<?php

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

class Argus_ANIS_Client {

	const STATUS_OPTION       = 'argus_wpd_anis_status'; 
	const TIER_OPTION         = 'argus_wpd_anis_tier';
	const LAST_ERROR_OPTION   = 'argus_wpd_anis_last_error';
	const LAST_REGISTER_OPTION = 'argus_wpd_anis_last_register';

	const LAST_SYNC_OPTION    = 'argus_wpd_anis_last_sync';
	const LAST_SUCCESS_OPTION = 'argus_wpd_anis_last_success';
	const RETRY_STAGE_OPTION     = 'argus_wpd_anis_retry_stage';
	const NEXT_RETRY_AT_OPTION   = 'argus_wpd_anis_next_retry_at';
	const SYNC_WATERMARK_OPTION = 'argus_wpd_anis_sync_watermark';
	const FEATURES_OPTION     = 'argus_wpd_anis_features';

	const SINCE_FORMAT = 'Y-m-d H:i:s';

	const DELTA_RETENTION_DAYS = 7;
	const SAFETY_MARGIN_DAYS   = 6; 
	const DRIFT_CORRECTION_HOURS = 24;

	const REPORT_SCENARIOS = array( 'http_crawl', 'brute_force', 'waf_block', 'scanner', 'exploit_attempt', 'spam' );

	const CIRCUIT_OPTION       = 'argus_wpd_anis_circuit';
	const CIRCUIT_FAILURE_THRESHOLD = 3;
	const CIRCUIT_COOLDOWN_SECS      = 300;

	const AUTO_BAN_CONFIDENCE_THRESHOLD = 70;

	const MAX_LOCAL_REPUTATION_ROWS = 50000;

	public static function init() {
		add_action( 'argus_wpd_ip_banned', array( __CLASS__, 'maybe_report' ), 10, 4 );
	}

	public static function is_configured() {
		return '' !== trim( self::base_url() );
	}

	public static function is_enabled() {
		if ( defined( 'ARGUS_WPD_ANIS_DISABLED' ) && ARGUS_WPD_ANIS_DISABLED ) {
			return false;
		}
		return (bool) Argus_Settings::get( 'anis_enabled', true ) && self::is_configured();
	}

	public static function is_connected() {
		return self::is_enabled() && 'registered' === get_option( self::STATUS_OPTION, '' );
	}

	protected static function circuit_state() {
		return wp_parse_args(
			get_option( self::CIRCUIT_OPTION, array() ),
			array( 'state' => 'closed', 'failures' => 0, 'opened_at' => 0 )
		);
	}

	protected static function circuit_allows_request() {
		$circuit = self::circuit_state();

		if ( 'closed' === $circuit['state'] ) {
			return true;
		}

		if ( 'open' === $circuit['state'] ) {
			if ( time() - (int) $circuit['opened_at'] >= self::CIRCUIT_COOLDOWN_SECS ) {
				
				$circuit['state'] = 'half_open';
				update_option( self::CIRCUIT_OPTION, $circuit, false );
				return true;
			}
			return false;
		}

		return true;
	}

	protected static function circuit_record_success() {
		update_option( self::CIRCUIT_OPTION, array( 'state' => 'closed', 'failures' => 0, 'opened_at' => 0 ), false );
	}

	protected static function circuit_record_failure() {
		$circuit = self::circuit_state();
		$failures = (int) $circuit['failures'] + 1;

		if ( 'half_open' === $circuit['state'] || $failures >= self::CIRCUIT_FAILURE_THRESHOLD ) {
			if ( 'open' !== $circuit['state'] ) {
				Argus_Events::record( 'anis_circuit_open', 'medium', 'ANIS appears unreachable -- pausing outbound requests temporarily.', array( 'failures' => $failures ) );
			}
			update_option( self::CIRCUIT_OPTION, array( 'state' => 'open', 'failures' => $failures, 'opened_at' => time() ), false );
			return;
		}

