# Tetris Refactoring TODO List

## 🚀 Phase 1: Foundation (Week 1-2) - CRITICAL ✅ COMPLETED

### Core Architecture Setup

- [x] Create `ApplicationManager` class
  - [x] Design interface and basic structure
  - [x] Implement initialize(), run(), shutdown() methods
  - [x] Move SDL initialization from main() to ApplicationManager
  - [x] Add proper error handling and cleanup
  - [x] Test basic application lifecycle

- [x] Extract `RenderManager` class
  - [x] Create rendering abstraction layer
  - [x] Move SDL_Window and SDL_Renderer management
  - [x] Implement viewport and scaling logic
  - [x] Add texture and primitive rendering methods
  - [x] Test rendering pipeline isolation

- [x] Implement basic `StateManager` improvements
  - [x] Enhance current StateManager with stack support
  - [x] Add state validation and error handling
  - [x] Implement proper state lifecycle management
  - [x] Test state transitions thoroughly

**✅ MILESTONE ACHIEVED**: Core architecture foundation is complete! We now have:
- Clean separation between main() and application logic
- Abstracted rendering system
- Enhanced state management with proper lifecycle
- Working refactored application (`tetris_refactored.exe`) alongside original
- Proper error handling and logging throughout

### Immediate Code Cleanup
- [ ] Remove global variables from main.cpp
  - [ ] Move static variables to appropriate managers
  - [ ] Remove global texture and font variables
  - [ ] Eliminate global state flags
  - [ ] Clean up static function declarations

- [ ] Extract constants to configuration
  - [ ] Create Config namespace with all constants
  - [ ] Remove magic numbers from main.cpp
  - [ ] Define window size constants
  - [ ] Set up gameplay timing constants

## 🔧 Phase 2: Core Systems (Week 3-4) - HIGH PRIORITY

### Input Management
- [x] Create `InputManager` class
  - [x] Implement keyboard state tracking
  - [x] Add mouse input handling
  - [x] Create event handler registration system
  - [x] Implement DAS/ARR logic in InputManager
  - [x] Test input responsiveness and accuracy

- [x] Refactor event handling in main()
  - [x] Move SDL event polling to InputManager
  - [x] Replace inline event handlers with registered callbacks
  - [x] Simplify main loop event processing
  - [x] Test all input scenarios (keyboard, mouse, gamepad)

### Asset Management
- [ ] Create `AssetManager` class
  - [ ] Design resource loading interface
  - [ ] Implement texture management
  - [ ] Add font loading and management
  - [ ] Create sound asset handling
  - [ ] Add resource cleanup and error handling

- [ ] Migrate existing asset loading
  - [ ] Move texture loading from main() to AssetManager
  - [ ] Convert font initialization to use AssetManager
  - [ ] Update StateContext to use AssetManager
  - [ ] Test asset loading and memory management

### State System Enhancement
- [ ] Implement `IGameState` interface
  - [ ] Define clear state contract
  - [ ] Add update(), render(), handleEvent() methods
  - [ ] Implement proper state lifecycle
  - [ ] Add state type identification

- [ ] Create `StateFactory` pattern
  - [ ] Design state creation interface
  - [ ] Implement factory registration system
  - [ ] Add state parameter passing
  - [ ] Test dynamic state creation

## 🎨 Phase 3: Rendering Systems (Week 5-6) - MEDIUM PRIORITY

### UI Rendering Separation
- [ ] Create `UIRenderer` class
  - [ ] Extract button rendering logic
  - [ ] Implement popup rendering system
  - [ ] Add progress bar rendering
  - [ ] Create menu rendering components
  - [ ] Test UI rendering consistency

- [ ] Refactor state rendering
  - [ ] Update LoadingState to use UIRenderer
  - [ ] Modify MenuState rendering
  - [ ] Enhance LevelSelectorState visuals
  - [ ] Test all state rendering paths

### Game Rendering Optimization
- [ ] Create `GameRenderer` class
  - [ ] Extract game board rendering
  - [ ] Implement piece rendering system
  - [ ] Add background management
  - [ ] Create HUD rendering components
  - [ ] Optimize rendering performance

- [ ] Enhance visual effects
  - [ ] Improve line clearing effects
  - [ ] Add piece drop animations
  - [ ] Enhance particle systems
  - [ ] Implement screen transitions

### Background System
- [ ] Create `BackgroundManager` class
  - [ ] Implement level-based backgrounds
  - [ ] Add background caching system
  - [ ] Create smooth transitions
  - [ ] Test background loading performance

## ⚙️ Phase 4: Configuration (Week 7) - MEDIUM PRIORITY

### Configuration System
- [ ] Implement `ConfigManager` class
  - [ ] Design configuration storage
  - [ ] Add file loading/saving
  - [ ] Implement runtime configuration updates
  - [ ] Add configuration validation
  - [ ] Test configuration persistence

