//! Distributed communication and messaging
//!
//! This module handles all aspects of communication between nodes in the distributed
//! computing framework, including protocols, routing, security, and optimization.

use super::cluster::NodeId;
use super::types::DistributedComputingConfig;
use crate::error::{CoreError, CoreResult};
#[cfg(feature = "serialization")]
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::net::SocketAddr;
use std::time::{Duration, Instant};

/// Distributed communication layer
#[derive(Debug)]
pub struct DistributedCommunication {
    /// Communication protocols
    #[allow(dead_code)]
    protocols: Vec<CommunicationProtocol>,
    /// Message routing
    #[allow(dead_code)]
    routing: MessageRouting,
    /// Security layer
    #[allow(dead_code)]
    security: CommunicationSecurity,
    /// Performance optimization
    #[allow(dead_code)]
    optimization: CommunicationOptimization,
}

/// Communication protocols
#[derive(Debug, Clone)]
pub enum CommunicationProtocol {
    TCP,
    UDP,
    HTTP,
    GRpc,
    MessageQueue,
    WebSocket,
    Custom(String),
}

/// Message routing
#[derive(Debug)]
pub struct MessageRouting {
    /// Routing table
    #[allow(dead_code)]
    routing_table: HashMap<NodeId, RoutingEntry>,
    /// Message queues
    #[allow(dead_code)]
    message_queues: HashMap<NodeId, MessageQueue>,
    /// Routing algorithms
    #[allow(dead_code)]
    routing_algorithms: Vec<RoutingAlgorithm>,
}

/// Routing entry
#[derive(Debug, Clone)]
pub struct RoutingEntry {
    /// Direct connection
    pub direct_connection: Option<SocketAddr>,
    /// Relay nodes
    pub relay_nodes: Vec<NodeId>,
    /// Connection quality
    pub quality_score: f64,
    /// Last update
    pub last_updated: Instant,
}

/// Message queue
#[derive(Debug)]
pub struct MessageQueue {
    /// Pending messages
    #[allow(dead_code)]
    pending_messages: Vec<Message>,
    /// Priority queues
    #[allow(dead_code)]
    priority_queues: HashMap<MessagePriority, Vec<Message>>,
    /// Queue statistics
    #[allow(dead_code)]
    statistics: QueueStatistics,
}

/// Message representation
#[derive(Debug, Clone)]
pub struct Message {
    /// Message ID
    pub id: MessageId,
    /// Source node
    pub source: NodeId,
    /// Destination node
    pub destination: NodeId,
    /// Message type
    pub messagetype: MessageType,
    /// Payload
    pub payload: Vec<u8>,
    /// Priority
    pub priority: MessagePriority,
    /// Timestamp
    pub timestamp: Instant,
    /// Expiration time
    pub expires_at: Option<Instant>,
}

/// Message identifier

#[cfg_attr(feature = "serialization", derive(Serialize, Deserialize))]
#[derive(Debug, Clone, Hash, PartialEq, Eq)]
pub struct MessageId(pub String);

/// Message types
#[cfg_attr(feature = "serialization", derive(Serialize, Deserialize))]
#[derive(Debug, Clone)]
pub enum MessageType {
    TaskAssignment,
    TaskResult,
    Heartbeat,
    ResourceUpdate,
    ControlCommand,
    DataTransfer,
    ErrorReport,
}

/// Message priority

#[cfg_attr(feature = "serialization", derive(Serialize, Deserialize))]
#[derive(Debug, Clone, PartialEq, Eq, Hash)]
pub enum MessagePriority {
    Critical,
    High,
    Normal,
    Low,
}

/// Queue statistics
#[derive(Debug, Clone)]
pub struct QueueStatistics {
    /// Messages queued
    pub messages_queued: u64,
    /// Messages sent
    pub messages_sent: u64,
    /// Messages failed
    pub messages_failed: u64,
    /// Average queue time
    pub avg_queue_time: Duration,
}