		update_option( self::CIRCUIT_OPTION, array( 'state' => 'closed', 'failures' => $failures, 'opened_at' => 0 ), false );
	}

	public static function circuit_is_open() {
		return 'open' === self::circuit_state()['state'];
	}

	protected static function base_url() {
		if ( defined( 'ARGUS_WPD_ANIS_BASE_URL' ) && ARGUS_WPD_ANIS_BASE_URL ) {
			return untrailingslashit( ARGUS_WPD_ANIS_BASE_URL );
		}
		return untrailingslashit( (string) Argus_Settings::get( 'anis_base_url', '' ) );
	}

	protected static function license_key() {
		if ( defined( 'ARGUS_WPD_ANIS_LICENSE_KEY' ) && ARGUS_WPD_ANIS_LICENSE_KEY ) {
			return trim( ARGUS_WPD_ANIS_LICENSE_KEY );
		}
		return trim( (string) Argus_Settings::get( 'anis_license_key', '' ) );
	}

	const INSTALL_SECRET_OPTION = 'argus_wpd_anis_install_secret';

	public static function instance_hash() {
		$secret = get_option( self::INSTALL_SECRET_OPTION );
		if ( ! $secret ) {
			$secret = bin2hex( random_bytes( 24 ) );
			update_option( self::INSTALL_SECRET_OPTION, $secret, false );
		}
		return substr( hash( 'sha256', $secret ), 0, 16 );
	}

	public static function register() {
		if ( ! self::is_configured() ) {
			return array( 'success' => false, 'message' => __( 'Set an ANIS server address first.', 'argus-wordpress-defence' ) );
		}
		if ( ! self::circuit_allows_request() ) {
			return array( 'success' => false, 'message' => __( 'ANIS is temporarily unreachable -- will retry automatically.', 'argus-wordpress-defence' ) );
		}

		$license_key = self::license_key();
		$body = array( 'instance_hash' => self::instance_hash(), 'version' => ARGUS_WPD_VERSION );
		if ( '' !== $license_key ) {
			$body['license_key'] = $license_key;
		}

		$response = wp_remote_post(
			self::base_url() . '/api/v1/instances/register',
			array(
				'timeout' => 15,
				'headers' => array( 'Content-Type' => 'application/json' ),
				'body'    => wp_json_encode( $body ),
			)
		);

		if ( is_wp_error( $response ) ) {
			self::circuit_record_failure();
			self::record_error( $response->get_error_message() );
			return array( 'success' => false, 'message' => $response->get_error_message() );
		}
		if ( 200 !== (int) wp_remote_retrieve_response_code( $response ) ) {
			self::circuit_record_failure();
			$message = self::extract_error_message( $response );
			self::record_error( $message );
			return array( 'success' => false, 'message' => $message );
		}

		$data = json_decode( wp_remote_retrieve_body( $response ), true );
		if ( ! is_array( $data ) || empty( $data['status'] ) ) {
			self::circuit_record_failure();
			self::record_error( __( 'ANIS returned an unexpected response.', 'argus-wordpress-defence' ) );
			return array( 'success' => false, 'message' => __( 'ANIS returned an unexpected response.', 'argus-wordpress-defence' ) );
		}

		self::circuit_record_success();
		update_option( self::STATUS_OPTION, 'registered', false );
		update_option( self::TIER_OPTION, $data['tier'] ?? 'community', false );
		update_option( self::LAST_REGISTER_OPTION, current_time( 'mysql', true ), false );
		update_option( self::LAST_ERROR_OPTION, '', false );
		if ( isset( $data['features'] ) && is_array( $data['features'] ) ) {
			update_option( self::FEATURES_OPTION, $data['features'], false );
		}

