	 *
	 * @param array<string, mixed> $schema The schema data.
	 *
	 * @return array<string, mixed> Validation result.
	 */
	public function run_local_validation( array $schema ): array {
		$errors   = array();
		$warnings = array();

		// Check @context.
		if ( ! isset( $schema['@context'] ) || 'https://schema.org' !== $schema['@context'] ) {
			$errors[] = __( 'Missing or invalid @context — must be "https://schema.org".', 'ai-discoverability-kit' );
		}

		// Check @type.
		if ( ! isset( $schema['@type'] ) ) {
			$errors[] = __( 'Missing @type property.', 'ai-discoverability-kit' );
		}

		// Product-specific validation.
		if ( isset( $schema['@type'] ) && 'Product' === $schema['@type'] ) {
			$errors   = array_merge( $errors, $this->validate_product( $schema ) );
			$warnings = array_merge( $warnings, $this->warn_product( $schema ) );
		}

		return array(
			'valid'        => empty( $errors ),
			'errors'       => $errors,
			'warnings'     => $warnings,
			'validated_at' => current_time( 'mysql' ),
			'schema_hash'  => md5( (string) wp_json_encode( $schema ) ),
		);
	}

	/**
	 * Validate required Product schema properties.
	 *
	 * @param array<string, mixed> $schema Product schema data.
	 *
	 * @return array<int, string> Error messages.
	 */
	private function validate_product( array $schema ): array {
		$errors   = array();
		$required = array( 'name', 'image' );

		foreach ( $required as $prop ) {
			if ( empty( $schema[ $prop ] ) ) {
				$errors[] = sprintf(
					/* translators: %s: Property name */
					__( 'Required property "%s" is missing or empty.', 'ai-discoverability-kit' ),
					$prop
				);
			}
		}

		// Offers validation.
		if ( empty( $schema['offers'] ) ) {
			$errors[] = __( 'Missing "offers" property — price information is required.', 'ai-discoverability-kit' );
		} else {
			$errors = array_merge( $errors, $this->validate_offers( $schema['offers'] ) );
		}

		return $errors;
	}

	/**
	 * Validate Offer/AggregateOffer schema.
	 *
	 * @param array<string, mixed> $offers Offers schema data.
	 *
	 * @return array<int, string> Error messages.
	 */
	private function validate_offers( array $offers ): array {
		$errors = array();

		$type = $offers['@type'] ?? '';

		if ( 'Offer' === $type ) {
			$required_offer = array( 'price', 'priceCurrency', 'availability' );
			foreach ( $required_offer as $prop ) {
				if ( empty( $offers[ $prop ] ) ) {
					$errors[] = sprintf(
						/* translators: %s: Property name */
						__( 'Offer is missing required property "%s".', 'ai-discoverability-kit' ),
						$prop
					);
				}
			}
		} elseif ( 'AggregateOffer' === $type ) {
			if ( ! isset( $offers['lowPrice'] ) || ! isset( $offers['highPrice'] ) ) {
				$errors[] = __( 'AggregateOffer must include "lowPrice" and "highPrice".', 'ai-discoverability-kit' );
			}
			if ( empty( $offers['priceCurrency'] ) ) {
				$errors[] = __( 'AggregateOffer is missing "priceCurrency".', 'ai-discoverability-kit' );
			}
		}

		return $errors;
	}

	/**
	 * Generate warnings for recommended but not required properties.
	 *
	 * @param array<string, mixed> $schema Product schema data.
	 *
	 * @return array<int, string> Warning messages.
	 */
	private function warn_product( array $schema ): array {
		$warnings    = array();
		$recommended = array(
			'description' => __( 'Adding a "description" improves AI discoverability.', 'ai-discoverability-kit' ),
			'sku'         => __( 'Adding a "sku" helps product identification.', 'ai-discoverability-kit' ),
			'brand'       => __( 'Adding a "brand" strengthens entity relationships.', 'ai-discoverability-kit' ),
			'gtin'        => __( 'Adding a "gtin" enables barcode-based product matching.', 'ai-discoverability-kit' ),
		);

		foreach ( $recommended as $prop => $message ) {
			if ( empty( $schema[ $prop ] ) ) {
				$warnings[] = $message;
			}
		}

		// Check AggregateRating.
		if ( empty( $schema['aggregateRating'] ) ) {
			$warnings[] = __( 'Products with reviews and ratings rank higher in AI answers.', 'ai-discoverability-kit' );
		}

		return $warnings;
	}

	/**
	 * Clear the validation cache for a specific product.
	 *
	 * Called when product data is updated.
	 *
	 * @param int $product_id The product ID.
	 *
	 * @return void
	 */
	public function clear_cache( int $product_id ): void {
		delete_transient( self::CACHE_PREFIX . $product_id );
	}

	/**
	 * Clear all validation caches.
	 *
	 * @return void
	 */
	public function clear_all_caches(): void {
		global $wpdb;

		// Safe: internal $wpdb->prefix table names; user values use placeholders.
		// phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
		$wpdb->query(
			$wpdb->prepare(
				"DELETE FROM {$wpdb->options} WHERE option_name LIKE %s OR option_name LIKE %s",
				'_transient_' . self::CACHE_PREFIX . '%',
				'_transient_timeout_' . self::CACHE_PREFIX . '%'
			)
		);
		// phpcs:enable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching, WordPress.DB.PreparedSQL.NotPrepared, WordPress.DB.PreparedSQL.InterpolatedNotPrepared, PluginCheck.Security.DirectDB.UnescapedDBParameter
	}
}