synapse 1.1.0

//! QUIC Transport Implementation for Synapse
//! 
//! Provides modern, high-performance communication using the QUIC protocol
//! with built-in encryption, multiplexing, and improved performance over TCP.

use crate::{
    types::*,
    error::Result,
    circuit_breaker::CircuitBreaker,
    transport::{Transport, TransportRoute, TransportMetrics, abstraction::MessageUrgency},
    synapse::blockchain::serialization::{DateTimeWrapper, UuidWrapper},
};
use async_trait::async_trait;
use std::{
    net::SocketAddr,
    sync::Arc,
    time::{Duration, Instant},
    collections::HashMap,
};
use tokio::sync::{RwLock, mpsc};
use tracing::{info, debug, warn, error};
use serde::{Serialize, Deserialize};

// Note: This is a conceptual implementation. In practice, you'd use a QUIC library like quinn
// For now, we'll create the structure and interfaces

/// QUIC Transport for high-performance, secure communication
pub struct QuicTransport {
    local_addr: SocketAddr,
    circuit_breaker: Arc<CircuitBreaker>,
    metrics: Arc<RwLock<TransportMetrics>>,
    connections: Arc<RwLock<HashMap<String, QuicConnection>>>,
    config: QuicConfig,
}

/// QUIC connection state
#[derive(Debug, Clone)]
struct QuicConnection {
    peer_addr: SocketAddr,
    connection_id: String,
    established_at: Instant,
    streams: u32,
    last_activity: Instant,
    rtt: Option<Duration>,
}

/// QUIC Transport Configuration
#[derive(Debug, Clone)]
pub struct QuicConfig {
    pub max_concurrent_streams: u32,
    pub keep_alive_interval: Duration,
    pub idle_timeout: Duration,
    pub max_packet_size: usize,
    pub congestion_control: CongestionControl,
    pub enable_0rtt: bool,
    pub certificate_path: Option<String>,
    pub private_key_path: Option<String>,
}

/// Congestion control algorithms
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum CongestionControl {
    NewReno,
    Cubic,
    Bbr,
    BbrV2,
}

impl Default for QuicConfig {
    fn default() -> Self {
        Self {
            max_concurrent_streams: 1000,
            keep_alive_interval: Duration::from_secs(30),
            idle_timeout: Duration::from_secs(300),
            max_packet_size: 1400,
            congestion_control: CongestionControl::Cubic,
            enable_0rtt: true,
            certificate_path: None,
            private_key_path: None,
        }
    }
}

impl QuicTransport {
    /// Create a new QUIC transport
    pub async fn new(local_addr: SocketAddr, config: QuicConfig) -> Result<Self> {
        info!("Initializing QUIC Transport on {}", local_addr);
        
        Ok(Self {
            local_addr,
            circuit_breaker: Arc::new(CircuitBreaker::new(
                Duration::from_secs(5),  // Timeout
                3,                       // Failure threshold  
                Duration::from_secs(30), // Recovery timeout
            )),
            metrics: Arc::new(RwLock::new(TransportMetrics::default())),
            connections: Arc::new(RwLock::new(HashMap::new())),
            config,
        })
    }
    
    /// Start QUIC server
    pub async fn start_server(&self) -> Result<()> {
        info!("Starting QUIC server on {}", self.local_addr);
        
        // In a real implementation, this would:
        // 1. Create a QUIC endpoint using quinn or similar
        // 2. Set up TLS certificates for encryption
        // 3. Configure connection parameters
        // 4. Start accepting incoming connections
        
        let connections = self.connections.clone();
        let metrics = self.metrics.clone();
        let config = self.config.clone();
        
        tokio::spawn(async move {
            // Mock server implementation
            info!("QUIC server simulation started");
            
            // This would be the main server loop accepting connections
            loop {
                // Simulate accepting a connection
                tokio::time::sleep(Duration::from_secs(10)).await;
                
                // In practice, handle incoming QUIC connections here
                debug!("Would handle incoming QUIC connection");
            }
        });
        
        Ok(())
    }
    
    /// Connect to a QUIC endpoint
    pub async fn connect_to(&self, addr: SocketAddr, server_name: &str) -> Result<String> {
        debug!("Connecting to QUIC endpoint {} ({})", addr, server_name);
        
        // Check circuit breaker
        if !self.circuit_breaker.can_proceed() {
            return Err("QUIC circuit breaker is open".into());
        }
        
        let start_time = Instant::now();
        
        // In a real implementation, this would:
        // 1. Create a QUIC connection to the remote endpoint
        // 2. Perform TLS handshake with SNI
        // 3. Potentially use 0-RTT if available
        // 4. Return connection handle
        
        // Simulate connection establishment
        let connection_id = format!("quic-{}-{}", addr, start_time.elapsed().as_millis());
        
        let connection = QuicConnection {
            peer_addr: addr,
            connection_id: connection_id.clone(),
            established_at: start_time,
            streams: 0,
            last_activity: Instant::now(),
            rtt: Some(Duration::from_millis(25)), // Simulated RTT
        };
        
        // Store connection
        {
            let mut connections = self.connections.write().await;
            connections.insert(connection_id.clone(), connection);
        }
        
        // Update metrics
        let duration = start_time.elapsed();
        self.circuit_breaker.record_result(start_time, true).await;
        
        {
            let mut metrics = self.metrics.write().await;
            metrics.connections_established += 1;
            metrics.average_latency = Some(duration);
        }
        
        info!("Connected to QUIC endpoint {} in {:?}", addr, duration);
        Ok(connection_id)
    }
    
    /// Send data over a QUIC stream
    pub async fn send_stream_data(&self, connection_id: &str, data: &[u8]) -> Result<()> {
        debug!("Sending {} bytes over QUIC stream {}", data.len(), connection_id);
        