		Argus_Events::record( 'anis_registered', 'info', sprintf( 'Connected to ANIS (%s tier)', $data['tier'] ?? 'community' ), array( 'tier' => $data['tier'] ?? 'community' ) );

		return array( 'success' => true, 'message' => sprintf( __( 'Connected -- %s tier.', 'argus-wordpress-defence' ), $data['tier'] ?? 'community' ) );
	}

	protected static function record_error( $message ) {
		update_option( self::STATUS_OPTION, 'error', false );
		update_option( self::LAST_ERROR_OPTION, $message, false );
	}

	protected static function extract_error_message( $response ) {
		$code = (int) wp_remote_retrieve_response_code( $response );
		$body = json_decode( wp_remote_retrieve_body( $response ), true );
		if ( is_array( $body ) && ! empty( $body['message'] ) ) {
			return sprintf( 'ANIS returned %d: %s', $code, $body['message'] );
		}
		return sprintf( 'ANIS returned HTTP %d.', $code );
	}

	public static function sync() {
		if ( ! self::is_connected() ) {
			return array( 'success' => false, 'message' => __( 'Not connected to ANIS.', 'argus-wordpress-defence' ) );
		}

		$watermark = get_option( self::SYNC_WATERMARK_OPTION, '' );
		$last_full = get_option( self::LAST_SYNC_OPTION, '' );

		$needs_snapshot = '' === $watermark
			|| ( '' !== $watermark && strtotime( $watermark . ' UTC' ) < strtotime( '-' . self::SAFETY_MARGIN_DAYS . ' days', current_time( 'timestamp', true ) ) )
			|| ( '' !== $last_full && strtotime( $last_full . ' UTC' ) < strtotime( '-' . self::DRIFT_CORRECTION_HOURS . ' hours', current_time( 'timestamp', true ) ) );

		if ( $needs_snapshot ) {
			return self::sync_snapshot();
		}

		$result = self::sync_delta();
		if ( ! $result['success'] ) {
			return self::sync_snapshot(); 
		}
		return $result;
	}

	const RETRY_DELAYS_MINUTES = array( 5, 5, 15, 30 );

	public static function scheduled_sync() {
		$result = self::sync();
		if ( $result['success'] ) {
			self::clear_retry_ladder();
		} else {
			self::start_retry_ladder();
		}
		return $result;
	}

	protected static function start_retry_ladder() {
		update_option( self::RETRY_STAGE_OPTION, 0, false );
		update_option( self::NEXT_RETRY_AT_OPTION, time() + ( self::RETRY_DELAYS_MINUTES[0] * MINUTE_IN_SECONDS ), false );
	}

	protected static function clear_retry_ladder() {
		delete_option( self::RETRY_STAGE_OPTION );
		delete_option( self::NEXT_RETRY_AT_OPTION );
	}

	public static function maybe_retry_sync() {
		$stage = get_option( self::RETRY_STAGE_OPTION, null );
		if ( null === $stage ) {
			return; 
		}
		if ( time() < (int) get_option( self::NEXT_RETRY_AT_OPTION, 0 ) ) {
			return; 
		}

		$result = self::sync();
		if ( $result['success'] ) {
			self::clear_retry_ladder();
			return;
		}

		$next_stage = (int) $stage + 1;
		if ( ! isset( self::RETRY_DELAYS_MINUTES[ $next_stage ] ) ) {
			self::clear_retry_ladder(); 
			return;
		}
		update_option( self::RETRY_STAGE_OPTION, $next_stage, false );
		update_option( self::NEXT_RETRY_AT_OPTION, time() + ( self::RETRY_DELAYS_MINUTES[ $next_stage ] * MINUTE_IN_SECONDS ), false );
	}

	public static function sync_snapshot() {
		$response = self::get( '/api/v1/intelligence/decisions' );
		if ( is_wp_error( $response ) ) {
			return array( 'success' => false, 'message' => $response->get_error_message() );
		}

		$data = json_decode( wp_remote_retrieve_body( $response ), true );
		if ( ! is_array( $data ) || ! isset( $data['decisions'] ) ) {
			return array( 'success' => false, 'message' => __( 'ANIS returned an unexpected decisions response.', 'argus-wordpress-defence' ) );
		}

		global $wpdb;
		$table = Argus_DB::table( 'anis_reputation' );

