dees-catalog/readme.refactoring-summary.md

WYSIWYG Editor Refactoring Progress Summary

Completed Phases

Phase 1: Infrastructure ✅

• Created modular block handler architecture
• Implemented IBlockHandler interface and BaseBlockHandler class
• Created BlockRegistry for dynamic block type registration
• Set up proper file structure under blocks/ directory

Phase 2: Proof of Concept ✅

• Successfully migrated divider block as the simplest example
• Validated the architecture works correctly
• Established patterns for block migration

Phase 3: Text Blocks ✅

• Paragraph Block: Full editing support with text splitting, selection handling, and cursor tracking
• Heading Blocks: All three heading levels (h1, h2, h3) with unified handler
• Quote Block: Italic styling with border, full editing capabilities
• Code Block: Monospace font, tab handling, plain text paste support
• List Block: Bullet/numbered lists with proper list item management

Key Achievements

1. Preserved Critical Knowledge

• Static Rendering: Blocks use innerHTML in firstUpdated to prevent focus loss during typing
• Shadow DOM Selection: Implemented containsAcrossShadowDOM utility for proper selection detection
• Cursor Position Tracking: All editable blocks track cursor position across multiple events
• Content Splitting: HTML-aware splitting using Range API preserves formatting
• Focus Management: Microtask-based focus restoration ensures reliable cursor placement

2. Enhanced Architecture

• Each block type is now self-contained in its own file
• Block handlers are dynamically registered and loaded
• Common functionality is shared through base classes
• Styles are co-located with their block handlers

3. Maintained Functionality

• All keyboard navigation works (arrows, backspace, delete, enter)
• Text selection across Shadow DOM boundaries functions correctly
• Block merging and splitting behave as before
• IME (Input Method Editor) support is preserved
• Formatting shortcuts (Cmd/Ctrl+B/I/U/K) continue to work

Code Organization

ts_web/elements/wysiwyg/
├── dees-wysiwyg-block.ts (simplified main component)
├── wysiwyg.selection.ts (Shadow DOM selection utilities)
├── wysiwyg.blockregistration.ts (handler registration)
└── blocks/
    ├── index.ts (exports and registry)
    ├── block.base.ts (base handler interface)
    ├── decorative/
    │   └── divider.block.ts
    └── text/
        ├── paragraph.block.ts
        ├── heading.block.ts
        ├── quote.block.ts
        ├── code.block.ts
        └── list.block.ts

Next Steps

Phase 4: Media Blocks (In Progress)

• Image block with upload/drag-drop support
• YouTube block with video embedding
• Attachment block for file uploads

Phase 5: Content Blocks

• Markdown block with preview toggle
• HTML block with raw HTML editing

Phase 6: Cleanup

• Remove old code from main component
• Optimize bundle size
• Update documentation

Technical Improvements

1. Modularity: Each block type is now completely self-contained
2. Extensibility: New blocks can be added by creating a handler and registering it
3. Maintainability: Files are smaller and focused on single responsibilities
4. Type Safety: Strong TypeScript interfaces ensure consistent implementation
5. Performance: No degradation in performance; potential for lazy loading in future

Migration Pattern

For future block migrations, follow this pattern:

1. Create block handler extending BaseBlockHandler
2. Implement required methods: render(), setup(), getStyles()
3. Add helper methods for cursor/content management
4. Handle Shadow DOM selection properly using utilities
5. Register handler in wysiwyg.blockregistration.ts
6. Test all interactions (typing, selection, navigation)

The refactoring has been successful in making the codebase more maintainable while preserving all the hard-won functionality and edge case handling from the original implementation.