scirs2-linalg 0.4.2

//! Redundancy management for data and computation

use std::collections::HashMap;
use std::time::Instant;

/// Redundancy manager for data and computation
#[derive(Debug)]
pub struct RedundancyManager {
    /// Redundancy policies
    redundancy_policies: HashMap<String, RedundancyPolicy>,
    /// Active replicas
    active_replicas: HashMap<String, Vec<ReplicaInfo>>,
    /// Consistency manager
    consistency_manager: ConsistencyManager,
}

/// Policy for data/computation redundancy
#[derive(Debug, Clone)]
pub struct RedundancyPolicy {
    replication_factor: usize,
    consistency_level: ConsistencyLevel,
    placement_strategy: PlacementStrategy,
    update_strategy: UpdateStrategy,
}

/// Consistency levels for replicated data
#[derive(Debug, Clone, Copy)]
pub enum ConsistencyLevel {
    Eventual,
    Strong,
    Causal,
    Session,
}

/// Strategies for replica placement
#[derive(Debug, Clone, Copy)]
pub enum PlacementStrategy {
    Random,
    Geographic,
    LoadBased,
    NetworkBased,
    PerformanceBased,
}

/// Strategies for updating replicas
#[derive(Debug, Clone, Copy)]
pub enum UpdateStrategy {
    Synchronous,
    Asynchronous,
    Lazy,
    EventDriven,
}

/// Information about data replicas
#[derive(Debug, Clone)]
pub struct ReplicaInfo {
    replica_id: String,
    node_id: usize,
    data_version: u64,
    last_updated: Instant,
    integrity_status: IntegrityStatus,
    access_frequency: usize,
}

/// Status of data integrity
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum IntegrityStatus {
    Valid,
    Suspect,
    Corrupted,
    Unknown,
}

/// Consistency manager for distributed operations
#[derive(Debug)]
pub struct ConsistencyManager {
    /// Vector clocks for ordering
    vector_clocks: HashMap<usize, VectorClock>,
    /// Conflict resolution strategies
    conflict_resolution: ConflictResolutionStrategy,
    /// Consensus protocols
    consensus_protocol: ConsensusProtocol,
}

/// Vector clock for distributed ordering
#[derive(Debug, Clone)]
pub struct VectorClock {
    clocks: HashMap<usize, u64>,
    node_id: usize,
}

/// Strategies for resolving data conflicts
#[derive(Debug, Clone, Copy)]
pub enum ConflictResolutionStrategy {
    LastWriterWins,
    FirstWriterWins,
    Application,
    Manual,
    Merge,
}

/// Consensus protocols for distributed agreement
#[derive(Debug, Clone, Copy)]
pub enum ConsensusProtocol {
    Raft,
    PBFT,
    HotStuff,
    Tendermint,
}

impl RedundancyManager {
    /// Create a new redundancy manager
    pub fn new() -> Self {
        Self {
            redundancy_policies: HashMap::new(),
            active_replicas: HashMap::new(),
            consistency_manager: ConsistencyManager::new(),
        }
    }

    /// Set redundancy policy for a data type
    pub fn set_policy(&mut self, data_type: String, policy: RedundancyPolicy) {
        self.redundancy_policies.insert(data_type, policy);
    }

    /// Create replicas for data
    pub fn create_replicas(&mut self, data_id: String, data_type: &str) -> Result<Vec<String>, String> {
        let policy = self.redundancy_policies.get(data_type)
            .ok_or_else(|| format!("No redundancy policy found for data type: {}", data_type))?;

        let mut replica_ids = Vec::new();
        let mut replicas = Vec::new();

        for i in 0..policy.replication_factor {
            let replica_id = format!("{}_{}", data_id, i);
            let replica = ReplicaInfo {
                replica_id: replica_id.clone(),
                node_id: i, // Simplified placement
                data_version: 0,
                last_updated: Instant::now(),
                integrity_status: IntegrityStatus::Valid,
                access_frequency: 0,
            };

