Better custom oauth url return.

The authorizePath can include the host itself, so before concacting the host with the authorizePath check if the host is already present in the authorizePath.

app/src/main/java/chat/rocket/android/helper/OauthHelper.kt

@@ -84,7 +84,7 @@ object OauthHelper {
      * @return The Facebook Oauth URL.
      */
     fun getFacebookOauthUrl(clientId: String, serverUrl: String, state: String): String {
-        return  "https://facebook.com/v2.9/dialog/oauth" +
+        return "https://facebook.com/v2.9/dialog/oauth" +
                 "?client_id=$clientId" +
                 "&redirect_uri=${serverUrl.removeTrailingSlash()}/_oauth/facebook?close" +
                 "&state=$state" +
@@ -113,12 +113,18 @@ object OauthHelper {
         state: String,
         scope: String
     ): String {
-        return host +
-                authorizePath +
+        (authorizePath +
                 "?client_id=$clientId" +
                 "&redirect_uri=${serverUrl.removeTrailingSlash()}/_oauth/$serviceName" +
                 "&state=$state" +
                 "&scope=$scope" +
                 "&response_type=code"
+                ).let {
+            return if (it.contains(host)) {
+                it
+            } else {
+                host + it
+            }
+        }
     }
-}
+}
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