        // Check if connection exists
        let connection = {
            let connections = self.connections.read().await;
            connections.get(connection_id).cloned()
        };
        
        let mut connection = match connection {
            Some(conn) => conn,
            None => return Err(format!("QUIC connection {} not found", connection_id).into()),
        };
        
        // In a real implementation, this would:
        // 1. Open a new stream or use existing one
        // 2. Send data with flow control
        // 3. Handle potential stream errors
        // 4. Update stream state
        
        // Simulate sending data
        connection.streams += 1;
        connection.last_activity = Instant::now();
        
        // Update connection state
        {
            let mut connections = self.connections.write().await;
            connections.insert(connection_id.to_string(), connection);
        }
        
        // Update metrics
        {
            let mut metrics = self.metrics.write().await;
            metrics.messages_sent += 1;
            metrics.bytes_sent += data.len() as u64;
        }
        
        Ok(())
    }
    
    /// Get connection statistics
    pub async fn get_connection_stats(&self, connection_id: &str) -> Result<QuicConnectionStats> {
        let connections = self.connections.read().await;
        
        if let Some(connection) = connections.get(connection_id) {
            Ok(QuicConnectionStats {
                peer_addr: connection.peer_addr,
                established_duration: connection.established_at.elapsed(),
                active_streams: connection.streams,
                last_activity: connection.last_activity.elapsed(),
                rtt: connection.rtt,
                bytes_sent: 0, // Would track this in real implementation
                bytes_received: 0,
                packets_lost: 0,
                congestion_window: 0,
            })
        } else {
            Err(format!("Connection {} not found", connection_id).into())
        }
    }
    
    /// Close a QUIC connection
    pub async fn close_connection(&self, connection_id: &str, reason: &str) -> Result<()> {
        debug!("Closing QUIC connection {}: {}", connection_id, reason);
        
        let mut connections = self.connections.write().await;
        if connections.remove(connection_id).is_some() {
            info!("Closed QUIC connection {}", connection_id);
            Ok(())
        } else {
            Err(format!("Connection {} not found", connection_id).into())
        }
    }
    
    /// Get all active connections
    pub async fn get_active_connections(&self) -> Vec<String> {
        let connections = self.connections.read().await;
        connections.keys().cloned().collect()
    }
}

#[async_trait]
impl Transport for QuicTransport {
    async fn send_message(&self, target: &str, message: &SecureMessage) -> Result<()> {
        // Check circuit breaker
        if !self.circuit_breaker.can_proceed() {
            return Err("QUIC circuit breaker is open".into());
        }
        
        let start_time = Instant::now();
        
        // Parse target as socket address
        let target_addr: SocketAddr = target.parse()
            .map_err(|_| format!("Invalid QUIC target address: {}", target))?;
        
        // Try to find existing connection or create new one
        let connection_id = {
            let connections = self.connections.read().await;
            connections.values()
                .find(|conn| conn.peer_addr == target_addr)
                .map(|conn| conn.connection_id.clone())
        };
        
        let connection_id = match connection_id {
            Some(id) => id,
            None => {
                // Create new connection
                self.connect_to(target_addr, "synapse-peer").await?
            }
        };
        
        // Serialize message
        let serialized = bincode::serde::encode_to_vec(message, bincode::config::standard())?;
        
        // Send message
        match self.send_stream_data(&connection_id, &serialized).await {
            Ok(()) => {
                let duration = start_time.elapsed();
                self.circuit_breaker.record_result(start_time, true).await;
                
                debug!("Sent QUIC message to {} (duration: {:?})", target, duration);
                Ok(())
            }
            Err(e) => {
                self.circuit_breaker.record_result(start_time, false).await;
                error!("Failed to send QUIC message to {}: {}", target, e);
                Err(e)
            }
        }
    }
    
    async fn get_route_to(&self, target: &str) -> Result<TransportRoute> {
        if target.parse::<SocketAddr>().is_ok() {
            Ok(TransportRoute::Quic {
                address: target.to_string(),
                latency: Duration::from_millis(5), // Very low latency for QUIC
                reliability: 0.999, // Very high reliability
                multiplexed: true,
            })
        } else {
            Err("QUIC route not available".into())
        }
    }
    
    async fn supports_urgency(&self, urgency: MessageUrgency) -> bool {
        // QUIC is excellent for all urgency levels
        matches!(urgency, 
            MessageUrgency::Critical |
            MessageUrgency::RealTime | 
            MessageUrgency::Interactive | 
            MessageUrgency::Background |
            MessageUrgency::Batch
        )
    }
    
    async fn get_metrics(&self) -> TransportMetrics {
        self.metrics.read().await.clone()
    }
    
    async fn is_connected(&self) -> bool {
        let connections = self.connections.read().await;
        !connections.is_empty()
    }
    
    fn transport_type(&self) -> &'static str {
        "quic"
    }
}

/// QUIC connection statistics
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct QuicConnectionStats {
    pub peer_addr: SocketAddr,
    pub established_duration: Duration,
    pub active_streams: u32,
    pub last_activity: Duration,
    pub rtt: Option<Duration>,
    pub bytes_sent: u64,
    pub bytes_received: u64,
    pub packets_lost: u32,
    pub congestion_window: u32,
}

/// QUIC stream types
#[derive(Debug, Clone, Copy, Serialize, Deserialize)]
pub enum StreamType {
    Bidirectional,
    Unidirectional,
}

/// QUIC stream configuration
#[derive(Debug, Clone)]
pub struct StreamConfig {
    pub stream_type: StreamType,
    pub priority: u8,
    pub flow_control_limit: u64,
}