Barbera - Language Learning App

A Flutter-based language learning app focused on effective memorization through flashcards and spaced repetition.

Features

• ✅ Manual word creation with optional examples
• ✅ Active recall flashcards (tap to reveal)
• ✅ Intuitive swipe gestures:
  • Swipe RIGHT → Mark as "Known" (spaced repetition)
  • Swipe LEFT → Archive word
  • TAP → Flip card to see translation
• ✅ Spaced repetition algorithm (SM-2 inspired)
• ✅ Streaks and daily statistics
• ✅ Offline-first local storage (Hive)
• ✅ Clean, minimal UI

Getting Started

Prerequisites

• Flutter SDK (latest stable)
• Android Studio / Xcode for mobile development

Setup

1. Install Flutter dependencies:

flutter pub get

2. Generate Hive adapters (required for data models):

flutter pub run build_runner build --delete-conflicting-outputs

3. Run the app:

flutter run

Architecture

The app follows clean architecture principles with clear separation of concerns:

Domain Layer (lib/domain/)

• Entities: Core business objects (Flashcard, UserStats)
• Repositories: Abstract interfaces for data access
• Services: Business logic (spaced repetition algorithm)

Data Layer (lib/data/)

• Models: Hive-annotated data models
• Repositories: Concrete implementations using Hive storage
• Database: Hive initialization and setup

Presentation Layer (lib/presentation/)

• Screens: Main UI screens (Practice, Add Word, Stats)
• Widgets: Reusable components (FlashcardWidget, SwipeableFlashcardStack)
• Providers: Riverpod state management
• Navigation: GoRouter configuration

Key Components

Flashcard Interactions

• Swipe Gestures: Smooth pan gestures with visual feedback
• Card Flip: 3D flip animation on tap
• Threshold-based: Prevents accidental swipes

Spaced Repetition Algorithm

Based on SM-2 algorithm with adjustments:

• Initial ease factor: 2.5
• Correct answer: Increases ease factor, extends interval
• Incorrect answer: Decreases ease factor, resets to 1 day
• Intervals: 1 day → 6 days → exponential growth

Data Storage

• Hive: Fast, lightweight NoSQL database
• Offline-first: All data stored locally
• Type-safe: Generated adapters for models

Project Structure

lib/
├── data/
│   ├── database/
│   ├── models/
│   └── repositories/
├── domain/
│   ├── entities/
│   ├── repositories/
│   └── services/
├── presentation/
│   ├── navigation/
│   ├── providers/
│   ├── screens/
│   └── widgets/
└── main.dart

State Management

Using Riverpod for state management:

• flashcardNotifierProvider: Manages flashcard list and operations
• userStatsProvider: Tracks user statistics
• allFlashcardsProvider: Provides all flashcards for stats

Future Enhancements (Post-MVP)

• Multiple language support
• Import/export flashcards
• Audio pronunciation
• Dark mode
• Cloud sync
• Advanced statistics and analytics