- [ ] Migrate constants
  - [ ] Move window size settings
  - [ ] Convert gameplay constants
  - [ ] Update UI layout values
  - [ ] Set up default configurations

### Settings Management
- [ ] Create settings persistence
  - [ ] Save audio preferences
  - [ ] Store control mappings
  - [ ] Remember window settings
  - [ ] Test settings across restarts

## 📡 Phase 5: Event System (Week 8) - MEDIUM PRIORITY

### Event Bus Implementation
- [ ] Create `EventBus` template class
  - [ ] Implement subscription system
  - [ ] Add event publishing mechanism
  - [ ] Create handler management
  - [ ] Test event delivery reliability

- [ ] Define Game Events
  - [ ] Create LevelUp event
  - [ ] Implement LineCleared event
  - [ ] Add GameOver event
  - [ ] Define PieceSpawned event
  - [ ] Test event system integration

### Audio System Decoupling
- [ ] Convert audio callbacks to events
  - [ ] Replace sound callbacks with event handlers
  - [ ] Implement music management events
  - [ ] Add audio configuration events
  - [ ] Test audio system responsiveness

## 🔌 Phase 6: Dependency Injection (Week 9) - LOW PRIORITY

### Service Container
- [ ] Implement `ServiceContainer` class
  - [ ] Design service registration
  - [ ] Add dependency resolution
  - [ ] Implement service lifecycle
  - [ ] Test service dependencies

- [ ] Migrate to dependency injection
  - [ ] Update manager constructors
  - [ ] Implement service interfaces
  - [ ] Add service configuration
  - [ ] Test dependency resolution

## 🧪 Phase 7: Testing & Quality (Week 10) - LOW PRIORITY

### Unit Testing Setup
- [ ] Set up testing framework
  - [ ] Configure Google Test or Catch2
  - [ ] Create test project structure
  - [ ] Add basic test utilities
  - [ ] Set up automated test running

- [ ] Write core tests
  - [ ] Test ApplicationManager lifecycle
  - [ ] Validate StateManager transitions
  - [ ] Test InputManager functionality
  - [ ] Verify AssetManager operations
  - [ ] Test ConfigManager persistence

### Integration Testing
- [ ] Create integration test suite
  - [ ] Test manager interactions
  - [ ] Validate state transitions
  - [ ] Test complete game scenarios
  - [ ] Run performance regression tests

### Code Quality
- [ ] Add static analysis
  - [ ] Configure clang-tidy
  - [ ] Set up cppcheck
  - [ ] Add memory leak detection
  - [ ] Run code coverage analysis

## 🔧 Optimization Tasks - ONGOING

### Performance Optimization
- [ ] Profile rendering performance
  - [ ] Identify rendering bottlenecks
  - [ ] Optimize texture usage
  - [ ] Improve draw call batching
  - [ ] Test frame rate consistency

- [ ] Memory optimization
  - [ ] Analyze memory usage patterns
  - [ ] Optimize asset loading
  - [ ] Implement memory pooling where needed
  - [ ] Test for memory leaks

### Code Quality Improvements
- [ ] Documentation
  - [ ] Add comprehensive class documentation
  - [ ] Document API interfaces
  - [ ] Create usage examples
  - [ ] Write development guidelines

- [ ] Error Handling
  - [ ] Implement consistent error handling
  - [ ] Add logging system
  - [ ] Create error recovery mechanisms
  - [ ] Test error scenarios

### Platform Compatibility
- [ ] Cross-platform testing
  - [ ] Test on Windows
  - [ ] Validate Linux compatibility
  - [ ] Check macOS support
  - [ ] Test different screen resolutions

## 📊 Progress Tracking

### Metrics to Monitor
- [ ] **Code Complexity**: Reduce main() from 1,678 to <100 lines
- [ ] **Test Coverage**: Achieve >90% code coverage
- [ ] **Build Time**: Maintain fast compilation
- [ ] **Performance**: No regression in frame rate
- [ ] **Memory Usage**: Stable memory consumption

### Milestones
- [ ] **Milestone 1**: Basic managers extracted and working
- [ ] **Milestone 2**: State system fully refactored
- [ ] **Milestone 3**: Rendering system modularized
- [ ] **Milestone 4**: Configuration system implemented
- [ ] **Milestone 5**: Event system integrated
- [ ] **Milestone 6**: All tests passing, full documentation

### Success Criteria
- [ ] Main function reduced to application setup only
- [ ] All components unit testable
- [ ] Easy to add new features without modifying core code
- [ ] Clear separation of concerns throughout codebase
- [ ] Comprehensive documentation and examples

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## 📝 Notes

- **Priority levels**: CRITICAL = Must complete, HIGH = Important for maintainability, MEDIUM = Quality improvements, LOW = Nice to have
- **Estimated timeline**: 10 weeks for complete refactoring
- **Risk mitigation**: Each phase should maintain working application
- **Testing strategy**: Test after each major change to ensure no regressions
- **Documentation**: Update as you go, don't leave it for the end