aivpn-server 0.4.0

//! Prometheus Metrics (Phase 5)
//!
//! Implements monitoring and metrics export for AIVPN
//!
//! Features:
//! - Session count and state
//! - Packet processing rates
//! - Bandwidth usage
//! - Mask rotation events
//! - Neural module health
//! - DPI attack detection

#[cfg(feature = "metrics")]
use prometheus::{Counter, Encoder, Gauge, Histogram, HistogramOpts, Opts, Registry, TextEncoder};
#[cfg(feature = "metrics")]
use std::sync::Arc;
#[cfg(feature = "metrics")]
use tracing::warn;

/// Metrics collector
pub struct MetricsCollector {
    #[cfg(feature = "metrics")]
    registry: Registry,

    #[cfg(feature = "metrics")]
    sessions_total: Gauge,

    #[cfg(feature = "metrics")]
    sessions_active: Gauge,

    #[cfg(feature = "metrics")]
    packets_received: Counter,

    #[cfg(feature = "metrics")]
    packets_sent: Counter,

    #[cfg(feature = "metrics")]
    bytes_received: Counter,

    #[cfg(feature = "metrics")]
    bytes_sent: Counter,

    #[cfg(feature = "metrics")]
    packet_processing_time: Histogram,

    #[cfg(feature = "metrics")]
    tag_validation_time: Histogram,

    #[cfg(feature = "metrics")]
    mask_rotations: Counter,

    #[cfg(feature = "metrics")]
    key_rotations: Counter,

    #[cfg(feature = "metrics")]
    neural_checks_total: Counter,

    #[cfg(feature = "metrics")]
    neural_checks_failed: Counter,

    #[cfg(feature = "metrics")]
    dpi_attacks_detected: Counter,
}

impl MetricsCollector {
    /// Create new metrics collector
    pub fn new() -> Self {
        #[cfg(feature = "metrics")]
        {
            let registry = Registry::new();

            // Session metrics
            let sessions_total = Gauge::with_opts(Opts::new(
                "aivpn_sessions_total",
                "Total number of sessions",
            ))
            .unwrap();
            registry.register(Box::new(sessions_total.clone())).unwrap();

            let sessions_active = Gauge::with_opts(Opts::new(
                "aivpn_sessions_active",
                "Number of active sessions",
            ))
            .unwrap();
            registry
                .register(Box::new(sessions_active.clone()))
                .unwrap();

            // Packet metrics
            let packets_received = Counter::with_opts(Opts::new(
                "aivpn_packets_received_total",
                "Total packets received",
            ))
            .unwrap();
            registry
                .register(Box::new(packets_received.clone()))
                .unwrap();

            let packets_sent =
                Counter::with_opts(Opts::new("aivpn_packets_sent_total", "Total packets sent"))
                    .unwrap();
            registry.register(Box::new(packets_sent.clone())).unwrap();

            // Bandwidth metrics
            let bytes_received = Counter::with_opts(Opts::new(
                "aivpn_bytes_received_total",
                "Total bytes received",
            ))
            .unwrap();
            registry.register(Box::new(bytes_received.clone())).unwrap();

            let bytes_sent =
                Counter::with_opts(Opts::new("aivpn_bytes_sent_total", "Total bytes sent"))
                    .unwrap();
            registry.register(Box::new(bytes_sent.clone())).unwrap();

            // Performance metrics.
            // HistogramOpts is required here — Histogram::with_opts does not accept plain Opts.
            let packet_processing_time = Histogram::with_opts(HistogramOpts::new(
                "aivpn_packet_processing_seconds",
                "Packet processing time",
            ))
            .unwrap();
            registry
                .register(Box::new(packet_processing_time.clone()))
                .unwrap();

            let tag_validation_time = Histogram::with_opts(HistogramOpts::new(
                "aivpn_tag_validation_seconds",
                "Tag validation time",
            ))
            .unwrap();
            registry
                .register(Box::new(tag_validation_time.clone()))
                .unwrap();

            // Rotation metrics
            let mask_rotations = Counter::with_opts(Opts::new(
                "aivpn_mask_rotations_total",
                "Total mask rotations",
            ))
            .unwrap();
            registry.register(Box::new(mask_rotations.clone())).unwrap();

            let key_rotations = Counter::with_opts(Opts::new(
                "aivpn_key_rotations_total",
                "Total key rotations",
            ))
            .unwrap();
            registry.register(Box::new(key_rotations.clone())).unwrap();

