<?php
declare( strict_types=1 );

namespace Automattic\WooCommerce\Internal\EmailEditor;

use Automattic\WooCommerce\EmailEditor\Email_Editor_Container;
use Automattic\WooCommerce\EmailEditor\Engine\Personalizer;
use Automattic\WooCommerce\EmailEditor\Engine\Renderer\Renderer as EmailRenderer;
use Automattic\WooCommerce\Internal\EmailEditor\EmailTemplates\WooEmailTemplate;
use Automattic\WooCommerce\Internal\EmailEditor\WCTransactionalEmails\WCTransactionalEmails;
use Automattic\WooCommerce\Internal\EmailEditor\WCTransactionalEmails\WCTransactionalEmailPostsGenerator;
use Automattic\WooCommerce\Internal\EmailEditor\WCTransactionalEmails\WCTransactionalEmailPostsManager;

/**
 * Class responsible for rendering block-based emails.
 */
class BlockEmailRenderer {
	const WOO_EMAIL_CONTENT_PLACEHOLDER = '##WOO_CONTENT##';

	/**
	 * Service for rendering block emails
	 *
	 * @var EmailRenderer
	 */
	private $renderer;

	/**
	 * Service for personalization of emails
	 * It replaces personalization tags with actual values
	 *
	 * @var Personalizer
	 */
	private $personalizer;

	/**
	 * Service for extracting WooCommerce content from WC_Email object.
	 *
	 * @var WooContentProcessor
	 */
	private $woo_content_processor;

	/**
	 * WooCommerce Email Template Manager instance.
	 *
	 * @var WCTransactionalEmailPostsManager
	 */
	private $template_manager;

	/**
	 * Request-scoped cache of file template content, keyed by email type and
	 * locale. The canonical content is type-level (personalization happens
	 * later), so repeated sends of the same email type in one request — e.g.
	 * a bulk order status update — compute it once.
	 *
	 * @var array<string, string>
	 */
	private $file_template_content_cache = array();

	/**
	 * Constructor.
	 */
	public function __construct() {
		$editor_container       = Email_Editor_Container::container();
		$this->renderer         = $editor_container->get( EmailRenderer::class );
		$this->personalizer     = $editor_container->get( Personalizer::class );
		$this->template_manager = WCTransactionalEmailPostsManager::get_instance();
	}

	/**
	 * Initialize the renderer.
	 *
	 * @param WooContentProcessor $woo_content_processor Service for extracting WooCommerce content from WC_Email object.
	 * @internal
	 */
	final public function init( WooContentProcessor $woo_content_processor ): void {
		$this->woo_content_processor = $woo_content_processor;
		add_action( 'woocommerce_email_blocks_renderer_initialized', array( $this, 'register_block_renderers' ) );
	}

	/**
	 * Maybe render block-based email content.
	 *
	 * @param \WC_Email $wc_email WooCommerce email.
	 * @return string|null Modified email content
	 */
	public function maybe_render_block_email( \WC_Email $wc_email ): ?string {
		$email_post = $this->get_email_post_by_wc_email( $wc_email );

		// Without a published post, the file template is the source of truth
		// (WP Site Editor pattern). This method runs for every WC_Email when
		// the block email feature is enabled, so the fallback is limited to
		// emails opted in via the
		// `woocommerce_transactional_emails_for_block_editor` filter — for any
		// other email the template resolution would silently degrade to the
		// generic default block content. Those keep the classic pipeline.
		$file_template_content = '';
		if ( ! $email_post ) {
			if ( ! in_array( $wc_email->id, WCTransactionalEmails::get_transactional_emails(), true ) ) {
				return null;
			}

			// The canonical content (including the `woocommerce_email_content_post_data`
			// filter) is used, so what is sent matches both the editor scratchpad
			// content and the hash the cleanup migration compared against before
			// deleting a post. Keyed by locale as well: plugins may switch it
			// per recipient, and the markup contains translated strings.
			$cache_key = $wc_email->id . ':' . get_locale();
			if ( ! isset( $this->file_template_content_cache[ $cache_key ] ) ) {
				$this->file_template_content_cache[ $cache_key ] = WCTransactionalEmailPostsGenerator::compute_canonical_post_content( $wc_email );
			}
			$file_template_content = $this->file_template_content_cache[ $cache_key ];
			if ( '' === $file_template_content ) {
				return null;
			}
		}

