// server.js
require('dotenv').config();
const express        = require('express');
const mysql          = require('mysql2/promise');
const bodyParser     = require('body-parser');
const path           = require('path');
const axios          = require('axios');
const { uploadTrendsCsv } = require('./s3');

const app = express();
const PORT = process.env.PORT || 3000;

// In‑memory shift counters
const shiftCounters = {};

// Create MariaDB connection pool
// server.js (pool section)
const pool = mysql.createPool({
  host:            process.env.DB_HOST,
  port:            parseInt(process.env.DB_PORT, 10) || 3306,
  user:            process.env.DB_USER,
  password:        process.env.DB_PASSWORD,
  database:        process.env.DB_NAME,
  waitForConnections: true,
  connectionLimit: 10,
  queueLimit:      0,
  connectTimeout: 10000    // give it up to 10s before timing out
});


// Ensure readings table exists
(async () => {
  const createSQL = `
    CREATE TABLE IF NOT EXISTS readings (
      id INT AUTO_INCREMENT PRIMARY KEY,
      dockDoor INT NOT NULL,
      timestamp DATETIME NOT NULL,
      temperature DOUBLE,
      humidity DOUBLE,
      heatIndex DOUBLE
    );
  `;
  await pool.execute(createSQL);
})();

// Simple SSE setup
let clients = [];
app.get('/api/stream', (req, res) => {
  res.set({
    'Content-Type': 'text/event-stream',
    'Cache-Control': 'no-cache',
    Connection: 'keep-alive'
  });
  res.flushHeaders();
  clients.push(res);
  req.on('close', () => {
    clients = clients.filter(c => c !== res);
  });
});
function broadcast(event, data) {
  const msg = `event: ${event}\ndata: ${JSON.stringify(data)}\n\n`;
  clients.forEach(c => c.write(msg));
}

// Compute heat index (NOAA formula)
function computeHeatIndex(T, R) {
  const c1=-42.379, c2=2.04901523, c3=10.14333127;
  const c4=-0.22475541, c5=-6.83783e-3, c6=-0.05481717;
  const c7=0.00122874,  c8=0.00085282,  c9=-0.00000199;
  const HI = c1 + c2*T + c3*R + c4*T*R
      + c5*T*T + c6*R*R + c7*T*T*R
      + c8*T*R*R + c9*T*T*R*R;
  return Math.round(HI * 100) / 100;
}

// Determine shift info in EST
function getShiftInfo(now) {
  // Convert to EST
  const estNow = new Date(now.toLocaleString('en-US', { timeZone: 'America/New_York' }));
  const h = estNow.getHours(), m = estNow.getMinutes();
  let shift, shiftStart;

  if (h > 7 || (h === 7 && m >= 0)) {
    if (h < 17 || (h === 17 && m < 30)) {
      shift = 'Day';
      shiftStart = new Date(estNow);
      shiftStart.setHours(7,0,0,0);
    } else {
      shift = 'Night';
      shiftStart = new Date(estNow);
      shiftStart.setHours(17,30,0,0);
    }
  } else {
    shift = 'Night';
    shiftStart = new Date(estNow);
    shiftStart.setDate(shiftStart.getDate() - 1);
    shiftStart.setHours(17,30,0,0);
  }

  const key = `${shift}-${shiftStart.toISOString().slice(0,10)}-${shiftStart.getHours()}${shiftStart.getMinutes()}`;
  return { shift, shiftStart, key, estNow };
}

// Middleware & static files
app.use(bodyParser.json());
app.use(express.static(path.join(__dirname, 'public')));

// Dual‐reading POST endpoint
app.post('/api/readings', async (req, res) => {
  try {
    const { inbound, outbound } = req.body;
    const hiIn  = computeHeatIndex(inbound.temperature,  inbound.humidity);
    const hiOut = computeHeatIndex(outbound.temperature, outbound.humidity);

