scirs2-linalg 0.4.2

//! Network topology analysis for distributed operations

use std::collections::HashMap;
use std::net::IpAddr;
use std::time::Instant;
use crate::distributed::config::CompressionAlgorithm;

/// Network topology analyzer
#[derive(Debug)]
pub struct NetworkTopologyAnalyzer {
    /// Current topology
    current_topology: NetworkTopology,
    /// Topology history
    topology_history: Vec<TopologySnapshot>,
    /// Analysis algorithms
    analysis_algorithms: HashMap<String, TopologyAnalysisAlgorithm>,
    /// Optimization recommendations
    optimization_recommendations: Vec<TopologyOptimization>,
}

/// Network topology representation
#[derive(Debug, Clone)]
pub struct NetworkTopology {
    /// Nodes in the network
    nodes: HashMap<usize, NetworkNode>,
    /// Connections between nodes
    connections: HashMap<(usize, usize), ConnectionInfo>,
    /// Routing table
    routing_table: HashMap<(usize, usize), Vec<usize>>,
}

/// Information about a network node
#[derive(Debug, Clone)]
pub struct NetworkNode {
    node_id: usize,
    ip_address: IpAddr,
    port: u16,
    capabilities: NodeCapabilities,
    location: Option<GeographicLocation>,
}

/// Capabilities of a network node
#[derive(Debug, Clone)]
pub struct NodeCapabilities {
    max_bandwidth: u64,
    supported_protocols: Vec<CommunicationProtocol>,
    compression_support: Vec<CompressionAlgorithm>,
    encryption_support: bool,
}

/// Communication protocols
#[derive(Debug, Clone, Copy)]
pub enum CommunicationProtocol {
    TCP,
    UDP,
    RDMA,
    InfiniBand,
    Custom,
}

/// Geographic location for topology-aware placement
#[derive(Debug, Clone)]
pub struct GeographicLocation {
    latitude: f64,
    longitude: f64,
    datacenter: Option<String>,
    region: Option<String>,
}

/// Connection information between nodes
#[derive(Debug, Clone)]
pub struct ConnectionInfo {
    bandwidth: u64,
    latency: f64,
    reliability: f64,
    cost: f64,
    protocol: CommunicationProtocol,
}

/// Snapshot of network topology at a point in time
#[derive(Debug, Clone)]
pub struct TopologySnapshot {
    timestamp: Instant,
    topology: NetworkTopology,
    performance_metrics: HashMap<String, f64>,
    detected_issues: Vec<TopologyIssue>,
}

/// Issue detected in network topology
#[derive(Debug, Clone)]
pub struct TopologyIssue {
    issue_type: TopologyIssueType,
    severity: IssueSeverity,
    affected_nodes: Vec<usize>,
    description: String,
    suggested_fixes: Vec<String>,
}

/// Types of topology issues
#[derive(Debug, Clone, Copy)]
pub enum TopologyIssueType {
    Bottleneck,
    SinglePointOfFailure,
    SuboptimalRouting,
    LoadImbalance,
    LatencyHotspot,
    BandwidthConstrain,
}

/// Severity of topology issues
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
pub enum IssueSeverity {
    Low,
    Medium,
    High,
    Critical,
}

/// Algorithm for analyzing network topology
#[derive(Debug)]
pub enum TopologyAnalysisAlgorithm {
    ShortestPath,
    MaxFlow,
    CentralityAnalysis,
    CommunityDetection,
    LoadBalanceAnalysis,
    FailureImpactAnalysis,
}

/// Optimization recommendation for topology
#[derive(Debug, Clone)]
pub struct TopologyOptimization {
    optimization_type: OptimizationType,
    expected_improvement: f64,
    implementation_cost: f64,
    risk_level: RiskLevel,
    description: String,
    implementation_steps: Vec<String>,
}

/// Types of topology optimizations
#[derive(Debug, Clone, Copy)]
pub enum OptimizationType {
    AddConnection,
    RemoveConnection,
    RebalanceLoad,
    UpgradeBandwidth,
    RerouteTraffic,
    AddRedundancy,
}

/// Risk level for optimizations
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
pub enum RiskLevel {
    Low,
    Medium,
    High,
    VeryHigh,
}

impl NetworkTopologyAnalyzer {
    /// Create a new network topology analyzer
    pub fn new() -> Self {
        Self {
            current_topology: NetworkTopology::new(),
            topology_history: Vec::new(),
            analysis_algorithms: HashMap::new(),
            optimization_recommendations: Vec::new(),
        }
    }

