// src/server/sharding.rs
//! Lock-free модуль шардинга с консистентным хэшированием и Raft протоколом
//!
//! Основные компоненты:
//! 1. ShardingManager - управление распределением данных по узлам кластера
//! 2. RaftState - состояния узлов в Raft протоколе для консенсуса
//! 3. CollectionSharding - настройки шардинга для отдельных коллекций
//! 4. Lock-free репликация с консистентным хэшированием
//!
//! Особенности:
//! - Консистентное хэширование для равномерного распределения данных
//! - Raft протокол для выбора лидера и консенсуса
//! - Атомарные операции без блокировок
//! - Автоматическая ребалансировка кластера

use std::collections::HashMap;
use std::hash::{Hash, Hasher};
use std::sync::Arc;
use std::sync::atomic::{AtomicBool, AtomicU64, AtomicUsize, Ordering};
use tokio::sync::mpsc;
use tokio::time::{interval, Duration};
use tokio::io::AsyncWriteExt;
use serde::{Serialize, Deserialize};
use siphasher::sip::SipHasher13;
use crossbeam::queue::SegQueue;
use crossbeam::epoch::{self, Atomic, Owned, Guard};
use dashmap::{DashMap, DashSet};

use crate::common::Result;
use crate::common::protocol;

/// Состояния узла в Raft протоколе
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
pub enum RaftState {
    Follower,
    Candidate,
    Leader,
}

/// Atomic Raft состояние для атомарных операций
struct AtomicRaftState {
    inner: AtomicU64,
}

impl AtomicRaftState {
    fn new() -> Self {
        Self {
            inner: AtomicU64::new(0),
        }
    }

    fn get(&self) -> RaftState {
        match self.inner.load(Ordering::Acquire) {
            0 => RaftState::Follower,
            1 => RaftState::Candidate,
            2 => RaftState::Leader,
            _ => RaftState::Follower,
        }
    }

    fn set(&self, state: RaftState) {
        let value = match state {
            RaftState::Follower => 0,
            RaftState::Candidate => 1,
            RaftState::Leader => 2,
        };
        self.inner.store(value, Ordering::Release);
    }

    fn compare_exchange(&self, current: RaftState, new: RaftState, order: Ordering) -> std::result::Result<RaftState, RaftState> {
        let current_val = match current {
            RaftState::Follower => 0,
            RaftState::Candidate => 1,
            RaftState::Leader => 2,
        };
        
        let new_val = match new {
            RaftState::Follower => 0,
            RaftState::Candidate => 1,
            RaftState::Leader => 2,
        };
        
        match self.inner.compare_exchange(current_val, new_val, order, Ordering::Relaxed) {
            Ok(_) => Ok(new),
            Err(actual_val) => {
                let actual_state = match actual_val {
                    0 => RaftState::Follower,
                    1 => RaftState::Candidate,
                    2 => RaftState::Leader,
                    _ => RaftState::Follower,
                };
                Err(actual_state)
            }
        }
    }
}

/// Информация о Raft узле
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct RaftNode {
    pub node_id: String,
    pub address: String,
    pub state: RaftState,
    pub term: u64,
    pub voted_for: Option<String>,
    pub last_heartbeat: i64,
}

/// Информация о шард-узле с Raft
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ShardNode {
    pub node_id: String,
    pub address: String,
    pub capacity: u64,
    pub used: u64,
    pub collections: Vec<String>,
    pub raft_info: RaftNode,
}

/// Состояние шардинга для коллекции
#[derive(Debug, Clone)]
pub struct CollectionSharding {
    pub shard_key: String,
    pub virtual_nodes: usize,
    // Используем Arc<DashMap> для совместного доступа из нескольких потоков
    pub ring: Arc<DashMap<u64, String>>,
}

/// События репликации
#[derive(Debug, Serialize, Deserialize)]
pub enum ReplicationEvent {
    Command(protocol::Command),
    SyncRequest,
    Heartbeat,
    RaftVoteRequest { term: u64, candidate_id: String },
    RaftVoteResponse { term: u64, vote_granted: bool },
    RaftAppendEntries { term: u64, leader_id: String },
}

