mlmf 0.2.0

//! Distributed model loader implementation.
//!
//! This module provides the main distributed model loading functionality,
//! integrating with the caching system and managing model shards across nodes.

use std::collections::HashMap;
use std::sync::Arc;
use tokio::sync::{RwLock, Mutex};
use std::time::{Duration, Instant};
use serde::{Deserialize, Serialize};

use crate::distributed::*;
use crate::cached_loader::CachedModelLoader;
use anyhow::{Result, anyhow};
// Simplified without LoadedModel for initial implementation

/// Distributed model loader that manages models across multiple nodes
pub struct DistributedModelLoader {
    /// Configuration for distributed deployment
    config: Arc<DistributedConfig>,
    
    /// Cached model loader for individual node loading
    cached_loader: Arc<CachedModelLoader>,
    
    /// Registry of active distributed models
    models: Arc<RwLock<HashMap<String, DistributedModel>>>,
    
    /// Node manager for cluster coordination
    node_manager: Arc<NodeManager>,
    
    /// Shard manager for model distribution
    shard_manager: Arc<ShardManager>,
    
    /// Load balancer for request distribution
    load_balancer: Arc<LoadBalancer>,
    
    /// Health monitor for node monitoring
    health_monitor: Arc<HealthMonitor>,
    
    /// Statistics tracking
    stats: Arc<RwLock<DistributedStats>>,
}

/// Node manager for cluster coordination
pub struct NodeManager {
    /// Active nodes in the cluster
    active_nodes: Arc<RwLock<HashMap<String, NodeInfo>>>,
    
    /// Communication client for inter-node communication
    communication: Arc<CommunicationManager>,
    
    /// Node discovery mechanism
    discovery: Arc<NodeDiscovery>,
}

/// Information about an active node
#[derive(Debug, Clone)]
pub struct NodeInfo {
    /// Node configuration
    pub config: NodeConfig,
    
    /// Current node status
    pub status: NodeStatus,
    
    /// Node statistics
    pub stats: NodeStats,
    
    /// Last heartbeat timestamp
    pub last_heartbeat: Instant,
}

/// Status of a node in the cluster
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum NodeStatus {
    /// Node is healthy and available
    Healthy,
    
    /// Node is degraded but still functional
    Degraded,
    
    /// Node is unhealthy but may recover
    Unhealthy,
    
    /// Node has failed and is unavailable
    Failed,
    
    /// Node is being drained
    Draining,
    
    /// Node is offline
    Offline,
}

/// Statistics for a node
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
pub struct NodeStats {
    /// Number of requests processed
    pub requests_processed: u64,
    
    /// Average response time in milliseconds
    pub avg_response_time_ms: f64,
    
    /// Current CPU utilization (0.0 to 1.0)
    pub cpu_utilization: f32,
    
    /// Current memory utilization (0.0 to 1.0)
    pub memory_utilization: f32,
    
    /// Current network utilization (0.0 to 1.0)
    pub network_utilization: f32,
    
    /// Number of active model shards
    pub active_shards: usize,
    
    /// Error count in the last period
    pub error_count: u64,
}

/// Shard manager for model distribution
pub struct ShardManager {
    /// Active shards across all nodes
    shards: Arc<RwLock<HashMap<String, ModelShard>>>,
    
    /// Placement optimizer
    placement_optimizer: Arc<PlacementOptimizer>,
    
    /// Migration manager for shard movement
    migration_manager: Arc<MigrationManager>,
}

/// Placement optimizer for optimal shard placement
pub struct PlacementOptimizer {
    /// Current placement strategy
    strategy: PlacementStrategy,
    
    /// Resource monitor for placement decisions
    resource_monitor: Arc<ResourceMonitor>,
}

/// Migration manager for moving shards between nodes
pub struct MigrationManager {
    /// Active migrations
    active_migrations: Arc<RwLock<HashMap<String, Migration>>>,
    
    /// Migration queue
    migration_queue: Arc<Mutex<Vec<MigrationRequest>>>,
}

/// Information about an active migration
#[derive(Debug, Clone)]
pub struct Migration {
    /// Migration ID
    pub migration_id: String,
    
