<?php
/**
 * User Notifications class.
 *
 * @package WP_FediStream
 */

namespace WP_FediStream\User;

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

/**
 * Handles user notifications (in-app and email).
 */
class Notifications {

	/**
	 * Notification types.
	 */
	const TYPE_NEW_RELEASE      = 'new_release';
	const TYPE_NEW_FOLLOWER     = 'new_follower';
	const TYPE_FEDIVERSE_LIKE   = 'fediverse_like';
	const TYPE_FEDIVERSE_BOOST  = 'fediverse_boost';
	const TYPE_PLAYLIST_ADDED   = 'playlist_added';
	const TYPE_PURCHASE         = 'purchase';
	const TYPE_SYSTEM           = 'system';

	/**
	 * Constructor.
	 */
	public function __construct() {
		// AJAX handlers.
		add_action( 'wp_ajax_fedistream_get_notifications', array( $this, 'ajax_get_notifications' ) );
		add_action( 'wp_ajax_fedistream_mark_notification_read', array( $this, 'ajax_mark_read' ) );
		add_action( 'wp_ajax_fedistream_mark_all_notifications_read', array( $this, 'ajax_mark_all_read' ) );
		add_action( 'wp_ajax_fedistream_delete_notification', array( $this, 'ajax_delete' ) );

		// Notification triggers.
		add_action( 'fedistream_album_published', array( $this, 'notify_new_release' ), 10, 1 );
		add_action( 'fedistream_track_published', array( $this, 'notify_new_track' ), 10, 1 );
		add_action( 'fedistream_artist_followed', array( $this, 'notify_artist_followed' ), 10, 2 );
		add_action( 'fedistream_activitypub_like_received', array( $this, 'notify_fediverse_like' ), 10, 2 );
		add_action( 'fedistream_activitypub_announce_received', array( $this, 'notify_fediverse_boost' ), 10, 2 );

		// Email notifications.
		add_action( 'fedistream_notification_created', array( $this, 'maybe_send_email' ), 10, 2 );

		// Admin bar notification count.
		add_action( 'admin_bar_menu', array( $this, 'add_notification_indicator' ), 100 );

		// Enqueue scripts.
		add_action( 'wp_enqueue_scripts', array( $this, 'enqueue_scripts' ) );
	}

	/**
	 * Enqueue notification scripts.
	 *
	 * @return void
	 */
	public function enqueue_scripts(): void {
		if ( ! is_user_logged_in() ) {
			return;
		}

		wp_enqueue_script(
			'fedistream-notifications',
			WP_FEDISTREAM_URL . 'assets/js/notifications.js',
			array( 'jquery' ),
			WP_FEDISTREAM_VERSION,
			true
		);

		wp_localize_script(
			'fedistream-notifications',
			'fedistreamNotifications',
			array(
				'ajaxUrl'      => admin_url( 'admin-ajax.php' ),
				'nonce'        => wp_create_nonce( 'fedistream_notifications' ),
				'pollInterval' => 60000, // 1 minute.
				'i18n'         => array(
					'noNotifications' => __( 'No notifications', 'wp-fedistream' ),
					'markAllRead'     => __( 'Mark all as read', 'wp-fedistream' ),
					'viewAll'         => __( 'View all notifications', 'wp-fedistream' ),
					'justNow'         => __( 'Just now', 'wp-fedistream' ),
					'error'           => __( 'An error occurred.', 'wp-fedistream' ),
				),
			)
		);
	}

	/**
	 * Create a notification.
	 *
	 * @param int    $user_id User ID.
	 * @param string $type    Notification type.
	 * @param string $title   Notification title.
	 * @param string $message Notification message.
	 * @param array  $data    Additional data.
	 * @return int|false Notification ID or false on failure.
	 */
	public static function create( int $user_id, string $type, string $title, string $message, array $data = array() ) {
		global $wpdb;

		$table = $wpdb->prefix . 'fedistream_notifications';

		$result = $wpdb->insert(
			$table,
			array(
				'user_id'    => $user_id,
				'type'       => $type,
				'title'      => $title,
				'message'    => $message,
				'data'       => wp_json_encode( $data ),
				'is_read'    => 0,
				'created_at' => current_time( 'mysql' ),
			),
			array( '%d', '%s', '%s', '%s', '%s', '%d', '%s' )
		);

		if ( $result ) {
			$notification_id = $wpdb->insert_id;