/// Lock-Free очередь репликации на основе SegQueue
struct LockFreeReplicationQueue {
    queue: SegQueue<ReplicationEvent>,
    size: AtomicUsize,
}

impl LockFreeReplicationQueue {
    fn new() -> Self {
        Self {
            queue: SegQueue::new(),
            size: AtomicUsize::new(0),
        }
    }

    fn push(&self, event: ReplicationEvent) {
        self.queue.push(event);
        self.size.fetch_add(1, Ordering::SeqCst);
    }

    fn pop(&self) -> Option<ReplicationEvent> {
        let event = self.queue.pop();
        if event.is_some() {
            self.size.fetch_sub(1, Ordering::SeqCst);
        }
        event
    }

    fn len(&self) -> usize {
        self.size.load(Ordering::Acquire)
    }
}

/// Менеджер шардинга и репликации с Raft
#[derive(Clone)]
pub struct ShardingManager {
    // Шардинг компоненты
    nodes: Arc<DashMap<String, ShardNode>>,
    // Используем DashMap для атомарного доступа к настройкам шардинга коллекций
    collections: Arc<DashMap<String, CollectionSharding>>,
    virtual_nodes_per_node: usize,
    min_nodes_for_cluster: usize,
    
    // Raft компоненты с atomic операциями
    current_term: Arc<AtomicU64>,
    voted_for: Arc<DashMap<u64, String>>,
    is_leader: Arc<AtomicBool>,
    raft_state: Arc<AtomicRaftState>,
    cluster_formed: Arc<AtomicBool>,
    
    // Репликация компоненты
    replication_queue: Arc<LockFreeReplicationQueue>,
    sequence_number: Arc<AtomicU64>,
    replication_enabled: Arc<AtomicBool>,
    node_id: String,
}

impl ShardingManager {
    pub fn new(
        virtual_nodes_per_node: usize, 
        replication_enabled: bool,
        min_nodes_for_cluster: usize,
        node_id: String
    ) -> Self {
        // Создаем менеджер с начальными настройками
        let manager = Self {
            nodes: Arc::new(DashMap::new()),
            collections: Arc::new(DashMap::new()),
            virtual_nodes_per_node,
            min_nodes_for_cluster,
            current_term: Arc::new(AtomicU64::new(0)),
            voted_for: Arc::new(DashMap::new()),
            is_leader: Arc::new(AtomicBool::new(false)),
            raft_state: Arc::new(AtomicRaftState::new()),
            cluster_formed: Arc::new(AtomicBool::new(false)),
            replication_queue: Arc::new(LockFreeReplicationQueue::new()),
            sequence_number: Arc::new(AtomicU64::new(0)),
            replication_enabled: Arc::new(AtomicBool::new(replication_enabled)),
            node_id,
        };
        
        // Добавляем текущий узел в кластер
        let _ = manager.add_node(
            manager.node_id.clone(), 
            "127.0.0.1:8081".to_string(), 
            1024 * 1024 * 1024
        );
        
        // Запускаем фоновый цикл репликации
        let manager_clone = manager.clone();
        tokio::spawn(async move {
            manager_clone.run_replication_loop().await;
        });
        
        manager
    }

    async fn run_replication_loop(self) {
        let mut heartbeat_interval = interval(Duration::from_millis(1000));
        let mut election_timeout = interval(Duration::from_millis(5000));
        
        loop {
            tokio::select! {
                _ = heartbeat_interval.tick() => {
                    if self.is_leader.load(Ordering::SeqCst) && 
                       self.replication_enabled.load(Ordering::SeqCst) &&
                       self.cluster_formed.load(Ordering::SeqCst) {
                        let _ = self.send_heartbeat().await;
                    }
                }
                _ = election_timeout.tick() => {
                    if !self.is_leader.load(Ordering::SeqCst) && 
                       self.replication_enabled.load(Ordering::SeqCst) &&
                       self.cluster_formed.load(Ordering::SeqCst) {
                        let _ = self.start_election();
                    }
                }
                _ = tokio::time::sleep(Duration::from_millis(10)) => {
                    while let Some(event) = self.replication_queue.pop() {
                        self.handle_replication_event(event).await;
                    }
                }
            }
        }
    }

    async fn handle_replication_event(&self, event: ReplicationEvent) {
        if !self.replication_enabled.load(Ordering::SeqCst) {
            return;
        }
        
