import { Router, Request, Response } from 'express';
import { getStore } from './store.js';
import { calculateAllResults } from './aggregation.js';

// List of connected SSE clients
const clients: Response[] = [];

export const sseRouter = Router();

/**
 * SSE endpoint: GET /api/results/stream
 */
sseRouter.get('/api/results/stream', (req: Request, res: Response) => {
  // Set SSE headers
  res.setHeader('Content-Type', 'text/event-stream');
  res.setHeader('Cache-Control', 'no-cache');
  res.setHeader('Connection', 'keep-alive');

  // Add client to list
  clients.push(res);

  // Send initial data immediately on connect
  const store = getStore();
  const criteriaCount = store.session.config.criteria.length;
  const results = calculateAllResults(store.scores, store.teams, criteriaCount);
  const payload = JSON.stringify({ results, timestamp: new Date().toISOString() });
  res.write(`event: scores_updated\ndata: ${payload}\n\n`);

  // Remove client on disconnect
  req.on('close', () => {
    const index = clients.indexOf(res);
    if (index !== -1) {
      clients.splice(index, 1);
    }
  });
});

/**
 * Broadcast current results to all connected SSE clients.
 * Called whenever scores change.
 */
export function broadcastUpdate(): void {
  const store = getStore();
  const criteriaCount = store.session.config.criteria.length;
  const results = calculateAllResults(store.scores, store.teams, criteriaCount);
  const payload = JSON.stringify({ results, timestamp: new Date().toISOString() });
  const message = `event: scores_updated\ndata: ${payload}\n\n`;

  for (const client of clients) {
    client.write(message);
  }
}