			/**
			 * Fires when a notification is created.
			 *
			 * @param int   $notification_id Notification ID.
			 * @param array $notification    Notification data.
			 */
			do_action(
				'fedistream_notification_created',
				$notification_id,
				array(
					'user_id' => $user_id,
					'type'    => $type,
					'title'   => $title,
					'message' => $message,
					'data'    => $data,
				)
			);

			return $notification_id;
		}

		return false;
	}

	/**
	 * Get notifications for a user.
	 *
	 * @param int  $user_id   User ID.
	 * @param bool $unread_only Only get unread notifications.
	 * @param int  $limit     Number of notifications to retrieve.
	 * @param int  $offset    Offset for pagination.
	 * @return array
	 */
	public static function get_for_user( int $user_id, bool $unread_only = false, int $limit = 20, int $offset = 0 ): array {
		global $wpdb;

		$table = $wpdb->prefix . 'fedistream_notifications';
		$where = 'WHERE user_id = %d';
		$params = array( $user_id );

		if ( $unread_only ) {
			$where   .= ' AND is_read = 0';
		}

		$params[] = $limit;
		$params[] = $offset;

		$notifications = $wpdb->get_results(
			$wpdb->prepare(
				"SELECT * FROM {$table} {$where} ORDER BY created_at DESC LIMIT %d OFFSET %d",
				...$params
			)
		);

		$result = array();

		foreach ( $notifications as $notification ) {
			$result[] = array(
				'id'         => (int) $notification->id,
				'type'       => $notification->type,
				'title'      => $notification->title,
				'message'    => $notification->message,
				'data'       => json_decode( $notification->data, true ) ?: array(),
				'is_read'    => (bool) $notification->is_read,
				'created_at' => $notification->created_at,
				'read_at'    => $notification->read_at,
			);
		}

		return $result;
	}

	/**
	 * Get unread count for a user.
	 *
	 * @param int $user_id User ID.
	 * @return int
	 */
	public static function get_unread_count( int $user_id ): int {
		global $wpdb;

		$table = $wpdb->prefix . 'fedistream_notifications';

		$count = $wpdb->get_var(
			$wpdb->prepare(
				"SELECT COUNT(*) FROM {$table} WHERE user_id = %d AND is_read = 0",
				$user_id
			)
		);

		return (int) $count;
	}

	/**
	 * Mark a notification as read.
	 *
	 * @param int $notification_id Notification ID.
	 * @param int $user_id         User ID (for verification).
	 * @return bool
	 */
	public static function mark_read( int $notification_id, int $user_id ): bool {
		global $wpdb;

		$table = $wpdb->prefix . 'fedistream_notifications';

		$result = $wpdb->update(
			$table,
			array(
				'is_read' => 1,
				'read_at' => current_time( 'mysql' ),
			),
			array(
				'id'      => $notification_id,
				'user_id' => $user_id,
			),
			array( '%d', '%s' ),
			array( '%d', '%d' )
		);

		return false !== $result;
	}

	/**
	 * Mark all notifications as read for a user.
	 *
	 * @param int $user_id User ID.
	 * @return bool
	 */
	public static function mark_all_read( int $user_id ): bool {
		global $wpdb;

		$table = $wpdb->prefix . 'fedistream_notifications';

		$result = $wpdb->update(
			$table,
			array(
				'is_read' => 1,
				'read_at' => current_time( 'mysql' ),
			),
			array(
				'user_id' => $user_id,
				'is_read' => 0,
			),
			array( '%d', '%s' ),
			array( '%d', '%d' )
		);

		return false !== $result;
	}

	/**
	 * Delete a notification.
	 *
	 * @param int $notification_id Notification ID.
	 * @param int $user_id         User ID (for verification).
	 * @return bool
	 */
	public static function delete( int $notification_id, int $user_id ): bool {
		global $wpdb;

		$table = $wpdb->prefix . 'fedistream_notifications';

