Currencny Converter MVVM + Clean Architecture

✨ A Currency Converter with MVVM + Clean Architecture using Fixer API ✨ The application is offline first. On Free API. It fetches currency data for first time and then gives users ability to pull new data on demand.

Usecase:

• Usecase-1 : Downloads Currency rates from "latest" endpoints and caches in local Database. Displays Date of last update. In case of No internet, user can continue to do currency conversions
• Usecase-2: User can see last X days (currently 3) history of his selections, from "Time-series" endpoint of API in following forms:
• In the Form of list (Requires Internet)
• In the form of Graph (Requires Internet)
• Usecase-3: User can see conversion of his current selection into 10 other popular currencies
• Unit Test: So Far unit tests are written for the first Usecase only. I will continue adding unit tests.

Architecture

Uses concepts of the notorious Uncle Bob's architecture called Clean Architecture.

• Better separation of concerns. Each module has a clear API., Feature related classes life in different modules and can't be referenced without explicit module dependency.
• Every layer is using their own model and a 'LayerObjectMapper' class is used to convert an object to its relative pattern
• Usecases represents a UI use cases, communication between Repo and UI is done through it and maps repo object back to UI objects.

Tech stack - Library:

• Kotlin
• Coroutines - A coroutine is a concurrency design pattern that you can use on Android to simplify code that executes asynchronously
• Flow - Flow is used to pass (send) a stream of data that can be computed asynchronously
• Dagger-Hilt - for dependency injection.
• LiveData - For reactive style programming (from VM to UI).
• ViewModel - Stores UI-related data that isn't destroyed on UI changes.
• Room - Used to create room db and store the data.
• Navigation - Used to navigate between fragments
• Data Binding - Used to bind UI components in your XML layouts.
• Retrofit - Used for REST api communication.
• OkHttp - HTTP client that's efficient by default: HTTP/2 support allows all requests to the same host to share a socket
• Gson - Used to convert Java Objects into their JSON representation and vice versa.
• Ktlint - ktlint aims to capture the official Kotlin coding conventions and Android Kotlin Style Guide. Testing
• Google-truth - Google Truth
• Mockito - Mockito
• JUnit JUnit

Future Improvements:

• Finish writing test cases
• Add work Manager to download data on specific intervals

Screenshots: