#!/usr/bin/env python3
"""
比特币P2P网络连接管理
演示连接策略、连接多样性和健康检测机制
"""

import time
import random
import socket
import threading


class ConnectionManager:
    """P2P网络连接管理器"""
    
    def __init__(self):
        self.outbound_peers = []    # 主动连接的节点
        self.inbound_peers = []     # 被动接受的连接
        self.max_outbound = 8       # 最大主动连接数
        self.max_inbound = 125      # 最大被动连接数
        self.addr_manager = None    # 地址管理器
        self.server_socket = None   # 服务器套接字
        
    def maintain_outbound_connections(self):
        """维持主动连接"""
        target_connections = self.max_outbound
        
        while len(self.outbound_peers) < target_connections:
            if self.addr_manager:
                # 从地址管理器选择节点
                addr = self.addr_manager.select_peer_to_connect()
                if addr and self.try_connect(addr):
                    self.outbound_peers.append(addr)
                    print(f"建立主动连接: {addr}")
            
            time.sleep(1)  # 避免连接风暴
    
    def accept_inbound_connections(self):
        """接受被动连接"""
        max_inbound = self.max_inbound
        
        if not self.server_socket:
            print("服务器套接字未初始化")
            return
            
        while len(self.inbound_peers) < max_inbound:
            try:
                client_socket, addr = self.server_socket.accept()
                # 验证连接合法性
                if self.validate_inbound_connection(addr):
                    self.inbound_peers.append(client_socket)
                    self.handle_peer(client_socket)
                    print(f"接受被动连接: {addr}")
            except socket.timeout:
                continue
            except Exception as e:
                print(f"接受连接时出错: {e}")
                break
    
    def try_connect(self, addr):
        """尝试连接到节点"""
        try:
            sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
            sock.settimeout(5)
            sock.connect((addr, 8333))
            return sock
        except Exception as e:
            print(f"连接失败 {addr}: {e}")
            return None
    
    def validate_inbound_connection(self, addr):
        """验证入站连接"""
        # 检查IP是否在黑名单中
        # 检查连接数限制
        # 检查地理分布
        return True  # 简化实现
    
    def handle_peer(self, peer_socket):
        """处理对等节点"""
        # 创建新线程处理节点通信
        thread = threading.Thread(target=self._peer_handler, args=(peer_socket,))
        thread.daemon = True
        thread.start()
    
    def _peer_handler(self, peer_socket):
        """节点通信处理器"""
        while True:
            try:
                # 接收和处理消息
                data = peer_socket.recv(4096)
                if not data:
                    break
                # 处理接收到的数据
                self.process_peer_message(data)
            except Exception as e:
                print(f"处理节点消息出错: {e}")
                break
        peer_socket.close()
    
    def process_peer_message(self, data):
        """处理节点消息"""
        # 解析和处理不同类型的消息
        pass


class DiversityManager:
    """连接多样性管理"""
    
    def __init__(self, peers):
        self.peers = peers
    
    def ensure_geographic_diversity(self):
        """确保地理多样性"""
        # 避免所有连接集中在同一个/16网段
        subnets = {}
        for peer in self.peers:
            if hasattr(peer, 'ip'):
                subnet = '.'.join(peer.ip.split('.')[0:2])
                subnets[subnet] = subnets.get(subnet, 0) + 1
        
        # 限制单一子网的连接数量
        max_per_subnet = 2
        for subnet, count in subnets.items():
            if count > max_per_subnet:
                print(f"子网 {subnet} 连接过多 ({count}), 需要断开多余连接")
                # self.disconnect_excess_peers_from_subnet(subnet)
    
    def maintain_protocol_diversity(self):
        """维护协议版本多样性"""
        # 保持与不同协议版本的连接
        version_groups = {}
        for peer in self.peers:
            if hasattr(peer, 'protocol_version'):
                version = peer.protocol_version
                version_groups.setdefault(version, []).append(peer)
        
        # 确保向后兼容性
        min_old_version_peers = 2
        old_version_peers = [p for p in self.peers 
                           if hasattr(p, 'protocol_version') and p.protocol_version < 70015]
        
        if len(old_version_peers) < min_old_version_peers:
            print("需要寻找更多老版本协议的节点")
            # self.seek_old_version_peers()


class HealthMonitor:
    """连接健康监测"""
    
    def __init__(self, peers):
        self.peers = peers
        self.ping_timeout = 90  # 90秒超时
    
    def heartbeat_check(self):
        """心跳检测"""
        for peer in self.peers:
            if hasattr(peer, 'last_message'):
                if time.time() - peer.last_message > self.ping_timeout:
                    # 发送ping消息
                    ping_nonce = random.randint(0, 2**64-1)
                    self.send_ping(peer, ping_nonce)
                    peer.ping_time = time.time()
                    peer.expected_pong = ping_nonce
    
    def send_ping(self, peer, nonce):
        """发送ping消息"""
        ping_msg = {
            'type': 'ping',
            'nonce': nonce,
            'timestamp': time.time()
        }
        print(f"发送ping到节点 {peer}: {ping_msg}")
        # 实际发送逻辑
    
    def handle_pong(self, peer, pong_msg):
        """处理pong响应"""
        if hasattr(peer, 'expected_pong') and pong_msg['nonce'] == peer.expected_pong:
            # 计算延迟
            latency = time.time() - peer.ping_time
            peer.latency = latency
            print(f"节点 {peer} 延迟: {latency:.3f}s")
        else:
            print(f"收到无效的pong响应从节点 {peer}")


def demo_connection_management():
    """演示连接管理功能"""
    print("=== P2P连接管理演示 ===")
    
    # 1. 初始化连接管理器
    conn_manager = ConnectionManager()
    print("连接管理器初始化完成")
    
    # 2. 模拟一些节点连接
    mock_peers = [
        {'ip': '192.168.1.1', 'protocol_version': 70016},
        {'ip': '192.168.1.2', 'protocol_version': 70015},
        {'ip': '10.0.0.1', 'protocol_version': 70016},
        {'ip': '172.16.0.1', 'protocol_version': 70014},
    ]
    
    # 3. 演示多样性管理
    print("\n3. 检查连接多样性...")
    diversity = DiversityManager(mock_peers)
    diversity.ensure_geographic_diversity()
    diversity.maintain_protocol_diversity()
    
    # 4. 演示健康监测
    print("\n4. 执行健康检测...")
    for peer in mock_peers:
        peer['last_message'] = time.time() - 100  # 模拟100秒前的消息
    
    health_monitor = HealthMonitor(mock_peers)
    health_monitor.heartbeat_check()
    
    print("\n连接管理演示完成")


if __name__ == "__main__":
    demo_connection_management()