		$result = $wpdb->delete(
			$table,
			array(
				'id'      => $notification_id,
				'user_id' => $user_id,
			),
			array( '%d', '%d' )
		);

		return (bool) $result;
	}

	/**
	 * AJAX: Get notifications.
	 *
	 * @return void
	 */
	public function ajax_get_notifications(): void {
		check_ajax_referer( 'fedistream_notifications', 'nonce' );

		if ( ! is_user_logged_in() ) {
			wp_send_json_error( array( 'message' => __( 'Not logged in.', 'wp-fedistream' ) ) );
		}

		$user_id     = get_current_user_id();
		$unread_only = isset( $_POST['unread_only'] ) && $_POST['unread_only'];
		$limit       = isset( $_POST['limit'] ) ? absint( $_POST['limit'] ) : 20;
		$offset      = isset( $_POST['offset'] ) ? absint( $_POST['offset'] ) : 0;

		$notifications = self::get_for_user( $user_id, $unread_only, $limit, $offset );
		$unread_count  = self::get_unread_count( $user_id );

		wp_send_json_success(
			array(
				'notifications' => $notifications,
				'unread_count'  => $unread_count,
			)
		);
	}

	/**
	 * AJAX: Mark notification as read.
	 *
	 * @return void
	 */
	public function ajax_mark_read(): void {
		check_ajax_referer( 'fedistream_notifications', 'nonce' );

		if ( ! is_user_logged_in() ) {
			wp_send_json_error( array( 'message' => __( 'Not logged in.', 'wp-fedistream' ) ) );
		}

		$notification_id = isset( $_POST['notification_id'] ) ? absint( $_POST['notification_id'] ) : 0;

		if ( ! $notification_id ) {
			wp_send_json_error( array( 'message' => __( 'Invalid notification.', 'wp-fedistream' ) ) );
		}

		$user_id = get_current_user_id();
		$result  = self::mark_read( $notification_id, $user_id );

		if ( $result ) {
			wp_send_json_success(
				array(
					'unread_count' => self::get_unread_count( $user_id ),
				)
			);
		} else {
			wp_send_json_error( array( 'message' => __( 'Failed to update notification.', 'wp-fedistream' ) ) );
		}
	}

	/**
	 * AJAX: Mark all notifications as read.
	 *
	 * @return void
	 */
	public function ajax_mark_all_read(): void {
		check_ajax_referer( 'fedistream_notifications', 'nonce' );

		if ( ! is_user_logged_in() ) {
			wp_send_json_error( array( 'message' => __( 'Not logged in.', 'wp-fedistream' ) ) );
		}

		$user_id = get_current_user_id();
		$result  = self::mark_all_read( $user_id );

		if ( $result ) {
			wp_send_json_success( array( 'unread_count' => 0 ) );
		} else {
			wp_send_json_error( array( 'message' => __( 'Failed to update notifications.', 'wp-fedistream' ) ) );
		}
	}

	/**
	 * AJAX: Delete notification.
	 *
	 * @return void
	 */
	public function ajax_delete(): void {
		check_ajax_referer( 'fedistream_notifications', 'nonce' );

		if ( ! is_user_logged_in() ) {
			wp_send_json_error( array( 'message' => __( 'Not logged in.', 'wp-fedistream' ) ) );
		}

		$notification_id = isset( $_POST['notification_id'] ) ? absint( $_POST['notification_id'] ) : 0;

		if ( ! $notification_id ) {
			wp_send_json_error( array( 'message' => __( 'Invalid notification.', 'wp-fedistream' ) ) );
		}

		$user_id = get_current_user_id();
		$result  = self::delete( $notification_id, $user_id );

		if ( $result ) {
			wp_send_json_success(
				array(
					'unread_count' => self::get_unread_count( $user_id ),
				)
			);
		} else {
			wp_send_json_error( array( 'message' => __( 'Failed to delete notification.', 'wp-fedistream' ) ) );
		}
	}

	/**
	 * Notify followers of a new album release.
	 *
	 * @param int $album_id Album post ID.
	 * @return void
	 */
	public function notify_new_release( int $album_id ): void {
		$album = get_post( $album_id );
		if ( ! $album ) {
			return;
		}