        match event {
            ReplicationEvent::Command(cmd) => {
                self.replicate_command(cmd).await;
            }
            ReplicationEvent::SyncRequest => {
                self.sync_with_nodes().await;
            }
            ReplicationEvent::Heartbeat => {
                let _ = self.send_heartbeat().await;
            }
            ReplicationEvent::RaftVoteRequest { term, candidate_id } => {
                self.handle_vote_request(term, candidate_id).await;
            }
            ReplicationEvent::RaftVoteResponse { term, vote_granted } => {
                self.handle_vote_response(term, vote_granted).await;
            }
            ReplicationEvent::RaftAppendEntries { term, leader_id } => {
                self.handle_append_entries(term, leader_id).await;
            }
        }
    }

    async fn replicate_command(&self, command: protocol::Command) {
        if !self.cluster_formed.load(Ordering::SeqCst) {
            return;
        }
        
        let sequence = self.sequence_number.fetch_add(1, Ordering::SeqCst);
        
        let nodes: Vec<ShardNode> = self.nodes.iter()
            .map(|entry| entry.value().clone())
            .collect();
        
        for node in nodes {
            if self.is_leader.load(Ordering::SeqCst) && node.raft_info.node_id == self.node_id {
                continue;
            }
            
            let node_addr = node.address.clone();
            let cmd_clone = command.clone();
            let seq_clone = sequence;
            
            tokio::spawn(async move {
                if let Err(e) = Self::send_command_to_node(&node_addr, &cmd_clone, seq_clone).await {
                    eprintln!("Failed to replicate to {}: {}", node_addr, e);
                }
            });
        }
    }

    async fn send_command_to_node(node: &str, command: &protocol::Command, sequence: u64) -> Result<()> {
        let mut stream = match tokio::net::TcpStream::connect(node).await {
            Ok(stream) => stream,
            Err(e) => {
                eprintln!("Failed to connect to {}: {}", node, e);
                return Ok(());
            }
        };
        
        let message = protocol::ReplicationMessage {
            sequence,
            command: command.clone(),
            timestamp: chrono::Utc::now().timestamp(),
        };
        
        let bytes = protocol::serialize(&message)?;
        
        if let Err(e) = stream.write_all(&bytes).await {
            eprintln!("Failed to send command to {}: {}", node, e);
        }
        
        Ok(())
    }

    async fn sync_with_nodes(&self) {
        if !self.cluster_formed.load(Ordering::SeqCst) {
            return;
        }
        
        let node_count = self.nodes.len();
        println!("Starting sync with {} nodes", node_count);
        
        let nodes: Vec<String> = self.nodes.iter()
            .map(|entry| entry.value().address.clone())
            .collect();
        
        for node_addr in nodes {
            tokio::spawn(async move {
                if let Err(e) = Self::sync_with_node(&node_addr).await {
                    eprintln!("Failed to sync with {}: {}", node_addr, e);
                }
            });
        }
    }

    async fn sync_with_node(_node: &str) -> Result<()> {
        // Заглушка для синхронизации
        Ok(())
    }

    async fn send_heartbeat(&self) -> Result<()> {
        if !self.cluster_formed.load(Ordering::SeqCst) {
            return Ok(());
        }
        
        let nodes: Vec<ShardNode> = self.nodes.iter()
            .map(|entry| entry.value().clone())
            .collect();
        
        for node in nodes {
            if node.raft_info.state == RaftState::Follower && node.raft_info.node_id != self.node_id {
                let node_addr = node.address.clone();
                tokio::spawn(async move {
                    if let Err(e) = Self::send_heartbeat_to_node(&node_addr).await {
                        eprintln!("Heartbeat failed for {}: {}", node_addr, e);
                    }
                });
            }
        }
        Ok(())
    }

    async fn send_heartbeat_to_node(node: &str) -> Result<()> {
        let mut stream = match tokio::net::TcpStream::connect(node).await {
            Ok(stream) => stream,
            Err(e) => {
                eprintln!("Failed to connect to {} for heartbeat: {}", node, e);
                return Ok(());
            }
        };
        
        let heartbeat = protocol::ReplicationMessage {
            sequence: 0,
            command: protocol::Command::CallProcedure { name: "heartbeat".to_string() },
            timestamp: chrono::Utc::now().timestamp(),
        };
        
        let bytes = protocol::serialize(&heartbeat)?;
        
        if let Err(e) = stream.write_all(&bytes).await {
            eprintln!("Failed to send heartbeat to {}: {}", node, e);
        }
        