            // Neural module metrics
            let neural_checks_total = Counter::with_opts(Opts::new(
                "aivpn_neural_checks_total",
                "Total neural resonance checks",
            ))
            .unwrap();
            registry
                .register(Box::new(neural_checks_total.clone()))
                .unwrap();

            let neural_checks_failed = Counter::with_opts(Opts::new(
                "aivpn_neural_checks_failed_total",
                "Failed neural resonance checks",
            ))
            .unwrap();
            registry
                .register(Box::new(neural_checks_failed.clone()))
                .unwrap();

            // Security metrics
            let dpi_attacks_detected = Counter::with_opts(Opts::new(
                "aivpn_dpi_attacks_detected_total",
                "DPI attacks detected",
            ))
            .unwrap();
            registry
                .register(Box::new(dpi_attacks_detected.clone()))
                .unwrap();

            Self {
                registry,
                sessions_total,
                sessions_active,
                packets_received,
                packets_sent,
                bytes_received,
                bytes_sent,
                packet_processing_time,
                tag_validation_time,
                mask_rotations,
                key_rotations,
                neural_checks_total,
                neural_checks_failed,
                dpi_attacks_detected,
            }
        }

        #[cfg(not(feature = "metrics"))]
        Self {}
    }

    /// Update session count
    pub fn update_session_count(&self, total: usize, active: usize) {
        #[cfg(feature = "metrics")]
        {
            // Gauge::set takes f64
            self.sessions_total.set(total as f64);
            self.sessions_active.set(active as f64);
        }

        #[cfg(not(feature = "metrics"))]
        let _ = (total, active);
    }

    /// Record packet received
    pub fn record_packet_received(&self, bytes: usize) {
        #[cfg(feature = "metrics")]
        {
            self.packets_received.inc();
            // Counter::inc_by takes f64
            self.bytes_received.inc_by(bytes as f64);
        }

        #[cfg(not(feature = "metrics"))]
        let _ = bytes;
    }

    /// Record packet sent
    pub fn record_packet_sent(&self, bytes: usize) {
        #[cfg(feature = "metrics")]
        {
            self.packets_sent.inc();
            // Counter::inc_by takes f64
            self.bytes_sent.inc_by(bytes as f64);
        }

        #[cfg(not(feature = "metrics"))]
        let _ = bytes;
    }

    /// Record packet processing time
    pub fn record_processing_time(&self, _seconds: f64) {
        #[cfg(feature = "metrics")]
        {
            self.packet_processing_time.observe(_seconds);
        }
    }

    /// Record tag validation time
    pub fn record_tag_validation_time(&self, _seconds: f64) {
        #[cfg(feature = "metrics")]
        {
            self.tag_validation_time.observe(_seconds);
        }
    }

    /// Record mask rotation
    pub fn record_mask_rotation(&self) {
        #[cfg(feature = "metrics")]
        {
            self.mask_rotations.inc();
        }
    }

    /// Record key rotation
    pub fn record_key_rotation(&self) {
        #[cfg(feature = "metrics")]
        {
            self.key_rotations.inc();
        }
    }

    /// Record neural check
    pub fn record_neural_check(&self, _failed: bool) {
        #[cfg(feature = "metrics")]
        {
            self.neural_checks_total.inc();
            if _failed {
                self.neural_checks_failed.inc();
            }
        }
    }

    /// Record DPI attack detection
    pub fn record_dpi_attack(&self) {
        #[cfg(feature = "metrics")]
        {
            self.dpi_attacks_detected.inc();
            warn!("DPI attack detected!");
        }
    }

    /// Export metrics in Prometheus text exposition format (Content-Type: text/plain; version=0.0.4)
    pub fn gather(&self) -> String {
        #[cfg(feature = "metrics")]
        {
            let encoder = TextEncoder::new();
            let metric_families = self.registry.gather();
            // encode() writes to impl Write; use a Vec<u8> buffer then convert to String.
            let mut buf = Vec::new();
            encoder
                .encode(&metric_families, &mut buf)
                .unwrap_or_default();
            String::from_utf8(buf).unwrap_or_default()
        }

        #[cfg(not(feature = "metrics"))]
        {
            String::new()
        }
    }
}

impl Default for MetricsCollector {
    fn default() -> Self {
        Self::new()
    }
}

/// Returns the current Prometheus metrics in text exposition format.
/// The caller is responsible for serving this as HTTP with
/// Content-Type: text/plain; version=0.0.4
#[cfg(feature = "metrics")]
pub async fn metrics_handler(collector: Arc<MetricsCollector>) -> String {
    collector.gather()
}