import fs from "fs";
import path from "path";
import { createHash, randomBytes } from "crypto";

interface StoredUser {
  username: string;
  passwordHash: string;
  salt: string;
  name: string;
  role: "admin" | "user";
}

interface User {
  username: string;
  name: string;
  role: "admin" | "user";
}

// 密码哈希
export function hashPassword(password: string, salt: string): string {
  return createHash("sha256").update(salt + password).digest("hex");
}

// 生成密码哈希（用于创建用户）
export function generatePasswordHash(password: string): { hash: string; salt: string } {
  const salt = randomBytes(16).toString("hex");
  const hash = hashPassword(password, salt);
  return { hash, salt };
}

// 从请求头获取用户信息
export function getAuthFromRequest(request: Request): User | null {
  const authHeader = request.headers.get("X-Auth-User");
  if (!authHeader) return null;
  const stored = findStoredUser(authHeader);
  if (!stored) return null;
  return { username: stored.username, name: stored.name, role: stored.role };
}

// 查找用户
function findStoredUser(username: string): StoredUser | null {
  const users = loadStoredUsers();
  return users.find(u => u.username === username) || null;
}

// 认证用户
export function authenticateUser(username: string, password: string): User | null {
  const stored = findStoredUser(username);
  if (!stored) return null;
  const hash = hashPassword(password, stored.salt);
  if (hash !== stored.passwordHash) return null;
  return { username: stored.username, name: stored.name, role: stored.role };
}

// 加载用户列表
function loadStoredUsers(): StoredUser[] {
  try {
    const usersPath = path.join(process.cwd(), "users.json");
    if (!fs.existsSync(usersPath)) return [];
    const data = JSON.parse(fs.readFileSync(usersPath, "utf-8"));
    return data.users || [];
  } catch {
    return [];
  }
}

// 是否是管理员
export function isAdmin(request: Request): boolean {
  const user = getAuthFromRequest(request);
  return user?.role === "admin";
}