		$woo_content = $this->woo_content_processor->get_woo_content( $wc_email );
		return $this->render_block_email( $email_post, $file_template_content, $woo_content, $wc_email );
	}

	/**
	 * Render block email content from the saved post or the file template markup.
	 *
	 * @param \WP_Post|null $email_post Email post, or null to render from the file template content.
	 * @param string        $file_template_content File template block markup, used when no post is given.
	 * @param string        $woo_content WooCommerce email content.
	 * @param \WC_Email     $wc_email WooCommerce email.
	 * @return string|null Rendered email content, or null when rendering fails.
	 */
	private function render_block_email( ?\WP_Post $email_post, string $file_template_content, string $woo_content, \WC_Email $wc_email ): ?string {
		try {
			// Set email context before rendering so blocks can access it.
			$filter_callback = function ( $context = array() ) use ( $wc_email ) {
				return array_merge( $context, $this->build_email_context( $wc_email ) );
			};
			add_filter( 'woocommerce_email_editor_rendering_email_context', $filter_callback, 10, 1 );

			$subject   = $wc_email->get_subject();
			$preheader = $wc_email->get_preheader();

			if ( $email_post ) {
				$rendered_email_data = $this->renderer->render( $email_post, $subject, $preheader, 'en' );
			} else {
				$rendered_email_data = $this->renderer->render_from_content( $file_template_content, ( new WooEmailTemplate() )->get_slug(), $subject, $preheader, 'en' );
			}

			$personalized_email = $this->personalizer->personalize_content( $rendered_email_data['html'] );
			$rendered_email     = str_replace( self::WOO_EMAIL_CONTENT_PLACEHOLDER, $woo_content, $personalized_email );

			// Remove the filter after rendering to prevent context leakage.
			remove_filter( 'woocommerce_email_editor_rendering_email_context', $filter_callback );

			add_filter( 'woocommerce_email_styles', array( $this->woo_content_processor, 'prepare_css' ), 10, 2 );
			return $rendered_email;
		} catch ( \Throwable $e ) {
			// Catching \Throwable on purpose: this is the last safety net
			// before sending, and an \Error (e.g. a TypeError from an
			// unresolvable template) must also fall back to the classic
			// pipeline instead of fataling the request that triggered the email.
			wc_caught_exception( $e, __METHOD__, array( $email_post, $woo_content, $wc_email ) );
			// Remove the filter in case of exception.
			if ( isset( $filter_callback ) ) {
				remove_filter( 'woocommerce_email_editor_rendering_email_context', $filter_callback );
			}
			return null;
		}
	}

	/**
	 * Get the email post for a given WC_Email.
	 *
	 * Only published posts are used for rendering: unpublished states
	 * (auto-draft, draft, trash) are editing scratchpads or removed content
	 * and must not affect outgoing emails.
	 *
	 * @param \WC_Email $email WooCommerce email.
	 * @return \WP_Post|null
	 */
	private function get_email_post_by_wc_email( \WC_Email $email ): ?\WP_Post {
		$email_post = $this->template_manager->get_email_post( $email->id );

		if ( $email_post && 'publish' !== $email_post->post_status ) {
			return null;
		}

		return $email_post;
	}

	/**
	 * Build email context from WC_Email object.
	 *
	 * Extracts relevant context data from the WC_Email object that can be used
	 * by blocks during rendering, such as user ID, email address, order information, etc.
	 *
	 * Blocks that need cart product information can derive it from the user_id or email
	 * using CartCheckoutUtils::get_cart_product_ids_for_user().
	 *
	 * @param \WC_Email $wc_email WooCommerce email object.
	 * @return array Email context data.
	 */
	private function build_email_context( \WC_Email $wc_email ): array {
		$recipient_raw = $wc_email->get_recipient();
		$emails        = array_values( array_filter( array_map( 'sanitize_email', array_map( 'trim', explode( ',', $recipient_raw ) ) ) ) );
		$context       = array(
			'recipient_email' => $emails[0] ?? null,
		);

		// Extract order-related context if the email object is an order.
		if ( isset( $wc_email->object ) && $wc_email->object instanceof \WC_Order ) {
			$order              = $wc_email->object;
			$context['user_id'] = $order->get_customer_id();
		}

		return $context;
	}
}