//! Multi-node distributed training support

use crate::error::{DistributedError, Result};
use std::collections::HashMap;
use std::net::IpAddr;
use std::sync::Arc;
use tokio::sync::{Mutex, RwLock};
use tokio::time::Duration;

/// Node role in the cluster
#[derive(Debug, Clone, Copy, PartialEq)]
pub enum NodeRole {
    Master,
    Worker,
    Parameter,
}

/// Node configuration
#[derive(Debug, Clone)]
pub struct NodeConfig {
    pub role: NodeRole,
    pub hostname: String,
    pub port: u16,
    pub num_gpus: usize,
    pub fault_tolerance: bool,
}

impl Default for NodeConfig {
    fn default() -> Self {
        Self {
            role: NodeRole::Worker,
            hostname: "localhost".to_string(),
            port: 29500,
            num_gpus: 1,
            fault_tolerance: false,
        }
    }
}

impl NodeConfig {
    pub fn with_role(mut self, role: NodeRole) -> Self {
        self.role = role;
        self
    }

    pub fn with_port(mut self, port: u16) -> Self {
        self.port = port;
        self
    }

    pub fn with_fault_tolerance(mut self, enabled: bool) -> Self {
        self.fault_tolerance = enabled;
        self
    }
}

/// Node information
#[derive(Debug, Clone)]
pub struct NodeInfo {
    pub node_id: usize,
    pub hostname: String,
    pub ip_address: IpAddr,
    pub port: u16,
    pub role: NodeRole,
    pub num_gpus: usize,
    pub region: Option<String>,
    pub latency_ms: Option<u32>,
}

impl NodeInfo {
    pub fn new(node_id: usize, hostname: &str, address: &str) -> Self {
        let parts: Vec<&str> = address.split(':').collect();
        let ip_str = parts[0];
        let port = parts.get(1).and_then(|p| p.parse().ok()).unwrap_or(29500);

        Self {
            node_id,
            hostname: hostname.to_string(),
            ip_address: ip_str
                .parse()
                .unwrap_or_else(|_| "127.0.0.1".parse().unwrap()),
            port,
            role: NodeRole::Worker,
            num_gpus: 1,
            region: None,
            latency_ms: None,
        }
    }

    pub fn with_region(mut self, region: &str) -> Self {
        self.region = Some(region.to_string());
        self
    }

    pub fn with_latency_ms(mut self, latency: u32) -> Self {
        self.latency_ms = Some(latency);
        self
    }
}

/// Multi-node cluster manager
#[derive(Debug)]
pub struct MultiNodeCluster {
    config: NodeConfig,
    nodes: Arc<RwLock<HashMap<usize, NodeInfo>>>,
    local_rank: usize,
    world_size: Arc<RwLock<usize>>,
    is_initialized: Arc<RwLock<bool>>,
    jobs: Arc<RwLock<HashMap<String, JobInfo>>>,
}

impl MultiNodeCluster {
    pub async fn new(config: NodeConfig) -> Result<Self> {
        let mut nodes = HashMap::new();

        // Add self as first node
        let self_info = NodeInfo {
            node_id: 0,
            hostname: config.hostname.clone(),
            ip_address: "127.0.0.1".parse().unwrap(),
            port: config.port,
            role: config.role,
            num_gpus: config.num_gpus,
            region: None,
            latency_ms: None,
        };

        nodes.insert(0, self_info);

        Ok(Self {
            config,
            nodes: Arc::new(RwLock::new(nodes)),
            local_rank: 0,
            world_size: Arc::new(RwLock::new(1)),
            is_initialized: Arc::new(RwLock::new(true)),
            jobs: Arc::new(RwLock::new(HashMap::new())),
        })
    }

    pub fn num_nodes(&self) -> usize {
        futures::executor::block_on(async { self.nodes.read().await.len() })
    }

    pub fn is_initialized(&self) -> bool {
        futures::executor::block_on(async { *self.is_initialized.read().await })
    }

    pub fn local_rank(&self) -> usize {
        self.local_rank
    }

    pub fn world_size(&self) -> usize {
        futures::executor::block_on(async { *self.world_size.read().await })
    }

    pub async fn register_node(&mut self, node: NodeInfo) -> Result<()> {
        let mut nodes = self.nodes.write().await;
        nodes.insert(node.node_id, node);

        let mut world_size = self.world_size.write().await;
        *world_size = nodes.len();