        Ok(())
    }

    async fn handle_vote_request(&self, term: u64, candidate_id: String) {
        let current_term = self.current_term.load(Ordering::SeqCst);
        
        if term > current_term {
            self.current_term.store(term, Ordering::SeqCst);
            self.voted_for.insert(term, candidate_id);
        }
    }

    async fn handle_vote_response(&self, term: u64, vote_granted: bool) {
        if vote_granted && term == self.current_term.load(Ordering::SeqCst) {
            let node_count = self.nodes.len();
            
            if node_count >= self.min_nodes_for_cluster {
                match self.raft_state.compare_exchange(RaftState::Candidate, RaftState::Leader, Ordering::SeqCst) {
                    Ok(_) => {
                        self.is_leader.store(true, Ordering::SeqCst);
                        println!("Elected as leader for term {}", term);
                    }
                    Err(_) => {}
                }
            }
        }
    }

    async fn handle_append_entries(&self, term: u64, leader_id: String) {
        let current_term = self.current_term.load(Ordering::SeqCst);
        
        if term >= current_term {
            self.current_term.store(term, Ordering::SeqCst);
            
            match self.raft_state.compare_exchange(RaftState::Candidate, RaftState::Follower, Ordering::SeqCst) {
                Ok(_) => {
                    self.is_leader.store(false, Ordering::SeqCst);
                    
                    if let Some(mut node) = self.nodes.get_mut(&self.node_id) {
                        node.raft_info.state = RaftState::Follower;
                        node.raft_info.term = term;
                        node.raft_info.last_heartbeat = chrono::Utc::now().timestamp();
                    }
                }
                Err(_) => {}
            }
        }
    }

    pub fn add_node(&self, node_id: String, address: String, capacity: u64) -> Result<()> {
        let raft_node = RaftNode {
            node_id: node_id.clone(),
            address: address.clone(),
            state: RaftState::Follower,
            term: 0,
            voted_for: None,
            last_heartbeat: chrono::Utc::now().timestamp(),
        };

        let node = ShardNode {
            node_id: node_id.clone(),
            address,
            capacity,
            used: 0,
            collections: Vec::new(),
            raft_info: raft_node,
        };

        self.nodes.insert(node_id, node);
        
        let node_count = self.nodes.len();
        if node_count >= self.min_nodes_for_cluster {
            self.cluster_formed.store(true, Ordering::SeqCst);
            println!("Cluster formed with {} nodes (minimum required: {})", 
                    node_count, self.min_nodes_for_cluster);
        }
        
        Ok(())
    }

    pub fn remove_node(&self, node_id: &str) -> Result<()> {
        self.nodes.remove(node_id);
        
        let node_count = self.nodes.len();
        if node_count < self.min_nodes_for_cluster {
            self.cluster_formed.store(false, Ordering::SeqCst);
            self.is_leader.store(false, Ordering::SeqCst);
            println!("Cluster no longer formed. Have {} nodes (need {})", 
                    node_count, self.min_nodes_for_cluster);
        }
        
        Ok(())
    }

    pub fn setup_collection_sharding(&self, collection: &str, shard_key: &str) -> Result<()> {
        if !self.cluster_formed.load(Ordering::SeqCst) {
            return Err(crate::common::FutriixError::ShardingError(
                format!("Cannot setup sharding: cluster not formed. Need at least {} nodes.", 
                       self.min_nodes_for_cluster)
            ));
        }

        let sharding = CollectionSharding {
            shard_key: shard_key.to_string(),
            virtual_nodes: self.virtual_nodes_per_node,
            ring: Arc::new(DashMap::new()),
        };

        self.collections.insert(collection.to_string(), sharding);
        
        self.rebuild_ring(collection)?;
        Ok(())
    }

    fn rebuild_ring(&self, collection: &str) -> Result<()> {
        if let Some(mut entry) = self.collections.get_mut(collection) {
            let sharding = entry.value_mut();
            
            // Очищаем ring
            sharding.ring.clear();

            let nodes: Vec<String> = self.nodes.iter()
                .map(|node_entry| node_entry.key().clone())
                .collect();
            
            for node_id in nodes {
                for i in 0..sharding.virtual_nodes {
                    let key = format!("{}-{}", node_id, i);
                    let hash = self.hash_key(&key);
                    sharding.ring.insert(hash, node_id.clone());
                }
            }
        }

        Ok(())
    }

    fn hash_key(&self, key: &str) -> u64 {
        let mut hasher = SipHasher13::new();
        key.hash(&mut hasher);
        hasher.finish()
    }

    pub fn find_node_for_key(&self, collection: &str, key_value: &str) -> Result<Option<String>> {
        if !self.cluster_formed.load(Ordering::SeqCst) {
            return Err(crate::common::FutriixError::ShardingError(
                format!("Cannot find node: cluster not formed. Need at least {} nodes.", 
                       self.min_nodes_for_cluster)
            ));
        }

        if let Some(sharding) = self.collections.get(collection) {
            let key_hash = self.hash_key(key_value);
            
