💸 CashFlow MobileApp

A modern Kotlin-based Android app for personal finance management.

CashFlow is a modern Android application designed to make personal finance tracking effortless. It combines expense management, receipt scanning, and real-time currency conversion into one seamless experience. Stay on top of your spending habits, keep your transactions organized, and let CashFlow handle the details for you — all with modern Android tools and smooth UX.

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📱 Core Features

• 💸 Expense & Income Tracking – Record, categorize, and manage your daily transactions effortlessly.
• 📊 Transaction Overview – Keep track of your spending and earnings history in one clean interface.
• 📸 Receipt Scanning – Take a photo of a receipt and automatically extract the amount using text recognition.
• 🌍 Live Currency Rates – Fetch real-time exchange rates from Frankfurter API.
• 🔐 User Authentication (Room Database) – Local login with SHA-256 password hashing.
• 💾 Local Storage (Room + DataStore) – Save users and transactions on-device.
• ⚙️ Smart Sensors (UX Enhancements) –
  • Shake the device to auto logout.
  • Flip the phone upside down to dim the screen.
• 🧭 MVVM + Hilt + Navigation – Modular, scalable architecture for clean code and maintainability.

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🧠 Tech Stack

Built with modern Android technologies and Jetpack components for performance, scalability, and clean architecture.

• Kotlin 2.0.21
• Android Studio Meerkat | 2024.3.1
• Min SDK 24
• Target SDK 35

🏗️ Architecture & Design

• Kotlin – Main programming language
• MVVM (Model–View–ViewModel) – Reactive architecture for maintainable UI
• Hilt (Dagger) – Dependency injection for modular design
• Coroutines & Flow – Asynchronous and reactive data handling
• Jetpack Navigation – Type-safe and structured screen navigation

🧩 Data & Persistence

• Room – Local database for users and transactions
• DataStore – Lightweight persistence for user preferences
• Repository Pattern – Single source of truth connecting API and database

🌐 APIs & Networking

• Frankfurter.dev API – Real-time currency exchange rates

📷 Device & ML Features

• CameraX – Built-in camera support for receipt scanning
• ML Kit Text Recognition – Extract text and amounts from images
• Accelerometer Sensors – Used for shake and flip detection

🧩 UI & UX

• Material Design 3 – Modern and consistent Android design system
• Jetpack Compose – Modern declarative UI toolkit for building responsive layouts.

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🚀 Setup & Installation

1. Clone the repository

   git clone https://github.com/M-Stasiak/CashFlow_MobileApp.git
   cd CashFlow_MobileApp

2. Open the project in Android Studio (latest version).
3. Sync Gradle to download all dependencies.
4. Run the app on an emulator or a physical device (Android 7.0+).
5. (Optional) Ensure you have internet access for currency rate fetching via the Frankfurter API.

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🌍 API Reference

• Frankfurter API – Used to fetch live currency exchange rates.
  Example endpoint:

  https://api.frankfurter.dev/v1/latest?from=USD&to=EUR

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🧩 App Architecture Overview

CashFlow follows the MVVM (Model–View–ViewModel) architecture pattern to ensure a clean separation of concerns, scalability, and testability.

           +-------------------------------------+
           |              UI Layer               |
           | (MainActivity + Composable Screens) |
           |    ↓ observes state via ViewModel   |
           +------------------▲------------------+
                              |
                              | StateFlow
                              |
             +----------------▼----------------+
             |          ViewModel Layer        |
             |  - Handles UI logic             |
             |  - Exposes state to UI          |
             |  - Calls repository functions   |
             +----------------▲----------------+
                              |
                              | suspend functions
                              |
             +----------------▼----------------+
             |          Repository Layer       |
             |  - Combines local + remote data |
             +----------------▲----------------+
                              |
             +----------------+----------------+
             |                                 |
   +---------▼----------+            +---------▼---------+
   |     Local Data     |            |    Remote Data    |
   | (Room / DataStore) |            | (Frankfurter API) |
   +--------------------+            +-------------------+

🏗️ Key Principles

• Single Source of Truth: Repository abstracts data from Room and network sources.
• Reactive UI: LiveData or StateFlow updates the UI automatically.
• Dependency Injection: Hilt provides lifecycle-safe dependencies.
• Coroutines: Handle asynchronous tasks efficiently.
• Separation of Concerns: Each layer has a clear responsibility.

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🖼️ Screenshots

Login Screen	Dashboard	Receipt Scanner

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📜 License

This project is licensed under the MIT License.

Note: This is an educational project created solely for learning purposes and not intended for commercial use.