//! 网络传输模块
//! 
//! 处理网络连接的建立、维护和数据传输

#![allow(dead_code, unused_variables, missing_docs)]

use crate::types::NodeId;
use std::collections::HashMap;
use std::net::SocketAddr;
use std::sync::Arc;
use tokio::sync::RwLock;

/// 传输层配置
#[derive(Debug, Clone)]
pub struct TransportConfig {
    /// 本地监听地址
    pub listen_addr: SocketAddr,
    /// 最大连接数
    pub max_connections: usize,
    /// 连接超时（秒）
    pub connection_timeout: u64,
    /// 是否启用TLS
    pub enable_tls: bool,
    /// 是否启用NAT穿透
    pub enable_nat_traversal: bool,
    /// 传输协议
    pub protocol: TransportProtocol,
}

/// 传输协议
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum TransportProtocol {
    /// TCP协议
    Tcp,
    /// UDP协议
    Udp,
    /// WebSocket协议
    WebSocket,
    /// QUIC协议
    Quic,
}

/// 连接状态
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ConnectionStatus {
    /// 连接中
    Connecting,
    /// 已连接
    Connected,
    /// 断开连接中
    Disconnecting,
    /// 已断开
    Disconnected,
    /// 连接失败
    Failed,
}

/// 连接信息
#[derive(Debug, Clone)]
pub struct ConnectionInfo {
    /// 远程节点ID
    pub remote_node_id: NodeId,
    /// 远程地址
    pub remote_addr: SocketAddr,
    /// 连接状态
    pub status: ConnectionStatus,
    /// 建立时间
    pub established_at: std::time::SystemTime,
    /// 最后活动时间
    pub last_activity: std::time::SystemTime,
    /// 发送字节数
    pub bytes_sent: u64,
    /// 接收字节数
    pub bytes_received: u64,
    /// 连接质量评分（0-100）
    pub quality_score: u8,
}

/// 传输层管理器
pub struct TransportManager {
    /// 配置
    config: TransportConfig,
    /// 本地节点ID
    local_node_id: NodeId,
    /// 活跃连接
    connections: Arc<RwLock<HashMap<NodeId, ConnectionInfo>>>,
    /// 连接统计
    stats: Arc<RwLock<TransportStats>>,
}

/// 传输统计
#[derive(Debug, Clone, Default)]
pub struct TransportStats {
    /// 总连接尝试次数
    pub total_connection_attempts: u64,
    /// 成功连接次数
    pub successful_connections: u64,
    /// 失败连接次数
    pub failed_connections: u64,
    /// 当前活跃连接数
    pub active_connections: usize,
    /// 总发送字节数
    pub total_bytes_sent: u64,
    /// 总接收字节数
    pub total_bytes_received: u64,
    /// 平均连接质量
    pub average_quality_score: f64,
}

impl TransportManager {
    /// 创建新的传输管理器
    pub fn new(config: TransportConfig, local_node_id: NodeId) -> Self {
        Self {
            config,
            local_node_id,
            connections: Arc::new(RwLock::new(HashMap::new())),
            stats: Arc::new(RwLock::new(TransportStats::default())),
        }
    }
    
    /// 启动传输层
    pub async fn start(&self) -> Result<(), String> {
        println!("🚀 启动传输层，监听地址: {}", self.config.listen_addr);
        
        match self.config.protocol {
            TransportProtocol::Tcp => self.start_tcp().await,
            TransportProtocol::Udp => self.start_udp().await,
            TransportProtocol::WebSocket => self.start_websocket().await,
            TransportProtocol::Quic => self.start_quic().await,
        }
    }
    
    /// 启动TCP传输
    async fn start_tcp(&self) -> Result<(), String> {
        println!("  使用TCP协议");
        
        // 在实际实现中，这里会启动TCP服务器
        // 目前只是模拟启动
        tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;
        
        println!("  TCP传输层启动成功");
        Ok(())
    }
    
    /// 启动UDP传输
    async fn start_udp(&self) -> Result<(), String> {
        println!("  使用UDP协议");
        
        // 在实际实现中，这里会启动UDP服务器
        tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;
        
        println!("  UDP传输层启动成功");
        Ok(())
    }
    
    /// 启动WebSocket传输
    async fn start_websocket(&self) -> Result<(), String> {
        println!("  使用WebSocket协议");
        
        // 在实际实现中，这里会启动WebSocket服务器
        tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;
        
        println!("  WebSocket传输层启动成功");
        Ok(())
    }
    
    /// 启动QUIC传输
    async fn start_quic(&self) -> Result<(), String> {
        println!("  使用QUIC协议");
        
        // 在实际实现中，这里会启动QUIC服务器
        tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;
        
        println!("  QUIC传输层启动成功");
        Ok(())
    }
    
    /// 连接到远程节点
    pub async fn connect_to_node(&self, node_id: &NodeId, addr: SocketAddr) -> Result<(), String> {
        println!("🔗 连接到节点 {} ({})", node_id, addr);
        
        let mut stats = self.stats.write().await;
        stats.total_connection_attempts += 1;
        
        // 模拟连接过程
        tokio::time::sleep(tokio::time::Duration::from_millis(50)).await;
        
        // 模拟连接成功率
        let success = rand::random::<f64>() > 0.1; // 90%成功率
        
        if success {
            let mut connections = self.connections.write().await;
            
            let connection_info = ConnectionInfo {
                remote_node_id: node_id.clone(),
                remote_addr: addr,
                status: ConnectionStatus::Connected,
                established_at: std::time::SystemTime::now(),
                last_activity: std::time::SystemTime::now(),
                bytes_sent: 0,
                bytes_received: 0,
                quality_score: 85, // 初始质量评分
            };
            
            connections.insert(node_id.clone(), connection_info);
            
            stats.successful_connections += 1;
            stats.active_connections = connections.len();
            
            println!("✅ 成功连接到节点 {}", node_id);
            Ok(())
        } else {
            stats.failed_connections += 1;
            
            println!("❌ 连接到节点 {} 失败", node_id);
            Err("连接失败".to_string())
        }
    }
    
    /// 断开与节点的连接
    pub async fn disconnect_from_node(&self, node_id: &NodeId) -> Result<(), String> {
        println!("🔌 断开与节点 {} 的连接", node_id);
        
        let mut connections = self.connections.write().await;
        
        if let Some(connection) = connections.get_mut(node_id) {
            connection.status = ConnectionStatus::Disconnected;
            connections.remove(node_id);
            
            let mut stats = self.stats.write().await;
            stats.active_connections = connections.len();
            
            println!("✅ 已断开与节点 {} 的连接", node_id);
            Ok(())
        } else {
            println!("⚠️  节点 {} 未连接", node_id);
            Err("节点未连接".to_string())
        }
    }
    
    /// 发送数据到节点
    pub async fn send_to_node(&self, node_id: &NodeId, data: &[u8]) -> Result<usize, String> {
        let mut connections = self.connections.write().await;
        
        if let Some(connection) = connections.get_mut(node_id) {
            if connection.status != ConnectionStatus::Connected {
                return Err("连接未就绪".to_string());
            }
            
            // 模拟发送过程
            let bytes_sent = data.len();
            connection.bytes_sent += bytes_sent as u64;
            connection.last_activity = std::time::SystemTime::now();
            
            // 模拟网络质量影响
            let success_rate = connection.quality_score as f64 / 100.0;
            let success = rand::random::<f64>() < success_rate;
            
            if success {
                let mut stats = self.stats.write().await;
                stats.total_bytes_sent += bytes_sent as u64;
                
                println!("📤 发送 {} 字节到节点 {}", bytes_sent, node_id);
                Ok(bytes_sent)
            } else {
                println!("⚠️  发送到节点 {} 失败（网络质量: {}%）", node_id, connection.quality_score);
                Err("发送失败".to_string())
            }
        } else {
            Err("节点未连接".to_string())
        }
    }
    
