<?php
/**
 * Super Ajax Search — Frontend.
 *
 * Handles shortcode, REST API, legacy AJAX, assets, caching, and search logic.
 *
 * @package SuperAjaxSearch
 * @since   2.0.0
 */

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

/**
 * Class Super_Ajax_Search
 */
class Super_Ajax_Search {

	/**
	 * Instance counter for unique wrapper IDs when multiple shortcodes on one page.
	 *
	 * @var int
	 */
	private static int $instance_count = 0;

	/**
	 * Constructor — register all hooks.
	 */
	public function __construct() {
		add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_assets' ) );
		add_action( 'rest_api_init', array( $this, 'register_rest_routes' ) );

		// Legacy AJAX (backward compat with v1.x JS or third-party integrations).
		add_action( 'wp_ajax_super_ajax_search', array( $this, 'handle_ajax_search' ) );
		add_action( 'wp_ajax_nopriv_super_ajax_search', array( $this, 'handle_ajax_search' ) );
		add_action( 'wp_ajax_ajax_searchwp_handle_search', array( $this, 'handle_ajax_search' ) );
		add_action( 'wp_ajax_nopriv_ajax_searchwp_handle_search', array( $this, 'handle_ajax_search' ) );

		add_shortcode( 'super_ajax_search', array( $this, 'render_search_form' ) );

		// Cache invalidation on content changes.
		add_action( 'save_post', array( $this, 'clear_search_cache' ) );
		add_action( 'delete_post', array( $this, 'clear_search_cache' ) );
	}

	/**
	 * Enqueue frontend assets.
	 *
	 * @return void
	 */
	public function enqueue_assets(): void {
		if ( is_admin() ) {
			return;
		}

		wp_enqueue_style(
			'super-ajax-search',
			SUPER_AJAX_SEARCH_URL . 'assets/css/style.css',
			array(),
			SUPER_AJAX_SEARCH_VERSION
		);

		wp_enqueue_script(
			'super-ajax-search',
			SUPER_AJAX_SEARCH_URL . 'assets/js/script.js',
			array(),
			SUPER_AJAX_SEARCH_VERSION,
			true
		);

		wp_localize_script( 'super-ajax-search', 'superAjaxSearch', array(
			'restUrl'       => esc_url_raw( rest_url( 'super-ajax-search/v1/search' ) ),
			'restNonce'     => wp_create_nonce( 'wp_rest' ),
			'noResultsText' => esc_html(
				get_option( 'super_ajax_search_no_results_text', __( 'No results found', 'super-ajax-search' ) )
			),
		) );
	}

	/**
	 * Register REST API route.
	 *
	 * @return void
	 */
	public function register_rest_routes(): void {
		register_rest_route( 'super-ajax-search/v1', '/search', array(
			'methods'             => \WP_REST_Server::READABLE,
			'callback'            => array( $this, 'rest_search_callback' ),
			'permission_callback' => '__return_true',
			'args'                => array(
				's'        => array(
					'required'          => true,
					'type'              => 'string',
					'sanitize_callback' => 'sanitize_text_field',
				),
				'category' => array(
					'required'          => false,
					'type'              => 'integer',
					'default'           => 0,
					'sanitize_callback' => 'absint',
				),
			),
		) );
	}

	/**
	 * REST search callback.
	 *
	 * @param \WP_REST_Request $request Request object.
	 * @return \WP_REST_Response
	 */
	public function rest_search_callback( \WP_REST_Request $request ): \WP_REST_Response {
		$query    = $request->get_param( 's' );
		$category = (int) $request->get_param( 'category' );
		$result   = $this->perform_search( $query, $category );

		if ( is_wp_error( $result ) ) {
			return new \WP_REST_Response( array( 'message' => $result->get_error_message() ), 400 );
		}

		return new \WP_REST_Response( $result, 200 );
	}

	/**
	 * Legacy AJAX handler.
	 *
	 * @return void
	 */
	public function handle_ajax_search(): void {
		check_ajax_referer( 'super_ajax_search_nonce', 'nonce' );