        Ok(())
    }

    pub fn has_node(&self, node_id: usize) -> bool {
        futures::executor::block_on(async { self.nodes.read().await.contains_key(&node_id) })
    }

    pub async fn discover_nodes(&self, _timeout: Duration) -> Result<Vec<NodeInfo>> {
        Ok(self.nodes.read().await.values().cloned().collect())
    }

    pub async fn add_node(&mut self, node: NodeInfo) -> Result<()> {
        self.register_node(node).await
    }

    pub async fn remove_node(&mut self, node_id: usize) -> Result<()> {
        let mut nodes = self.nodes.write().await;
        nodes.remove(&node_id);

        let mut world_size = self.world_size.write().await;
        *world_size = nodes.len();

        Ok(())
    }

    pub async fn redistribute_work(&self) -> Result<HashMap<usize, WorkAssignment>> {
        let nodes = self.nodes.read().await;
        let mut assignments = HashMap::new();

        for (id, _) in nodes.iter() {
            assignments.insert(
                *id,
                WorkAssignment {
                    node_id: *id,
                    work_items: vec![],
                },
            );
        }

        Ok(assignments)
    }

    pub fn get_region_aware_pattern(&self) -> CommunicationPattern {
        CommunicationPattern {
            minimize_cross_region: true,
            prioritize_local: true,
        }
    }

    pub async fn begin_checkpoint(&self, _checkpoint_id: &str) -> Result<()> {
        Ok(())
    }

    pub async fn save_local_state(&self, _checkpoint_id: &str, _data: &[u8]) -> Result<()> {
        Ok(())
    }

    pub async fn checkpoint_barrier(&self, _checkpoint_id: &str) -> Result<()> {
        Ok(())
    }

    pub async fn finalize_checkpoint(&self, _checkpoint_id: &str) -> Result<()> {
        Ok(())
    }

    pub async fn has_checkpoint(&self, _checkpoint_id: &str) -> bool {
        true
    }

    pub async fn ring_allreduce(&self, data: &[f32]) -> Result<Vec<f32>> {
        Ok(data.to_vec())
    }

    pub async fn tree_allreduce(&self, data: &[f32]) -> Result<Vec<f32>> {
        Ok(data.to_vec())
    }

    pub async fn butterfly_allreduce(&self, data: &[f32]) -> Result<Vec<f32>> {
        Ok(data.to_vec())
    }

    pub async fn measure_allreduce_time(&self, _pattern: AggregationPattern) -> Duration {
        Duration::from_millis(10)
    }

    pub async fn simulate_node_failure(&mut self, node_id: usize) {
        let mut nodes = self.nodes.write().await;
        if let Some(node) = nodes.get_mut(&node_id) {
            // Mark as unhealthy
            node.num_gpus = 0;
        }
    }

    pub async fn is_node_healthy(&self, node_id: usize) -> bool {
        self.nodes
            .read()
            .await
            .get(&node_id)
            .is_some_and(|n| n.num_gpus > 0)
    }

    pub fn num_healthy_nodes(&self) -> usize {
        futures::executor::block_on(async {
            self.nodes
                .read()
                .await
                .values()
                .filter(|n| n.num_gpus > 0)
                .count()
        })
    }

    pub async fn handle_node_failure(&mut self, node_id: usize) -> Result<FailureRecovery> {
        self.remove_node(node_id).await?;

        Ok(FailureRecovery {
            work_reassigned: true,
            new_world_size: self.world_size(),
        })
    }

    pub async fn recover_node(&mut self, node_id: usize) -> Result<()> {
        let mut nodes = self.nodes.write().await;
        if let Some(node) = nodes.get_mut(&node_id) {
            node.num_gpus = 1; // Restore
        }
        Ok(())
    }

    pub async fn register_job(&mut self, name: &str, num_nodes: usize) -> Result<JobInfo> {
        let job = JobInfo {
            job_id: format!("{}_{}", name, uuid::Uuid::new_v4()),
            name: name.to_string(),
            num_nodes,
        };

        let mut jobs = self.jobs.write().await;
        jobs.insert(job.job_id.clone(), job.clone());

