import fs from 'fs';
import path from 'path';
import { User } from './types';
import bcrypt from 'bcryptjs';
import { SignJWT, jwtVerify } from 'jose';
import { cookies } from 'next/headers';

const USERS_FILE = path.join(process.cwd(), 'data', 'users.json');
const SECRET_KEY = new TextEncoder().encode(process.env.JWT_SECRET || 'fallback-secret-key-change-me');

// --- User Management ---

export function getUsers(): User[] {
  if (!fs.existsSync(USERS_FILE)) {
    fs.writeFileSync(USERS_FILE, JSON.stringify([]));
    return [];
  }
  try {
    const data = fs.readFileSync(USERS_FILE, 'utf8');
    return JSON.parse(data);
  } catch (e) {
    return [];
  }
}

export function saveUser(user: User) {
  const users = getUsers();
  const existingIndex = users.findIndex(u => u.username === user.username);
  
  if (existingIndex >= 0) {
    users[existingIndex] = user;
  } else {
    users.push(user);
  }
  
  fs.writeFileSync(USERS_FILE, JSON.stringify(users, null, 2));
}

export function findUser(username: string): User | undefined {
  return getUsers().find(u => u.username === username);
}

// --- Security Utils ---

export async function hashPassword(password: string): Promise<string> {
  return await bcrypt.hash(password, 10);
}

export async function verifyPassword(password: string, hash: string): Promise<boolean> {
  return await bcrypt.compare(password, hash);
}

// --- Session Management (JWT) ---

export async function createSession(user: User) {
  const token = await new SignJWT({ username: user.username, chatId: user.chatId })
    .setProtectedHeader({ alg: 'HS256' })
    .setExpirationTime('7d')
    .sign(SECRET_KEY);

  cookies().set('session', token, {
    httpOnly: true,
    secure: process.env.NODE_ENV === 'production',
    sameSite: 'lax',
    maxAge: 60 * 60 * 24 * 7, // 7 days
    path: '/',
  });
}

export async function verifySession() {
  const session = cookies().get('session')?.value;
  if (!session) return null;

  try {
    const { payload } = await jwtVerify(session, SECRET_KEY);
    return payload as { username: string; chatId: string };
  } catch (error) {
    return null;
  }
}

export function destroySession() {
  cookies().delete('session');
}