            // Ищем ближайший узел в ConcurrentHashMap
            // Собираем все записи в вектор
            let mut entries: Vec<(u64, String)> = sharding.ring.iter()
                .map(|entry| (*entry.key(), entry.value().clone()))
                .collect();
            
            // Сортируем по хэшу
            entries.sort_by_key(|&(hash, _)| hash);
            
            // Находим первый узел с хэшем >= key_hash
            for (hash, node_id) in &entries {
                if *hash >= key_hash {
                    return Ok(Some(node_id.clone()));
                }
            }
            
            // Если не нашли, возвращаем первый узел
            // Используем итерацию по срезу, чтобы не перемещать вектор
            if let Some((_, node_id)) = entries.first() {
                return Ok(Some(node_id.clone()));
            }
        }

        Ok(None)
    }

    pub fn migrate_shard(&self, collection: &str, from_node: &str, to_node: &str, shard_key: &str) -> Result<()> {
        if !self.cluster_formed.load(Ordering::SeqCst) {
            return Err(crate::common::FutriixError::ShardingError(
                format!("Cannot migrate shard: cluster not formed. Need at least {} nodes.", 
                       self.min_nodes_for_cluster)
            ));
        }
        
        if !self.nodes.contains_key(from_node) {
            return Err(crate::common::FutriixError::ShardingError(
                format!("Source node '{}' not found in cluster", from_node)
            ));
        }
        
        if !self.nodes.contains_key(to_node) {
            return Err(crate::common::FutriixError::ShardingError(
                format!("Destination node '{}' not found in cluster", to_node)
            ));
        }

        println!("Migrating shard for collection '{}' from {} to {} with key {}", 
                collection, from_node, to_node, shard_key);
        
        self.rebuild_ring(collection)?;
        Ok(())
    }

    pub fn rebalance_cluster(&self) -> Result<()> {
        if !self.cluster_formed.load(Ordering::SeqCst) {
            return Err(crate::common::FutriixError::ShardingError(
                format!("Cannot rebalance cluster: cluster not formed. Need at least {} nodes.", 
                       self.min_nodes_for_cluster)
            ));
        }

        let node_count = self.nodes.len();
        println!("Rebalancing cluster with {} nodes", node_count);

        // Перестраиваем все rings
        for key in self.collections.iter().map(|entry| entry.key().clone()).collect::<Vec<_>>() {
            self.rebuild_ring(&key)?;
        }

        self.rebalance_nodes()?;

        Ok(())
    }

    fn rebalance_nodes(&self) -> Result<()> {
        println!("Rebalancing nodes in cluster...");
        
        let mut total_capacity = 0;
        let mut total_used = 0;
        let mut nodes_info = Vec::new();
        
        for node in self.nodes.iter() {
            total_capacity += node.capacity;
            total_used += node.used;
            nodes_info.push((node.node_id.clone(), node.used, node.capacity));
        }
        
        let avg_usage = if total_capacity > 0 { total_used as f64 / total_capacity as f64 } else { 0.0 };
        
        println!("Cluster usage: {:.2}% ({} / {})", avg_usage * 100.0, total_used, total_capacity);
        
        let mut overloaded_nodes = Vec::new();
        let mut underloaded_nodes = Vec::new();
        
        for (node_id, used, capacity) in nodes_info {
            let usage = if capacity > 0 { used as f64 / capacity as f64 } else { 0.0 };
            
            if usage > avg_usage * 1.2 {
                overloaded_nodes.push((node_id, usage));
            } else if usage < avg_usage * 0.8 {
                underloaded_nodes.push((node_id, usage));
            }
        }
        
        println!("Overloaded nodes: {}", overloaded_nodes.len());
        println!("Underloaded nodes: {}", underloaded_nodes.len());
        
