Simplify API caching slightly (closes #1)

We can do this now that the API data for each date is populated using a transaction

src/helpers/ApiHelper.js

@@ -74,65 +74,22 @@ class ApiHelper {
   }
 
   static async _getCache() {
-    // If there's a cache matching the current year/month, return it
+    // If there's a cache matching the current year/month, return it in order to avoid calling the API
     const currentYearMonthString = ApiHelper._getCurrentYearMonthString();
     if (await caches.has(currentYearMonthString)) {
       return await caches.open(currentYearMonthString);
     }
 
-    // If the latest year/month in the API is current and the API is finished syncing,
-    // delete all old caches and return a new one for the current year/month
+    // If the latest year/month in the API is current, delete all the old caches before returning the new one
     const latestYearMonthString = await ApiHelper._getLatestYearMonthStringFromApi();
-    if (
-      latestYearMonthString === currentYearMonthString &&
-      ApiHelper._isApiFinishedSyncing(currentYearMonthString)
-    ) {
+    if (latestYearMonthString === currentYearMonthString) {
       await ApiHelper._deleteAllCaches();
-      return await caches.open(currentYearMonthString);
     }
 
-    // If we end up here, return a cache for the latest year/month in the API
+    // Return a cache for the latest year/month in the API (whether the current month or a previous one)
     return await caches.open(latestYearMonthString);
   }
 
-  static async _isApiFinishedSyncing(yearMonthString) {
-    return (
-      (await ApiHelper._getNumberOfLanguagesFromApi(yearMonthString)) ===
-      (await ApiHelper._getTotalNumberOfLanguages())
-    );
-  }
-
-  static async _getNumberOfLanguagesFromApi(yearMonthString) {
-    const where = {
-      date: yearMonthString,
-    };
-    const apiUrl = encodeURI(
-      `${API_BASE_URL}/api/scores/count?where=${JSON.stringify(
-        where
-      )}&access_token=${API_TOKEN}`
-    );
-    const response = await fetch(apiUrl);
-
-    return (await response.json()).count;
-  }
-
-  static async _getTotalNumberOfLanguages() {
-    const response = await fetch(
-      'https://raw.githubusercontent.com/bmaupin/langtrends-api/master/server/boot/classes/languages.json'
-    );
-    const languages = await response.json();
-
-    return Object.keys(languages).reduce(
-      (numberOfIncludedLanguages, languageName) => {
-        if (languages[languageName].include === true) {
-          numberOfIncludedLanguages += 1;
-        }
-        return numberOfIncludedLanguages;
-      },
-      0
-    );
-  }
-
   static _getCurrentYearMonthString() {
     return new Date().toISOString().slice(0, 7);
   }