(function(back) {
  const SETTINGS_FILE = "pebble.json";

  // initialize with default settings...
  let s = {'bg': '#0f0', 'color': 'Green', 'theme':'System', 'showlock':'false'}

  // ...and overwrite them with any saved values
  // This way saved values are preserved if a new version adds more settings
  const storage = require('Storage')
  let settings = storage.readJSON(SETTINGS_FILE, 1) || s;
  const saved = settings || {}
  for (const key in saved) {
    s[key] = saved[key]
  }

  function save() {
    settings = s
    storage.write(SETTINGS_FILE, settings)
  }

  var color_options = ['Green','Orange','Cyan','Purple','Red','Blue'];
  var bg_code = ['#0f0','#ff0','#0ff','#f0f','#f00','#00f'];
  var theme_options = ['System', 'Light', 'Dark'];
  var lock_options = ['false', 'true'];
  
  E.showMenu({
    '': { 'title': 'Pebble Clock' },
    '< Back': back,
    'Colour': {
      value: 0 | color_options.indexOf(s.color),
      min: 0, max: 5,
      format: v => color_options[v],
      onchange: v => {
        s.color = color_options[v];
        s.bg = bg_code[v];
        save();
      }
    },
    'Theme': {
      value: 0 | theme_options.indexOf(s.theme),
      min: 0, max: theme_options.length - 1,
      format: v => theme_options[v],
      onchange: v => {
        s.theme = theme_options[v];
        save();
      }
    },
    'Show Lock': {
      value: 0 | lock_options.indexOf(s.showlock),
      min: 0, max: lock_options.length - 1,
      format: v => lock_options[v],
      onchange: v => {
        s.showlock = lock_options[v];
        save();
      }
    }
  });
})