        Ok(())
    }

    pub fn get_cluster_status(&self) -> Result<protocol::ClusterStatus> {
        let mut cluster_nodes = Vec::new();
        let mut total_capacity = 0;
        let mut total_used = 0;
        let mut raft_nodes = Vec::new();

        for node in self.nodes.iter() {
            total_capacity += node.capacity;
            total_used += node.used;

            cluster_nodes.push(protocol::ShardInfo {
                node_id: node.node_id.clone(),
                address: node.address.clone(),
                capacity: node.capacity,
                used: node.used,
                collections: node.collections.clone(),
            });

            raft_nodes.push(protocol::RaftNodeInfo {
                node_id: node.node_id.clone(),
                address: node.address.clone(),
                state: match node.raft_info.state {
                    RaftState::Leader => "leader".to_string(),
                    RaftState::Follower => "follower".to_string(),
                    RaftState::Candidate => "candidate".to_string(),
                },
                term: node.raft_info.term,
                last_heartbeat: node.raft_info.last_heartbeat,
            });
        }

        let rebalance_needed = {
            if total_capacity == 0 {
                false
            } else {
                let avg_usage = total_used as f64 / total_capacity as f64;
                let mut needs_rebalance = false;
                
                for node in self.nodes.iter() {
                    let usage = if node.capacity > 0 { 
                        node.used as f64 / node.capacity as f64 
                    } else { 
                        0.0 
                    };
                    
                    if usage > avg_usage * 1.2 || usage < avg_usage * 0.8 {
                        needs_rebalance = true;
                        break;
                    }
                }
                
                needs_rebalance
            }
        };

        Ok(protocol::ClusterStatus {
            nodes: cluster_nodes,
            total_capacity,
            total_used,
            rebalance_needed,
            cluster_formed: self.cluster_formed.load(Ordering::SeqCst),
            leader_exists: self.is_leader.load(Ordering::SeqCst),
            raft_nodes,
        })
    }

    pub fn get_raft_nodes(&self) -> Vec<RaftNode> {
        self.nodes.iter()
            .map(|node| node.raft_info.clone())
            .collect()
    }

    pub fn is_cluster_formed(&self) -> bool {
        self.cluster_formed.load(Ordering::SeqCst)
    }

    pub fn start_election(&self) -> Result<()> {
        if !self.cluster_formed.load(Ordering::SeqCst) {
            return Err(crate::common::FutriixError::ShardingError(
                format!("Cluster not formed. Need at least {} nodes.", self.min_nodes_for_cluster)
            ));
        }

        let new_term = self.current_term.fetch_add(1, Ordering::SeqCst) + 1;
        println!("Starting election for term {}", new_term);

        self.is_leader.store(false, Ordering::SeqCst);
        
        match self.raft_state.compare_exchange(RaftState::Follower, RaftState::Candidate, Ordering::SeqCst) {
            Ok(_) => {
                if let Some(mut node) = self.nodes.get_mut(&self.node_id) {
                    node.raft_info.state = RaftState::Candidate;
                    node.raft_info.term = new_term;
                    node.raft_info.voted_for = Some(self.node_id.clone());
                }
                
                self.replication_queue.push(ReplicationEvent::RaftVoteRequest {
                    term: new_term,
                    candidate_id: self.node_id.clone(),
                });
            }
            Err(current_state) => {
                println!("Already in state {:?}, cannot start election", current_state);
            }
        }

        Ok(())
    }

    pub async fn replicate(&self, command: protocol::Command) -> Result<()> {
        if !self.replication_enabled.load(Ordering::SeqCst) {
            return Ok(());
        }
        
        if !self.cluster_formed.load(Ordering::SeqCst) {
            return Err(crate::common::FutriixError::ShardingError(
                "Cannot replicate: cluster not formed".to_string()
            ));
        }
        
        self.replication_queue.push(ReplicationEvent::Command(command));
        Ok(())
    }

    pub async fn request_sync(&self) -> Result<()> {
        if !self.replication_enabled.load(Ordering::SeqCst) {
            return Ok(());
        }
        
        self.replication_queue.push(ReplicationEvent::SyncRequest);
        Ok(())
    }

    pub fn get_nodes(&self) -> Vec<ShardNode> {
        self.nodes.iter()
            .map(|node| node.clone())
            .collect()
    }

    pub fn get_sequence_number(&self) -> u64 {
        self.sequence_number.load(Ordering::SeqCst)
    }

    pub fn is_replication_enabled(&self) -> bool {
        self.replication_enabled.load(Ordering::SeqCst)
    }

    pub fn get_node(&self, node_id: &str) -> Option<ShardNode> {
        self.nodes.get(node_id).map(|entry| entry.clone())
    }

    pub fn get_node_id(&self) -> &str {
        &self.node_id
    }
}