    /// Shard being migrated
    pub shard_id: String,
    
    /// Source node
    pub source_node: String,
    
    /// Destination node
    pub destination_node: String,
    
    /// Migration status
    pub status: MigrationStatus,
    
    /// Start time
    pub started_at: Instant,
    
    /// Progress (0.0 to 1.0)
    pub progress: f32,
}

/// Status of a migration
#[derive(Debug, Clone, PartialEq)]
pub enum MigrationStatus {
    /// Migration is queued
    Queued,
    
    /// Migration is in progress
    InProgress,
    
    /// Migration completed successfully
    Completed,
    
    /// Migration failed
    Failed(String),
    
    /// Migration was cancelled
    Cancelled,
}

/// Request for shard migration
#[derive(Debug, Clone)]
pub struct MigrationRequest {
    /// Shard to migrate
    pub shard_id: String,
    
    /// Source node
    pub source_node: String,
    
    /// Destination node
    pub destination_node: String,
    
    /// Migration priority
    pub priority: MigrationPriority,
    
    /// Reason for migration
    pub reason: String,
}

/// Priority levels for migrations
#[derive(Debug, Clone, PartialEq, PartialOrd)]
pub enum MigrationPriority {
    /// Low priority migration
    Low,
    
    /// Normal priority migration
    Normal,
    
    /// High priority migration
    High,
    
    /// Emergency migration (node failure)
    Emergency,
}

/// Load balancer for request distribution
pub struct LoadBalancer {
    /// Load balancing strategy
    strategy: LoadBalancingStrategy,
    
    /// Request router
    router: Arc<RequestRouter>,
    
    /// Health checker for nodes
    health_checker: Arc<HealthChecker>,
}

/// Request router for distributing requests
pub struct RequestRouter {
    /// Routing table
    routing_table: Arc<RwLock<RoutingTable>>,
    
    /// Session affinity tracker
    session_tracker: Arc<SessionTracker>,
}

/// Routing table for request distribution
#[derive(Debug, Clone)]
pub struct RoutingTable {
    /// Routes for each model
    pub model_routes: HashMap<String, Vec<Route>>,
    
    /// Default routes
    pub default_routes: Vec<Route>,
}

/// A route to a specific node/shard
#[derive(Debug, Clone)]
pub struct Route {
    /// Target node ID
    pub node_id: String,
    
    /// Target shard ID (if applicable)
    pub shard_id: Option<String>,
    
    /// Route weight for load balancing
    pub weight: f32,
    
    /// Route health status
    pub healthy: bool,
    
    /// Last response time
    pub last_response_time: Duration,
}

/// Session affinity tracker
pub struct SessionTracker {
    /// Active sessions
    sessions: Arc<RwLock<HashMap<String, SessionInfo>>>,
}

/// Information about a client session
#[derive(Debug, Clone)]
pub struct SessionInfo {
    /// Session ID
    pub session_id: String,
    
    /// Assigned node ID
    pub node_id: String,
    
    /// Last activity timestamp
    pub last_activity: Instant,
    
    /// Session creation time
    pub created_at: Instant,
}

/// Health checker for nodes
pub struct HealthChecker {
    /// Health check configuration
    config: HealthCheckConfig,
    
    /// Active health checks
    active_checks: Arc<RwLock<HashMap<String, HealthCheck>>>,
}

/// Information about a health check
#[derive(Debug, Clone)]
pub struct HealthCheck {
    /// Node being checked
    pub node_id: String,
    
    /// Last check time
    pub last_check: Instant,
    
    /// Check result
    pub result: HealthCheckResult,
    
    /// Consecutive failures
    pub consecutive_failures: u32,
    
    /// Consecutive successes
    pub consecutive_successes: u32,
}

/// Result of a health check
#[derive(Debug, Clone)]
pub enum HealthCheckResult {
    /// Health check passed
    Healthy { response_time: Duration },
    
