<?php
/**
 * Schema Engine — orchestrates JSON-LD schema generation and injection.
 *
 * Injects structured data via the wp_head hook (priority 5) so that
 * AI crawlers (GPTBot, PerplexityBot, ClaudeBot) which do not execute
 * JavaScript can still parse the schema.
 *
 * @package AICommerce\Schema
 */

declare(strict_types=1);

namespace AICommerce\Schema;

/**
 * Orchestrates schema generation and output for WooCommerce product pages.
 */
class SchemaEngine {

	/**
	 * Product schema generator.
	 *
	 * @var ProductSchema
	 */
	private ProductSchema $product_schema;

	/**
	 * Entity chain builder (BreadcrumbList, Brand, Organization).
	 *
	 * @var EntityChain
	 */
	private EntityChain $entity_chain;

	/**
	 * Conflict detector for third-party SEO plugins.
	 *
	 * @var ConflictDetector
	 */
	private ConflictDetector $conflict_detector;

	/**
	 * FAQ schema generator.
	 *
	 * @var FaqSchema|null
	 */
	private ?FaqSchema $faq_schema;

	/**
	 * Speakable schema generator.
	 *
	 * @var SpeakableSchema|null
	 */
	private ?SpeakableSchema $speakable_schema;

	/**
	 * Constructor.
	 *
	 * @param ProductSchema        $product_schema    Product schema generator.
	 * @param EntityChain          $entity_chain      Entity chain builder.
	 * @param ConflictDetector     $conflict_detector  SEO plugin conflict detector.
	 * @param FaqSchema|null       $faq_schema        FAQ schema generator.
	 * @param SpeakableSchema|null $speakable_schema  Speakable schema generator.
	 */
	public function __construct(
		ProductSchema $product_schema,
		EntityChain $entity_chain,
		ConflictDetector $conflict_detector,
		?FaqSchema $faq_schema = null,
		?SpeakableSchema $speakable_schema = null
	) {
		$this->product_schema    = $product_schema;
		$this->entity_chain      = $entity_chain;
		$this->conflict_detector = $conflict_detector;
		$this->faq_schema        = $faq_schema;
		$this->speakable_schema  = $speakable_schema;
	}

	/**
	 * Inject JSON-LD schema into wp_head.
	 *
	 * Hooked at priority 5 so it runs before most theme/plugin output.
	 * Only fires on WooCommerce product pages.
	 *
	 * @return void
	 */
	public function inject(): void {
		if ( ! $this->should_inject() ) {
			return;
		}

		$product = wc_get_product( get_the_ID() );
		if ( ! $product instanceof \WC_Product ) {
			return;
		}

		$schemas = $this->build_schemas( $product );

		if ( empty( $schemas ) ) {
			return;
		}

		$this->output_json_ld( $schemas );
	}

	/**
	 * Determine if schema should be injected on the current page.
	 *
	 * @return bool
	 */
	private function should_inject(): bool {
		// Only on single product pages (requires WooCommerce).
		if ( ! function_exists( 'is_product' ) || ! is_product() ) {
			return false;
		}

		// Check if schema injection is enabled.
		$enabled = get_option( 'aicommerce_schema_enabled', true );
		if ( ! $enabled ) {
			return false;
		}

		return true;
	}

	/**
	 * Build all schema objects for a product.
	 *
	 * @param \WC_Product $product The WooCommerce product.
	 *
	 * @return array<int, array<string, mixed>> Array of schema.org objects.
	 */
	public function build_schemas( \WC_Product $product ): array {
		// Check schema cache.
		$product_id = $product->get_id();
		$hash       = $this->compute_cache_hash( $product );
		$cached     = get_post_meta( $product_id, '_aicommerce_schema_cache', true );

		if ( is_array( $cached ) && ! empty( $cached ) ) {
			$stored_hash = (string) get_post_meta( $product_id, '_aicommerce_schema_hash', true );
			if ( $stored_hash === $hash ) {
				/** This filter is documented below. */
				return apply_filters( 'aicommerce_schemas', $cached, $product );
			}
		}

