<?php
/**
 * Prometheus Integration.
 *
 * @package WP_FediStream
 */

namespace WP_FediStream\Prometheus;

// Prevent direct file access.
if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Main Prometheus integration class.
 *
 * Exposes FediStream metrics for Prometheus monitoring via the
 * wp_prometheus_collect_metrics action hook.
 */
class Integration {

	/**
	 * Whether WP Prometheus is active.
	 *
	 * @var bool
	 */
	private bool $prometheus_active = false;

	/**
	 * Constructor.
	 */
	public function __construct() {
		// Check WP Prometheus immediately since we're instantiated during plugins_loaded.
		$this->check_prometheus();

		// If plugins_loaded hasn't fully completed, hook init at priority 20.
		// Otherwise, run init directly.
		if ( ! did_action( 'plugins_loaded' ) || doing_action( 'plugins_loaded' ) ) {
			add_action( 'plugins_loaded', array( $this, 'init' ), 20 );
		} else {
			$this->init();
		}
	}

	/**
	 * Check if WP Prometheus is active.
	 *
	 * @return void
	 */
	public function check_prometheus(): void {
		$this->prometheus_active = defined( 'WP_PROMETHEUS_VERSION' )
			|| class_exists( 'WP_Prometheus\Plugin' );
	}

	/**
	 * Initialize Prometheus integration.
	 *
	 * @return void
	 */
	public function init(): void {
		if ( ! $this->prometheus_active ) {
			return;
		}

		// Register metrics collector.
		add_action( 'wp_prometheus_collect_metrics', array( $this, 'collect_metrics' ) );
	}

	/**
	 * Check if Prometheus is active.
	 *
	 * @return bool
	 */
	public function is_active(): bool {
		return $this->prometheus_active;
	}

	/**
	 * Collect FediStream metrics.
	 *
	 * @param object $collector The Prometheus collector.
	 * @return void
	 */
	public function collect_metrics( $collector ): void {
		// Register and collect all metric categories.
		$this->collect_content_metrics( $collector );
		$this->collect_engagement_metrics( $collector );
		$this->collect_user_metrics( $collector );

		if ( $this->is_woocommerce_enabled() ) {
			$this->collect_woocommerce_metrics( $collector );
		}

		if ( $this->is_activitypub_enabled() ) {
			$this->collect_activitypub_metrics( $collector );
		}
	}

	/**
	 * Collect content metrics.
	 *
	 * @param object $collector The Prometheus collector.
	 * @return void
	 */
	private function collect_content_metrics( $collector ): void {
		// Content count by type and status.
		$content_gauge = $collector->register_gauge(
			'fedistream_content_total',
			'Total FediStream content count',
			array( 'type', 'status' )
		);

		$post_types = array(
			'fedistream_artist',
			'fedistream_album',
			'fedistream_track',
			'fedistream_playlist',
		);

		foreach ( $post_types as $post_type ) {
			$type_label = str_replace( 'fedistream_', '', $post_type );
			$counts     = wp_count_posts( $post_type );

			foreach ( array( 'publish', 'draft', 'pending' ) as $status ) {
				$count = isset( $counts->$status ) ? (int) $counts->$status : 0;
				$content_gauge->set( $count, array( $type_label, $status ) );
			}
		}

		// Genre count.
		$genres_gauge = $collector->register_gauge(
			'fedistream_genres_total',
			'Total number of genres',
			array()
		);
		$genre_count  = wp_count_terms( array( 'taxonomy' => 'fedistream_genre' ) );
		$genres_gauge->set( is_wp_error( $genre_count ) ? 0 : (int) $genre_count, array() );

		// Mood count.
		$moods_gauge = $collector->register_gauge(
			'fedistream_moods_total',
			'Total number of moods',
			array()
		);
		$mood_count  = wp_count_terms( array( 'taxonomy' => 'fedistream_mood' ) );
		$moods_gauge->set( is_wp_error( $mood_count ) ? 0 : (int) $mood_count, array() );
	}

	/**
	 * Collect engagement metrics.
	 *
	 * @param object $collector The Prometheus collector.
	 * @return void
	 */
	private function collect_engagement_metrics( $collector ): void {
		global $wpdb;