    /// Health check failed
    Unhealthy { error: String },
    
    /// Health check timed out
    Timeout,
    
    /// Health check was skipped
    Skipped,
}

/// Health monitor for overall cluster health
pub struct HealthMonitor {
    /// Monitor configuration
    config: Arc<DistributedConfig>,
    
    /// Cluster health status
    cluster_health: Arc<RwLock<ClusterHealth>>,
    
    /// Alert manager
    alert_manager: Arc<AlertManager>,
}

/// Overall cluster health information
#[derive(Debug, Clone)]
pub struct ClusterHealth {
    /// Overall health status
    pub status: ClusterHealthStatus,
    
    /// Number of healthy nodes
    pub healthy_nodes: usize,
    
    /// Total number of nodes
    pub total_nodes: usize,
    
    /// Number of available model shards
    pub available_shards: usize,
    
    /// Total number of shards
    pub total_shards: usize,
    
    /// Last update timestamp
    pub last_updated: Instant,
}

/// Cluster health status
#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
pub enum ClusterHealthStatus {
    /// Cluster is healthy
    Healthy,
    
    /// Cluster is degraded but functional
    Degraded,
    
    /// Cluster is in critical state
    Critical,
    
    /// Cluster is unavailable
    Unavailable,
}

/// Alert manager for notifications
pub struct AlertManager {
    /// Alert configuration
    config: AlertConfig,
    
    /// Active alerts
    active_alerts: Arc<RwLock<HashMap<String, Alert>>>,
}

/// Alert configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AlertConfig {
    /// Enable alerting
    pub enabled: bool,
    
    /// Alert channels
    pub channels: Vec<AlertChannel>,
    
    /// Alert rules
    pub rules: Vec<AlertRule>,
}

/// Alert channel configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum AlertChannel {
    /// Log alerts to console
    Console,
    
    /// Send email alerts
    Email { smtp_config: SmtpConfig },
    
    /// Send webhook alerts
    Webhook { url: String, headers: HashMap<String, String> },
    
    /// Send Slack alerts
    Slack { webhook_url: String },
}

/// SMTP configuration for email alerts
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct SmtpConfig {
    /// SMTP server host
    pub host: String,
    
    /// SMTP server port
    pub port: u16,
    
    /// Username for authentication
    pub username: String,
    
    /// Password for authentication
    pub password: String,
    
    /// From email address
    pub from: String,
    
    /// To email addresses
    pub to: Vec<String>,
}

/// Alert rule configuration
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct AlertRule {
    /// Rule name
    pub name: String,
    
    /// Rule condition
    pub condition: AlertCondition,
    
    /// Alert severity
    pub severity: AlertSeverity,
    
    /// Notification channels
    pub channels: Vec<String>,
}

/// Alert condition
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum AlertCondition {
    /// Node health condition
    NodeHealth { status: NodeStatus },
    
    /// Cluster health condition
    ClusterHealth { status: ClusterHealthStatus },
    
    /// Resource utilization condition
    ResourceUtilization { resource: String, threshold: f32 },
    
    /// Error rate condition
    ErrorRate { threshold: f32, window_minutes: u32 },
    
    /// Response time condition
    ResponseTime { threshold_ms: u64, percentile: f32 },
}

/// Alert severity levels
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq, PartialOrd)]
pub enum AlertSeverity {
    /// Informational alert
    Info,
    
    /// Warning alert
    Warning,
    
    /// Error alert
    Error,
    
    /// Critical alert
    Critical,
}

/// Active alert information
#[derive(Debug, Clone)]
pub struct Alert {
    /// Alert ID
    pub alert_id: String,
    
    /// Alert rule that triggered
    pub rule_name: String,
    
    /// Alert message
    pub message: String,
    
    /// Alert severity
    pub severity: AlertSeverity,
    
    /// Alert creation time
    pub created_at: Instant,
    
    /// Alert status
    pub status: AlertStatus,
}

/// Status of an alert
#[derive(Debug, Clone, PartialEq)]
pub enum AlertStatus {
    /// Alert is active
    Active,
    
