const fs = require('fs');
const path = require('path');
const crypto = require('crypto');
const webpush = require('web-push');

const ENV_PATH = path.join(__dirname, '..', '.env');

function loadEnv() {
  const env = {};
  if (fs.existsSync(ENV_PATH)) {
    for (const line of fs.readFileSync(ENV_PATH, 'utf8').split('\n')) {
      const m = line.match(/^\s*([A-Z0-9_]+)\s*=\s*(.*)\s*$/);
      if (m && !line.trim().startsWith('#')) env[m[1]] = m[2].replace(/^["']|["']$/g, '');
    }
  }
  return env;
}

function saveEnv(env) {
  const lines = [];
  for (const [k, v] of Object.entries(env)) lines.push(`${k}=${v}`);
  fs.writeFileSync(ENV_PATH, lines.join('\n') + '\n', 'utf8');
}

function ensure(key, generator) {
  if (process.env[key] || env[key]) return process.env[key] || env[key];
  const value = generator();
  env[key] = value;
  saveEnv(env);
  return value;
}

const env = loadEnv();

function ensureVapidPair() {
  if ((process.env.VAPID_PUBLIC_KEY || env.VAPID_PUBLIC_KEY) && (process.env.VAPID_PRIVATE_KEY || env.VAPID_PRIVATE_KEY)) {
    return {
      publicKey: process.env.VAPID_PUBLIC_KEY || env.VAPID_PUBLIC_KEY,
      privateKey: process.env.VAPID_PRIVATE_KEY || env.VAPID_PRIVATE_KEY,
    };
  }
  const pair = webpush.generateVAPIDKeys();
  env.VAPID_PUBLIC_KEY = pair.publicKey;
  env.VAPID_PRIVATE_KEY = pair.privateKey;
  saveEnv(env);
  return pair;
}

const vapid = ensureVapidPair();

const config = {
  port: Number(process.env.PORT || env.PORT || 3000),
  apiKey: process.env.DEEPSEEK_API_KEY || env.DEEPSEEK_API_KEY || '',
  appPassword: process.env.APP_PASSWORD || env.APP_PASSWORD || '',
  model: process.env.MODEL || env.MODEL || 'deepseek-v4-flash',
  thinking: process.env.THINKING || env.THINKING || 'enabled',
  baseUrl: process.env.DEEPSEEK_BASE_URL || env.DEEPSEEK_BASE_URL || 'https://api.deepseek.com',
  sessionSecret: ensure('SESSION_SECRET', () => crypto.randomBytes(32).toString('hex')),
  vapidPublicKey: vapid.publicKey,
  vapidPrivateKey: vapid.privateKey,
};

module.exports = { config };