/// Routing algorithms
#[derive(Debug, Clone)]
pub enum RoutingAlgorithm {
    ShortestPath,
    LoadBalanced,
    LatencyOptimized,
    BandwidthOptimized,
    Adaptive,
}

/// Communication security
#[derive(Debug)]
pub struct CommunicationSecurity {
    /// Encryption settings
    #[allow(dead_code)]
    encryption: EncryptionSettings,
    /// Authentication settings
    #[allow(dead_code)]
    authentication: AuthenticationSettings,
    /// Certificate management
    #[allow(dead_code)]
    certificates: CertificateManager,
    /// Security policies
    #[allow(dead_code)]
    policies: SecurityPolicies,
}

/// Encryption settings
#[derive(Debug, Clone)]
pub struct EncryptionSettings {
    /// Encryption algorithm
    pub algorithm: EncryptionAlgorithm,
    /// Key size
    pub key_size: u32,
    /// Key exchange method
    pub key_exchange: KeyExchangeMethod,
    /// Enable perfect forward secrecy
    pub enable_pfs: bool,
}

/// Encryption algorithms
#[derive(Debug, Clone)]
pub enum EncryptionAlgorithm {
    AES256,
    ChaCha20Poly1305,
    RSA,
    ECC,
}

/// Key exchange methods
#[derive(Debug, Clone)]
pub enum KeyExchangeMethod {
    DiffieHellman,
    ECDH,
    RSA,
    PSK,
}

/// Authentication settings
#[derive(Debug, Clone)]
pub struct AuthenticationSettings {
    /// Authentication method
    pub method: AuthenticationMethod,
    /// Token lifetime
    pub token_lifetime: Duration,
    /// Multi-factor authentication
    pub enable_mfa: bool,
    /// Certificate validation
    pub certificate_validation: bool,
}

/// Authentication methods
#[derive(Debug, Clone)]
pub enum AuthenticationMethod {
    Certificate,
    Token,
    Kerberos,
    OAuth2,
    Custom(String),
}

/// Certificate manager
#[derive(Debug)]
pub struct CertificateManager {
    /// Root certificates
    #[allow(dead_code)]
    root_certificates: Vec<Certificate>,
    /// Node certificates
    #[allow(dead_code)]
    node_certificates: HashMap<NodeId, Certificate>,
    /// Certificate revocation list
    #[allow(dead_code)]
    revocation_list: Vec<String>,
}

/// Certificate representation
#[derive(Debug, Clone)]
pub struct Certificate {
    /// Certificate data
    pub data: Vec<u8>,
    /// Subject
    pub subject: String,
    /// Issuer
    pub issuer: String,
    /// Valid from
    pub valid_from: Instant,
    /// Valid until
    pub valid_until: Instant,
    /// Serial number
    pub serial_number: String,
}

/// Security policies
#[derive(Debug, Clone)]
pub struct SecurityPolicies {
    /// Minimum security level
    pub min_security_level: SecurityLevel,
    /// Allowed cipher suites
    pub allowed_cipher_suites: Vec<String>,
    /// Connection timeout
    pub connection_timeout: Duration,
    /// Maximum message size
    pub max_message_size: usize,
}

/// Security levels
#[derive(Debug, Clone)]
pub enum SecurityLevel {
    None,
    Basic,
    Standard,
    High,
    Maximum,
}

/// Communication optimization
#[derive(Debug)]
pub struct CommunicationOptimization {
    /// Compression settings
    #[allow(dead_code)]
    compression: CompressionSettings,
    /// Bandwidth optimization
    #[allow(dead_code)]
    bandwidth_optimization: BandwidthOptimization,
    /// Latency optimization
    #[allow(dead_code)]
    latency_optimization: LatencyOptimization,
    /// Connection pooling
    #[allow(dead_code)]
    connection_pooling: ConnectionPooling,
}