            replica_ids.push(replica_id.clone());
            replicas.push(replica);
        }

        self.active_replicas.insert(data_id, replicas);
        Ok(replica_ids)
    }

    /// Update replica data
    pub fn update_replica(&mut self, data_id: &str, replica_id: &str, version: u64) -> Result<(), String> {
        if let Some(replicas) = self.active_replicas.get_mut(data_id) {
            if let Some(replica) = replicas.iter_mut().find(|r| r.replica_id == replica_id) {
                replica.data_version = version;
                replica.last_updated = Instant::now();
                Ok(())
            } else {
                Err(format!("Replica {} not found for data {}", replica_id, data_id))
            }
        } else {
            Err(format!("No replicas found for data {}", data_id))
        }
    }

    /// Get replica information
    pub fn get_replicas(&self, data_id: &str) -> Option<&Vec<ReplicaInfo>> {
        self.active_replicas.get(data_id)
    }

    /// Check data consistency
    pub fn check_consistency(&self, data_id: &str) -> Result<bool, String> {
        let replicas = self.active_replicas.get(data_id)
            .ok_or_else(|| format!("No replicas found for data {}", data_id))?;

        if replicas.is_empty() {
            return Ok(true);
        }

        let first_version = replicas[0].data_version;
        let all_consistent = replicas.iter().all(|r| r.data_version == first_version);

        Ok(all_consistent)
    }

    /// Remove corrupted replicas
    pub fn remove_corrupted_replicas(&mut self, data_id: &str) -> usize {
        if let Some(replicas) = self.active_replicas.get_mut(data_id) {
            let initial_count = replicas.len();
            replicas.retain(|r| r.integrity_status != IntegrityStatus::Corrupted);
            initial_count - replicas.len()
        } else {
            0
        }
    }
}

impl ConsistencyManager {
    fn new() -> Self {
        Self {
            vector_clocks: HashMap::new(),
            conflict_resolution: ConflictResolutionStrategy::LastWriterWins,
            consensus_protocol: ConsensusProtocol::Raft,
        }
    }

    /// Initialize vector clock for a node
    pub fn initialize_vector_clock(&mut self, node_id: usize) {
        let clock = VectorClock {
            clocks: HashMap::new(),
            node_id,
        };
        self.vector_clocks.insert(node_id, clock);
    }

    /// Update vector clock for an operation
    pub fn update_vector_clock(&mut self, node_id: usize) {
        if let Some(clock) = self.vector_clocks.get_mut(&node_id) {
            let current_value = clock.clocks.get(&node_id).copied().unwrap_or(0);
            clock.clocks.insert(node_id, current_value + 1);
        }
    }

    /// Compare vector clocks to determine ordering
    pub fn compare_clocks(&self, node1: usize, node2: usize) -> ClockComparison {
        let clock1 = self.vector_clocks.get(&node1);
        let clock2 = self.vector_clocks.get(&node2);

        match (clock1, clock2) {
            (Some(c1), Some(c2)) => {
                // Simplified comparison logic
                let v1 = c1.clocks.get(&node1).copied().unwrap_or(0);
                let v2 = c2.clocks.get(&node2).copied().unwrap_or(0);

                if v1 < v2 {
                    ClockComparison::Before
                } else if v1 > v2 {
                    ClockComparison::After
                } else {
                    ClockComparison::Concurrent
                }
            }
            _ => ClockComparison::Incomparable,
        }
    }
}

/// Result of vector clock comparison
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ClockComparison {
    Before,
    After,
    Concurrent,
    Incomparable,
}

impl Default for RedundancyPolicy {
    fn default() -> Self {
        Self {
            replication_factor: 3,
            consistency_level: ConsistencyLevel::Eventual,
            placement_strategy: PlacementStrategy::LoadBased,
            update_strategy: UpdateStrategy::Asynchronous,
        }
    }
}