<?php
/**
 * Editor UI for the AI Translator plugin.
 *
 * Registers the REST endpoint, the Classic editor metabox, and the Block editor
 * sidebar that lets editors translate the current post.
 *
 * @package ROBOTSTXT\AI_Translator
 * @since   1.0.0
 */

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

if ( ! class_exists( 'AI_Translator_Editor_UI' ) ) {

	/**
	 * Editor UI registration and REST endpoint handler.
	 *
	 * @since 1.0.0
	 */
	class AI_Translator_Editor_UI {

		/**
		 * Allowed field names that can be translated through the REST endpoint.
		 *
		 * @since 1.0.0
		 * @var array<int,string>
		 */
		const ALLOWED_FIELDS = array( 'title', 'content' );

		/**
		 * Settings handler.
		 *
		 * @since 1.0.0
		 * @var AI_Translator_Settings
		 */
		private $settings;

		/**
		 * Translator handler.
		 *
		 * @since 1.0.0
		 * @var AI_Translator_Translator
		 */
		private $translator;

		/**
		 * Constructor.
		 *
		 * @since 1.0.0
		 *
		 * @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 1.0.0
		 *
		 * @return void
		 */
		public function register() {
			add_action( 'rest_api_init', array( $this, 'register_rest_routes' ) );
			add_action( 'enqueue_block_editor_assets', array( $this, 'enqueue_block_editor_assets' ) );
			add_action( 'admin_enqueue_scripts', array( $this, 'enqueue_classic_editor_assets' ) );
			add_action( 'add_meta_boxes', array( $this, 'register_classic_meta_box' ) );
		}

		/**
		 * Registers the REST API routes.
		 *
		 * @since 1.0.0
		 *
		 * @return void
		 */
		public function register_rest_routes() {
			register_rest_route(
				AI_TRANSLATOR_REST_NAMESPACE,
				'/translate',
				array(
					'methods'             => WP_REST_Server::CREATABLE,
					'callback'            => array( $this, 'handle_translate_request' ),
					'permission_callback' => array( $this, 'check_translate_permissions' ),
					'args'                => array(
						'post_id'       => array(
							'type'              => 'integer',
							'required'          => true,
							'minimum'           => 1,
							'sanitize_callback' => 'absint',
							'validate_callback' => 'rest_validate_request_arg',
						),
						'fields'        => array(
							'type'              => 'array',
							'required'          => true,
							'minItems'          => 1,
							'uniqueItems'       => true,
							'items'             => array(
								'type' => 'string',
								'enum' => self::ALLOWED_FIELDS,
							),
							'sanitize_callback' => 'rest_sanitize_request_arg',
							'validate_callback' => 'rest_validate_request_arg',
						),
						'target_locale' => array(
							'type'              => 'string',
							'required'          => true,
							'pattern'           => '^[A-Za-z]{2,3}(_[A-Za-z0-9]{2,8})?$',
							'maxLength'         => 20,
							'sanitize_callback' => array( $this, 'sanitize_locale' ),
							'validate_callback' => 'rest_validate_request_arg',
						),
					),
				)
			);
		}

		/**
		 * Sanitises a locale string.
		 *
		 * @since 1.0.0
		 *
		 * @param mixed $value Raw value.
		 *
		 * @return string
		 */
		public function sanitize_locale( $value ) {
			$value = is_string( $value ) ? $value : '';
			$value = preg_replace( '/[^A-Za-z0-9_\-]/', '', $value );

			if ( ! is_string( $value ) ) {
				return '';
			}

			return substr( $value, 0, 20 );
		}

		/**
		 * REST permission callback for the translate endpoint.
		 *
		 * @since 1.0.0
		 *
		 * @param WP_REST_Request $request The request object.
		 *
		 * @return bool|WP_Error True if allowed, WP_Error otherwise.
		 */
		public function check_translate_permissions( WP_REST_Request $request ) {
			$post_id_param = $request->get_param( 'post_id' );
			$post_id       = is_numeric( $post_id_param ) ? (int) $post_id_param : 0;

			if ( $post_id <= 0 || ! current_user_can( 'edit_post', $post_id ) ) {
				return new WP_Error(
					'rest_forbidden',
					__( 'Sorry, you are not allowed to edit this post.', 'robotstxt-ai-translator' ),
					array( 'status' => rest_authorization_required_code() )
				);
			}

			return true;
		}

		/**
		 * REST callback for the translate endpoint.
		 *
		 * @since 1.0.0
		 *
		 * @param WP_REST_Request $request The request object.
		 *
		 * @return WP_REST_Response|WP_Error
		 */
		public function handle_translate_request( WP_REST_Request $request ) {
			$post_id_param       = $request->get_param( 'post_id' );
			$target_locale_param = $request->get_param( 'target_locale' );

