Simulate two-phase commit for wake up state change

Instead of implementing a real two-phase commit, and because we don't use
Ajax requests, change the browser's state only after the server durably
saved the state change. This way, we prevent data-loss if the person wakes
up, taps "Wake Up" and the server crashes / rejects the submit.

app.rb

@@ -112,6 +112,7 @@ def table_name_from_user_id(user_id)
 
   @user_id = user_id
   @app = :app
+  @wakeup = params[:wakeup] == "1"
   erb :app, layout: :layout
 end
 
@@ -126,7 +127,7 @@ def table_name_from_user_id(user_id)
   halt 400, "Bad Request: unrecognized sleep_type" if sleep_type.nil?
 
   DB[table_name_from_user_id(user_id)].insert(timezone: tz.name, start_at: start_at, end_at: end_at, sleep_type: sleep_type)
-  redirect "/me/#{user_id}"
+  redirect "/me/#{user_id}?wakeup=1"
 end
 
 get %r{\A/me/#{UUID_RE}/analytics} do |user_id|

public/js/bundle.js

@@ -55,6 +55,9 @@ NoFrillsSleepTracker.renderAppAwake = function(rootNode, store, userId, sleepTab
           store.setItem("start-nap-at-epoch", new Date().getTime());
           store.setItem("state", "napping");
 
+          // remove any pending "wakeup=1" param from the URL
+          history.pushState(null, "", document.location.pathname);
+
           // rerender the app's UI
           setTimeout(NoFrillsSleepTracker.renderApp.bind(window, rootNode, store, userId), 0);
         }));
@@ -70,6 +73,9 @@ NoFrillsSleepTracker.renderAppAwake = function(rootNode, store, userId, sleepTab
           store.setItem("start-sleep-at-epoch", new Date().getTime());
           store.setItem("state", "sleeping");
 
+          // remove any pending "wakeup=1" param from the URL
+          history.pushState(null, "", document.location.pathname);
+
           // rerender the app's UI
           setTimeout(NoFrillsSleepTracker.renderApp.bind(window, rootNode, store, userId), 0);
         }));
@@ -108,8 +114,6 @@ NoFrillsSleepTracker.renderAppSleeping = function(rootNode, store, userId, sleep
   form.addEventListener("submit", function(ev) {
     clearInterval(timerId);
     form.appendChild(NoFrillsSleepTracker.createHiddenInput("end_at", new Date().getTime()));
-    store.setItem("state", "awake");
-    store.removeItem("start-sleep-at-epoch");
   });
   form.appendChild(state);
   form.appendChild(NoFrillsSleepTracker.createSubmitButton("Wake up!"));
@@ -143,15 +147,19 @@ NoFrillsSleepTracker.renderAppNapping = function(rootNode, store, userId) {
   form.addEventListener("submit", function(ev) {
     clearInterval(timerId);
     form.appendChild(NoFrillsSleepTracker.createHiddenInput("end_at", new Date().getTime()));
-    store.setItem("state", "awake");
-    store.removeItem("start-nap-at-epoch");
   });
   form.appendChild(state);
   form.appendChild(NoFrillsSleepTracker.createSubmitButton("Wake from nap"));
 
   rootNode.appendChild(form);
 }
 
+NoFrillsSleepTracker.wakeUp = function(store) {
+  store.setItem("state", "awake");
+  store.removeItem("start-nap-at-epoch");
+  store.removeItem("start-sleep-at-epoch");
+}
+
 NoFrillsSleepTracker.renderApp = function(rootNode, store, userId, sleepTable) {
   var timezone = store.getItem("timezone") || "America/New_York";
   var state = store.getItem("state") || "awake";

views/app.erb

@@ -15,6 +15,14 @@
       if (params[0] === "timezone") NoFrillsSleepTracker.setTimezone(window.localStorage, param[1]);
     }
 
+    if (<%= @wakeup %>) {
+      // Reset state when the server tells us to do so
+      // Since we don't do 2 phase commit, or use an Ajax request to change the server's state,
+      // we have to wait until the server acknowledges the state change before resetting our
+      // localStorage state.
+      NoFrillsSleepTracker.wakeUp(window.localStorage);
+    }
+
     NoFrillsSleepTracker.renderApp(document.getElementById("app"), window.localStorage, userId, <%= @last5.to_json %>);
   } else {
     NoFrillsSleepTracker.renderLocalStorageDisabled(document.getElementById("app"));