We developed the required chatting application using the very recent cross-platform development tool Flutter. Flutter is a tool developed by Google that makes use of the Dart language. Very recently, and in the middle of our developement process, official version 1.0 has been released, making it actually out of the beta phase.

The app fulfills all the required basic functionalities, as well as implements some of the extra ones.

Such extra functionalities are:

• Voice-to-text Input: using the Google Speech-to-Text API, a user can record a voice message, which is then converted to text and sent as text message;

• Link Preview: using the web REST service LinkPreview, whenever a URL is detected in a text message (only the first one), metadata information is retrieved from the web service and shown in the UI to all the users receiving the message;

• Emoticons Library: users can send both static and dynamic emoticons (as also shown in the screenshots below) as content of a message;

• Text Processing: using the Google Cloud Translation API, messages are translated from whatever language they are written into a language set by the user. Translation can happen on-demand, by long pressing on a message, or automatically so that the translated content is shown directly next to the message in the original language. The settings regarding the destination language as well as the translation mode (on-demand or automatic) can be changed from the settings screen.

• Themes Support: users can choose between a light theme (chosen by default) and a dark theme.

The repository contains the following files/folders:

• README.md: this file;
• deploy.sh: the deployment bash script needed to deploy cloud functions on GCP and build and run the flutter application on an Android target device;
• backend: contains firebase-specific configuration files needed to correctly deploy the cloud functions.Then, the subfolder functions contains the NodeJS functions to be deployed;
• frontend: contains Flutter-specific files representing the mobile application. For more info about how Flutter projects are structured, please visit the official website.

In order to run the deployment script, which handles all the necessary operations in order to deploy the cloud functions and build and run the Android application on a target Android device, first thing needed is to move into the root of the project.

cd application_folder/

Then, executable permissions might not be set and need to be given to the script in order to properly interact with the filesystem.

chmod +x deploy.sh

The last step is as simple as running the deployment script.

./deploy.sh