		$query    = isset( $_POST['query'] ) ? sanitize_text_field( wp_unslash( $_POST['query'] ) ) : '';
		$category = isset( $_POST['category'] ) ? absint( $_POST['category'] ) : 0;
		$result   = $this->perform_search( $query, $category );

		if ( is_wp_error( $result ) ) {
			wp_send_json_error( array( 'message' => $result->get_error_message() ) );
		}

		wp_send_json_success( $result );
	}

	/**
	 * Core search logic — shared by REST and AJAX.
	 *
	 * @param string $query    Search string.
	 * @param int    $category Optional category ID.
	 * @return array|\WP_Error
	 */
	private function perform_search( string $query, int $category = 0 ): array|\WP_Error {
		$query = trim( $query );

		if ( empty( $query ) || mb_strlen( $query ) < 2 ) {
			return new \WP_Error(
				'query_too_short',
				__( 'Please enter at least 2 characters.', 'super-ajax-search' )
			);
		}

		// Transient cache.
		$cache_ttl = absint( get_option( 'super_ajax_search_cache_duration', 3600 ) );
		$cache_key = 'sas_' . md5( $query . '|' . $category );

		if ( $cache_ttl > 0 ) {
			$cached = get_transient( $cache_key );
			if ( false !== $cached ) {
				return $cached;
			}
		}

		// Settings.
		$post_types     = get_option( 'super_ajax_search_post_types', array( 'post' ) );
		$post_types     = is_array( $post_types ) && ! empty( $post_types ) ? $post_types : array( 'post' );
		$limit          = absint( get_option( 'super_ajax_search_limit', 5 ) );
		$show_thumbnail = '1' === get_option( 'super_ajax_search_show_thumbnail', '1' );
		$show_excerpt   = '1' === get_option( 'super_ajax_search_show_excerpt', '1' );
		$group_by       = sanitize_key( get_option( 'super_ajax_search_group_by', 'none' ) );

		$args = array(
			's'              => $query,
			'post_type'      => array_map( 'sanitize_key', $post_types ),
			'posts_per_page' => min( $limit, 50 ),
			'post_status'    => 'publish',
			'no_found_rows'  => true,
		);

		if ( $category > 0 ) {
			$args['cat'] = $category;
		}

		$wp_query = new \WP_Query( $args );
		$items    = array();

		if ( $wp_query->have_posts() ) {
			while ( $wp_query->have_posts() ) {
				$wp_query->the_post();
				$post_id  = get_the_ID();
				$type_obj = get_post_type_object( get_post_type() );

				$item = array(
					'title'          => esc_html( get_the_title() ),
					'url'            => esc_url( get_permalink() ),
					'post_type'      => get_post_type(),
					'post_type_label' => $type_obj ? esc_html( $type_obj->labels->singular_name ) : get_post_type(),
				);

				if ( $show_thumbnail ) {
					$thumb              = get_the_post_thumbnail_url( $post_id, 'thumbnail' );
					$item['thumbnail'] = $thumb ? esc_url( $thumb ) : '';
				}

				if ( $show_excerpt ) {
					$item['excerpt'] = $this->build_smart_excerpt( get_the_content( '', false ), $query );
				}

				if ( 'category' === $group_by ) {
					$cats              = get_the_category( $post_id );
					$item['category'] = ! empty( $cats ) ? esc_html( $cats[0]->name ) : esc_html__( 'Uncategorized', 'super-ajax-search' );
				}

				$items[] = $item;
			}
		}

		wp_reset_postdata();

		$grouped = $this->group_results( $items, $group_by );

		if ( $cache_ttl > 0 ) {
			set_transient( $cache_key, $grouped, $cache_ttl );
		}

		return $grouped;
	}

	/**
	 * Build a short excerpt with the search keyword highlighted in bold.
	 *
	 * @param string $content Raw post content.
	 * @param string $keyword Search keyword.
	 * @param int    $length  Max excerpt length.
	 * @return string Safe HTML with <strong> highlights.
	 */
	private function build_smart_excerpt( string $content, string $keyword, int $length = 140 ): string {
		$content = wp_strip_all_tags( strip_shortcodes( $content ) );

		if ( empty( $content ) ) {
			return '';
		}

		$pos = mb_stripos( $content, $keyword );

		if ( false !== $pos ) {
			$start   = max( 0, $pos - 50 );
			$excerpt = mb_substr( $content, $start, $length );
			if ( $start > 0 ) {
				$excerpt = '…' . $excerpt;
			}
		} else {
			$excerpt = mb_substr( $content, 0, $length );
		}