		$artist_id = get_post_meta( $album_id, '_fedistream_album_artist', true );
		if ( ! $artist_id ) {
			return;
		}

		$artist = get_post( $artist_id );
		if ( ! $artist ) {
			return;
		}

		// Get all local followers of this artist.
		$followers = $this->get_artist_local_followers( $artist_id );

		foreach ( $followers as $user_id ) {
			self::create(
				$user_id,
				self::TYPE_NEW_RELEASE,
				sprintf(
					/* translators: %s: artist name */
					__( 'New release from %s', 'wp-fedistream' ),
					$artist->post_title
				),
				sprintf(
					/* translators: 1: artist name, 2: album title */
					__( '%1$s released a new album: %2$s', 'wp-fedistream' ),
					$artist->post_title,
					$album->post_title
				),
				array(
					'album_id'   => $album_id,
					'artist_id'  => $artist_id,
					'album_url'  => get_permalink( $album ),
					'artist_url' => get_permalink( $artist ),
					'thumbnail'  => get_the_post_thumbnail_url( $album, 'thumbnail' ),
				)
			);
		}
	}

	/**
	 * Notify followers of a new track.
	 *
	 * @param int $track_id Track post ID.
	 * @return void
	 */
	public function notify_new_track( int $track_id ): void {
		$track = get_post( $track_id );
		if ( ! $track ) {
			return;
		}

		// Get artist from track or album.
		$artist_ids = get_post_meta( $track_id, '_fedistream_artist_ids', true );
		if ( empty( $artist_ids ) ) {
			$album_id   = get_post_meta( $track_id, '_fedistream_album_id', true );
			$artist_id  = $album_id ? get_post_meta( $album_id, '_fedistream_album_artist', true ) : 0;
			$artist_ids = $artist_id ? array( $artist_id ) : array();
		}

		if ( empty( $artist_ids ) ) {
			return;
		}

		$artist_id = $artist_ids[0];
		$artist    = get_post( $artist_id );
		if ( ! $artist ) {
			return;
		}

		// Only notify for single releases (tracks without album).
		$album_id = get_post_meta( $track_id, '_fedistream_album_id', true );
		if ( $album_id ) {
			return; // Album release handles notification.
		}

		$followers = $this->get_artist_local_followers( $artist_id );

		foreach ( $followers as $user_id ) {
			self::create(
				$user_id,
				self::TYPE_NEW_RELEASE,
				sprintf(
					/* translators: %s: artist name */
					__( 'New track from %s', 'wp-fedistream' ),
					$artist->post_title
				),
				sprintf(
					/* translators: 1: artist name, 2: track title */
					__( '%1$s released a new track: %2$s', 'wp-fedistream' ),
					$artist->post_title,
					$track->post_title
				),
				array(
					'track_id'   => $track_id,
					'artist_id'  => $artist_id,
					'track_url'  => get_permalink( $track ),
					'artist_url' => get_permalink( $artist ),
				)
			);
		}
	}

	/**
	 * Notify artist when they get a new local follower.
	 *
	 * @param int $user_id   User ID who followed.
	 * @param int $artist_id Artist post ID.
	 * @return void
	 */
	public function notify_artist_followed( int $user_id, int $artist_id ): void {
		$artist = get_post( $artist_id );
		if ( ! $artist ) {
			return;
		}

		// Get the artist's WordPress user ID.
		$artist_user_id = get_post_meta( $artist_id, '_fedistream_user_id', true );
		if ( ! $artist_user_id ) {
			return;
		}

		$follower = get_user_by( 'id', $user_id );
		if ( ! $follower ) {
			return;
		}

		self::create(
			$artist_user_id,
			self::TYPE_NEW_FOLLOWER,
			__( 'New follower', 'wp-fedistream' ),
			sprintf(
				/* translators: %s: follower display name */
				__( '%s started following you', 'wp-fedistream' ),
				$follower->display_name
			),
			array(
				'follower_id'   => $user_id,
				'follower_name' => $follower->display_name,
			)
		);
	}

	/**
	 * Notify of a Fediverse like.
	 *
	 * @param int   $content_id Content post ID.
	 * @param array $actor      Actor data.
	 * @return void
	 */
	public function notify_fediverse_like( int $content_id, array $actor ): void {
		$post = get_post( $content_id );
		if ( ! $post ) {
			return;
		}

