quantrs2-device 0.1.3

//! Quantum Routing Protocols
//!
//! This module implements quantum-aware routing protocols that consider
//! entanglement resources, quantum channel quality, and fidelity degradation
//! for optimal quantum information routing.

use super::*;
use std::collections::{HashMap, BinaryHeap, HashSet};
use std::cmp::Ordering;

/// Quantum routing layer
pub struct QuantumRoutingLayer {
    config: QuantumRoutingConfig,
    routing_table: Arc<RwLock<QuantumRoutingTable>>,
    topology: Arc<RwLock<QuantumNetworkTopology>>,
    path_cache: Arc<RwLock<HashMap<String, QuantumPath>>>,
    entanglement_graph: Arc<RwLock<EntanglementGraph>>,
    routing_protocols: Vec<Box<dyn QuantumRoutingProtocol + Send + Sync>>,
}

/// Quantum routing configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct QuantumRoutingConfig {
    pub default_protocol: QuantumRoutingProtocolType,
    pub fidelity_threshold: f64,
    pub max_hops: usize,
    pub adaptive_routing: bool,
    pub load_balancing: bool,
    pub entanglement_aware: bool,
    pub topology_update_interval: Duration,
    pub path_optimization: PathOptimizationConfig,
    pub fault_tolerance: FaultToleranceConfig,
}

/// Quantum routing protocol types
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum QuantumRoutingProtocolType {
    QuantumOSPF,
    QuantumBGP,
    EntanglementAware,
    FidelityOptimized,
    QuantumDistanceVector,
    HybridQuantumClassical,
    Custom(String),
}

/// Path optimization configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PathOptimizationConfig {
    pub optimization_metric: OptimizationMetric,
    pub multi_objective: bool,
    pub weights: HashMap<String, f64>,
    pub constraints: Vec<PathConstraint>,
}

/// Optimization metrics
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum OptimizationMetric {
    MinimizeHops,
    MaximizeFidelity,
    MinimizeLatency,
    MaximizeEntanglement,
    MinimizeDecoherence,
    BalancedComposite,
    Custom(String),
}

/// Path constraints
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct PathConstraint {
    pub constraint_type: ConstraintType,
    pub threshold: f64,
    pub required: bool,
}

/// Constraint types
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum ConstraintType {
    MinFidelity,
    MaxLatency,
    MaxHops,
    MinBandwidth,
    RequireEntanglement,
    AvoidNodes(Vec<String>),
    Custom(String),
}

/// Fault tolerance configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct FaultToleranceConfig {
    pub backup_paths: usize,
    pub fast_reroute: bool,
    pub failure_detection_time: Duration,
    pub recovery_time_objective: Duration,
}

/// Quantum routing table
#[derive(Debug, Clone)]
pub struct QuantumRoutingTable {
    pub entries: HashMap<String, QuantumRoutingEntry>,
    pub default_route: Option<String>,
    pub last_update: SystemTime,
    pub version: u64,
}

/// Quantum routing entry
#[derive(Debug, Clone)]
pub struct QuantumRoutingEntry {
    pub destination: String,
    pub next_hop: String,
    pub interface: String,
    pub cost: f64,
    pub fidelity: f64,
    pub latency: Duration,
    pub entanglement_required: bool,
    pub path_quality: PathQuality,
    pub backup_paths: Vec<QuantumPath>,
    pub last_verified: SystemTime,
}

/// Path quality metrics
#[derive(Debug, Clone)]
pub struct PathQuality {
    pub overall_score: f64,
    pub fidelity_score: f64,
    pub latency_score: f64,
    pub stability_score: f64,
    pub entanglement_score: f64,
}

/// Quantum network topology
#[derive(Debug, Clone)]
pub struct QuantumNetworkTopology {
    pub nodes: HashMap<String, QuantumNode>,
    pub links: HashMap<String, QuantumLink>,
    pub topology_type: NetworkTopology,
    pub last_update: SystemTime,
    pub version: u64,
}