		$plays_table     = $wpdb->prefix . 'fedistream_plays';
		$favorites_table = $wpdb->prefix . 'fedistream_favorites';
		$follows_table   = $wpdb->prefix . 'fedistream_user_follows';
		$history_table   = $wpdb->prefix . 'fedistream_listening_history';

		// Total plays.
		$plays_gauge = $collector->register_gauge(
			'fedistream_plays_total',
			'Total track plays',
			array()
		);
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
		$total_plays = (int) $wpdb->get_var( "SELECT COUNT(*) FROM {$plays_table}" );
		$plays_gauge->set( $total_plays, array() );

		// Plays today.
		$plays_today_gauge = $collector->register_gauge(
			'fedistream_plays_today',
			'Track plays today',
			array()
		);
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
		$plays_today = (int) $wpdb->get_var(
			"SELECT COUNT(*) FROM {$plays_table} WHERE DATE(played_at) = CURDATE()"
		);
		$plays_today_gauge->set( $plays_today, array() );

		// Favorites by type.
		$favorites_gauge = $collector->register_gauge(
			'fedistream_favorites_total',
			'Total favorites by content type',
			array( 'type' )
		);
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
		$favorites_by_type = $wpdb->get_results(
			"SELECT content_type, COUNT(*) as count FROM {$favorites_table} GROUP BY content_type"
		);
		foreach ( $favorites_by_type as $row ) {
			$favorites_gauge->set( (int) $row->count, array( $row->content_type ) );
		}

		// Local follows.
		$follows_gauge = $collector->register_gauge(
			'fedistream_local_follows_total',
			'Total local artist follows',
			array()
		);
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
		$total_follows = (int) $wpdb->get_var( "SELECT COUNT(*) FROM {$follows_table}" );
		$follows_gauge->set( $total_follows, array() );

		// Listening history entries.
		$history_gauge = $collector->register_gauge(
			'fedistream_listening_history_entries',
			'Total listening history entries',
			array()
		);
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
		$history_count = (int) $wpdb->get_var( "SELECT COUNT(*) FROM {$history_table}" );
		$history_gauge->set( $history_count, array() );
	}

	/**
	 * Collect user metrics.
	 *
	 * @param object $collector The Prometheus collector.
	 * @return void
	 */
	private function collect_user_metrics( $collector ): void {
		global $wpdb;

		$favorites_table     = $wpdb->prefix . 'fedistream_favorites';
		$follows_table       = $wpdb->prefix . 'fedistream_user_follows';
		$notifications_table = $wpdb->prefix . 'fedistream_notifications';

		// Users with library (favorites).
		$users_library_gauge = $collector->register_gauge(
			'fedistream_users_with_library',
			'Users who have favorites',
			array()
		);
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
		$users_with_library = (int) $wpdb->get_var(
			"SELECT COUNT(DISTINCT user_id) FROM {$favorites_table}"
		);
		$users_library_gauge->set( $users_with_library, array() );

		// Users following artists.
		$users_following_gauge = $collector->register_gauge(
			'fedistream_users_following_artists',
			'Users following at least one artist',
			array()
		);
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
		$users_following = (int) $wpdb->get_var(
			"SELECT COUNT(DISTINCT user_id) FROM {$follows_table}"
		);
		$users_following_gauge->set( $users_following, array() );

		// Notifications by type and status.
		$notifications_gauge = $collector->register_gauge(
			'fedistream_notifications_total',
			'Notifications by type and status',
			array( 'type', 'status' )
		);
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
		$notifications = $wpdb->get_results(
			"SELECT type, is_read, COUNT(*) as count FROM {$notifications_table} GROUP BY type, is_read"
		);
		foreach ( $notifications as $row ) {
			$status = $row->is_read ? 'read' : 'unread';
			$notifications_gauge->set( (int) $row->count, array( $row->type, $status ) );
		}

		// Pending notifications (simple gauge).
		$pending_gauge = $collector->register_gauge(
			'fedistream_notifications_pending',
			'Total unread notifications',
			array()
		);
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
		$pending = (int) $wpdb->get_var(
			"SELECT COUNT(*) FROM {$notifications_table} WHERE is_read = 0"
		);
		$pending_gauge->set( $pending, array() );
	}

	/**
	 * Collect WooCommerce metrics.
	 *
	 * @param object $collector The Prometheus collector.
	 * @return void
	 */
	private function collect_woocommerce_metrics( $collector ): void {
		global $wpdb;