    // Shift & period logic
    const { shift, shiftStart, key, estNow } = getShiftInfo(new Date());
    shiftCounters[key] = (shiftCounters[key] || 0) + 1;
    const period = shiftCounters[key];

    // Insert both readings with server‐side NOW()
    const insertSQL = `
      INSERT INTO readings
        (dockDoor, timestamp, temperature, humidity, heatIndex)
      VALUES (?, NOW(), ?, ?, ?)
    `;
    await pool.execute(insertSQL, [inbound.dockDoor,  inbound.temperature,  inbound.humidity,  hiIn]);
    await pool.execute(insertSQL, [outbound.dockDoor, outbound.temperature, outbound.humidity, hiOut]);

    // Broadcast to SSE clients (use UTC ISO for front‐end)
    const isoNow = new Date().toISOString();
    broadcast('new-reading', { dockDoor: inbound.dockDoor,  timestamp: isoNow, ...inbound,  heatIndex: hiIn });
    broadcast('new-reading', { dockDoor: outbound.dockDoor, timestamp: isoNow, ...outbound, heatIndex: hiOut });

    // Format EST timestamp for Slack
    const estString = estNow.toLocaleString('en-US', {
      timeZone: 'America/New_York',
      hour12: false,
      year: 'numeric', month: '2-digit', day: '2-digit',
      hour: '2-digit', minute: '2-digit'
    });

    // Base Slack text
    let slackText =
        `${shift} Shift ${period} temperature checks for ${estString} EST

Inbound Dock Door: ${inbound.dockDoor}
Temp: ${inbound.temperature}°F
Humidity: ${inbound.humidity}%
Heat Index: ${hiIn}

Outbound Dock Door: ${outbound.dockDoor}
Temp: ${outbound.temperature}°F
Humidity: ${outbound.humidity}%
Heat Index: ${hiOut}`;

    // Upload today's CSV and append URL
    const dateKey = `${String(estNow.getFullYear())}${String(estNow.getMonth()+1).padStart(2,'0')}${String(estNow.getDate()).padStart(2,'0')}`;
    const [rows] = await pool.execute(
        `SELECT * FROM readings
       WHERE DATE(timestamp) = CURDATE()
       ORDER BY timestamp ASC`
    );
    try {
      const publicUrl = await uploadTrendsCsv(dateKey, rows);
      slackText += `\n\nDownload daily trends: ${publicUrl}`;
    } catch(uploadErr) {
      console.error('Failed to upload CSV to S3:', uploadErr);
    }

    // Send Slack notification
    await axios.post(process.env.SLACK_WEBHOOK_URL, { text: slackText });

    res.json({ success: true, shift, period });
  } catch (err) {
    console.error('POST /api/readings error:', err);
    res.status(500).json({ error: err.message });
  }
});

// Return all readings as JSON
app.get('/api/readings', async (req, res) => {
  try {
    const [rows] = await pool.execute(`SELECT * FROM readings ORDER BY timestamp ASC`);
    res.json(rows);
  } catch (err) {
    console.error('GET /api/readings error:', err);
    res.status(500).json({ error: err.message });
  }
});

// Export CSV of all readings
app.get('/api/export', async (req, res) => {
  try {
    const [rows] = await pool.execute(`SELECT * FROM readings ORDER BY timestamp ASC`);
    res.setHeader('Content-disposition', 'attachment; filename=readings.csv');
    res.set('Content-Type', 'text/csv');
    res.write('id,dockDoor,timestamp,temperature,humidity,heatIndex\n');
    rows.forEach(r => {
      // ensure ISO timestamp
      const ts = (r.timestamp instanceof Date)
          ? r.timestamp.toISOString()
          : r.timestamp;
      res.write(`${r.id},${r.dockDoor},${ts},${r.temperature},${r.humidity},${r.heatIndex}\n`);
    });
    res.end();
  } catch (err) {
    console.error('GET /api/export error:', err);
    res.status(500).send(err.message);
  }
});

app.listen(PORT, () => {
  console.log(`Server running on http://localhost:${PORT}`);
});