social-media-manager/services/gateway/server.js

require('dotenv').config();
const app = require('fastify')({ logger: false });
const axios = require('axios');
const { getDb } = require('./utils/MongoDBConnector');
const RabbitMQProducer = require('./utils/RabbitMQProducer');

const GRAPH_API = 'https://graph.facebook.com/v22.0';

// The public base URL of this app (used for OAuth redirect_uri)
const APP_BASE_URL = process.env.APP_BASE_URL || 'http://localhost:8081';

// ─── CORS ────────────────────────────────────────────────────────────────────

app.addHook('onSend', async (request, reply) => {
  reply.header('Access-Control-Allow-Origin', '*');
  reply.header('Access-Control-Allow-Methods', 'GET,POST,DELETE,OPTIONS');
  reply.header('Access-Control-Allow-Headers', 'Content-Type');
});

app.options('*', async (request, reply) => {
  reply.code(204).send();
});

// ─── Helpers ─────────────────────────────────────────────────────────────────

async function getCredentials(id) {
  const db = await getDb();
  return db.collection('platform_credentials').findOne({ _id: id });
}

async function setCredentials(id, data) {
  const db = await getDb();
  await db.collection('platform_credentials').updateOne(
    { _id: id },
    { $set: { _id: id, ...data, updatedAt: new Date() } },
    { upsert: true }
  );
}

async function deleteCredentials(id) {
  const db = await getDb();
  await db.collection('platform_credentials').deleteOne({ _id: id });
}

// ─── Legacy post route ────────────────────────────────────────────────────────

let rabbitMQProducer = new RabbitMQProducer();

app.post('/', async (request, reply) => {
  try {
    await rabbitMQProducer.sendMessage('formatter', request.body.message);
    reply.send({ status: 'ok' });
  } catch (error) {
    console.error('Error handling POST request:', error);
    reply.status(500).send({ error: 'Internal Server Error' });
  }
});

// ─── Meta App Credentials ────────────────────────────────────────────────────

// Save Facebook App ID + Secret (entered by user in Settings UI)
app.post('/credentials/meta-app', async (request, reply) => {
  const { appId, appSecret } = request.body || {};
  if (!appId || !appSecret) {
    return reply.code(400).send({ error: 'appId and appSecret are required' });
  }
  await setCredentials('meta_app', { appId, appSecret });
  return { success: true };
});

// Get Meta App config (secret is masked for UI display)
app.get('/credentials/meta-app', async () => {
  const cred = await getCredentials('meta_app');
  if (!cred) return { configured: false };
  return { configured: true, appId: cred.appId, appSecretHint: `****${cred.appSecret.slice(-4)}` };
});

// ─── Meta OAuth Flow ──────────────────────────────────────────────────────────

// Return the Facebook OAuth URL to redirect the user to
app.get('/auth/meta/init', async (request, reply) => {
  const cred = await getCredentials('meta_app');
  if (!cred?.appId) {
    return reply.code(400).send({ error: 'Save your Facebook App ID and Secret first' });
  }

  const redirectUri = `${APP_BASE_URL}/api/auth/meta/callback`;
  const scopes = [
    'pages_manage_posts',
    'pages_read_engagement',
    'instagram_basic',
    'instagram_content_publish',
    'instagram_manage_insights',
  ].join(',');

  const url = `https://www.facebook.com/v22.0/dialog/oauth?client_id=${cred.appId}&redirect_uri=${encodeURIComponent(redirectUri)}&scope=${scopes}&response_type=code`;
  return { url };
});

// OAuth callback — Facebook redirects here after user authorises
app.get('/auth/meta/callback', async (request, reply) => {
  const { code, error: oauthError } = request.query;

  if (oauthError) {
    return reply.redirect(`${APP_BASE_URL}/settings?meta_error=${encodeURIComponent(oauthError)}`);
  }

  if (!code) {
    return reply.redirect(`${APP_BASE_URL}/settings?meta_error=no_code`);
  }

  try {
    const appCred = await getCredentials('meta_app');
    if (!appCred?.appId) throw new Error('App credentials not configured');

    const redirectUri = `${APP_BASE_URL}/api/auth/meta/callback`;

    // Exchange code for short-lived token
    const shortRes = await axios.get(`${GRAPH_API}/oauth/access_token`, {
      params: {
        client_id: appCred.appId,
        client_secret: appCred.appSecret,
        redirect_uri: redirectUri,
        code,
      },
    });

