import { NextRequest, NextResponse } from 'next/server';
import fs from 'fs/promises';
import path from 'path';
import crypto from 'crypto';

const DATA_DIR = path.join(process.cwd(), 'data');
const USERS_FILE = path.join(DATA_DIR, 'users.json');

interface User {
  id: string;
  username: string;
  passwordHash: string;
  token: string;
  createdAt: string;
}

async function readUsers(): Promise<User[]> {
  try {
    const data = await fs.readFile(USERS_FILE, 'utf-8');
    return JSON.parse(data);
  } catch {
    return [];
  }
}

async function writeUsers(users: User[]): Promise<void> {
  await fs.writeFile(USERS_FILE, JSON.stringify(users, null, 2));
}

function hashPassword(password: string): string {
  return crypto.createHash('sha256').update(password).digest('hex');
}

function generateToken(): string {
  return crypto.randomBytes(32).toString('hex');
}

export async function POST(request: NextRequest) {
  try {
    const { username, password } = await request.json();
    
    if (!username || !password) {
      return NextResponse.json({ error: '用户名和密码不能为空' }, { status: 400 });
    }
    
    if (username.length < 3 || password.length < 6) {
      return NextResponse.json({ error: '用户名至少3位，密码至少6位' }, { status: 400 });
    }
    
    const users = await readUsers();
    
    if (users.find(u => u.username === username)) {
      return NextResponse.json({ error: '用户名已存在' }, { status: 400 });
    }
    
    const token = generateToken();
    const newUser: User = {
      id: crypto.randomUUID(),
      username,
      passwordHash: hashPassword(password),
      token,
      createdAt: new Date().toISOString()
    };
    
    users.push(newUser);
    await writeUsers(users);
    
    const response = NextResponse.json({ success: true, username });
    response.cookies.set('auth_token', token, {
      httpOnly: true,
      secure: false,
      sameSite: 'lax',
      maxAge: 60 * 60 * 24 * 7,
      path: '/'
    });
    
    return response;
  } catch (error) {
    console.error('Register error:', error);
    return NextResponse.json({ error: '注册失败' }, { status: 500 });
  }
}