<?php
/**
 * MultilingualPress integration for AI Translator.
 *
 * When MultilingualPress creates a new connected post (i.e. the editor saves
 * a source post and MLP syncs it to another site for the first time), this
 * class translates the source post's fields into the target site's language
 * and writes the result back to the newly created remote post.
 *
 * The hook `multilingualpress.metabox_after_update_remote_post` fires while
 * WordPress is already switched to the remote site, so wp_update_post() can
 * be called directly without an additional switch_to_blog().
 *
 * This integration only activates when:
 *   1. MultilingualPress is active (class_exists guard in bootstrap).
 *   2. "Auto-translate on MLP sync" is enabled in the plugin settings.
 *   3. An AI provider is configured for text generation.
 *
 * @package ROBOTSTXT\AI_Translator
 * @since   1.1.0
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

if ( ! class_exists( 'AI_Translator_MLP_Integration' ) ) {

	/**
	 * Hooks into MultilingualPress post synchronization to auto-translate
	 * newly connected posts.
	 *
	 * @since 1.1.0
	 */
	class AI_Translator_MLP_Integration {

		/**
		 * Settings handler.
		 *
		 * @since 1.1.0
		 * @var AI_Translator_Settings
		 */
		private $settings;

		/**
		 * Translator handler.
		 *
		 * @since 1.1.0
		 * @var AI_Translator_Translator
		 */
		private $translator;

		/**
		 * Constructor.
		 *
		 * @since 1.1.0
		 *
		 * @param AI_Translator_Settings   $settings   Settings handler.
		 * @param AI_Translator_Translator $translator Translator handler.
		 */
		public function __construct( AI_Translator_Settings $settings, AI_Translator_Translator $translator ) {
			$this->settings   = $settings;
			$this->translator = $translator;
		}

		/**
		 * Registers WordPress hooks.
		 *
		 * @since 1.1.0
		 *
		 * @return void
		 */
		public function register() {
			add_action(
				'multilingualpress.metabox_after_update_remote_post',
				array( $this, 'on_mlp_after_update_remote_post' ),
				10,
				3
			);
		}

		/**
		 * Translates the source post and updates the newly created remote post.
		 *
		 * Fires while WordPress is switched to the remote site, so
		 * wp_update_post() can be called directly.
		 *
		 * Only acts when:
		 *  - $operation is 'new' (first connection, not an update).
		 *  - The "auto_translate_on_mlp_create" setting is enabled.
		 *  - An AI provider is configured for text generation.
		 *
		 * @since 1.1.0
		 *
		 * @param \Inpsyde\MultilingualPress\TranslationUi\Post\RelationshipContext $context   MLP relationship context.
		 * @param array<string,scalar|null>                                         $post      Post data used to create the remote post.
		 * @param string                                                            $operation 'new' = first connection, 'leave' = update.
		 *
		 * @return void
		 */
		public function on_mlp_after_update_remote_post( $context, $post, $operation ) {
			unset( $post );

			if ( 'new' !== $operation ) {
				return;
			}

			$settings = $this->settings->get_settings();

			if ( empty( $settings['auto_translate_on_mlp_create'] ) ) {
				return;
			}

			if ( ! $this->translator->is_supported() ) {
				return;
			}

			// We are already on the remote site (MLP switched before firing this hook).
			// get_blog_option() with the explicit site ID is safe and avoids relying
			// on locale globals that may not be updated after switch_to_blog().
			$raw_locale    = get_blog_option( $context->remoteSiteId(), 'WPLANG' );
			$target_locale = is_string( $raw_locale ) && '' !== $raw_locale ? $raw_locale : 'en_US';

			// sourcePost() performs switch_to_blog internally and restores afterward.
			$source_post = $context->sourcePost();

			if ( ! $source_post instanceof WP_Post ) {
				return;
			}

			$remote_post_id = $context->remotePostId();
			$update         = array( 'ID' => $remote_post_id );
			$has_changes    = false;

			// ── Translate title ──────────────────────────────────────────────

			if ( ! empty( $settings['translate_title'] ) && '' !== trim( $source_post->post_title ) ) {
				$translated = $this->translator->translate( $source_post->post_title, $target_locale );
				if ( ! is_wp_error( $translated ) && '' !== $translated ) {
					$update['post_title'] = $translated;
					$has_changes          = true;
				}
			}

			// ── Translate content ────────────────────────────────────────────

			if ( ! empty( $settings['translate_content'] ) && '' !== trim( $source_post->post_content ) ) {
				$translated = $this->translator->translate( $source_post->post_content, $target_locale );
				if ( ! is_wp_error( $translated ) && '' !== $translated ) {
					$update['post_content'] = $translated;
					$has_changes            = true;
				}
			}

			// ── Translate excerpt ────────────────────────────────────────────

			if ( ! empty( $settings['translate_excerpt'] )
				&& '' !== trim( $source_post->post_excerpt )
				&& post_type_supports( $source_post->post_type, 'excerpt' )
			) {
				$translated = $this->translator->translate( $source_post->post_excerpt, $target_locale );
				if ( ! is_wp_error( $translated ) && '' !== $translated ) {
					$update['post_excerpt'] = $translated;
					$has_changes            = true;
				}
			}

			if ( $has_changes ) {
				// Already on the remote site — no switch_to_blog() needed.
				wp_update_post( wp_slash( $update ) );
			}
		}
	}
}