		$wpdb->query( "TRUNCATE TABLE {$table}" ); // phpcs:ignore

		foreach ( (array) $data['decisions'] as $decision ) {
			self::upsert_decision( $decision );
		}

		self::enforce_reputation_cap();

		$now = current_time( 'mysql', true );
		update_option( self::LAST_SYNC_OPTION, $now, false );
		update_option( self::LAST_SUCCESS_OPTION, $now, false );
		update_option( self::SYNC_WATERMARK_OPTION, gmdate( self::SINCE_FORMAT ), false );

		return array( 'success' => true, 'message' => sprintf( __( 'Synced %d decision(s) from ANIS (full snapshot).', 'argus-wordpress-defence' ), count( $data['decisions'] ) ) );
	}

	public static function sync_delta() {
		$since = get_option( self::SYNC_WATERMARK_OPTION, '' );
		if ( '' === $since ) {
			return array( 'success' => false, 'message' => 'no watermark' );
		}

		$response = self::get( '/api/v1/intelligence/decisions/delta?since=' . rawurlencode( $since ) );
		if ( is_wp_error( $response ) ) {
			return array( 'success' => false, 'message' => $response->get_error_message() );
		}

		$data = json_decode( wp_remote_retrieve_body( $response ), true );
		if ( ! is_array( $data ) || ! isset( $data['events'] ) ) {
			return array( 'success' => false, 'message' => __( 'ANIS returned an unexpected delta response.', 'argus-wordpress-defence' ) );
		}

		global $wpdb;
		$table = Argus_DB::table( 'anis_reputation' );

		foreach ( (array) $data['events'] as $event ) {
			if ( 'remove' === ( $event['event'] ?? '' ) ) {
				$wpdb->delete( $table, array( 'ip' => $event['ip'] ?? '' ), array( '%s' ) );
				continue;
			}
			self::upsert_decision( $event ); 
		}

		update_option( self::SYNC_WATERMARK_OPTION, gmdate( self::SINCE_FORMAT ), false );
		update_option( self::LAST_SUCCESS_OPTION, current_time( 'mysql', true ), false );
		self::enforce_reputation_cap();

		return array( 'success' => true, 'message' => sprintf( __( 'Synced %d change(s) from ANIS (incremental).', 'argus-wordpress-defence' ), count( $data['events'] ) ) );
	}

	protected static function enforce_reputation_cap() {
		global $wpdb;
		$table = Argus_DB::table( 'anis_reputation' );

		$total = (int) $wpdb->get_var( "SELECT COUNT(*) FROM {$table}" ); // phpcs:ignore
		if ( $total <= self::MAX_LOCAL_REPUTATION_ROWS ) {
			return;
		}

		$overflow = $total - self::MAX_LOCAL_REPUTATION_ROWS;
		$wpdb->query(
			$wpdb->prepare(
				"DELETE FROM {$table} ORDER BY confidence ASC, cached_at ASC LIMIT %d", // phpcs:ignore
				$overflow
			)
		);
	}

	protected static function upsert_decision( array $decision ) {
		if ( empty( $decision['ip'] ) ) {
			return;
		}
		global $wpdb;
		$table = Argus_DB::table( 'anis_reputation' );
		$now   = current_time( 'mysql', true );

		$decided_at = ! empty( $decision['created_at'] ) ? "'" . esc_sql( gmdate( 'Y-m-d H:i:s', strtotime( $decision['created_at'] ) ) ) . "'" : 'NULL';
		$expires_at = ! empty( $decision['expires_at'] ) ? "'" . esc_sql( gmdate( 'Y-m-d H:i:s', strtotime( $decision['expires_at'] ) ) ) . "'" : 'NULL';