    /// Update current topology
    pub fn update_topology(&mut self, topology: NetworkTopology) {
        // Save current topology to history
        let snapshot = TopologySnapshot {
            timestamp: Instant::now(),
            topology: self.current_topology.clone(),
            performance_metrics: HashMap::new(),
            detected_issues: Vec::new(),
        };
        self.topology_history.push(snapshot);

        // Update current topology
        self.current_topology = topology;

        // Analyze the new topology
        self.analyze_topology();
    }

    /// Analyze current topology
    fn analyze_topology(&mut self) {
        // Detect issues in the topology
        let issues = self.detect_topology_issues();

        // Generate optimization recommendations
        self.optimization_recommendations = self.generate_optimizations(&issues);

        // Update the latest snapshot with detected issues
        if let Some(latest_snapshot) = self.topology_history.last_mut() {
            latest_snapshot.detected_issues = issues;
        }
    }

    /// Detect issues in the current topology
    fn detect_topology_issues(&self) -> Vec<TopologyIssue> {
        let mut issues = Vec::new();

        // Check for bottlenecks
        issues.extend(self.detect_bottlenecks());

        // Check for single points of failure
        issues.extend(self.detect_single_points_of_failure());

        // Check for load imbalances
        issues.extend(self.detect_load_imbalances());

        issues
    }

    /// Detect network bottlenecks
    fn detect_bottlenecks(&self) -> Vec<TopologyIssue> {
        let mut bottlenecks = Vec::new();

        for ((source, dest), connection) in &self.current_topology.connections {
            // Check if bandwidth utilization is high
            if connection.bandwidth < 1000000 { // Less than 1 Gbps
                bottlenecks.push(TopologyIssue {
                    issue_type: TopologyIssueType::Bottleneck,
                    severity: IssueSeverity::Medium,
                    affected_nodes: vec![*source, *dest],
                    description: format!("Low bandwidth connection between nodes {} and {}", source, dest),
                    suggested_fixes: vec!["Upgrade connection bandwidth".to_string()],
                });
            }
        }

        bottlenecks
    }

    /// Detect single points of failure
    fn detect_single_points_of_failure(&self) -> Vec<TopologyIssue> {
        let mut spofs = Vec::new();

        // Check each node's connectivity
        for (&node_id, _node) in &self.current_topology.nodes {
            let connections_count = self.current_topology.connections.iter()
                .filter(|((source, dest), _)| *source == node_id || *dest == node_id)
                .count();

            if connections_count < 2 {
                spofs.push(TopologyIssue {
                    issue_type: TopologyIssueType::SinglePointOfFailure,
                    severity: IssueSeverity::High,
                    affected_nodes: vec![node_id],
                    description: format!("Node {} has insufficient redundant connections", node_id),
                    suggested_fixes: vec!["Add redundant connections".to_string()],
                });
            }
        }

        spofs
    }

    /// Detect load imbalances
    fn detect_load_imbalances(&self) -> Vec<TopologyIssue> {
        let mut imbalances = Vec::new();

        // Simplified load balance check based on connection count
        let node_connection_counts: HashMap<usize, usize> = self.current_topology.nodes.keys()
            .map(|&node_id| {
                let count = self.current_topology.connections.iter()
                    .filter(|((source, dest), _)| *source == node_id || *dest == node_id)
                    .count();
                (node_id, count)
            })
            .collect();

        if let (Some(max_connections), Some(min_connections)) = (
            node_connection_counts.values().max(),
            node_connection_counts.values().min()
        ) {
            let imbalance_ratio = *max_connections as f64 / (*min_connections as f64).max(1.0);

            if imbalance_ratio > 2.0 {
                imbalances.push(TopologyIssue {
                    issue_type: TopologyIssueType::LoadImbalance,
                    severity: IssueSeverity::Medium,
                    affected_nodes: self.current_topology.nodes.keys().copied().collect(),
                    description: "Significant load imbalance detected across nodes".to_string(),
                    suggested_fixes: vec!["Rebalance connections across nodes".to_string()],
                });
            }
        }

        imbalances
    }

    /// Generate optimization recommendations
    fn generate_optimizations(&self, issues: &[TopologyIssue]) -> Vec<TopologyOptimization> {
        let mut optimizations = Vec::new();

