#!/usr/bin/env python3
"""
比特币P2P网络基础节点实现
演示P2P网络的核心概念和基本功能
"""

import socket
import time
import hashlib
import struct
import random


class BitcoinP2PNetwork:
    """比特币P2P网络基础实现"""
    
    def __init__(self):
        self.peers = {}  # 连接的对等节点
        self.max_outbound = 8      # 最多主动连接8个节点
        self.max_inbound = 125     # 最多接受125个连接
        self.protocol_version = 70016  # 协议版本
        
    def network_topology(self):
        """比特币网络拓扑特点"""
        return {
            "结构类型": "无结构P2P网络",
            "连接方式": "随机+优选结合",
            "网络直径": "平均6跳",
            "容错能力": "高度冗余"
        }


class AddressManager:
    """地址管理器 - 智能管理节点地址"""
    
    def __init__(self):
        self.new_buckets = [{} for _ in range(1024)]    # 未验证的地址
        self.tried_buckets = [{} for _ in range(256)]   # 已验证的地址
        
    def add_address(self, addr, source):
        """添加新发现的地址"""
        # 根据IP地址计算桶索引
        bucket_id = hash(addr.ip) % len(self.new_buckets)
        
        # 地址去重和老化处理
        if not self.is_duplicate(addr):
            self.new_buckets[bucket_id][addr.ip] = {
                'address': addr,
                'source': source,
                'timestamp': time.time(),
                'attempts': 0
            }
    
    def select_peer_to_connect(self):
        """选择要连接的节点"""
        # 优先选择已验证的地址
        if self.tried_buckets:
            return self.select_from_tried()
        else:
            return self.select_from_new()
    
    def is_duplicate(self, addr):
        """检查地址是否重复"""
        # 简化实现
        return False
    
    def select_from_tried(self):
        """从已验证地址中选择"""
        # 简化实现
        return None
    
    def select_from_new(self):
        """从新地址中选择"""
        # 简化实现
        return None


class PeerQuality:
    """节点质量评估"""
    
    def __init__(self):
        self.latency = 0          # 延迟
        self.reliability = 1.0    # 可靠性评分
        self.misbehavior = 0      # 不当行为计数
        
    def update_quality(self, peer):
        """更新节点质量评估"""
        # 测量延迟
        if hasattr(peer, 'pong_received') and peer.pong_received:
            self.latency = time.time() - peer.ping_time
            
        # 评估可靠性
        if hasattr(peer, 'connection_drops') and peer.connection_drops > 3:
            self.reliability *= 0.8
            
        # 记录不当行为
        if hasattr(peer, 'invalid_messages') and peer.invalid_messages > 0:
            self.misbehavior += peer.invalid_messages


class BitcoinMessage:
    """比特币P2P消息格式"""
    
    def __init__(self, command, payload=b''):
        self.magic = b'\xf9\xbe\xb4\xd9'  # 主网魔法数
        self.command = command.ljust(12, b'\x00')
        self.payload = payload
        self.length = len(payload)
        self.checksum = hashlib.sha256(hashlib.sha256(payload).digest()).digest()[:4]
    
    def serialize(self):
        """序列化消息"""
        return (self.magic + self.command + 
                struct.pack('<I', self.length) + 
                self.checksum + self.payload)


if __name__ == "__main__":
    # 测试基础功能
    network = BitcoinP2PNetwork()
    print("网络拓扑信息:", network.network_topology())
    
    addr_manager = AddressManager()
    print("地址管理器初始化完成")
    
    # 创建测试消息
    msg = BitcoinMessage(b'ping', b'test_payload')
    serialized = msg.serialize()
    print(f"消息序列化长度: {len(serialized)} 字节")