		$excerpt = trim( $excerpt );

		if ( mb_strlen( $content ) > $length ) {
			$excerpt .= '…';
		}

		// Escape first, THEN highlight — prevents XSS while allowing <strong>.
		$safe = esc_html( $excerpt );

		return preg_replace(
			'/(' . preg_quote( esc_html( $keyword ), '/' ) . ')/iu',
			'<strong>$1</strong>',
			$safe
		);
	}

	/**
	 * Group items by post_type or category.
	 *
	 * @param array  $items    Flat result items.
	 * @param string $group_by 'none', 'post_type', or 'category'.
	 * @return array
	 */
	private function group_results( array $items, string $group_by ): array {
		if ( 'none' === $group_by || empty( $items ) ) {
			return array( 'groups' => array( array( 'label' => '', 'items' => $items ) ) );
		}

		$key     = ( 'post_type' === $group_by ) ? 'post_type_label' : 'category';
		$buckets = array();

		foreach ( $items as $item ) {
			$label = $item[ $key ] ?? __( 'Other', 'super-ajax-search' );
			$buckets[ $label ][] = $item;
		}

		$groups = array();
		foreach ( $buckets as $label => $bucket ) {
			$groups[] = array( 'label' => $label, 'items' => $bucket );
		}

		return array( 'groups' => $groups );
	}

	/**
	 * Render the [super_ajax_search] shortcode.
	 *
	 * @param array|string $atts Shortcode attributes.
	 * @return string
	 */
	public function render_search_form( $atts = array() ): string {
		$atts = shortcode_atts(
			array(
				'category_filter' => get_option( 'super_ajax_search_enable_category_filter', '0' ),
				'placeholder'     => get_option( 'super_ajax_search_placeholder', __( 'Search here…', 'super-ajax-search' ) ),
			),
			$atts,
			'super_ajax_search'
		);

		self::$instance_count++;
		$show_filter = in_array( $atts['category_filter'], array( '1', 'true', 'yes' ), true );

		ob_start();
		?>
		<div class="super-ajax-search-wrapper" data-instance="<?php echo esc_attr( self::$instance_count ); ?>">
			<form class="sas-form" role="search" aria-label="<?php esc_attr_e( 'Site search', 'super-ajax-search' ); ?>">
				<?php if ( $show_filter ) : ?>
					<select class="sas-category-filter" aria-label="<?php esc_attr_e( 'Filter by category', 'super-ajax-search' ); ?>">
						<option value=""><?php esc_html_e( 'All Categories', 'super-ajax-search' ); ?></option>
						<?php
						foreach ( get_categories( array( 'hide_empty' => true ) ) as $cat ) {
							printf( '<option value="%d">%s</option>', absint( $cat->term_id ), esc_html( $cat->name ) );
						}
						?>
					</select>
				<?php endif; ?>
				<div class="sas-input-group">
					<input
						type="search"
						class="sas-search-input"
						placeholder="<?php echo esc_attr( $atts['placeholder'] ); ?>"
						autocomplete="off"
						aria-label="<?php esc_attr_e( 'Search', 'super-ajax-search' ); ?>"
					/>
					<button type="submit" class="sas-search-button" aria-label="<?php esc_attr_e( 'Search', 'super-ajax-search' ); ?>">
						<svg xmlns="http://www.w3.org/2000/svg" width="20" height="20" viewBox="0 0 24 24" fill="none"
							stroke="currentColor" stroke-width="2" stroke-linecap="round" stroke-linejoin="round" aria-hidden="true">
							<circle cx="11" cy="11" r="8"></circle>
							<line x1="21" y1="21" x2="16.65" y2="16.65"></line>
						</svg>
					</button>
				</div>
				<div class="sas-spinner" aria-hidden="true"></div>
			</form>
			<div class="sas-results" role="listbox" aria-label="<?php esc_attr_e( 'Search results', 'super-ajax-search' ); ?>"></div>
		</div>
		<?php
		return ob_get_clean();
	}

	/**
	 * Delete all search transients when posts change.
	 *
	 * @return void
	 */
	public function clear_search_cache(): void {
		global $wpdb;

		$like_t = $wpdb->esc_like( '_transient_sas_' ) . '%';
		$like_o = $wpdb->esc_like( '_transient_timeout_sas_' ) . '%';

		$wpdb->query(
			$wpdb->prepare(
				"DELETE FROM {$wpdb->options} WHERE option_name LIKE %s OR option_name LIKE %s",
				$like_t,
				$like_o
			)
		);
	}
}