From c5c94bc3ab0deb8a6848d93943287f10f4bd1948 Mon Sep 17 00:00:00 2001
From: Daniel Gasienica <daniel@signal.org>
Date: Wed, 28 Mar 2018 13:05:49 -0400
Subject: [PATCH] Extract `getMigrationVersions`

---
 js/modules/migrations/run_migrations.js | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/js/modules/migrations/run_migrations.js b/js/modules/migrations/run_migrations.js
index ac130d847..84635542a 100644
--- a/js/modules/migrations/run_migrations.js
+++ b/js/modules/migrations/run_migrations.js
@@ -3,6 +3,8 @@
 const isFunction = require('lodash/isFunction');
 const isObject = require('lodash/isObject');
 const isString = require('lodash/isString');
+const head = require('lodash/head');
+const last = require('lodash/last');
 
 const { deferredToPromise } = require('../deferred_to_promise');
 
@@ -30,3 +32,17 @@ exports.runMigrations = async ({ Backbone, database } = {}) => {
   console.log('Close database connection');
   await closeDatabaseConnection({ Backbone });
 };
+
+const getMigrationVersions = (database) => {
+  if (!isObject(database) || !Array.isArray(database.migrations)) {
+    throw new TypeError('"database" is required');
+  }
+
+  const firstMigration = head(database.migrations);
+  const lastMigration = last(database.migrations);
+
+  const firstVersion = firstMigration ? parseInt(firstMigration.version, 10) : null;
+  const lastVersion = lastMigration ? parseInt(lastMigration.version, 10) : null;
+
+  return { firstVersion, lastVersion };
+};