		$schemas = array();

		// Product + Offer schema (always included).
		$product_data = $this->product_schema->generate( $product );
		if ( ! empty( $product_data ) ) {
			// Merge Speakable into Product schema if available.
			if ( null !== $this->speakable_schema ) {
				$speakable = $this->speakable_schema->generate( $product );
				if ( ! empty( $speakable ) ) {
					$product_data['speakable'] = $speakable;
				}
			}

			$schemas[] = $product_data;
		}

		// BreadcrumbList schema.
		$breadcrumb = $this->entity_chain->build_breadcrumb( $product );
		if ( ! empty( $breadcrumb ) ) {
			$schemas[] = $breadcrumb;
		}

		// FAQPage schema.
		if ( null !== $this->faq_schema ) {
			$faq = $this->faq_schema->generate( $product );
			if ( ! empty( $faq ) ) {
				$schemas[] = $faq;
			}
		}

		// Store in cache.
		update_post_meta( $product_id, '_aicommerce_schema_cache', $schemas );
		update_post_meta( $product_id, '_aicommerce_schema_hash', $hash );

		/**
		 * Filters the complete array of schema objects before output.
		 *
		 * @param array<int, array<string, mixed>> $schemas Array of schema.org objects.
		 * @param \WC_Product                      $product The WooCommerce product.
		 */
		$schemas = apply_filters( 'aicommerce_schemas', $schemas, $product );

		return $schemas;
	}

	/**
	 * Output JSON-LD script tags.
	 *
	 * Each schema object gets its own script tag for maximum parser compatibility.
	 *
	 * @param array<int, array<string, mixed>> $schemas Schema objects to output.
	 *
	 * @return void
	 */
	private function output_json_ld( array $schemas ): void {
		foreach ( $schemas as $schema ) {
			$json = wp_json_encode( $schema, JSON_HEX_TAG | JSON_HEX_AMP | JSON_UNESCAPED_UNICODE );

			if ( false === $json ) {
				continue;
			}

			printf(
				'<script type="application/ld+json">%s</script>' . "\n",
				$json // phpcs:ignore WordPress.Security.EscapeOutput.OutputNotEscaped -- Safe JSON-LD: JSON_HEX_TAG|JSON_HEX_AMP escape <, >, & so it cannot break out of the script element.
			);
		}
	}

	/**
	 * Get the product schema generator.
	 *
	 * @return ProductSchema
	 */
	public function get_product_schema(): ProductSchema {
		return $this->product_schema;
	}

	/**
	 * Get the entity chain builder.
	 *
	 * @return EntityChain
	 */
	public function get_entity_chain(): EntityChain {
		return $this->entity_chain;
	}

	/**
	 * Get the conflict detector.
	 *
	 * @return ConflictDetector
	 */
	public function get_conflict_detector(): ConflictDetector {
		return $this->conflict_detector;
	}

	/**
	 * Compute a hash for cache invalidation.
	 *
	 * Based on the product modified date and plugin version.
	 *
	 * @param \WC_Product $product The product.
	 *
	 * @return string MD5 hash.
	 */
	private function compute_cache_hash( \WC_Product $product ): string {
		$modified = $product->get_date_modified();
		$date_str = $modified ? $modified->date( 'Y-m-d H:i:s' ) : '';

		return md5( $date_str . '|' . AICOMMERCE_VERSION );
	}

	/**
	 * Clear the schema cache for a product.
	 *
	 * @param int $product_id The product ID.
	 *
	 * @return void
	 */
	public function clear_schema_cache( int $product_id ): void {
		delete_post_meta( $product_id, '_aicommerce_schema_cache' );
		delete_post_meta( $product_id, '_aicommerce_schema_hash' );
	}
}