BangleApps/apps/widbaroalarm/widget.js

(function() {
  let lastPressure;
  let avrPressure;
  let threeHourAvrPressure;

  const LOG_FILE = "widbaroalarm.log.json";
  const SETTINGS_FILE = "widbaroalarm.json";
  const storage = require('Storage');
  let settings = Object.assign(
    storage.readJSON("widbaroalarm.default.json", true) || {},
    storage.readJSON(SETTINGS_FILE, true) || {}
  );

  function setting(key) {
    return settings[key];
  }
  const interval = setting("interval");

  let history3 = storage.readJSON(LOG_FILE, true) || []; // history of recent 3 hours

  function showAlarm(body, title) {
    if (body == undefined) return;

    require("notify").show({
      title: title || "Pressure",
      body: body,
      icon: require("heatshrink").decompress(atob("jEY4cA///gH4/++mkK30kiWC4H8x3BGDmSGgYDCgmSoEAg3bsAIDpAIFkmSpMAm3btgIFDQwIGNQpTYkAIJwAHEgMoCA0JgMEyBnBCAW3KoQQDhu3oAIH5JnDBAW24IIBEYm2EYwACBCIACA"))
    });

    if (setting("buzz") &&
      !(storage.readJSON('setting.json', 1) || {}).quiet) {
      Bangle.buzz();
    }
  }

  let alreadyWarned = false;

  function baroHandler(data) {
    if (data === undefined) {
      setTimeout(() => Bangle.getPressure().then(baroHandler), 500);
    } else {
      lastPressure = Math.round(data.pressure);
      if (lastPressure == undefined || lastPressure <= 0) return;

      const ts = Math.round(Date.now() / 1000); // seconds
      const d = {
        "ts": ts,
        "p": lastPressure
      };

      // delete entries older than 3h
      for (let i = 0; i < history3.length; i++) {
        if (history3[i]["ts"] < ts - (3 * 60 * 60)) {
          history3.shift();
        }
      }
      // delete oldest entries until we have max 50
      while (history3.length > 50) {
        history3.shift();
      }

      history3.push(d);
      // write data to storage
      storage.writeJSON(LOG_FILE, history3);

      // we need at least three entries for reliable detection
      if (history3.length >= 3) {

        // calculate average of recent three entries
        avrPressure = (history3[history3.length - 1]["p"] + history3[history3.length - 2]["p"] + history3[history3.length - 3]["p"]) / 3;

        if (setting("lowalarm") && avrPressure <= setting("min")) {
          showAlarm("Pressure low: " + Math.round(avrPressure) + " hPa");
          alreadyWarned = true;
        }
        if (setting("highalarm") && avrPressure >= setting("max")) {
          showAlarm("Pressure high: " + Math.round(avrPressure) + " hPa");
          alreadyWarned = true;
        }

        if (!alreadyWarned) {
          // 3h change detection
          const drop3halarm = setting("drop3halarm");
          const raise3halarm = setting("raise3halarm");
          if (drop3halarm > 0 || raise3halarm > 0) {
            // we need at least 30min of data for reliable detection
            if (history3[0]["ts"] > ts - (30 * 60)) {
              return;
            }

            // Average of oldest three entries
            const oldestAvgPressure = (history3[0]["p"] + history3[1]["p"] + history3[2]["p"]) / 3;
            if (oldestAvgPressure != undefined && oldestAvgPressure > 0) {
              const diff = oldestAvgPressure - avrPressure;

              // drop alarm
              if (drop3halarm > 0 && oldestAvgPressure > avrPressure) {
                if (Math.abs(diff) > drop3halarm) {
                  showAlarm((Math.round(Math.abs(diff) * 10) / 10) + " hPa/3h from " +
                    Math.round(oldestAvgPressure) + " to " + Math.round(avrPressure) + " hPa",
                    "Pressure drop"));
                }
              }

              // raise alarm
              if (raise3halarm > 0 && oldestAvgPressure < avrPressure) {
                if (Math.abs(diff) > raise3halarm) {
                  showAlarm((Math.round(Math.abs(diff) * 10) / 10) + " hPa/3h from " +
                    Math.round(oldestAvgPressure) + " to " + Math.round(avrPressure) + " hPa",
                    "Pressure raise"));
                }
              }
            }
          }
        }
      }

      // calculate 3h average for widget
      let sum = 0;
      for (let i = 0; i < history3.length; i++) {
        sum += history3[i]["p"];
      }
      threeHourAvrPressure = sum / history3.length;
    }
  }

  function check() {
    Bangle.getPressure().then(baroHandler);
  }

  function reload() {
    check();
  }

  function draw() {
    g.reset();
    if (setting("show") && lastPressure != undefined) {
      g.setFont("6x8", 1).setFontAlign(1, 0);
      g.drawString(Math.round(lastPressure), this.x + 24, this.y + 6);
      if (threeHourAvrPressure != undefined && threeHourAvrPressure > 0) {
        g.drawString(Math.round(threeHourAvrPressure), this.x + 24, this.y + 6 + 10);
      }
    }
  }

  if (global.WIDGETS != undefined && typeof WIDGETS === "object") {
    WIDGETS["baroalarm"] = {
      width: setting("show") ? 24 : 0,
      reload: reload,
      area: "tr",
      draw: draw
    };
  }

  // Let's delay the first check a bit
  setTimeout(function() {
    check();
    if (interval > 0) {
      setInterval(check, interval * 60000);
    }
  }, 10000);

})();