			$post_id       = is_numeric( $post_id_param ) ? (int) $post_id_param : 0;
			$fields        = (array) $request->get_param( 'fields' );
			$target_locale = is_string( $target_locale_param ) ? $target_locale_param : '';

			$post = get_post( $post_id );

			if ( ! $post instanceof WP_Post ) {
				return new WP_Error(
					'ai_translator_post_not_found',
					__( 'Post not found.', 'robotstxt-ai-translator' ),
					array( 'status' => 404 )
				);
			}

			$installed = $this->translator->get_installed_locales();
			if ( ! in_array( $target_locale, $installed, true ) ) {
				return new WP_Error(
					'ai_translator_invalid_locale',
					__( 'The selected language is not installed on this site.', 'robotstxt-ai-translator' ),
					array( 'status' => 400 )
				);
			}

			$site_settings = $this->settings->get_settings();
			$allowed       = array();

			if ( in_array( 'title', $fields, true ) && ! empty( $site_settings['translate_title'] ) ) {
				$allowed[] = 'title';
			}
			if ( in_array( 'content', $fields, true ) && ! empty( $site_settings['translate_content'] ) ) {
				$allowed[] = 'content';
			}

			if ( empty( $allowed ) ) {
				return new WP_Error(
					'ai_translator_no_fields',
					__( 'No translatable fields were selected, or the requested fields are disabled in the settings.', 'robotstxt-ai-translator' ),
					array( 'status' => 400 )
				);
			}

			$response = array();

			if ( in_array( 'title', $allowed, true ) ) {
				$translated = $this->translator->translate( $post->post_title, $target_locale );
				if ( is_wp_error( $translated ) ) {
					return $this->error_with_status( $translated, 502 );
				}
				$response['title'] = $translated;
			}

			if ( in_array( 'content', $allowed, true ) ) {
				$translated = $this->translator->translate( $post->post_content, $target_locale );
				if ( is_wp_error( $translated ) ) {
					return $this->error_with_status( $translated, 502 );
				}
				$response['content'] = $translated;
			}

			return new WP_REST_Response( $response, 200 );
		}

		/**
		 * Attaches an HTTP status to a WP_Error without overwriting existing data.
		 *
		 * @since 1.0.0
		 *
		 * @param WP_Error $error  The original error.
		 * @param int      $status HTTP status code to add.
		 *
		 * @return WP_Error
		 */
		private function error_with_status( WP_Error $error, $status ) {
			$existing = (array) $error->get_error_data();
			$error->add_data( array_merge( $existing, array( 'status' => (int) $status ) ) );

			return $error;
		}

		/**
		 * Registers the Classic editor metabox.
		 *
		 * @since 1.0.0
		 *
		 * @return void
		 */
		public function register_classic_meta_box() {
			$screen = function_exists( 'get_current_screen' ) ? get_current_screen() : null;

			// The block editor already shows the AI Translator via the PluginSidebar
			// (translation icon in the top-right). Skipping metabox registration there
			// avoids duplicating the UI in the post settings panel.
			if ( $screen && method_exists( $screen, 'is_block_editor' ) && $screen->is_block_editor() ) {
				return;
			}

			$post_types = $this->get_supported_post_types();

			foreach ( $post_types as $post_type ) {
				add_meta_box(
					'ai-translator',
					__( 'AI Translator', 'robotstxt-ai-translator' ),
					array( $this, 'render_classic_meta_box' ),
					$post_type,
					'side',
					'default'
				);
			}
		}

		/**
		 * Renders the Classic editor metabox content.
		 *
		 * @since 1.0.0
		 *
		 * @param WP_Post $post The current post.
		 *
		 * @return void
		 */
		public function render_classic_meta_box( $post ) {
			$languages = $this->get_language_list();
			$settings  = $this->settings->get_settings();

