/**
 * OAuth Proxy Server for Challonge API
 *
 * This server handles OAuth token exchange and refresh for the Challonge API.
 * It keeps client_secret secure by running on the backend.
 *
 * Usage:
 *   Development: node server/oauth-proxy.js
 *   Production: Deploy as serverless function or Express app
 */

import 'dotenv/config';
import express from 'express';
import cors from 'cors';
import fetch from 'node-fetch';

const app = express();
const PORT = process.env.OAUTH_PROXY_PORT || 3001;

// Environment variables (set in .env file)
const CLIENT_ID = process.env.CHALLONGE_CLIENT_ID;
const CLIENT_SECRET = process.env.CHALLONGE_CLIENT_SECRET;
const REDIRECT_URI =
  process.env.CHALLONGE_REDIRECT_URI || 'http://localhost:5173/oauth/callback';

// Validate required environment variables
if (!CLIENT_ID || !CLIENT_SECRET) {
  console.error('❌ Missing required environment variables:');
  console.error('   CHALLONGE_CLIENT_ID');
  console.error('   CHALLONGE_CLIENT_SECRET');
  console.error('\nSet these in your .env file or environment.');
  process.exit(1);
}

app.use(
  cors({
    origin:
      process.env.NODE_ENV === 'production'
        ? process.env.FRONTEND_URL
        : [
            'http://localhost:5173',
            'http://localhost:5174',
            'http://localhost:5175'
          ]
  })
);
app.use(express.json());

/**
 * Exchange authorization code for access token
 * POST /oauth/token
 */
app.post('/oauth/token', async (req, res) => {
  const { code } = req.body;

  if (!code) {
    return res.status(400).json({ error: 'Missing authorization code' });
  }

  try {
    const response = await fetch('https://api.challonge.com/oauth/token', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/x-www-form-urlencoded'
      },
      body: new URLSearchParams({
        grant_type: 'authorization_code',
        client_id: CLIENT_ID,
        client_secret: CLIENT_SECRET,
        code: code,
        redirect_uri: REDIRECT_URI
      })
    });

    const data = await response.json();

    if (!response.ok) {
      console.error('Token exchange failed:', data);
      return res.status(response.status).json(data);
    }

    console.log('✅ Token exchange successful');
    res.json(data);
  } catch (error) {
    console.error('Token exchange error:', error);
    res.status(500).json({
      error: 'Token exchange failed',
      message: error.message
    });
  }
});

/**
 * Refresh access token
 * POST /oauth/refresh
 */
app.post('/oauth/refresh', async (req, res) => {
  const { refresh_token } = req.body;

  if (!refresh_token) {
    return res.status(400).json({ error: 'Missing refresh token' });
  }

  try {
    const response = await fetch('https://api.challonge.com/oauth/token', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/x-www-form-urlencoded'
      },
      body: new URLSearchParams({
        grant_type: 'refresh_token',
        client_id: CLIENT_ID,
        client_secret: CLIENT_SECRET,
        refresh_token: refresh_token
      })
    });

    const data = await response.json();

    if (!response.ok) {
      console.error('Token refresh failed:', data);
      return res.status(response.status).json(data);
    }

    console.log('✅ Token refresh successful');
    res.json(data);
  } catch (error) {
    console.error('Token refresh error:', error);
    res.status(500).json({
      error: 'Token refresh failed',
      message: error.message
    });
  }
});

/**
 * Health check endpoint
 * GET /health
 */
app.get('/health', (req, res) => {
  res.json({
    status: 'ok',
    service: 'oauth-proxy',
    configured: !!(CLIENT_ID && CLIENT_SECRET)
  });
});

app.listen(PORT, () => {
  console.log(`🔐 OAuth Proxy Server running on http://localhost:${PORT}`);
  console.log(`📝 Client ID: ${CLIENT_ID}`);
  console.log(`🔗 Redirect URI: ${REDIRECT_URI}`);
  console.log('\n✅ Ready to handle OAuth requests');
});