Roller Coasters

🧭 Overview

Roller Coasters is a personal playground where I experiment with modern Android development practices, libraries, and tools. It is a space to try new APIs, patterns, and approaches, especially around Jetpack Compose, without the constraints of production code.

The project is under active development and the codebase is not yet stable or nearly finished.

📷 Screenshots

💡 Light Theme

🌙 Dark Theme

⚙️ Tech Stack & Architecture

This project is built using modern Android development practices and libraries:

• Language: 100% Kotlin
• UI: Jetpack Compose for declarative UI.
  • Theming: Material 3 (Material You) with dynamic color support.
  • Navigation: Navigation Compose (Navigation 2) for screen transitions.
• Architecture: Follows Google's official "Guide to app architecture", combining MVVM (Model-View-ViewModel) with principles from Clean Architecture.
  • UI Layer: State-driven UI using ViewModel, State, and Actions. ViewModels follow a declarative approach.
  • Domain Layer: (Optional) UseCases encapsulate specific business logic (e.g., GetFavoriteCoastersUseCase).
  • Data Layer: Repository pattern providing a single source of truth.
• Asynchronicity: Kotlin Coroutines & Flows for managing background tasks and data streams.
• Dependency Injection: Hilt for managing dependencies throughout the app.
• Networking: Ktor Client for REST API communication.
• Serialization: Kotlinx.serialization for JSON parsing.
• Testing:
  • Unit Tests: JUnit 4 & Mockk
  • Screenshot Tests: Paparazzi
  • UI Tests: Compose Test Rules

📱 App Features

• Explore Feed: View roller coasters, filterable by various criteria (specs, materials, etc.).
• Favorites: Mark and view your favorite roller coasters.
• Details Screen: See detailed information and images for each coaster.
• Settings:
  • Customize theme (Light/Dark/System)
  • Enable/disable dynamic color
  • Adjust color contrast
  • Change language (English, Spanish and Galician)
  • Select measurement system (Metric/Imperial).
• Modern UI:
  • Dynamic Theming (Material You).
  • Support for multiple languages.
  • Edge-to-edge display.
  • Predictive back navigation.
• About Screen: Information about the project/developer.

Getting Started

These instructions follow the default dev branch. Dependency versions are defined in the version catalog.

Requirements

• JDK 17, selected as the Gradle JDK in Android Studio or through JAVA_HOME for command-line builds.
• Android SDK Platform 36 and Android SDK Platform-Tools.
• An emulator or Android device running API 26 (Android 8.0) or newer to run the app.
• Use the checked-in Gradle wrapper; a separate Gradle installation is not needed.

Setup

Clone the default branch and open the project root in Android Studio:

git clone --branch dev https://github.com/Sottti/RollerCoasters.git
cd RollerCoasters

Set the SDK location in the root local.properties file. Android Studio normally creates this file; for command-line setup, create it with your own SDK path:

sdk.dir=/absolute/path/to/Android/sdk

This file is ignored by Git. Sync the project, select the app run configuration, and choose a device.

Build and Run

Build the debug APK:

./gradlew :app:assembleDebug

With an emulator running or a device connected with USB debugging enabled, install the debug app:

./gradlew :app:installDebug

Open Roller Coasters on the device, or use Run in Android Studio to build, install, and launch it.

Running Tests

Run all local unit tests, including Android module tests and the plain Kotlin/JVM module tests:

./gradlew test

For a narrower run, target individual modules:

./gradlew :domain:roller-coasters:test :presentation:settings:testDebugUnitTest

Verify the Paparazzi screenshots against the checked-in baselines without an emulator:

./gradlew verifyPaparazziDebug

When a visual change is intentional, update the baselines and review the resulting image diff:

./gradlew recordPaparazziDebug

Device-based tests require a running emulator or connected device:

./gradlew connectedDebugAndroidTest

The existing CI workflow runs assembleDebug and testDebugUnitTest. The test command above also covers the plain Kotlin/JVM modules.

📁 Project Structure

The app is split into Gradle modules by responsibility:

Directory	Responsibility
app/	Application entry point, startup, manifest, and app packaging.
presentation/	Compose screens, ViewModels, navigation, the design system, previews, and screenshot-test support.
domain/	Models, repository contracts, and use cases.
data/	Repository implementations, local storage, network access, settings, and background synchronization.
di/	Dependency wiring across the app's layers.
utils/	Shared lifecycle and date/time utilities.
buildSrc/	Shared Gradle module definitions.

See settings.gradle.kts for the complete module list.

🚀 Planned Features or Improvements

• Search: Find roller coasters by name.
• Parks: Add information about amusement parks.
• Enhanced Discovery: More filtering options (manufacturer, park, etc.).
• Robustness: Improved error handling and empty state displays.
• UI/UX: Add animations; improve support for large screens and foldables.
• Navigation: Migrate from Navigation Compose (Navigation 2) to Navigation 3.

📜 License

This project is licensed under the MIT License - see the LICENSE file for details.