/// Quantum network node
#[derive(Debug, Clone)]
pub struct QuantumNode {
    pub node_id: String,
    pub node_type: QuantumNodeType,
    pub capabilities: QuantumNodeCapabilities,
    pub status: NodeStatus,
    pub position: Option<NodePosition>,
    pub entanglement_capacity: usize,
    pub quantum_memory: usize,
    pub classical_interfaces: Vec<String>,
    pub quantum_interfaces: Vec<String>,
}

/// Quantum node types
#[derive(Debug, Clone, PartialEq)]
pub enum QuantumNodeType {
    QuantumRouter,
    QuantumRepeater,
    QuantumEndpoint,
    HybridNode,
    QuantumGateway,
    EntanglementSource,
}

/// Node capabilities
#[derive(Debug, Clone)]
pub struct QuantumNodeCapabilities {
    pub entanglement_generation: bool,
    pub entanglement_swapping: bool,
    pub quantum_error_correction: bool,
    pub quantum_memory: bool,
    pub quantum_teleportation: bool,
    pub quantum_key_distribution: bool,
    pub supported_protocols: Vec<String>,
}

/// Node status
#[derive(Debug, Clone, PartialEq)]
pub enum NodeStatus {
    Active,
    Degraded,
    Maintenance,
    Failed,
    Unknown,
}

/// Node position for geographical routing
#[derive(Debug, Clone)]
pub struct NodePosition {
    pub latitude: f64,
    pub longitude: f64,
    pub altitude: Option<f64>,
}

/// Quantum network link
#[derive(Debug, Clone)]
pub struct QuantumLink {
    pub link_id: String,
    pub source_node: String,
    pub destination_node: String,
    pub link_type: QuantumLinkType,
    pub quantum_channel: QuantumChannelInfo,
    pub classical_channel: ClassicalChannelInfo,
    pub status: LinkStatus,
    pub performance_metrics: LinkMetrics,
}

/// Quantum link types
#[derive(Debug, Clone, PartialEq)]
pub enum QuantumLinkType {
    Direct,
    Repeater,
    Satellite,
    Underground,
    Wireless,
    Hybrid,
}

/// Quantum channel information
#[derive(Debug, Clone)]
pub struct QuantumChannelInfo {
    pub channel_type: QuantumChannelType,
    pub fidelity: f64,
    pub coherence_time: Duration,
    pub loss_rate: f64,
    pub noise_characteristics: NoiseCharacteristics,
    pub entanglement_rate: f64,
}

/// Classical channel information
#[derive(Debug, Clone)]
pub struct ClassicalChannelInfo {
    pub protocol: ClassicalProtocol,
    pub bandwidth: f64,
    pub latency: Duration,
    pub packet_loss: f64,
    pub jitter: Duration,
}

/// Link status
#[derive(Debug, Clone, PartialEq)]
pub enum LinkStatus {
    Up,
    Down,
    Degraded,
    Congested,
    Maintenance,
}

/// Link performance metrics
#[derive(Debug, Clone)]
pub struct LinkMetrics {
    pub utilization: f64,
    pub throughput: f64,
    pub error_rate: f64,
    pub availability: f64,
    pub last_measured: SystemTime,
}

/// Noise characteristics
#[derive(Debug, Clone)]
pub struct NoiseCharacteristics {
    pub depolarizing_rate: f64,
    pub dephasing_rate: f64,
    pub amplitude_damping: f64,
    pub thermal_noise: f64,
}

/// Quantum path representation
#[derive(Debug, Clone)]
pub struct QuantumPath {
    pub path_id: String,
    pub source: String,
    pub destination: String,
    pub hops: Vec<QuantumHop>,
    pub total_cost: f64,
    pub end_to_end_fidelity: f64,
    pub total_latency: Duration,
    pub entanglement_consumption: f64,
    pub path_reliability: f64,
    pub created_at: SystemTime,
    pub validity_period: Duration,
}

/// Quantum hop in a path
#[derive(Debug, Clone)]
pub struct QuantumHop {
    pub from_node: String,
    pub to_node: String,
    pub link_id: String,
    pub hop_cost: f64,
    pub hop_fidelity: f64,
    pub hop_latency: Duration,
    pub entanglement_required: bool,
    pub error_correction: bool,
}

