server.js

import express from "express";
import http from "http";
import { Server } from "socket.io";
import Bme280 from "bme280";

const app = express();
const server = http.createServer(app);
const io = new Server(server);

// change port here
const PORT = process.env.PORT || 3000;

const DAY_MS = 24 * 60 * 60 * 1000;
const HALF_DAY_MS = 12 * 60 * 60 * 1000;

app.use(express.static("public"));

// store history in memory
let history = [];

let latestData = {
  temperature: null,
  humidity: null,
  pressure: null,
  updated_at: null,
  stats12h: null,
  stats24h: null
};

app.get("/json", (req, res) => {
  res.json(latestData);
});

function getStats(data) {
  return {
    tempHigh: data.length ? Math.max(...data.map(x => x.temperature)) : null,
    tempLow: data.length ? Math.min(...data.map(x => x.temperature)) : null,

    humHigh: data.length ? Math.max(...data.map(x => x.humidity)) : null,
    humLow: data.length ? Math.min(...data.map(x => x.humidity)) : null,

    pressHigh: data.length ? Math.max(...data.map(x => x.pressure)) : null,
    pressLow: data.length ? Math.min(...data.map(x => x.pressure)) : null
  };
}

(async () => {
  try {
    const bme280 = await Bme280.open({
      i2cBusNumber: 1,
      i2cAddress: 0x76
    });

    console.log("BME280 initialised");

    setInterval(async () => {
      try {
        const reading = await bme280.read();
        const now = Date.now();

        const sample = {
          temperature: Number(reading.temperature.toFixed(2)),
          humidity: Number(reading.humidity.toFixed(2)),
          pressure: Number(reading.pressure.toFixed(2)),
          timestamp: now
        };

        history.push(sample);

        history = history.filter(x => now - x.timestamp < DAY_MS);

        const history12 = history.filter(x => now - x.timestamp < HALF_DAY_MS);
        const history24 = history;

        latestData = {
          temperature: sample.temperature,
          humidity: sample.humidity,
          pressure: sample.pressure,
          updated_at: now,
          stats12h: getStats(history12),
          stats24h: getStats(history24)
        };

        io.emit("sensorData", latestData);

      } catch (err) {
        console.error("Sensor read failed:", err);
      }

    }, 1000);

  } catch (err) {
    console.error("BME280 init failed:", err);
  }

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

})();