		$artist_user_id = $this->get_content_owner_user_id( $content_id );
		if ( ! $artist_user_id ) {
			return;
		}

		$actor_name = $actor['name'] ?? $actor['preferredUsername'] ?? __( 'Someone', 'wp-fedistream' );

		self::create(
			$artist_user_id,
			self::TYPE_FEDIVERSE_LIKE,
			__( 'New like from Fediverse', 'wp-fedistream' ),
			sprintf(
				/* translators: 1: actor name, 2: content title */
				__( '%1$s liked your %2$s', 'wp-fedistream' ),
				$actor_name,
				$post->post_title
			),
			array(
				'content_id'   => $content_id,
				'content_type' => $post->post_type,
				'actor_uri'    => $actor['id'] ?? '',
				'actor_name'   => $actor_name,
				'actor_icon'   => $actor['icon']['url'] ?? '',
			)
		);
	}

	/**
	 * Notify of a Fediverse boost/announce.
	 *
	 * @param int   $content_id Content post ID.
	 * @param array $actor      Actor data.
	 * @return void
	 */
	public function notify_fediverse_boost( int $content_id, array $actor ): void {
		$post = get_post( $content_id );
		if ( ! $post ) {
			return;
		}

		$artist_user_id = $this->get_content_owner_user_id( $content_id );
		if ( ! $artist_user_id ) {
			return;
		}

		$actor_name = $actor['name'] ?? $actor['preferredUsername'] ?? __( 'Someone', 'wp-fedistream' );

		self::create(
			$artist_user_id,
			self::TYPE_FEDIVERSE_BOOST,
			__( 'New boost from Fediverse', 'wp-fedistream' ),
			sprintf(
				/* translators: 1: actor name, 2: content title */
				__( '%1$s boosted your %2$s', 'wp-fedistream' ),
				$actor_name,
				$post->post_title
			),
			array(
				'content_id'   => $content_id,
				'content_type' => $post->post_type,
				'actor_uri'    => $actor['id'] ?? '',
				'actor_name'   => $actor_name,
				'actor_icon'   => $actor['icon']['url'] ?? '',
			)
		);
	}

	/**
	 * Maybe send email notification.
	 *
	 * @param int   $notification_id Notification ID.
	 * @param array $notification    Notification data.
	 * @return void
	 */
	public function maybe_send_email( int $notification_id, array $notification ): void {
		$user_id = $notification['user_id'];
		$type    = $notification['type'];

		// Check user preference for email notifications.
		$email_enabled = get_user_meta( $user_id, 'fedistream_email_notifications', true );
		if ( '0' === $email_enabled ) {
			return;
		}

		// Check specific notification type preference.
		$type_enabled = get_user_meta( $user_id, 'fedistream_email_' . $type, true );
		if ( '0' === $type_enabled ) {
			return;
		}

		$user = get_user_by( 'id', $user_id );
		if ( ! $user || ! $user->user_email ) {
			return;
		}

		$subject = sprintf(
			/* translators: 1: site name, 2: notification title */
			__( '[%1$s] %2$s', 'wp-fedistream' ),
			get_bloginfo( 'name' ),
			$notification['title']
		);

		$message = $this->build_email_message( $notification );

		$headers = array(
			'Content-Type: text/html; charset=UTF-8',
		);

		wp_mail( $user->user_email, $subject, $message, $headers );
	}

	/**
	 * Build email message HTML.
	 *
	 * @param array $notification Notification data.
	 * @return string
	 */
	private function build_email_message( array $notification ): string {
		$site_name = get_bloginfo( 'name' );
		$site_url  = home_url();

		$html = '<!DOCTYPE html><html><head><meta charset="UTF-8"></head><body>';
		$html .= '<div style="max-width: 600px; margin: 0 auto; font-family: Arial, sans-serif;">';
		$html .= '<h2 style="color: #333;">' . esc_html( $notification['title'] ) . '</h2>';
		$html .= '<p style="color: #666; font-size: 16px;">' . esc_html( $notification['message'] ) . '</p>';

