(() => {
let STOR = require("Storage");
let lastSpeed;

function drawFace() {
  // variables
  var first_run = true;
  var naNShown = false;  // just for performance; if the speed is unknown, then refresh the display once
  var speedFont = "6x8";
  var speedSize = 8;
  var speedNaNSize = 3;
  var textFont = "Vector";
  var textSize = 14;
  var linePadding = 50;
  var lineWidth = 2;
  var maxSpeedFont = "Vector";
  var maxSpeedSize = 20;
  var maxSpeedTextSize = 10;
  var maxSpeed = 0; // speed score
  var maxSpeedEver = Number(STOR.read("maxspeed.trailsense.json")) || 0;

  // Some initialization
  Bangle.setGPSPower(true);
  g.setFontAlign(0,0);
  g.setColor(g.theme.bg);
  g.fillRect(0,0,g.getWidth(), g.getHeight());
  g.setColor(g.theme.fg2);
  g.fillRect(0, linePadding-2, g.getWidth(), linePadding);
  g.fillRect(0, g.getHeight()-linePadding, g.getWidth(), g.getHeight()-linePadding+2);
  // text
  g.setColor(g.theme.fg2);
  g.setFont(textFont, textSize);
  g.drawString("km/h", g.getWidth()/2, g.getHeight() - linePadding - 20);
  g.drawString("Speed:", g.getWidth()/2, linePadding + 20);

  g.setColor(g.theme.fg2);
  g.setFont(maxSpeedFont, maxSpeedTextSize);
  g.drawString("Maxspeed [km/h]: NOW/EVER", g.getWidth()/2, g.getHeight()-maxSpeedTextSize/2);

  Bangle.loadWidgets();
  Bangle.drawWidgets();

  // utilitiy functions
  function round(value, decimals) {
    return Number(Math.round(value+'e'+decimals)+'e-'+decimals);
  }


  Bangle.on("GPS", 
    (gps_fix) => {
      var speed = round(gps_fix.speed, 1);
      if(speed<3.4) speed="0.0";
      if(Number(speed)>maxSpeed) maxSpeed = speed;
      if(maxSpeed > maxSpeedEver) { STOR.write("maxspeed.trailsense.json", maxSpeed.toString()); }
      maxSpeedEver = Number(STOR.read("maxspeed.trailsense.json")) || 0;

      if((speed != lastSpeed || first_run) && !isNaN(speed)) {
        first_run = false;
        naNShown = false;  // update naNShown for accidently signal loss (so that the loop down there can run again)

        // clear screen
        g.setColor(g.theme.bg);
        g.fillRect(0, g.getHeight()/2-30, g.getWidth(), g.getHeight()/2+30);

        // draw speed
        g.setColor(g.theme.fg);
        g.setFont(speedFont, speedSize);
        g.drawString(speed, g.getWidth()/2, g.getHeight()/2);

        // draw speed highscore
        g.setColor(g.theme.bg);
        g.fillRect(0, g.getHeight()-maxSpeedSize*2, g.getWidth(), g.getHeight()-maxSpeedSize/2)
        g.setColor(g.theme.fg);
        g.setFont(maxSpeedFont, maxSpeedSize);
        g.drawString(round(maxSpeed, 1) + " / " + maxSpeedEver, g.getWidth()/2, g.getHeight()-maxSpeedSize);
      } else if(isNaN(speed) && !naNShown) {
        g.setColor(g.theme.bg);
        g.fillRect(0, g.getHeight()/2-30, g.getWidth(), g.getHeight()/2+30);
        g.setColor(g.theme.fg);
        g.setFont(speedFont, speedNaNSize);
        g.drawString("Loading...", g.getWidth()/2, g.getHeight()/2);

        naNShown = true;
      }
      lastSpeed = speed;  // set last speed var for next loop
  })
}

function stop() {
  g.clear();
  Bangle.removeAllListeners();
  Bangle.setGPSPower(false);
}

return { drawFace:drawFace, stop:stop };
})();