const express = require('express');
const cors = require('cors');
const path = require('path');
const fs = require('fs');

const trading = require('./lib/sources/trading');
const retail = require('./lib/sources/retail');
const supplyChain = require('./lib/sources/supply-chain');
const smartCity = require('./lib/sources/smart-city');
const fraud = require('./lib/sources/fraud');
const { fetchCameraFrame } = require('./lib/camera-proxy');

const PORT = process.env.PORT || 3010;
const app = express();
app.use(cors());
app.use((req, res, next) => {
  res.setHeader('Referrer-Policy', 'strict-origin-when-cross-origin');
  next();
});
app.use(express.json());

const SOURCES = {
  trading: { label: 'Trading & FX', fetch: () => trading.getTradingData(), interval: 2000 },
  retail: { label: 'Retail Intelligence', fetch: () => retail.getRetailData(), interval: 2000 },
  'supply-chain': { label: 'Supply Chain', fetch: () => supplyChain.getSupplyChainData(), interval: 2500 },
  fraud: { label: 'Fraud Detection', fetch: () => fraud.getFraudSnapshot(), interval: 1500 },
  'smart-city': { label: 'Smart City', fetch: () => smartCity.getSmartCityData(), interval: 1500 }
};

app.get('/health', (req, res) => {
  res.json({ status: 'ok', service: 'mek-tech-showcase', ts: new Date().toISOString() });
});

app.get('/api/status', async (req, res) => {
  const status = {};
  for (const [key, src] of Object.entries(SOURCES)) {
    try {
      await src.fetch();
      status[key] = { ok: true, label: src.label };
    } catch (e) {
      status[key] = { ok: false, label: src.label, error: e.message };
    }
  }
  res.json({ ts: new Date().toISOString(), verticals: status });
});

app.get('/api/smart-city/camera/:id', (req, res) => {
  const cam = smartCity.getCameraById(req.params.id);
  if (!cam) return res.status(404).json({ error: 'Camera not found' });
  res.json(cam);
});

app.get('/api/smart-city/camera/:id/frame', async (req, res) => {
  try {
    const frame = await fetchCameraFrame(req.params.id);
    if (!frame) return res.status(502).json({ error: 'Frame unavailable' });
    res.setHeader('Content-Type', frame.contentType);
    res.setHeader('Cache-Control', 'no-store, no-cache, must-revalidate');
    res.setHeader('Access-Control-Allow-Origin', '*');
    res.send(frame.buffer);
  } catch (e) {
    res.status(500).json({ error: e.message });
  }
});

app.get('/api/:vertical', async (req, res) => {
  const src = SOURCES[req.params.vertical];
  if (!src) return res.status(404).json({ error: 'Unknown vertical' });
  try {
    const data = await src.fetch();
    res.json(data);
  } catch (e) {
    res.status(500).json({ error: e.message });
  }
});

app.get('/stream/:vertical', async (req, res) => {
  const vertical = req.params.vertical;
  const src = SOURCES[vertical];
  if (!src) return res.status(404).end();

  res.setHeader('Content-Type', 'text/event-stream');
  res.setHeader('Cache-Control', 'no-cache');
  res.setHeader('Connection', 'keep-alive');
  res.flushHeaders();

  let closed = false;
  req.on('close', () => { closed = true; });

  async function push() {
    if (closed) return;
    try {
      const data = await src.fetch();
      res.write(`data: ${JSON.stringify(data)}\n\n`);
    } catch (e) {
      res.write(`event: error\ndata: ${JSON.stringify({ error: e.message })}\n\n`);
    }
  }

  await push();
  const iv = setInterval(async () => {
    if (closed) { clearInterval(iv); return; }
    await push();
  }, src.interval);

  req.on('close', () => clearInterval(iv));
});

const distPath = path.join(__dirname, '../frontend/dist');
if (fs.existsSync(distPath)) {
  app.use(express.static(distPath));
  app.get('*', (req, res) => {
    if (req.path.startsWith('/api') || req.path.startsWith('/stream')) return res.status(404).end();
    res.sendFile(path.join(distPath, 'index.html'));
  });
}

app.listen(PORT, '0.0.0.0', () => {
  console.log(`Mek-Tech Showcase running on http://0.0.0.0:${PORT}`);
});