    /// 广播数据到所有连接的节点
    pub async fn broadcast(&self, data: &[u8]) -> HashMap<NodeId, Result<usize, String>> {
        println!("📢 广播 {} 字节数据", data.len());
        
        let connections = self.connections.read().await;
        let mut results = HashMap::new();
        
        for (node_id, _) in connections.iter() {
            if connections[node_id].status == ConnectionStatus::Connected {
                // 在实际实现中，这里会并行发送
                let result = self.send_to_node(node_id, data).await;
                results.insert(node_id.clone(), result);
            }
        }
        
        results
    }
    
    /// 获取连接信息
    pub async fn get_connection_info(&self, node_id: &NodeId) -> Option<ConnectionInfo> {
        let connections = self.connections.read().await;
        connections.get(node_id).cloned()
    }
    
    /// 获取所有连接信息
    pub async fn get_all_connections(&self) -> Vec<ConnectionInfo> {
        let connections = self.connections.read().await;
        connections.values().cloned().collect()
    }
    
    /// 获取传输统计
    pub async fn get_stats(&self) -> TransportStats {
        self.stats.read().await.clone()
    }
    
    /// 更新连接质量
    pub async fn update_connection_quality(&self, node_id: &NodeId, quality_score: u8) -> Result<(), String> {
        let mut connections = self.connections.write().await;
        
        if let Some(connection) = connections.get_mut(node_id) {
            connection.quality_score = quality_score.clamp(0, 100);
            
            // 更新平均质量评分
            let mut stats = self.stats.write().await;
            let total_quality: u32 = connections.values().map(|c| c.quality_score as u32).sum();
            stats.average_quality_score = total_quality as f64 / connections.len() as f64;
            
            Ok(())
        } else {
            Err("节点未连接".to_string())
        }
    }
    
    /// 清理不活跃的连接
    pub async fn cleanup_inactive_connections(&self, max_inactive_seconds: u64) -> usize {
        let mut connections = self.connections.write().await;
        let initial_count = connections.len();
        
        let now = std::time::SystemTime::now();
        
        connections.retain(|_, connection| {
            if let Ok(duration) = now.duration_since(connection.last_activity) {
                duration.as_secs() <= max_inactive_seconds
            } else {
                true // 如果时间计算失败，保留连接
            }
        });
        
        let removed_count = initial_count - connections.len();
        if removed_count > 0 {
            println!("🧹 清理了 {} 个不活跃连接", removed_count);
            
            let mut stats = self.stats.write().await;
            stats.active_connections = connections.len();
        }
        
        removed_count
    }
}

impl Default for TransportConfig {
    fn default() -> Self {
        Self {
            listen_addr: "0.0.0.0:8080".parse().unwrap(),
            max_connections: 100,
            connection_timeout: 30,
            enable_tls: false,
            enable_nat_traversal: true,
            protocol: TransportProtocol::Tcp,
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use std::net::{IpAddr, Ipv4Addr};
    
    #[tokio::test]
    async fn test_transport_manager() {
        let config = TransportConfig::default();
        let manager = TransportManager::new(config, "local_node".to_string());
        
        // 测试启动传输层
        let result = manager.start().await;
        assert!(result.is_ok());
        
        // 测试连接到节点
        let remote_addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)), 8081);
        let result = manager.connect_to_node(&"node1".to_string(), remote_addr).await;
        
        // 由于是模拟，连接可能成功也可能失败
        if result.is_ok() {
            // 测试获取连接信息
            let info = manager.get_connection_info(&"node1".to_string()).await;
            assert!(info.is_some());
            
            if let Some(info) = info {
                assert_eq!(info.remote_node_id, "node1");
                assert_eq!(info.status, ConnectionStatus::Connected);
            }
            
            // 测试发送数据
            let data = b"test data";
            let result = manager.send_to_node(&"node1".to_string(), data).await;
            assert!(result.is_ok() || result.is_err()); // 可能成功也可能失败
            
            // 测试断开连接
            let result = manager.disconnect_from_node(&"node1".to_string()).await;
            assert!(result.is_ok());
        }
        
        // 测试获取统计
        let stats = manager.get_stats().await;
        assert!(stats.total_connection_attempts >= 1);
    }
}