		$wpdb->query(
			$wpdb->prepare(
				"INSERT INTO {$table} (ip, action, confidence, reports, source, reason, decided_at, expires_at, cached_at)
				VALUES (%s, %s, %d, %d, %s, %s, {$decided_at}, {$expires_at}, %s)
				ON DUPLICATE KEY UPDATE action = VALUES(action), confidence = VALUES(confidence), reports = VALUES(reports), source = VALUES(source), reason = VALUES(reason), decided_at = VALUES(decided_at), expires_at = VALUES(expires_at), cached_at = VALUES(cached_at)", // phpcs:ignore
				$decision['ip'],
				$decision['action'] ?? 'allow',
				(int) ( $decision['confidence'] ?? 0 ),
				(int) ( $decision['reports'] ?? 0 ),
				$decision['source'] ?? '',
				$decision['reason'] ?? '',
				$now
			)
		);
	}

	public static function cached_reputation( $ip ) {
		global $wpdb;
		$table = Argus_DB::table( 'anis_reputation' );
		return $wpdb->get_row( $wpdb->prepare( "SELECT * FROM {$table} WHERE ip = %s", $ip ) ); // phpcs:ignore
	}

	public static function maybe_enforce( $ip ) {
		if ( ! self::is_enabled() ) {
			return false;
		}
		$row = self::cached_reputation( $ip );
		if ( ! $row || 'ban' !== $row->action || (int) $row->confidence < self::AUTO_BAN_CONFIDENCE_THRESHOLD ) {
			return false;
		}
		if ( $row->expires_at && strtotime( $row->expires_at . ' UTC' ) < time() ) {
			return false;
		}

		Argus_Ban_Engine::ban(
			$ip,
			Argus_Ban_Engine::SOURCE_ARGUS_CLOUD,
			sprintf( 'Flagged by ANIS community threat intelligence (confidence %d, %d report(s))', $row->confidence, $row->reports ),
			array( 'anis_reason' => $row->reason, 'anis_source' => $row->source ),
			Argus_Ban_Engine::LEVEL_EXTENDED
		);

		return true;
	}

	public static function maybe_report( $ip, $source, $reason, $level ) {
		if ( ! self::is_enabled() ) {
			return;
		}
		$scenario = self::scenario_for_source( $source );
		if ( ! $scenario ) {
			return;
		}
		if ( ! filter_var( $ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE ) ) {
			return; 
		}

		self::report_async( $ip, $scenario );
	}

	protected static function scenario_for_source( $source ) {
		$map = array(
			Argus_Ban_Engine::SOURCE_LOCAL_WAF   => 'waf_block',
			Argus_Ban_Engine::SOURCE_BRUTE_FORCE => 'brute_force',
		);
		return $map[ $source ] ?? null;
	}

	public static function report_async( $ip, $scenario, $confidence = null, $country = null ) {
		if ( ! in_array( $scenario, self::REPORT_SCENARIOS, true ) ) {
			return;
		}
		if ( self::circuit_is_open() ) {
			return; 
		}
		$body = array(
			'instance_hash' => self::instance_hash(),
			'ip'             => $ip,
			'scenario'       => $scenario,
		);
		if ( null !== $confidence ) {
			$body['confidence'] = max( 1, min( 100, (int) $confidence ) );
		}
		if ( $country ) {
			$body['country'] = $country;
		}

		wp_remote_post(
			self::base_url() . '/api/v1/intelligence/report',
			array(
				'timeout'  => 5,
				'blocking' => false,
				'headers'  => array( 'Content-Type' => 'application/json' ),
				'body'     => wp_json_encode( $body ),
			)
		);
	}

	public static function check_ip_live( $ip ) {
		if ( ! self::is_enabled() || ! self::circuit_allows_request() ) {
			return null;
		}
		if ( ! filter_var( $ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE ) ) {
			return null;
		}

		$instance = self::instance_hash();
		$args = array( 'timeout' => 2 ); 
		if ( $instance ) {
			$args['headers'] = array( 'X-ANIS-Instance' => $instance );
		}

