import * as os from 'os';
import * as fs from 'fs';
import * as path from 'path';
import * as crypto from 'crypto';
import type { HardwareFingerprint } from './types';

// 实例 ID 存储路径
const INSTANCE_ID_FILE = path.join(process.cwd(), 'data', '.instance-id');

/**
 * 获取 machine-id
 * Linux: /etc/machine-id 或 /var/lib/dbus/machine-id
 * Windows: 使用 hostname + 网卡信息生成
 * Docker: 使用容器 ID 或挂载的 machine-id
 */
async function getMachineId(): Promise<string> {
  // 尝试读取 Linux machine-id
  const machineIdPaths = [
    '/etc/machine-id',
    '/var/lib/dbus/machine-id',
  ];

  for (const filePath of machineIdPaths) {
    try {
      const machineId = fs.readFileSync(filePath, 'utf8').trim();
      if (machineId) {
        return machineId;
      }
    } catch {
      // 文件不存在，继续尝试下一个
    }
  }

  // 尝试读取 Docker 容器 ID
  try {
    const cgroupContent = fs.readFileSync('/proc/self/cgroup', 'utf8');
    const match = cgroupContent.match(/docker[/-]([a-f0-9]{64})/);
    if (match) {
      return match[1].substring(0, 32);
    }
  } catch {
    // 不在 Docker 容器中
  }

  // Windows 或其他系统：使用 hostname + 网卡信息生成
  const hostname = os.hostname();
  const networkInterfaces = os.networkInterfaces();
  const macs: string[] = [];

  for (const interfaces of Object.values(networkInterfaces)) {
    if (interfaces) {
      for (const iface of interfaces) {
        if (!iface.internal && iface.mac !== '00:00:00:00:00:00') {
          macs.push(iface.mac);
        }
      }
    }
  }

  const data = `${hostname}-${macs.sort().join('-')}`;
  return crypto.createHash('md5').update(data).digest('hex');
}

/**
 * 获取主网卡 MAC 地址
 */
function getPrimaryMacAddress(): string {
  const networkInterfaces = os.networkInterfaces();
  
  // 优先查找常见的网卡名称
  const preferredNames = ['eth0', 'en0', 'ens33', 'enp0s3', 'Ethernet', 'Wi-Fi'];
  
  for (const name of preferredNames) {
    const interfaces = networkInterfaces[name];
    if (interfaces) {
      for (const iface of interfaces) {
        if (!iface.internal && iface.mac !== '00:00:00:00:00:00') {
          return iface.mac;
        }
      }
    }
  }

  // 如果没有找到，返回第一个非内部网卡的 MAC
  for (const interfaces of Object.values(networkInterfaces)) {
    if (interfaces) {
      for (const iface of interfaces) {
        if (!iface.internal && iface.mac !== '00:00:00:00:00:00') {
          return iface.mac;
        }
      }
    }
  }

  return '00:00:00:00:00:00';
}

/**
 * 获取或创建实例 ID
 * 实例 ID 在首次激活时生成，并持久化存储
 */
async function getOrCreateInstanceId(): Promise<string> {
  // 确保目录存在
  const dir = path.dirname(INSTANCE_ID_FILE);
  if (!fs.existsSync(dir)) {
    fs.mkdirSync(dir, { recursive: true });
  }

  // 尝试读取现有的实例 ID
  try {
    const instanceId = fs.readFileSync(INSTANCE_ID_FILE, 'utf8').trim();
    if (instanceId) {
      return instanceId;
    }
  } catch {
    // 文件不存在
  }

  // 生成新的实例 ID
  const instanceId = crypto.randomBytes(16).toString('hex');
  fs.writeFileSync(INSTANCE_ID_FILE, instanceId);
  
  return instanceId;
}

/**
 * 生成硬件指纹
 */
export async function generateFingerprint(): Promise<HardwareFingerprint> {
  const [machineId, instanceId] = await Promise.all([
    getMachineId(),
    getOrCreateInstanceId(),
  ]);

  return {
    machineId,
    hostname: os.hostname(),
    macAddress: getPrimaryMacAddress(),
    instanceId,
  };
}

/**
 * 获取实例 ID
 */
export async function getInstanceId(): Promise<string> {
  return getOrCreateInstanceId();
}

/**
 * 计算两个指纹的匹配分数
 * 返回 0-100 的分数
 */
export function calculateFingerprintMatchScore(
  stored: HardwareFingerprint,
  current: HardwareFingerprint
): number {
  let score = 0;

  // machineId 权重 40%
  if (stored.machineId === current.machineId) {
    score += 40;
  }

  // hostname 权重 20%
  if (stored.hostname === current.hostname) {
    score += 20;
  }

  // macAddress 权重 30%
  if (stored.macAddress === current.macAddress) {
    score += 30;
  }

  // instanceId 权重 10%
  if (stored.instanceId === current.instanceId) {
    score += 10;
  }

  return score;
}

/**
 * 检查指纹是否匹配（60% 阈值）
 */
export function isFingerprintMatch(
  stored: HardwareFingerprint,
  current: HardwareFingerprint
): boolean {
  return calculateFingerprintMatchScore(stored, current) >= 60;
}