/// Entanglement graph for routing
#[derive(Debug, Clone)]
pub struct EntanglementGraph {
    pub entanglement_links: HashMap<String, EntanglementLink>,
    pub entanglement_paths: HashMap<String, Vec<String>>,
    pub last_update: SystemTime,
}

/// Entanglement link
#[derive(Debug, Clone)]
pub struct EntanglementLink {
    pub link_id: String,
    pub node_a: String,
    pub node_b: String,
    pub entanglement_rate: f64,
    pub fidelity: f64,
    pub available_pairs: usize,
    pub reserved_pairs: usize,
    pub coherence_time: Duration,
}

/// Quantum routing protocol trait
#[async_trait::async_trait]
pub trait QuantumRoutingProtocol {
    async fn compute_path(&self, source: &str, destination: &str, requirements: &PathRequirements) -> DeviceResult<QuantumPath>;
    async fn update_topology(&mut self, topology: &QuantumNetworkTopology) -> DeviceResult<()>;
    async fn handle_link_failure(&mut self, link_id: &str) -> DeviceResult<()>;
    async fn optimize_existing_paths(&mut self) -> DeviceResult<Vec<QuantumPath>>;
    fn get_protocol_type(&self) -> QuantumRoutingProtocolType;
}

/// Path requirements for routing
#[derive(Debug, Clone)]
pub struct PathRequirements {
    pub min_fidelity: Option<f64>,
    pub max_latency: Option<Duration>,
    pub max_hops: Option<usize>,
    pub entanglement_required: bool,
    pub bandwidth_required: Option<f64>,
    pub reliability_required: Option<f64>,
    pub preferred_nodes: Vec<String>,
    pub avoided_nodes: Vec<String>,
}

impl QuantumRoutingLayer {
    /// Create a new quantum routing layer
    pub async fn new(config: &QuantumRoutingConfig) -> DeviceResult<Self> {
        let routing_table = Arc::new(RwLock::new(QuantumRoutingTable::new()));
        let topology = Arc::new(RwLock::new(QuantumNetworkTopology::new()));
        let path_cache = Arc::new(RwLock::new(HashMap::new()));
        let entanglement_graph = Arc::new(RwLock::new(EntanglementGraph::new()));

        // Initialize routing protocols
        let mut routing_protocols: Vec<Box<dyn QuantumRoutingProtocol + Send + Sync>> = vec![];

        match config.default_protocol {
            QuantumRoutingProtocolType::QuantumOSPF => {
                routing_protocols.push(Box::new(QuantumOSPFProtocol::new()));
            }
            QuantumRoutingProtocolType::EntanglementAware => {
                routing_protocols.push(Box::new(EntanglementAwareProtocol::new()));
            }
            QuantumRoutingProtocolType::FidelityOptimized => {
                routing_protocols.push(Box::new(FidelityOptimizedProtocol::new()));
            }
            _ => {
                routing_protocols.push(Box::new(QuantumOSPFProtocol::new()));
            }
        }

        Ok(Self {
            config: config.clone(),
            routing_table,
            topology,
            path_cache,
            entanglement_graph,
            routing_protocols,
        })
    }

    /// Initialize the routing layer
    pub async fn initialize(&mut self) -> DeviceResult<()> {
        // Initialize routing protocols
        for protocol in &mut self.routing_protocols {
            let topology = self.topology.read().await;
            protocol.update_topology(&topology).await?;
        }

        // Start topology monitoring
        self.start_topology_monitoring().await;

        Ok(())
    }

    /// Find optimal path between source and destination
    pub async fn find_path(&self, source: &str, destination: &str, requirements: PathRequirements) -> DeviceResult<QuantumPath> {
        // Check cache first
        let cache_key = format!("{}:{}", source, destination);
        {
            let cache = self.path_cache.read().await;
            if let Some(cached_path) = cache.get(&cache_key) {
                if self.is_path_valid(cached_path).await {
                    return Ok(cached_path.clone());
                }
            }
        }

        // Use appropriate routing protocol
        let protocol = &self.routing_protocols[0]; // Use first protocol for now
        let path = protocol.compute_path(source, destination, &requirements).await?;

