Reset zulipServices object during login.

During login, new zulipServices object should be created to prevent
unnecessary caching of previously entered server url.
Also, any leading or trailing whitespaces should be removed from the url
before making the network request.

Fixes: #227.

Author: Sam1301

app/src/main/java/com/zulip/android/ZulipApp.java

@@ -187,7 +187,7 @@ private void afterLogin() {
     }
 
     public ZulipServices getZulipServices() {
-        if(zulipServices == null) {
+        if (zulipServices == null) {
             HttpLoggingInterceptor logging = new HttpLoggingInterceptor().setLevel(HttpLoggingInterceptor.Level.BODY);
             zulipServices = new Retrofit.Builder()
                     .client(new OkHttpClient.Builder().readTimeout(60, TimeUnit.SECONDS)
@@ -202,6 +202,10 @@ public ZulipServices getZulipServices() {
         return zulipServices;
     }
 
+    public void setZulipServices(ZulipServices zulipServices) {
+        this.zulipServices = zulipServices;
+    }
+
     public Gson getGson() {
         if(gson == null) {
             gson = buildGson();

app/src/main/java/com/zulip/android/activities/LoginActivity.java

@@ -151,6 +151,10 @@ protected void onStop() {
 
     private void checkForError() {
         String serverURL = serverIn.getText().toString();
+
+        // trim leading or trailing white spaces in Url
+        serverURL = serverURL.trim();
+
         int errorMessage = R.string.invalid_server_domain;
         String httpScheme = (BuildConfig.DEBUG) ? "http" : "https";
 
@@ -184,6 +188,11 @@ public void onSaveInstanceState(Bundle savedInstanceState){
     }
 
     private void showBackends(String httpScheme, String serverURL) {
+        // if server url does not end with "/", then append it
+        if (!serverURL.endsWith("/")) {
+            serverURL = serverURL + "/";
+        }
+
         Uri serverUri = Uri.parse(serverURL);
 
         serverUri = serverUri.buildUpon().scheme(httpScheme).build();
@@ -198,6 +207,9 @@ private void showBackends(String httpScheme, String serverURL) {
         mServerEditText.setEnabled(false);
         ((ZulipApp) getApplication()).setServerURL(serverUri.toString());
 
+        // create new zulipServices object every time by setting it to null
+        getApp().setZulipServices(null);
+
         getServices()
                 .getAuthBackends()
                 .enqueue(new DefaultCallback<ZulipBackendResponse>() {