			?>
			<div id="ai-translator-classic" class="ai-translator-classic" data-post-id="<?php echo esc_attr( (string) $post->ID ); ?>">
				<?php if ( ! $this->translator->is_available() ) : ?>
					<p><?php echo esc_html__( 'The WordPress AI plugin is not active. Translation is unavailable.', 'robotstxt-ai-translator' ); ?></p>
				<?php elseif ( empty( $settings['translate_title'] ) && empty( $settings['translate_content'] ) ) : ?>
					<p><?php echo esc_html__( 'No translation fields are enabled in settings.', 'robotstxt-ai-translator' ); ?></p>
				<?php elseif ( empty( $languages ) ) : ?>
					<p><?php echo esc_html__( 'No languages are installed on this site.', 'robotstxt-ai-translator' ); ?></p>
				<?php else : ?>
					<p>
						<label for="ai-translator-locale"><?php echo esc_html__( 'Target language', 'robotstxt-ai-translator' ); ?></label>
						<select id="ai-translator-locale" class="widefat">
							<?php foreach ( $languages as $language ) : ?>
								<option value="<?php echo esc_attr( $language['locale'] ); ?>"><?php echo esc_html( $language['name'] ); ?></option>
							<?php endforeach; ?>
						</select>
					</p>

					<p>
						<button type="button" class="button button-primary" id="ai-translator-classic-button">
							<?php echo esc_html__( 'Translate', 'robotstxt-ai-translator' ); ?>
						</button>
					</p>

					<p class="description">
						<?php echo esc_html__( 'Save the post before translating to ensure the latest content is used. The translation replaces the current title and/or content.', 'robotstxt-ai-translator' ); ?>
					</p>

					<div id="ai-translator-classic-status" class="ai-translator-status" role="status" aria-live="polite"></div>
				<?php endif; ?>
			</div>
			<?php
		}

		/**
		 * Enqueues assets for the Classic editor.
		 *
		 * @since 1.0.0
		 *
		 * @param string $hook Current admin page hook.
		 *
		 * @return void
		 */
		public function enqueue_classic_editor_assets( $hook ) {
			if ( ! in_array( $hook, array( 'post.php', 'post-new.php' ), true ) ) {
				return;
			}

			$screen = function_exists( 'get_current_screen' ) ? get_current_screen() : null;

			if ( $screen && method_exists( $screen, 'is_block_editor' ) && $screen->is_block_editor() ) {
				return;
			}

			$this->enqueue_assets( 'classic' );
		}

		/**
		 * Enqueues assets for the Block editor.
		 *
		 * @since 1.0.0
		 *
		 * @return void
		 */
		public function enqueue_block_editor_assets() {
			$this->enqueue_assets( 'block' );
		}

		/**
		 * Common asset enqueue logic for both editors.
		 *
		 * @since 1.0.0
		 *
		 * @param string $context Either 'classic' or 'block'.
		 *
		 * @return void
		 */
		private function enqueue_assets( $context ) {
			$dependencies = array( 'wp-api-fetch', 'wp-i18n' );

			if ( 'block' === $context ) {
				$dependencies = array_merge(
					$dependencies,
					array(
						'wp-plugins',
						'wp-editor',
						'wp-element',
						'wp-components',
						'wp-data',
						'wp-blocks',
					)
				);
			}

			$asset_ver = AI_TRANSLATOR_VERSION . '.' . (string) filemtime( AI_TRANSLATOR_DIR . 'assets/js/editor.js' );

			wp_register_script(
				'ai-translator-editor',
				AI_TRANSLATOR_URL . 'assets/js/editor.js',
				$dependencies,
				$asset_ver,
				true
			);

			wp_register_style(
				'ai-translator-editor',
				AI_TRANSLATOR_URL . 'assets/css/editor.css',
				array(),
				$asset_ver
			);