        // Cache the path
        {
            let mut cache = self.path_cache.write().await;
            cache.insert(cache_key, path.clone());
        }

        // Update routing table
        self.update_routing_table_entry(destination, &path).await?;

        Ok(path)
    }

    /// Establish route for a connection
    pub async fn establish_route(&self, connection_id: &str, destination: &str) -> DeviceResult<()> {
        let requirements = PathRequirements {
            min_fidelity: Some(self.config.fidelity_threshold),
            max_latency: None,
            max_hops: Some(self.config.max_hops),
            entanglement_required: self.config.entanglement_aware,
            bandwidth_required: None,
            reliability_required: None,
            preferred_nodes: vec![],
            avoided_nodes: vec![],
        };

        let _path = self.find_path("local", destination, requirements).await?;

        // Store route for connection
        // Implementation would store connection-specific routing info

        Ok(())
    }

    /// Route quantum data
    pub async fn route_data(&self, destination: &str, data: QuantumData) -> DeviceResult<()> {
        // Get routing entry
        let routing_table = self.routing_table.read().await;
        let entry = routing_table.entries.get(destination)
            .ok_or_else(|| DeviceError::InvalidInput(format!("No route to {}", destination)))?;

        // Check if entanglement is required
        if entry.entanglement_required {
            self.verify_entanglement_availability(&entry.next_hop).await?;
        }

        // Forward data to next hop
        self.forward_to_next_hop(&entry.next_hop, data).await?;

        Ok(())
    }

    /// Receive data from routing layer
    pub async fn receive_data(&self) -> DeviceResult<QuantumData> {
        // Simulate receiving data
        Ok(QuantumData::default())
    }

    /// Handle link failure and reroute
    pub async fn handle_link_failure(&self, link_id: &str) -> DeviceResult<()> {
        // Update topology
        {
            let mut topology = self.topology.write().await;
            if let Some(link) = topology.links.get_mut(link_id) {
                link.status = LinkStatus::Down;
            }
        }

        // Notify routing protocols
        for protocol in &self.routing_protocols {
            // Note: This requires the protocol to be mutable, which conflicts with the trait design
            // In a real implementation, this would be handled differently
        }

        // Clear affected cached paths
        self.clear_affected_paths(link_id).await;

        // Recompute routing table
        self.recompute_routing_table().await?;

        Ok(())
    }

    /// Cleanup route
    pub async fn cleanup_route(&self, _connection_id: &str) -> DeviceResult<()> {
        // Cleanup connection-specific routing information
        Ok(())
    }

    /// Update network topology
    pub async fn update_topology(&self, topology_update: TopologyUpdate) -> DeviceResult<()> {
        let mut topology = self.topology.write().await;

        match topology_update.update_type {
            TopologyUpdateType::NodeAdded => {
                if let Some(node) = topology_update.node {
                    topology.nodes.insert(node.node_id.clone(), node);
                }
            }
            TopologyUpdateType::NodeRemoved => {
                topology.nodes.remove(&topology_update.node_id);
            }
            TopologyUpdateType::LinkAdded => {
                if let Some(link) = topology_update.link {
                    topology.links.insert(link.link_id.clone(), link);
                }
            }
            TopologyUpdateType::LinkRemoved => {
                topology.links.remove(&topology_update.link_id);
            }
            TopologyUpdateType::LinkStatusChanged => {
                if let Some(link) = topology.links.get_mut(&topology_update.link_id) {
                    link.status = topology_update.new_status.unwrap_or(LinkStatus::Unknown);
                }
            }
        }

        topology.version += 1;
        topology.last_update = SystemTime::now();