/// Compression settings
#[derive(Debug, Clone)]
pub struct CompressionSettings {
    /// Compression algorithm
    pub algorithm: CompressionAlgorithm,
    /// Compression level
    pub level: u8,
    /// Minimum size for compression
    pub minsize_bytes: usize,
    /// Enable adaptive compression
    pub adaptive: bool,
}

/// Compression algorithms
#[derive(Debug, Clone)]
pub enum CompressionAlgorithm {
    Gzip,
    Zstd,
    LZ4,
    Snappy,
    Brotli,
}

/// Bandwidth optimization
#[derive(Debug, Clone)]
pub struct BandwidthOptimization {
    /// Enable message batching
    pub enable_batching: bool,
    /// Batch size
    pub batch_size: usize,
    /// Batch timeout
    pub batch_timeout: Duration,
    /// Enable delta compression
    pub enable_delta_compression: bool,
}

/// Latency optimization
#[derive(Debug, Clone)]
pub struct LatencyOptimization {
    /// TCP no delay
    pub tcp_nodelay: bool,
    /// Keep alive settings
    pub keep_alive: bool,
    /// Connection pre-warming
    pub connection_prewarming: bool,
    /// Priority scheduling
    pub priority_scheduling: bool,
}

/// Connection pooling
#[derive(Debug, Clone)]
pub struct ConnectionPooling {
    /// Pool size per node
    pub poolsize_per_node: usize,
    /// Connection idle timeout
    pub idle_timeout: Duration,
    /// Connection reuse limit
    pub reuse_limit: u32,
    /// Enable health checking
    pub enable_health_checking: bool,
}

// Implementations
impl DistributedCommunication {
    pub fn new(config: &DistributedComputingConfig) -> CoreResult<Self> {
        Ok(Self {
            protocols: vec![CommunicationProtocol::GRpc, CommunicationProtocol::TCP],
            routing: MessageRouting {
                routing_table: HashMap::new(),
                message_queues: HashMap::new(),
                routing_algorithms: vec![RoutingAlgorithm::Adaptive],
            },
            security: CommunicationSecurity {
                encryption: EncryptionSettings {
                    algorithm: EncryptionAlgorithm::AES256,
                    key_size: 256,
                    key_exchange: KeyExchangeMethod::ECDH,
                    enable_pfs: true,
                },
                authentication: AuthenticationSettings {
                    method: AuthenticationMethod::Certificate,
                    token_lifetime: Duration::from_secs(60 * 60),
                    enable_mfa: false,
                    certificate_validation: true,
                },
                certificates: CertificateManager {
                    root_certificates: Vec::new(),
                    node_certificates: HashMap::new(),
                    revocation_list: Vec::new(),
                },
                policies: SecurityPolicies {
                    min_security_level: SecurityLevel::High,
                    allowed_cipher_suites: vec!["TLS_AES_256_GCM_SHA384".to_string()],
                    connection_timeout: Duration::from_secs(30),
                    max_message_size: 10 * 1024 * 1024, // 10MB
                },
            },
            optimization: CommunicationOptimization {
                compression: CompressionSettings {
                    algorithm: CompressionAlgorithm::Zstd,
                    level: 3,
                    minsize_bytes: 1024,
                    adaptive: true,
                },
                bandwidth_optimization: BandwidthOptimization {
                    enable_batching: true,
                    batch_size: 100,
                    batch_timeout: Duration::from_millis(10),
                    enable_delta_compression: true,
                },
                latency_optimization: LatencyOptimization {
                    tcp_nodelay: true,
                    keep_alive: true,
                    connection_prewarming: true,
                    priority_scheduling: true,
                },
                connection_pooling: ConnectionPooling {
                    poolsize_per_node: 10,
                    idle_timeout: Duration::from_secs(300),
                    reuse_limit: 1000,
                    enable_health_checking: true,
                },
            },
        })
    }

    pub fn start(&mut self) -> CoreResult<()> {
        println!("📡 Starting distributed communication...");
        Ok(())
    }
}