		$purchases_table = $wpdb->prefix . 'fedistream_purchases';

		// Purchases by type.
		$purchases_gauge = $collector->register_gauge(
			'fedistream_purchases_total',
			'Total purchases by content type',
			array( 'type' )
		);
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
		$purchases = $wpdb->get_results(
			"SELECT content_type, COUNT(*) as count FROM {$purchases_table} GROUP BY content_type"
		);
		foreach ( $purchases as $row ) {
			$purchases_gauge->set( (int) $row->count, array( $row->content_type ) );
		}

		// Unique customers.
		$customers_gauge = $collector->register_gauge(
			'fedistream_customers_total',
			'Unique customers with purchases',
			array()
		);
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
		$customers = (int) $wpdb->get_var(
			"SELECT COUNT(DISTINCT user_id) FROM {$purchases_table}"
		);
		$customers_gauge->set( $customers, array() );

		// WooCommerce products count (FediStream types).
		if ( function_exists( 'wc_get_products' ) ) {
			$products_gauge = $collector->register_gauge(
				'fedistream_products_total',
				'FediStream products in WooCommerce',
				array( 'type' )
			);

			foreach ( array( 'fedistream_album', 'fedistream_track' ) as $type ) {
				$products = wc_get_products(
					array(
						'type'   => $type,
						'limit'  => -1,
						'return' => 'ids',
					)
				);
				$products_gauge->set( count( $products ), array( $type ) );
			}
		}
	}

	/**
	 * Collect ActivityPub metrics.
	 *
	 * @param object $collector The Prometheus collector.
	 * @return void
	 */
	private function collect_activitypub_metrics( $collector ): void {
		global $wpdb;

		$followers_table = $wpdb->prefix . 'fedistream_followers';
		$reactions_table = $wpdb->prefix . 'fedistream_reactions';

		// Total ActivityPub followers.
		$followers_gauge = $collector->register_gauge(
			'fedistream_activitypub_followers_total',
			'Total ActivityPub followers across all artists',
			array()
		);
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
		$total_followers = (int) $wpdb->get_var( "SELECT COUNT(*) FROM {$followers_table}" );
		$followers_gauge->set( $total_followers, array() );

		// Followers by artist (top 10 to avoid cardinality explosion).
		$followers_by_artist_gauge = $collector->register_gauge(
			'fedistream_activitypub_followers_by_artist',
			'Followers per artist',
			array( 'artist_id', 'artist_name' )
		);
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
		$followers_by_artist = $wpdb->get_results(
			"SELECT artist_id, COUNT(*) as count FROM {$followers_table} GROUP BY artist_id ORDER BY count DESC LIMIT 10"
		);
		foreach ( $followers_by_artist as $row ) {
			$artist      = get_post( $row->artist_id );
			$artist_name = $artist ? $artist->post_title : 'Unknown';
			$followers_by_artist_gauge->set( (int) $row->count, array( $row->artist_id, $artist_name ) );
		}

		// Reactions by type (if table exists).
		// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
		$table_exists = $wpdb->get_var(
			$wpdb->prepare( 'SHOW TABLES LIKE %s', $reactions_table )
		);

		if ( $table_exists ) {
			$reactions_gauge = $collector->register_gauge(
				'fedistream_activitypub_reactions_total',
				'Fediverse reactions by type',
				array( 'type' )
			);
			// phpcs:ignore WordPress.DB.DirectDatabaseQuery.DirectQuery,WordPress.DB.DirectDatabaseQuery.NoCaching
			$reactions = $wpdb->get_results(
				"SELECT reaction_type, COUNT(*) as count FROM {$reactions_table} GROUP BY reaction_type"
			);
			foreach ( $reactions as $row ) {
				$reactions_gauge->set( (int) $row->count, array( $row->reaction_type ) );
			}
		}
	}

	/**
	 * Check if WooCommerce integration is enabled.
	 *
	 * @return bool
	 */
	private function is_woocommerce_enabled(): bool {
		return get_option( 'wp_fedistream_enable_woocommerce', 0 )
			&& class_exists( 'WooCommerce' );
	}

	/**
	 * Check if ActivityPub integration is enabled.
	 *
	 * @return bool
	 */
	private function is_activitypub_enabled(): bool {
		return (bool) get_option( 'wp_fedistream_enable_activitypub', 1 );
	}
}