Extract database and settings modules

js/modules/settings.js

@@ -0,0 +1,63 @@
+const isObject = require('lodash/isObject');
+const isString = require('lodash/isString');
+
+
+const ITEMS_STORE_NAME = 'items';
+const LAST_PROCESSED_INDEX_KEY = 'attachmentMigration_lastProcessedIndex';
+const IS_MIGRATION_COMPLETE_KEY = 'attachmentMigration_isComplete';
+
+// Public API
+exports.getAttachmentMigrationLastProcessedIndex = connection =>
+  getItem(connection, LAST_PROCESSED_INDEX_KEY);
+
+exports.setAttachmentMigrationLastProcessedIndex = (connection, value) =>
+  setItem(connection, LAST_PROCESSED_INDEX_KEY, value);
+
+exports.isAttachmentMigrationComplete = async connection =>
+  Boolean(await getItem(connection, IS_MIGRATION_COMPLETE_KEY));
+
+exports.markAttachmentMigrationComplete = connection =>
+  setItem(connection, IS_MIGRATION_COMPLETE_KEY, true);
+
+// Private API
+const getItem = (connection, key) => {
+  if (!isObject(connection)) {
+    throw new TypeError('"connection" is required');
+  }
+
+  if (!isString(key)) {
+    throw new TypeError('"key" must be a string');
+  }
+
+  const transaction = connection.transaction(ITEMS_STORE_NAME, 'readonly');
+  const itemsStore = transaction.objectStore(ITEMS_STORE_NAME);
+  const request = itemsStore.get(key);
+  return new Promise((resolve, reject) => {
+    request.onerror = event =>
+      reject(event.target.error);
+
+    request.onsuccess = event =>
+      resolve(event.target.result ? event.target.result.value : null);
+  });
+};
+
+const setItem = (connection, key, value) => {
+  if (!isObject(connection)) {
+    throw new TypeError('"connection" is required');
+  }
+
+  if (!isString(key)) {
+    throw new TypeError('"key" must be a string');
+  }
+
+  const transaction = connection.transaction(ITEMS_STORE_NAME, 'readwrite');
+  const itemsStore = transaction.objectStore(ITEMS_STORE_NAME);
+  const request = itemsStore.put({ id: key, value }, key);
+  return new Promise((resolve, reject) => {
+    request.onerror = event =>
+      reject(event.target.error);
+
+    request.onsuccess = () =>
+      resolve();
+  });
+};