        Ok(())
    }

    // Helper methods
    async fn is_path_valid(&self, _path: &QuantumPath) -> bool {
        // Check if path is still valid (links up, fidelity acceptable, etc.)
        true // Simplified for now
    }

    async fn update_routing_table_entry(&self, destination: &str, path: &QuantumPath) -> DeviceResult<()> {
        let mut routing_table = self.routing_table.write().await;

        if !path.hops.is_empty() {
            let next_hop = path.hops[0].to_node.clone();
            let entry = QuantumRoutingEntry {
                destination: destination.to_string(),
                next_hop,
                interface: "quantum0".to_string(), // Simplified
                cost: path.total_cost,
                fidelity: path.end_to_end_fidelity,
                latency: path.total_latency,
                entanglement_required: path.entanglement_consumption > 0.0,
                path_quality: PathQuality {
                    overall_score: 0.9,
                    fidelity_score: path.end_to_end_fidelity,
                    latency_score: 0.8,
                    stability_score: 0.9,
                    entanglement_score: 0.8,
                },
                backup_paths: vec![],
                last_verified: SystemTime::now(),
            };

            routing_table.entries.insert(destination.to_string(), entry);
        }

        Ok(())
    }

    async fn verify_entanglement_availability(&self, _next_hop: &str) -> DeviceResult<()> {
        // Verify that entanglement resources are available for the next hop
        Ok(())
    }

    async fn forward_to_next_hop(&self, _next_hop: &str, _data: QuantumData) -> DeviceResult<()> {
        // Forward data to the next hop
        Ok(())
    }

    async fn clear_affected_paths(&self, _link_id: &str) {
        // Clear cached paths that use the failed link
        let mut cache = self.path_cache.write().await;
        cache.clear(); // Simplified - should only clear affected paths
    }

    async fn recompute_routing_table(&self) -> DeviceResult<()> {
        // Recompute entire routing table
        let mut routing_table = self.routing_table.write().await;
        routing_table.version += 1;
        routing_table.last_update = SystemTime::now();
        Ok(())
    }

    async fn start_topology_monitoring(&self) {
        // Start background task for topology monitoring
        // This would periodically update topology and routing tables
    }
}

/// Topology update information
#[derive(Debug, Clone)]
pub struct TopologyUpdate {
    pub update_type: TopologyUpdateType,
    pub node_id: String,
    pub link_id: String,
    pub node: Option<QuantumNode>,
    pub link: Option<QuantumLink>,
    pub new_status: Option<LinkStatus>,
}

/// Topology update types
#[derive(Debug, Clone, PartialEq)]
pub enum TopologyUpdateType {
    NodeAdded,
    NodeRemoved,
    LinkAdded,
    LinkRemoved,
    LinkStatusChanged,
}

// Implementation of routing protocols
struct QuantumOSPFProtocol;
struct EntanglementAwareProtocol;
struct FidelityOptimizedProtocol;

impl QuantumOSPFProtocol {
    fn new() -> Self {
        Self
    }
}

impl EntanglementAwareProtocol {
    fn new() -> Self {
        Self
    }
}

impl FidelityOptimizedProtocol {
    fn new() -> Self {
        Self
    }
}

#[async_trait::async_trait]
impl QuantumRoutingProtocol for QuantumOSPFProtocol {
    async fn compute_path(&self, source: &str, destination: &str, _requirements: &PathRequirements) -> DeviceResult<QuantumPath> {
        // Implement quantum OSPF path computation
        Ok(QuantumPath {
            path_id: Uuid::new_v4().to_string(),
            source: source.to_string(),
            destination: destination.to_string(),
            hops: vec![],
            total_cost: 1.0,
            end_to_end_fidelity: 0.95,
            total_latency: Duration::from_millis(10),
            entanglement_consumption: 0.0,
            path_reliability: 0.99,
            created_at: SystemTime::now(),
            validity_period: Duration::from_secs(300),
        })
    }

    async fn update_topology(&mut self, _topology: &QuantumNetworkTopology) -> DeviceResult<()> {
        Ok(())
    }

    async fn handle_link_failure(&mut self, _link_id: &str) -> DeviceResult<()> {
        Ok(())
    }

    async fn optimize_existing_paths(&mut self) -> DeviceResult<Vec<QuantumPath>> {
        Ok(vec![])
    }

    fn get_protocol_type(&self) -> QuantumRoutingProtocolType {
        QuantumRoutingProtocolType::QuantumOSPF
    }
}

