/**
 * Values represent classes.
 *
 * classname: Only visible in class-state.
 * not-classname: Not visible in class-state.
 */
const States = {
  PUBLIC: "public",
  IDLE: "idle",
  RECORDING: "recording",
  SETUP: "setup",
};
Object.freeze(States);
let previousState = States.PUBLIC;
let currentState = States.PUBLIC;
let callbacks = {
  leaving: {},
  entering: {},
};

function updateVisibility() {
  u("." + previousState).addClass("hidden");
  u("." + currentState).removeClass("hidden");

  u(".not-" + previousState).removeClass("hidden");
  u(".not-" + currentState).addClass("hidden");

  processCallbacks();
}

function processCallbacks() {
  var cb = callbacks.leaving[previousState];
  if (cb !== undefined) cb();

  cb = callbacks.entering[currentState];
  if (cb !== undefined) cb();
}

function setState(state) {
  if (Object.values(States).includes(state) === false) {
    return;
  }

  previousState = currentState;
  currentState = state;

  localStorage.state = state;

  updateVisibility();
}

function initState() {
  var savedState = localStorage.state;
  if (savedState !== undefined) currentState = localStorage.state;
}