<?php
/**
 * PowerStack Admin Search - Anonymous Telemetry
 *
 * Handles anonymous telemetry tracking for plugin usage analytics.
 * No personal data is collected. Only anonymous installation data is sent.
 *
 * @package PowerStack_Admin_Search
 * @since 1.0.0
 */

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

/**
 * Class PowerStack_Telemetry
 *
 * Handles anonymous telemetry tracking events.
 */
class PowerStack_Telemetry {

	/**
	 * Instance of this class.
	 *
	 * @var PowerStack_Telemetry
	 */
	private static $instance = null;

	/**
	 * Site UUID option name.
	 *
	 * @var string
	 */
	private static $uuid_option = 'powerstack_site_uuid';

	/**
	 * Telemetry endpoint constant.
	 *
	 * @var string
	 */
	private static $endpoint = '';

	/**
	 * Plugin version.
	 *
	 * @var string
	 */
	private static $version = '';

	/**
	 * Plugin slug.
	 *
	 * @var string
	 */
	private static $slug = '';

	/**
	 * Get instance of this class.
	 *
	 * @return PowerStack_Telemetry
	 */
	public static function get_instance() {
		if ( null === self::$instance ) {
			self::$instance = new self();
		}
		return self::$instance;
	}

	/**
	 * Constructor.
	 */
	private function __construct() {
		self::$version = defined( 'POWERSTACK_ADMIN_SEARCH_VERSION' ) ? POWERSTACK_ADMIN_SEARCH_VERSION : '1.0.0';
		self::$slug = defined( 'POWERSTACK_ADMIN_SEARCH_SLUG' ) ? POWERSTACK_ADMIN_SEARCH_SLUG : 'powerstack-admin-search';
		self::$endpoint = defined( 'POWERSTACK_TELEMETRY_ENDPOINT' ) ? POWERSTACK_TELEMETRY_ENDPOINT : 'https://powerstackwp.com/wp-json/powerstack/v1/telemetry';
	}

	/**
	 * Check if telemetry is disabled.
	 *
	 * @return bool
	 */
	private function is_disabled() {
		return defined( 'POWERSTACK_DISABLE_TELEMETRY' ) && POWERSTACK_DISABLE_TELEMETRY;
	}

	/**
	 * Get or generate site UUID.
	 *
	 * @return string Site UUID.
	 */
	public function get_site_uuid() {
		$uuid = get_option( self::$uuid_option );

		if ( empty( $uuid ) ) {
			$uuid = $this->generate_uuid();
			update_option( self::$uuid_option, $uuid );
		}

		return $uuid;
	}

	/**
	 * Generate a random UUID v4.
	 *
	 * @return string UUID.
	 */
	private function generate_uuid() {
		$data = random_bytes( 16 );
		$data[6] = chr( ord( $data[6] ) & 0x0f | 0x40 ); // Version 4
		$data[8] = chr( ord( $data[8] ) & 0x3f | 0x80 ); // Variant

		return vsprintf( '%s%s-%s-%s-%s-%s%s%s', str_split( bin2hex( $data ), 4 ) );
	}

	/**
	 * Send telemetry event to endpoint.
	 *
	 * @param string $event Event type (activate, deactivate, uninstall, heartbeat).
	 * @return bool Success status.
	 */
	private function send_event( $event ) {
		if ( $this->is_disabled() ) {
			return false;
		}

		$payload = array(
			'event'          => $event,
			'site_id'        => $this->get_site_uuid(),
			'plugin_slug'    => self::$slug,
			'plugin_version' => self::$version,
		);

		// Send non-blocking request
		$response = wp_remote_post(
			self::$endpoint,
			array(
				'body'    => wp_json_encode( $payload ),
				'headers' => array(
					'Content-Type' => 'application/json',
				),
				'timeout' => 5,
				'blocking' => false,
			)
		);

		// Non-blocking request, so we can't check response directly
		// Error handling is done via WordPress error logging if needed
		return true;
	}

	/**
	 * Handle plugin activation event.
	 *
	 * @return bool
	 */
	public function track_activation() {
		if ( $this->is_disabled() ) {
			return false;
		}

		// Ensure UUID exists
		$this->get_site_uuid();

		// Schedule heartbeat cron
		if ( ! wp_next_scheduled( 'powerstack_telemetry_heartbeat' ) ) {
			wp_schedule_event( time(), 'daily', 'powerstack_telemetry_heartbeat' );
		}

		return $this->send_event( 'activate' );
	}

	/**
	 * Handle plugin deactivation event.
	 *
	 * @return bool
	 */
	public function track_deactivation() {
		if ( $this->is_disabled() ) {
			return false;
		}

		// Clear heartbeat cron
		$timestamp = wp_next_scheduled( 'powerstack_telemetry_heartbeat' );
		if ( $timestamp ) {
			wp_unschedule_event( $timestamp, 'powerstack_telemetry_heartbeat' );
		}

		return $this->send_event( 'deactivate' );
	}

	/**
	 * Handle plugin uninstall event.
	 *
	 * @return bool
	 */
	public function track_uninstall() {
		if ( $this->is_disabled() ) {
			return false;
		}

		// Send uninstall event before deleting data
		$result = $this->send_event( 'uninstall' );

		// Delete site UUID
		delete_option( self::$uuid_option );

		return $result;
	}

	/**
	 * Send daily heartbeat event.
	 *
	 * @return bool
	 */
	public function track_heartbeat() {
		if ( $this->is_disabled() ) {
			return false;
		}

		return $this->send_event( 'heartbeat' );
	}

	/**
	 * Initialize telemetry hooks.
	 */
	public function init() {
		// Register heartbeat cron callback
		add_action( 'powerstack_telemetry_heartbeat', array( $this, 'track_heartbeat' ) );
	}
}