refactor: migrate from pnpm workspaces to single-package structure with shared types

backend/src/index.ts

@@ -0,0 +1,187 @@
+import Fastify from 'fastify';
+import cors from '@fastify/cors';
+import EventEmitter from 'eventemitter3';
+import type { ChatMessage } from '@shared/chat';
+import { bootstrapInnertube, type IngestionContext } from './ingestion/youtubei';
+
+const MAX_MESSAGES = 500;
+
+export async function startBackend() {
+  const fastify = Fastify({
+    logger: true
+  });
+
+  await fastify.register(cors, { origin: true });
+
+  const store: ChatMessage[] = [];
+  let currentSelection: ChatMessage | null = null;
+  const overlayEmitter = new EventEmitter<{ update: (message: ChatMessage | null) => void }>();
+
+  const rawLiveId = process.env.YOUTUBE_LIVE_ID ?? '';
+  const parsedLiveId = extractLiveId(rawLiveId);
+  const shouldMock = !parsedLiveId;
+
+  let ingestion: IngestionContext | null = null;
+
+  if (!shouldMock) {
+    try {
+      console.log(`[Backend] Connecting to YouTube Live ID: ${parsedLiveId}`);
+      ingestion = await bootstrapInnertube(parsedLiveId);
+      console.log(`[Backend] ✓ YouTube chat connected successfully`);
+      ingestion.emitter.on('message', (message) => {
+        console.log(`[Chat] ${message.author}: ${message.text}`);
+        store.push(message);
+        if (store.length > MAX_MESSAGES) {
+          store.splice(0, store.length - MAX_MESSAGES);
+        }
+      });
+      ingestion.emitter.on('error', (error) => {
+        console.error('[Backend] Innertube ingestion error:', error);
+      });
+    } catch (error) {
+      console.error('[Backend] Failed to bootstrap Innertube; falling back to mock data:', error);
+    }
+  } else {
+    console.log('[Backend] No YOUTUBE_LIVE_ID found, running in mock mode');
+  }
+
+  if (!ingestion) {
+    seedMockMessages(store, overlayEmitter);
+  }
+
+  fastify.get('/health', async () => ({
+    status: 'ok',
+    messages: store.length,
+    selection: currentSelection?.id ?? null,
+    mode: ingestion ? 'live' : 'mock'
+  }));
+
+  fastify.get('/chat/messages', async () => ({
+    messages: store
+  }));
+
+  fastify.post<{ Body: { id?: string } }>('/overlay/selection', async (request, reply) => {
+    const { id } = request.body ?? {};
+    if (!id) {
+      reply.status(400);
+      return { error: 'id is required' };
+    }
+
+    const message = store.find((item) => item.id === id);
+    if (!message) {
+      reply.status(404);
+      return { error: 'message not found' };
+    }
+
+    currentSelection = message;
+    overlayEmitter.emit('update', currentSelection);
+
+    return { ok: true };
+  });
+
+  fastify.delete('/overlay/selection', async () => {
+    currentSelection = null;
+    overlayEmitter.emit('update', null);
+    return { ok: true };
+  });
+
+  fastify.options('/overlay/stream', async (request, reply) => {
+    reply.headers({
+      'Access-Control-Allow-Origin': '*',
+      'Access-Control-Allow-Methods': 'GET, OPTIONS',
+      'Access-Control-Allow-Headers': 'Content-Type'
+    });
+    reply.status(204).send();
+  });
+
+  fastify.get('/overlay/stream', async (request, reply) => {
+    reply.hijack();
+
+    const res = reply.raw;
+    res.setHeader('Content-Type', 'text/event-stream');
+    res.setHeader('Cache-Control', 'no-cache');
+    res.setHeader('Connection', 'keep-alive');
+    res.setHeader('Access-Control-Allow-Origin', '*');
+    res.setHeader('Access-Control-Allow-Methods', 'GET, OPTIONS');
+    res.setHeader('Access-Control-Allow-Headers', 'Content-Type');
+    res.writeHead(200);
+    res.write(': connected\n\n');
+
+    const send = (message: ChatMessage | null) => {
+      res.write(`event: selection\ndata: ${JSON.stringify({ message })}\n\n`);
+    };
+
+    const heartbeat = setInterval(() => {
+      res.write('event: heartbeat\ndata: {}\n\n');
+    }, 15000);
+
+    overlayEmitter.on('update', send);
+
+    if (currentSelection) {
+      send(currentSelection);
+    }
+
+    request.raw.on('close', () => {
+      clearInterval(heartbeat);
+      overlayEmitter.off('update', send);
+    });
+  });
+
+  const port = Number(process.env.PORT ?? 4100);
+
+  await fastify.listen({ port, host: '0.0.0.0' });
+
+  console.log(`[Backend] Server listening on http://localhost:${port}`);
+}
+
+function extractLiveId(input: string): string {
+  if (!input) return '';
+
+  const trimmed = input.trim();
+  if (/^[a-zA-Z0-9_-]{10,}$/.test(trimmed)) {
+    return trimmed;
+  }
+
+  try {
+    const url = new URL(trimmed);
+    if (url.searchParams.has('v')) {
+      return url.searchParams.get('v') ?? '';
+    }
+    const pathname = url.pathname.split('/').filter(Boolean).pop();
+    return pathname ?? '';
+  } catch (error) {
+    console.warn('Invalid YOUTUBE_LIVE_ID provided', error);
+    return '';
+  }
+}
+
+function seedMockMessages(
+  store: ChatMessage[],
+  overlayEmitter: EventEmitter<{ update: (message: ChatMessage | null) => void }>
+) {
+  let counter = 0;
+  const authors = ['Ada', 'Linus', 'Grace', 'Marge'];
+  setInterval(() => {
+    const message: ChatMessage = {
+      id: `mock-${Date.now()}`,
+      author: authors[counter % authors.length],
+      text: `Mock message #${counter}`,
+      publishedAt: new Date().toISOString()
+    };
+    store.push(message);
+    if (store.length > MAX_MESSAGES) {
+      store.splice(0, store.length - MAX_MESSAGES);
+    }
+    if (counter % 5 === 0) {
+      overlayEmitter.emit('update', message);
+    }
+    counter += 1;
+  }, 2000);
+}
+
+if (import.meta.url === `file://${process.argv[1]}`) {
+  startBackend().catch((error) => {
+    console.error('Failed to start backend', error);
+    process.exit(1);
+  });
+}