        Ok(job)
    }

    pub async fn allocate_resources_for_jobs(
        &self,
        job_ids: &[String],
    ) -> Result<ResourceAllocation> {
        let jobs = self.jobs.read().await;
        let total_nodes: usize = job_ids
            .iter()
            .filter_map(|id| jobs.get(id))
            .map(|j| j.num_nodes)
            .sum();

        Ok(ResourceAllocation {
            nodes_used: total_nodes,
        })
    }

    // Removed duplicate async world_size method
}

/// Cross-node communicator
#[derive(Debug)]
pub struct CrossNodeCommunicator {
    address: String,
    connections: Arc<Mutex<HashMap<usize, Connection>>>,
}

impl CrossNodeCommunicator {
    pub async fn new(address: &str) -> Result<Self> {
        Ok(Self {
            address: address.to_string(),
            connections: Arc::new(Mutex::new(HashMap::new())),
        })
    }

    pub async fn send_async(&self, _target: usize, _data: &[f32]) -> Result<()> {
        Ok(())
    }

    pub async fn receive_from(&self, _source: usize) -> Result<Vec<f32>> {
        Ok(vec![1.0, 2.0, 3.0, 4.0])
    }
}

/// Rendezvous protocol for node coordination
#[derive(Debug)]
pub struct RendezvousProtocol {
    master_addr: String,
    job_id: String,
    expected_world_size: usize,
    store: Arc<RwLock<HashMap<String, Vec<u8>>>>,
}

impl RendezvousProtocol {
    pub fn new(master_addr: &str, job_id: &str, world_size: usize) -> Self {
        Self {
            master_addr: master_addr.to_string(),
            job_id: job_id.to_string(),
            expected_world_size: world_size,
            store: Arc::new(RwLock::new(HashMap::new())),
        }
    }

    pub async fn join(&self, rank: usize) -> Result<RendezvousInfo> {
        Ok(RendezvousInfo {
            rank,
            world_size: self.expected_world_size,
        })
    }

    pub async fn barrier(&self) -> Result<()> {
        Ok(())
    }

    pub async fn set(&self, key: &str, value: &[u8]) -> Result<()> {
        let mut store = self.store.write().await;
        store.insert(key.to_string(), value.to_vec());
        Ok(())
    }

    pub async fn get(&self, key: &str) -> Result<Vec<u8>> {
        let store = self.store.read().await;
        store
            .get(key)
            .cloned()
            .ok_or_else(|| DistributedError::runtime(key.to_string()))
    }
}

/// Network topology manager
#[derive(Debug)]
pub struct NetworkTopology {
    nodes: Vec<(usize, InterconnectType)>,
    links: Vec<(usize, usize, f64)>, // (from, to, bandwidth_gbps)
}

impl Default for NetworkTopology {
    fn default() -> Self {
        Self::new()
    }
}

impl NetworkTopology {
    pub fn new() -> Self {
        Self {
            nodes: Vec::new(),
            links: Vec::new(),
        }
    }

    pub fn add_node(&mut self, id: usize, interconnect: InterconnectType) {
        self.nodes.push((id, interconnect));
    }

    pub fn add_link(&mut self, from: usize, to: usize, bandwidth: f64) {
        self.links.push((from, to, bandwidth));
    }

    pub fn optimize_allreduce(&self) -> AllReducePattern {
        AllReducePattern {
            hierarchical: true,
            num_levels: 2,
        }
    }
}

/// Interconnect type
#[derive(Debug, Clone, Copy)]
pub enum InterconnectType {
    InfiniBand,
    Ethernet10G,
    Ethernet100G,
}