#[async_trait::async_trait]
impl QuantumRoutingProtocol for EntanglementAwareProtocol {
    async fn compute_path(&self, source: &str, destination: &str, _requirements: &PathRequirements) -> DeviceResult<QuantumPath> {
        // Implement entanglement-aware path computation
        Ok(QuantumPath {
            path_id: Uuid::new_v4().to_string(),
            source: source.to_string(),
            destination: destination.to_string(),
            hops: vec![],
            total_cost: 2.0,
            end_to_end_fidelity: 0.92,
            total_latency: Duration::from_millis(15),
            entanglement_consumption: 1.0,
            path_reliability: 0.95,
            created_at: SystemTime::now(),
            validity_period: Duration::from_secs(200),
        })
    }

    async fn update_topology(&mut self, _topology: &QuantumNetworkTopology) -> DeviceResult<()> {
        Ok(())
    }

    async fn handle_link_failure(&mut self, _link_id: &str) -> DeviceResult<()> {
        Ok(())
    }

    async fn optimize_existing_paths(&mut self) -> DeviceResult<Vec<QuantumPath>> {
        Ok(vec![])
    }

    fn get_protocol_type(&self) -> QuantumRoutingProtocolType {
        QuantumRoutingProtocolType::EntanglementAware
    }
}

#[async_trait::async_trait]
impl QuantumRoutingProtocol for FidelityOptimizedProtocol {
    async fn compute_path(&self, source: &str, destination: &str, _requirements: &PathRequirements) -> DeviceResult<QuantumPath> {
        // Implement fidelity-optimized path computation
        Ok(QuantumPath {
            path_id: Uuid::new_v4().to_string(),
            source: source.to_string(),
            destination: destination.to_string(),
            hops: vec![],
            total_cost: 1.5,
            end_to_end_fidelity: 0.98,
            total_latency: Duration::from_millis(20),
            entanglement_consumption: 0.5,
            path_reliability: 0.97,
            created_at: SystemTime::now(),
            validity_period: Duration::from_secs(400),
        })
    }

    async fn update_topology(&mut self, _topology: &QuantumNetworkTopology) -> DeviceResult<()> {
        Ok(())
    }

    async fn handle_link_failure(&mut self, _link_id: &str) -> DeviceResult<()> {
        Ok(())
    }

    async fn optimize_existing_paths(&mut self) -> DeviceResult<Vec<QuantumPath>> {
        Ok(vec![])
    }

    fn get_protocol_type(&self) -> QuantumRoutingProtocolType {
        QuantumRoutingProtocolType::FidelityOptimized
    }
}

// Default implementations
impl QuantumRoutingTable {
    fn new() -> Self {
        Self {
            entries: HashMap::new(),
            default_route: None,
            last_update: SystemTime::now(),
            version: 0,
        }
    }
}

impl QuantumNetworkTopology {
    fn new() -> Self {
        Self {
            nodes: HashMap::new(),
            links: HashMap::new(),
            topology_type: NetworkTopology::Mesh,
            last_update: SystemTime::now(),
            version: 0,
        }
    }
}

impl EntanglementGraph {
    fn new() -> Self {
        Self {
            entanglement_links: HashMap::new(),
            entanglement_paths: HashMap::new(),
            last_update: SystemTime::now(),
        }
    }
}

impl Default for QuantumRoutingConfig {
    fn default() -> Self {
        Self {
            default_protocol: QuantumRoutingProtocolType::QuantumOSPF,
            fidelity_threshold: 0.9,
            max_hops: 10,
            adaptive_routing: true,
            load_balancing: true,
            entanglement_aware: true,
            topology_update_interval: Duration::from_secs(30),
            path_optimization: PathOptimizationConfig {
                optimization_metric: OptimizationMetric::BalancedComposite,
                multi_objective: true,
                weights: {
                    let mut weights = HashMap::new();
                    weights.insert("fidelity".to_string(), 0.4);
                    weights.insert("latency".to_string(), 0.3);
                    weights.insert("cost".to_string(), 0.3);
                    weights
                },
                constraints: vec![],
            },
            fault_tolerance: FaultToleranceConfig {
                backup_paths: 2,
                fast_reroute: true,
                failure_detection_time: Duration::from_secs(5),
                recovery_time_objective: Duration::from_secs(10),
            },
        }
    }
}