    /// Alert has been acknowledged
    Acknowledged,
    
    /// Alert has been resolved
    Resolved,
    
    /// Alert was a false positive
    Suppressed,
}

/// Communication manager for inter-node communication
pub struct CommunicationManager {
    /// Communication protocol
    protocol: CommunicationProtocol,
    
    /// Active connections
    connections: Arc<RwLock<HashMap<String, Connection>>>,
    
    /// Message serializer
    serializer: Arc<MessageSerializer>,
}

/// Connection to a remote node
pub struct Connection {
    /// Node ID
    pub node_id: String,
    
    /// Connection status
    pub status: ConnectionStatus,
    
    /// Last activity timestamp
    pub last_activity: Instant,
    
    /// Connection statistics
    pub stats: ConnectionStats,
}

/// Status of a connection
#[derive(Debug, Clone, PartialEq)]
pub enum ConnectionStatus {
    /// Connection is active
    Connected,
    
    /// Connection is being established
    Connecting,
    
    /// Connection is disconnected
    Disconnected,
    
    /// Connection failed
    Failed(String),
}

/// Statistics for a connection
#[derive(Debug, Clone, Default)]
pub struct ConnectionStats {
    /// Messages sent
    pub messages_sent: u64,
    
    /// Messages received
    pub messages_received: u64,
    
    /// Bytes sent
    pub bytes_sent: u64,
    
    /// Bytes received
    pub bytes_received: u64,
    
    /// Average round-trip time
    pub avg_rtt_ms: f64,
    
    /// Connection errors
    pub errors: u64,
}

/// Message serializer for inter-node communication
pub struct MessageSerializer {
    /// Serialization format
    format: SerializationFormat,
    
    /// Compression configuration
    compression: CompressionConfig,
}

/// Serialization formats
#[derive(Debug, Clone)]
pub enum SerializationFormat {
    /// JSON serialization
    Json,
    
    /// Binary serialization
    Bincode,
    
    /// Protocol Buffers
    Protobuf,
    
    /// MessagePack
    MessagePack,
}

/// Node discovery mechanism
pub struct NodeDiscovery {
    /// Discovery method
    method: DiscoveryMethod,
    
    /// Known nodes
    known_nodes: Arc<RwLock<HashMap<String, NodeConfig>>>,
}

/// Node discovery methods
#[derive(Debug, Clone)]
pub enum DiscoveryMethod {
    /// Static configuration
    Static { nodes: Vec<NodeConfig> },
    
    /// DNS-based discovery
    Dns { domain: String, port: u16 },
    
    /// Consul-based discovery
    Consul { address: String, service: String },
    
    /// Kubernetes-based discovery
    Kubernetes { namespace: String, service: String },
    
    /// Multicast discovery
    Multicast { group: String, port: u16 },
}

/// Resource monitor for tracking node resources
pub struct ResourceMonitor {
    /// Resource collection interval
    interval: Duration,
    
    /// Resource history
    history: Arc<RwLock<HashMap<String, Vec<ResourceSnapshot>>>>,
}

/// Snapshot of node resources at a point in time
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ResourceSnapshot {
    /// Timestamp of the snapshot
    pub timestamp: chrono::DateTime<chrono::Utc>,
    
    /// CPU utilization (0.0 to 1.0)
    pub cpu_utilization: f32,
    
    /// Memory utilization (0.0 to 1.0)
    pub memory_utilization: f32,
    
    /// Disk utilization (0.0 to 1.0)
    pub disk_utilization: f32,
    
    /// Network utilization (0.0 to 1.0)
    pub network_utilization: f32,
    
    /// Available memory in bytes
    pub available_memory: u64,
    
    /// Available disk space in bytes
    pub available_disk: u64,
}

/// Statistics for distributed operations
#[derive(Debug, Clone, Default, Serialize, Deserialize)]
pub struct DistributedStats {
    /// Total requests processed
    pub total_requests: u64,
    