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

			$data = array(
				'restNamespace' => AI_TRANSLATOR_REST_NAMESPACE,
				'restRoute'     => '/translate',
				'context'       => $context,
				'postId'        => $post_id,
				'available'     => $this->translator->is_available(),
				'languages'     => $this->get_language_list(),
				'settings'      => array(
					'translateTitle'   => ! empty( $settings['translate_title'] ),
					'translateContent' => ! empty( $settings['translate_content'] ),
				),
				'i18n'          => array(
					'translate'        => __( 'Translate', 'robotstxt-ai-translator' ),
					'translating'      => __( 'Translating…', 'robotstxt-ai-translator' ),
					'targetLanguage'   => __( 'Target language', 'robotstxt-ai-translator' ),
					'panelTitle'       => __( 'AI Translator', 'robotstxt-ai-translator' ),
					'success'          => __( 'Translation applied. Review and save the post.', 'robotstxt-ai-translator' ),
					'genericError'     => __( 'Translation failed.', 'robotstxt-ai-translator' ),
					'noLanguages'      => __( 'No languages are installed on this site.', 'robotstxt-ai-translator' ),
					'noFields'         => __( 'No translation fields are enabled in settings.', 'robotstxt-ai-translator' ),
					'aiUnavailable'    => __( 'The WordPress AI plugin is not active.', 'robotstxt-ai-translator' ),
					'saveBeforeWarn'   => __( 'You have unsaved changes. Save the post before translating to ensure the latest content is used.', 'robotstxt-ai-translator' ),
					'translateTitle'   => __( 'Translate title', 'robotstxt-ai-translator' ),
					'translateContent' => __( 'Translate content', 'robotstxt-ai-translator' ),
				),
			);

			wp_add_inline_script(
				'ai-translator-editor',
				'window.aiTranslatorData = ' . wp_json_encode( $data ) . ';',
				'before'
			);

			wp_enqueue_script( 'ai-translator-editor' );
			wp_enqueue_style( 'ai-translator-editor' );
		}

		/**
		 * Resolves the current post ID when enqueueing assets.
		 *
		 * @since 1.0.0
		 *
		 * @return int Post ID, or 0 when it cannot be determined.
		 */
		private function resolve_current_post_id() {
			$post = get_post();

			if ( $post instanceof WP_Post ) {
				return (int) $post->ID;
			}

			if ( isset( $_GET['post'] ) ) { // phpcs:ignore WordPress.Security.NonceVerification.Recommended
				$post_get = wp_unslash( $_GET['post'] ); // phpcs:ignore WordPress.Security.NonceVerification.Recommended
				return is_scalar( $post_get ) ? absint( $post_get ) : 0;
			}

			return 0;
		}

		/**
		 * Returns the post types where the metabox should appear.
		 *
		 * @since 1.0.0
		 *
		 * @return array<int,string>
		 */
		private function get_supported_post_types() {
			$post_types = get_post_types( array( 'public' => true ), 'names' );

			if ( ! is_array( $post_types ) ) {
				return array();
			}

			unset( $post_types['attachment'] );

			/**
			 * Filters the post types where the AI Translator metabox is registered.
			 *
			 * @since 1.0.0
			 *
			 * @param array<int,string> $post_types List of post type names.
			 */
			return (array) apply_filters( 'ai_translator_supported_post_types', array_values( $post_types ) );
		}

		/**
		 * Returns the list of languages available for translation on this site.
		 *
		 * Includes en_US plus any locales whose .mo files are installed.
		 *
		 * @since 1.0.0
		 *
		 * @return array<int,array{locale:string,name:string}>
		 */
		private function get_language_list() {
			$locales = $this->translator->get_installed_locales();

			if ( ! function_exists( 'wp_get_available_translations' ) ) {
				require_once ABSPATH . 'wp-admin/includes/translation-install.php';
			}

			$translations = function_exists( 'wp_get_available_translations' ) ? wp_get_available_translations() : array();
			$languages    = array();

			foreach ( $locales as $locale ) {
				if ( 'en_US' === $locale ) {
					$name = 'English (United States)';
				} elseif ( isset( $translations[ $locale ]['native_name'] ) && '' !== $translations[ $locale ]['native_name'] ) {
					$name = (string) $translations[ $locale ]['native_name'];
				} elseif ( isset( $translations[ $locale ]['english_name'] ) && '' !== $translations[ $locale ]['english_name'] ) {
					$name = (string) $translations[ $locale ]['english_name'];
				} else {
					$name = $locale;
				}

				$languages[] = array(
					'locale' => $locale,
					'name'   => $name,
				);
			}

			usort(
				$languages,
				static function ( $a, $b ) {
					return strcasecmp( $a['name'], $b['name'] );
				}
			);

			return $languages;
		}
	}
}