    // Upgrade to long-lived user token (~60 days)
    const longRes = await axios.get(`${GRAPH_API}/oauth/access_token`, {
      params: {
        grant_type: 'fb_exchange_token',
        client_id: appCred.appId,
        client_secret: appCred.appSecret,
        fb_exchange_token: shortRes.data.access_token,
      },
    });
    const userToken = longRes.data.access_token;

    // Fetch all managed Facebook Pages
    const pagesRes = await axios.get(`${GRAPH_API}/me/accounts`, {
      params: { access_token: userToken, fields: 'id,name,access_token,picture' },
    });

    const pages = [];
    const igAccounts = [];

    for (const page of pagesRes.data.data || []) {
      pages.push({
        id: page.id,
        name: page.name,
        accessToken: page.access_token,
        picture: page.picture?.data?.url || null,
        selected: false,
      });

      // Check for linked Instagram Business Account
      try {
        const igRes = await axios.get(`${GRAPH_API}/${page.id}`, {
          params: {
            fields: 'instagram_business_account',
            access_token: page.access_token,
          },
        });
        if (igRes.data.instagram_business_account?.id) {
          const igId = igRes.data.instagram_business_account.id;
          // Fetch IG account details
          const igProfile = await axios.get(`${GRAPH_API}/${igId}`, {
            params: {
              fields: 'id,username,name,profile_picture_url',
              access_token: userToken,
            },
          });
          igAccounts.push({
            id: igId,
            username: igProfile.data.username || igProfile.data.name,
            name: igProfile.data.name,
            avatar: igProfile.data.profile_picture_url || null,
            accessToken: userToken,
            pageId: page.id,
            selected: false,
          });
        }
      } catch (_) {
        // Page has no linked Instagram account — skip
      }
    }

    // Store discovery results for the UI to pick from
    await setCredentials('meta_discovery', { pages, igAccounts, discoveredAt: new Date() });

    reply.redirect(`${APP_BASE_URL}/settings?meta_discovery=1`);
  } catch (err) {
    console.error('[Gateway] Meta OAuth error:', err.response?.data || err.message);
    reply.redirect(`${APP_BASE_URL}/settings?meta_error=${encodeURIComponent(err.message)}`);
  }
});

// Return pending discovery results so the UI can render the page picker
app.get('/auth/meta/discovered', async () => {
  const discovery = await getCredentials('meta_discovery');
  if (!discovery) return { pages: [], igAccounts: [] };
  return { pages: discovery.pages || [], igAccounts: discovery.igAccounts || [] };
});

// User has chosen which pages/accounts to connect
app.post('/auth/meta/save', async (request, reply) => {
  const { selectedPageIds = [], selectedIgAccountIds = [] } = request.body || {};

  const discovery = await getCredentials('meta_discovery');
  if (!discovery) return reply.code(400).send({ error: 'No discovery data found — reconnect via OAuth' });

  const fbPages = (discovery.pages || []).map((p) => ({
    ...p,
    selected: selectedPageIds.includes(p.id),
  }));

  const igAccounts = (discovery.igAccounts || []).map((a) => ({
    ...a,
    selected: selectedIgAccountIds.includes(a.id),
  }));

  await setCredentials('facebook', { pages: fbPages });
  await setCredentials('instagram', { accounts: igAccounts });
  await deleteCredentials('meta_discovery');

  return { success: true, facebookPages: fbPages.filter((p) => p.selected).length, instagramAccounts: igAccounts.filter((a) => a.selected).length };
});

// Disconnect all Meta platforms
app.delete('/credentials/meta', async () => {
  await deleteCredentials('facebook');
  await deleteCredentials('instagram');
  await deleteCredentials('meta_discovery');
  return { success: true };
});

// ─── Credential Status ────────────────────────────────────────────────────────

// Aggregate connection status for all DB-managed platforms
app.get('/credentials', async () => {
  const [metaApp, fb, ig] = await Promise.all([
    getCredentials('meta_app'),
    getCredentials('facebook'),
    getCredentials('instagram'),
  ]);

  const fbPages = (fb?.pages || []).filter((p) => p.selected);
  const igAccounts = (ig?.accounts || []).filter((a) => a.selected);

  return {
    metaApp: { configured: !!(metaApp?.appId) },
    facebook: {
      connected: fbPages.length > 0,
      pages: fbPages.map(({ id, name, picture }) => ({ id, name, picture })),
    },
    instagram: {
      connected: igAccounts.length > 0,
      accounts: igAccounts.map(({ id, username, avatar }) => ({ id, username, avatar })),
    },
  };
});

module.exports = app;