const http    = require('http');
const path    = require('path');
const Koa     = require('koa');
const Router  = require('@koa/router');
const serve   = require('koa-static');
const { WebSocketServer, OPEN } = require('ws');
const P2000   = require('./src/p2000');
const { geocode, messageToQuery } = require('./src/geocoder');

const PORT = Number(process.env.PORT) || 10000;
const MAX_HISTORY = 500;

// ── Koa app ──────────────────────────────────────────────────────────────────
const app    = new Koa();
const router = new Router();

app.use(serve(path.join(__dirname, 'public')));

router.get('/health', ctx => {
  ctx.body = { status: 'ok', uptime: process.uptime(), messages: history.length };
});

// Paginated history — ?offset=0&limit=30&type=all
router.get('/api/messages', ctx => {
  const offset = Math.max(0, parseInt(ctx.query.offset) || 0);
  const limit  = Math.min(100, Math.max(1, parseInt(ctx.query.limit) || 30));
  const type   = ctx.query.type || 'all';
  const pool   = type === 'all' ? history : history.filter(m => m.type === type);
  ctx.body = {
    messages: pool.slice(offset, offset + limit),
    total:    pool.length,
    offset,
    limit,
  };
});

// Geocode a message by id — proxies Nominatim so the client never hits it directly
router.get('/api/geocode', async ctx => {
  const msg = history.find(m => m.id === ctx.query.id);
  if (!msg) { ctx.status = 404; ctx.body = { error: 'not found' }; return; }
  const query = messageToQuery(msg);
  if (!query) { ctx.body = { coords: null }; return; }
  const coords = await geocode(query);
  ctx.body = { coords, query };
});

app.use(router.routes()).use(router.allowedMethods());

// ── HTTP server ───────────────────────────────────────────────────────────────
const server = http.createServer(app.callback());

// ── WebSocket server ──────────────────────────────────────────────────────────
const wss = new WebSocketServer({ server, path: '/ws' });

const history = [];

function broadcast(payload) {
  const data = JSON.stringify(payload);
  for (const client of wss.clients) {
    if (client.readyState === OPEN) client.send(data);
  }
}

wss.on('connection', ws => {
  // Send existing history so the UI isn't blank on first load
  ws.send(JSON.stringify({ type: 'history', messages: history }));

  ws.on('error', err => console.error('[ws] client error:', err.message));
});

// ── P-2000 poller ─────────────────────────────────────────────────────────────
const p2000 = new P2000();

p2000.on('batch', messages => {
  history.push(...messages);
  if (history.length > MAX_HISTORY) history.splice(0, history.length - MAX_HISTORY);
  broadcast({ type: 'history', messages: history });
});

p2000.on('message', msg => {
  history.unshift(msg);
  if (history.length > MAX_HISTORY) history.pop();
  broadcast({ type: 'message', message: msg });
});

p2000.start();

// ── Start ─────────────────────────────────────────────────────────────────────
server.listen(PORT, () => {
  console.log(`[server] Listening on http://localhost:${PORT}`);
});

// Graceful shutdown
process.on('SIGINT',  () => { p2000.stop(); server.close(() => process.exit(0)); });
process.on('SIGTERM', () => { p2000.stop(); server.close(() => process.exit(0)); });