        for issue in issues {
            match issue.issue_type {
                TopologyIssueType::Bottleneck => {
                    optimizations.push(TopologyOptimization {
                        optimization_type: OptimizationType::UpgradeBandwidth,
                        expected_improvement: 0.5,
                        implementation_cost: 1000.0,
                        risk_level: RiskLevel::Low,
                        description: "Upgrade bandwidth to resolve bottleneck".to_string(),
                        implementation_steps: vec![
                            "Identify specific connection to upgrade".to_string(),
                            "Schedule maintenance window".to_string(),
                            "Upgrade hardware/configuration".to_string(),
                        ],
                    });
                }
                TopologyIssueType::SinglePointOfFailure => {
                    optimizations.push(TopologyOptimization {
                        optimization_type: OptimizationType::AddRedundancy,
                        expected_improvement: 0.8,
                        implementation_cost: 2000.0,
                        risk_level: RiskLevel::Medium,
                        description: "Add redundant connections to eliminate single point of failure".to_string(),
                        implementation_steps: vec![
                            "Design redundant topology".to_string(),
                            "Provision additional hardware".to_string(),
                            "Configure failover mechanisms".to_string(),
                        ],
                    });
                }
                TopologyIssueType::LoadImbalance => {
                    optimizations.push(TopologyOptimization {
                        optimization_type: OptimizationType::RebalanceLoad,
                        expected_improvement: 0.3,
                        implementation_cost: 500.0,
                        risk_level: RiskLevel::Low,
                        description: "Rebalance load distribution across nodes".to_string(),
                        implementation_steps: vec![
                            "Analyze current load patterns".to_string(),
                            "Redistribute connections".to_string(),
                            "Monitor performance improvements".to_string(),
                        ],
                    });
                }
                _ => {} // Handle other issue types as needed
            }
        }

        optimizations
    }

    /// Get current topology
    pub fn get_current_topology(&self) -> &NetworkTopology {
        &self.current_topology
    }

    /// Get topology history
    pub fn get_topology_history(&self) -> &[TopologySnapshot] {
        &self.topology_history
    }

    /// Get optimization recommendations
    pub fn get_optimization_recommendations(&self) -> &[TopologyOptimization] {
        &self.optimization_recommendations
    }

    /// Calculate shortest path between nodes
    pub fn shortest_path(&self, source: usize, destination: usize) -> Option<Vec<usize>> {
        // Simplified shortest path implementation
        if let Some(path) = self.current_topology.routing_table.get(&(source, destination)) {
            Some(path.clone())
        } else {
            None
        }
    }

    /// Calculate network centrality metrics
    pub fn calculate_centrality(&self) -> HashMap<usize, f64> {
        let mut centrality = HashMap::new();

        for &node_id in self.current_topology.nodes.keys() {
            let degree = self.current_topology.connections.iter()
                .filter(|((source, dest), _)| *source == node_id || *dest == node_id)
                .count();

            centrality.insert(node_id, degree as f64);
        }

        centrality
    }
}

impl NetworkTopology {
    /// Create a new empty network topology
    pub fn new() -> Self {
        Self {
            nodes: HashMap::new(),
            connections: HashMap::new(),
            routing_table: HashMap::new(),
        }
    }

    /// Add a node to the topology
    pub fn add_node(&mut self, node: NetworkNode) {
        self.nodes.insert(node.node_id, node);
    }

    /// Add a connection between nodes
    pub fn add_connection(&mut self, source: usize, destination: usize, connection: ConnectionInfo) {
        self.connections.insert((source, destination), connection);
    }

    /// Remove a node from the topology
    pub fn remove_node(&mut self, node_id: usize) {
        self.nodes.remove(&node_id);

        // Remove all connections involving this node
        self.connections.retain(|(source, dest), _| *source != node_id && *dest != node_id);

        // Update routing table
        self.routing_table.retain(|(source, dest), _| *source != node_id && *dest != node_id);
    }

    /// Get node information
    pub fn get_node(&self, node_id: usize) -> Option<&NetworkNode> {
        self.nodes.get(&node_id)
    }

    /// Get connection information
    pub fn get_connection(&self, source: usize, destination: usize) -> Option<&ConnectionInfo> {
        self.connections.get(&(source, destination))
    }

    /// Get all nodes
    pub fn get_nodes(&self) -> &HashMap<usize, NetworkNode> {
        &self.nodes
    }

    /// Get all connections
    pub fn get_connections(&self) -> &HashMap<(usize, usize), ConnectionInfo> {
        &self.connections
    }
}