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

const USERS_FILE = path.join(process.cwd(), 'data/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 [];
  }
}

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 });
    }
    
    const users = await readUsers();
    const user = users.find(u => u.username === username);
    
    if (!user || user.passwordHash !== hashPassword(password)) {
      return NextResponse.json({ error: '用户名或密码错误' }, { status: 401 });
    }
    
    const newToken = generateToken();
    user.token = newToken;
    await fs.writeFile(USERS_FILE, JSON.stringify(users, null, 2));
    
    const response = NextResponse.json({ success: true, username: user.username });
    response.cookies.set('auth_token', newToken, {
      httpOnly: true,
      secure: process.env.NODE_ENV === 'production',
      sameSite: 'lax',
      maxAge: 60 * 60 * 24 * 7,
      path: '/'
    });
    
    return response;
  } catch (error) {
    console.error('Login error:', error);
    return NextResponse.json({ error: '登录失败' }, { status: 500 });
  }
}