    /// Average response time across all nodes
    pub avg_response_time_ms: f64,
    
    /// Request throughput (requests per second)
    pub throughput_rps: f64,
    
    /// Cache hit ratio across all nodes
    pub cache_hit_ratio: f64,
    
    /// Number of active models
    pub active_models: usize,
    
    /// Total number of shards
    pub total_shards: usize,
    
    /// Number of migrations performed
    pub migrations_completed: u64,
    
    /// Average migration time
    pub avg_migration_time_ms: f64,
    
    /// Error rate (errors per second)
    pub error_rate: f64,
    
    /// Node availability (0.0 to 1.0)
    pub node_availability: f64,
}

impl DistributedModelLoader {
    /// Create a new distributed model loader
    pub fn new(config: DistributedConfig) -> Result<Self> {
        let config = Arc::new(config);
        let cached_loader = Arc::new(CachedModelLoader::new());
        
        let node_manager = Arc::new(NodeManager::new(config.clone())?);
        let shard_manager = Arc::new(ShardManager::new(config.clone())?);
        let load_balancer = Arc::new(LoadBalancer::new(config.clone())?);
        let health_monitor = Arc::new(HealthMonitor::new(config.clone())?);
        
        Ok(Self {
            config,
            cached_loader,
            models: Arc::new(RwLock::new(HashMap::new())),
            node_manager,
            shard_manager,
            load_balancer,
            health_monitor,
            stats: Arc::new(RwLock::new(DistributedStats::default())),
        })
    }

    /// Deploy a model across the distributed cluster
    pub async fn deploy_model<P: AsRef<std::path::Path>>(
        &self,
        model_path: P,
        model_id: String,
    ) -> Result<String> {
        // Implementation for deploying a model across nodes
        // This would involve:
        // 1. Analyzing the model for sharding
        // 2. Creating a deployment plan
        // 3. Distributing shards to nodes
        // 4. Setting up load balancing
        // 5. Starting health monitoring
        
        todo!("Implement model deployment")
    }

    /// Load a distributed model for inference
    pub async fn load_distributed_model(&self, _model_id: &str) -> Result<String> {
        // Implementation for loading a distributed model
        // This would coordinate loading across all shards
        
        todo!("Implement distributed model loading")
    }

    /// Get statistics for the distributed system
    pub async fn get_stats(&self) -> DistributedStats {
        self.stats.read().await.clone()
    }

    /// Get cluster health information
    pub async fn get_cluster_health(&self) -> ClusterHealth {
        self.health_monitor.get_cluster_health().await
    }

    /// Migrate a shard to a different node
    pub async fn migrate_shard(
        &self,
        shard_id: &str,
        target_node: &str,
    ) -> Result<String> {
        self.shard_manager
            .migrate_shard(shard_id, target_node)
            .await
    }

    /// Scale the cluster up or down
    pub async fn scale_cluster(&self, target_nodes: usize) -> Result<()> {
        // Implementation for scaling the cluster
        todo!("Implement cluster scaling")
    }
}

// Implementations for the various managers would follow...
// Due to length constraints, I'll implement the core functionality

impl NodeManager {
    fn new(config: Arc<DistributedConfig>) -> Result<Self> {
        // Initialize node manager
        todo!("Implement NodeManager::new")
    }
}

impl ShardManager {
    fn new(config: Arc<DistributedConfig>) -> Result<Self> {
        // Initialize shard manager
        todo!("Implement ShardManager::new")
    }

    async fn migrate_shard(&self, shard_id: &str, target_node: &str) -> Result<String> {
        // Implement shard migration
        todo!("Implement shard migration")
    }
}

impl LoadBalancer {
    fn new(config: Arc<DistributedConfig>) -> Result<Self> {
        // Initialize load balancer
        todo!("Implement LoadBalancer::new")
    }
}

impl HealthMonitor {
    fn new(config: Arc<DistributedConfig>) -> Result<Self> {
        // Initialize health monitor
        todo!("Implement HealthMonitor::new")
    }

    async fn get_cluster_health(&self) -> ClusterHealth {
        self.cluster_health.read().await.clone()
    }
}