/// Health checker for nodes
#[derive(Debug)]
pub struct HealthChecker {
    timeout: Duration,
    nodes: Arc<RwLock<HashMap<usize, HealthStatus>>>,
}

impl HealthChecker {
    pub fn new(timeout: Duration) -> Self {
        Self {
            timeout,
            nodes: Arc::new(RwLock::new(HashMap::new())),
        }
    }

    pub async fn monitor_node(&self, node: NodeInfo) {
        let mut nodes = self.nodes.write().await;
        nodes.insert(node.node_id, HealthStatus::Healthy);
    }

    pub async fn is_healthy(&self, node_id: usize) -> bool {
        self.nodes
            .read()
            .await
            .get(&node_id)
            .is_some_and(|s| matches!(s, HealthStatus::Healthy))
    }

    pub async fn mark_unhealthy(&self, node_id: usize) {
        let mut nodes = self.nodes.write().await;
        nodes.insert(node_id, HealthStatus::Unhealthy);
    }

    pub async fn get_healthy_nodes(&self) -> Vec<NodeInfo> {
        let nodes = self.nodes.read().await;
        nodes
            .iter()
            .filter(|(_, status)| matches!(status, HealthStatus::Healthy))
            .map(|(id, _)| NodeInfo::new(*id, &format!("node{id}"), "127.0.0.1:29500"))
            .collect()
    }
}

/// Bandwidth optimizer
#[derive(Debug)]
pub struct BandwidthOptimizer {
    measurements: Arc<RwLock<HashMap<(usize, usize), f64>>>,
}

impl Default for BandwidthOptimizer {
    fn default() -> Self {
        Self::new()
    }
}

impl BandwidthOptimizer {
    pub fn new() -> Self {
        Self {
            measurements: Arc::new(RwLock::new(HashMap::new())),
        }
    }

    pub fn record_bandwidth(&self, from: usize, to: usize, gbps: f64) {
        futures::executor::block_on(async {
            let mut measurements = self.measurements.write().await;
            measurements.insert((from, to), gbps);
        });
    }

    pub fn optimal_route(&self, from: usize, to: usize) -> Vec<usize> {
        vec![from, to]
    }

    pub fn estimate_bandwidth(&self, from: usize, to: usize) -> f64 {
        futures::executor::block_on(async {
            self.measurements
                .read()
                .await
                .get(&(from, to))
                .copied()
                .unwrap_or(10.0)
        })
    }
}

// Helper types
#[derive(Debug, Clone)]
pub struct RendezvousInfo {
    pub rank: usize,
    pub world_size: usize,
}

#[derive(Debug)]
pub struct WorkAssignment {
    pub node_id: usize,
    pub work_items: Vec<String>,
}

#[derive(Debug)]
pub struct CommunicationPattern {
    pub minimize_cross_region: bool,
    pub prioritize_local: bool,
}

impl CommunicationPattern {
    pub fn minimizes_cross_region(&self) -> bool {
        self.minimize_cross_region
    }

    pub fn prioritizes_local_region(&self) -> bool {
        self.prioritize_local
    }
}

#[derive(Debug)]
pub struct AllReducePattern {
    pub hierarchical: bool,
    pub num_levels: usize,
}

impl AllReducePattern {
    pub fn uses_hierarchical(&self) -> bool {
        self.hierarchical
    }

    pub fn num_levels(&self) -> usize {
        self.num_levels
    }
}

#[derive(Debug, Clone)]
pub enum AggregationPattern {
    Ring,
    Tree,
    Butterfly,
}

#[derive(Debug)]
pub struct FailureRecovery {
    pub work_reassigned: bool,
    pub new_world_size: usize,
}

#[derive(Debug, Clone)]
pub struct JobInfo {
    pub job_id: String,
    pub name: String,
    pub num_nodes: usize,
}

impl JobInfo {
    pub fn shares_nodes_with(&self, _other: &Self) -> bool {
        false
    }
}

#[derive(Debug)]
pub struct ResourceAllocation {
    pub nodes_used: usize,
}

impl ResourceAllocation {
    pub fn total_nodes_used(&self) -> usize {
        self.nodes_used
    }
}

#[derive(Debug)]
enum HealthStatus {
    Healthy,
    Unhealthy,
}

#[derive(Debug)]
struct Connection {
    _target: usize,
}