		// Add action link if available.
		$data = $notification['data'];
		$link = '';

		if ( ! empty( $data['album_url'] ) ) {
			$link = $data['album_url'];
		} elseif ( ! empty( $data['track_url'] ) ) {
			$link = $data['track_url'];
		} elseif ( ! empty( $data['artist_url'] ) ) {
			$link = $data['artist_url'];
		}

		if ( $link ) {
			$html .= '<p><a href="' . esc_url( $link ) . '" style="display: inline-block; padding: 10px 20px; background: #0073aa; color: #fff; text-decoration: none; border-radius: 4px;">' . esc_html__( 'View Details', 'wp-fedistream' ) . '</a></p>';
		}

		$html .= '<hr style="margin: 30px 0; border: none; border-top: 1px solid #eee;">';
		$html .= '<p style="color: #999; font-size: 12px;">' . sprintf(
			/* translators: %s: site name */
			esc_html__( 'This email was sent by %s.', 'wp-fedistream' ),
			'<a href="' . esc_url( $site_url ) . '">' . esc_html( $site_name ) . '</a>'
		) . '</p>';
		$html .= '</div></body></html>';

		return $html;
	}

	/**
	 * Add notification indicator to admin bar.
	 *
	 * @param \WP_Admin_Bar $admin_bar Admin bar instance.
	 * @return void
	 */
	public function add_notification_indicator( \WP_Admin_Bar $admin_bar ): void {
		if ( ! is_user_logged_in() ) {
			return;
		}

		$user_id      = get_current_user_id();
		$unread_count = self::get_unread_count( $user_id );

		$title = '<span class="ab-icon dashicons dashicons-bell"></span>';
		if ( $unread_count > 0 ) {
			$title .= '<span class="fedistream-notification-count">' . esc_html( $unread_count ) . '</span>';
		}

		$admin_bar->add_node(
			array(
				'id'    => 'fedistream-notifications',
				'title' => $title,
				'href'  => '#',
				'meta'  => array(
					'class' => 'fedistream-notifications-menu',
				),
			)
		);
	}

	/**
	 * Get local followers for an artist.
	 *
	 * @param int $artist_id Artist post ID.
	 * @return array User IDs.
	 */
	private function get_artist_local_followers( int $artist_id ): array {
		global $wpdb;

		$table = $wpdb->prefix . 'fedistream_user_follows';

		$user_ids = $wpdb->get_col(
			$wpdb->prepare(
				"SELECT user_id FROM {$table} WHERE artist_id = %d",
				$artist_id
			)
		);

		return array_map( 'intval', $user_ids );
	}

	/**
	 * Get the WordPress user ID who owns a piece of content.
	 *
	 * @param int $content_id Content post ID.
	 * @return int|null User ID or null.
	 */
	private function get_content_owner_user_id( int $content_id ): ?int {
		$post = get_post( $content_id );
		if ( ! $post ) {
			return null;
		}

		// For tracks, get artist.
		if ( 'fedistream_track' === $post->post_type ) {
			$artist_ids = get_post_meta( $content_id, '_fedistream_artist_ids', true );
			if ( ! empty( $artist_ids ) ) {
				$artist_id = $artist_ids[0];
				return (int) get_post_meta( $artist_id, '_fedistream_user_id', true ) ?: null;
			}

			$album_id  = get_post_meta( $content_id, '_fedistream_album_id', true );
			$artist_id = $album_id ? get_post_meta( $album_id, '_fedistream_album_artist', true ) : 0;
			if ( $artist_id ) {
				return (int) get_post_meta( $artist_id, '_fedistream_user_id', true ) ?: null;
			}
		}

		// For albums, get artist.
		if ( 'fedistream_album' === $post->post_type ) {
			$artist_id = get_post_meta( $content_id, '_fedistream_album_artist', true );
			if ( $artist_id ) {
				return (int) get_post_meta( $artist_id, '_fedistream_user_id', true ) ?: null;
			}
		}

		// For artists.
		if ( 'fedistream_artist' === $post->post_type ) {
			return (int) get_post_meta( $content_id, '_fedistream_user_id', true ) ?: null;
		}

		return null;
	}
}