		$response = wp_remote_get( self::base_url() . '/api/v1/intelligence/check/' . rawurlencode( $ip ), $args );

		if ( is_wp_error( $response ) || (int) wp_remote_retrieve_response_code( $response ) >= 500 ) {
			self::circuit_record_failure();
			return null;
		}
		self::circuit_record_success();

		if ( 200 !== (int) wp_remote_retrieve_response_code( $response ) ) {
			return null;
		}
		$data = json_decode( wp_remote_retrieve_body( $response ), true );
		if ( ! is_array( $data ) || ! isset( $data['action'] ) ) {
			return null;
		}

		return array( 'action' => $data['action'], 'score' => (int) ( $data['score'] ?? 0 ) );
	}

	protected static function get( $path ) {
		if ( ! self::circuit_allows_request() ) {
			return new WP_Error( 'argus_anis_circuit_open', __( 'ANIS is temporarily unreachable.', 'argus-wordpress-defence' ) );
		}

		$args = array( 'timeout' => 15 );
		$instance = self::instance_hash();
		if ( $instance ) {
			$args['headers'] = array( 'X-ANIS-Instance' => $instance );
		}
		$response = wp_remote_get( self::base_url() . $path, $args );

		if ( is_wp_error( $response ) || (int) wp_remote_retrieve_response_code( $response ) >= 500 ) {

			self::circuit_record_failure();
		} else {
			self::circuit_record_success();
		}

		return $response;
	}

	public static function stats() {
		if ( ! self::is_connected() ) {
			return null;
		}
		$response = self::get( '/api/v1/intelligence/stats' );
		if ( is_wp_error( $response ) || 200 !== (int) wp_remote_retrieve_response_code( $response ) ) {
			return null;
		}
		return json_decode( wp_remote_retrieve_body( $response ), true );
	}

	public static function feeds_status() {
		if ( ! self::is_connected() ) {
			return null;
		}
		$response = self::get( '/api/v1/feeds/status' );
		if ( is_wp_error( $response ) || 200 !== (int) wp_remote_retrieve_response_code( $response ) ) {
			return null;
		}
		$data = json_decode( wp_remote_retrieve_body( $response ), true );
		return is_array( $data ) ? ( $data['feeds'] ?? array() ) : array();
	}

	public static function local_reputation_count() {
		global $wpdb;
		return (int) $wpdb->get_var( 'SELECT COUNT(*) FROM ' . Argus_DB::table( 'anis_reputation' ) ); // phpcs:ignore
	}

	public static function blocked_count() {
		global $wpdb;
		return (int) $wpdb->get_var(
			$wpdb->prepare(
				'SELECT COUNT(*) FROM ' . Argus_DB::table( 'bans' ) . ' WHERE source = %s', // phpcs:ignore
				Argus_Ban_Engine::SOURCE_ARGUS_CLOUD
			)
		);
	}

	const SYNC_INTERVAL_SECS = HOUR_IN_SECONDS;

	public static function status() {
		$last_success = get_option( self::LAST_SUCCESS_OPTION, '' );

		return array(
			'configured'    => self::is_configured(),
			'enabled'       => (bool) Argus_Settings::get( 'anis_enabled', true ),
			'connected'     => self::is_connected(),
			'status'        => get_option( self::STATUS_OPTION, 'unconfigured' ),
			'last_error'    => get_option( self::LAST_ERROR_OPTION, '' ),

			'last_sync'     => $last_success,
			'next_sync'     => $last_success ? gmdate( 'Y-m-d H:i:s', strtotime( $last_success . ' UTC' ) + self::SYNC_INTERVAL_SECS ) : '',
			'local_count'   => self::local_reputation_count(),
			'blocked_count' => self::blocked_count(),
			'circuit_open'  => self::circuit_is_open(),

			'protection'    => self::protection_state(),
		);
	}

	protected static function protection_state() {
		if ( ! self::is_enabled() ) {
			return 'not_connected';
		}
		if ( self::circuit_is_open() && self::is_connected() ) {
			return 'limited'; 
		}
		return self::is_connected() ? 'active' : 'not_connected';
	}
}