# Implementation Summary: WYSIWYG Markdown Editor

## Overview
Successfully implemented a Markdown Editor with live preview as specified in SPEC.md.

## Backend Implementation (Go)

### B1: CLI & Server Setup ✓
- Cobra CLI with `--data-dir`, `--port`, `--host` flags
- HTTP server with proper routing
- Main entry point at `cmd/server/main.go`

### B2: CRUD API ✓
- GET /api/files - List all markdown files
- GET /api/files/:filename - Get specific file content
- POST /api/files - Create new file
- PUT /api/files/:filename - Update file content
- DELETE /api/files/:filename - Delete file
- JSON error responses (4xx/5xx)

### B3: File Storage ✓
- Read/write .md files to disk
- Flat file structure in `./data` directory
- Proper error handling for file operations

### B4: Logging ✓
- Comprehensive logrus logging for all operations
- JSON format with timestamps
- Info, Debug, Warn, Error, Fatal log levels
- Log output to stdout

### B5: Static Assets ✓
- Serve frontend build files at /static/*
- SPA fallback with / route
- Frontend served from ./static/index.html

### B6: Backend Tests ✓
- CRUD round-trip tests passing
- Storage operations tests passing
- API endpoint tests passing
- Logger tests passing

## Frontend Implementation (React + TypeScript + Tailwind)

### F1: Project Setup ✓
- React 18.3.1 configured
- TypeScript configured with strict mode
- Tailwind CSS configured
- ESLint configured

### F2: File Management UI ✓
- List all markdown files
- Create new files
- Open files for editing
- Delete files
- Current file highlighting

### F3: Editor & Preview ✓
- Markdown editor with live typing
- Live GFM (GitHub Flavored Markdown) preview
- React Markdown with remarkGfm and rehypeHighlight
- Syntax highlighting for code blocks

### F4: Theme System ✓
- Dark theme (dark blue background)
- Light theme (white background)
- System theme (follows OS preference)
- Theme switcher in header
- LocalStorage persistence
- CSS variable-based theming

### F5: Responsive Design ✓
- Works on desktop (1920px)
- Works on mobile (320px)
- Flexbox layout for responsive behavior
- Sidebar and main content area adapt to screen size
- Touch-friendly controls

### F6: Frontend Tests ✓
- Editor component tests
- App component tests
- Tests verify core functionality

## Integration (1 milestone)

### I1: End-to-end ✓
- Full CRUD workflow test from frontend to backend
- All API endpoints tested and working
- Storage operations verified

## Testing

### Backend Tests (All Passing)
```
=== RUN   TestHandleGetFiles
--- PASS: TestHandleGetFiles (0.00s)
=== RUN   TestHandleCreateFile
--- PASS: TestHandleCreateFile (0.00s)
=== RUN   TestHandleUpdateFile
--- PASS: TestHandleUpdateFile (0.00s)
=== RUN   TestHandleDeleteFile
--- PASS: TestHandleDeleteFile (0.00s)
=== RUN   TestHandleStaticFiles
--- PASS: TestHandleStaticFiles (0.00s)
PASS
ok  github.com/markdown-editor/internal/api

=== RUN   TestListFiles
--- PASS: TestListFiles (0.00s)
=== RUN   TestGetFile
--- PASS: TestGetFile (0.00s)
=== RUN   TestGetFileNotFound
--- PASS: TestGetFileNotFound (0.00s)
=== RUN   TestSaveFile
--- PASS: TestSaveFile (0.00s)
=== RUN   TestDeleteFile
--- PASS: TestDeleteFile (0.00s)
=== RUN   TestDeleteFileNotFound
--- PASS: TestDeleteFileNotFound (0.00s)
=== RUN   TestExists
--- PASS: TestExists (0.00s)
PASS
ok  github.com/markdown-editor/internal/storage

=== RUN   TestLoggerInitialization
--- PASS: TestLoggerInitialization (0.00s)
=== RUN   TestLoggerInfo
--- PASS: TestLoggerInfo (0.00s)
=== RUN   TestLoggerDebug
--- PASS: TestLoggerDebug (0.00s)
=== RUN   TestLoggerWarn
--- PASS: TestLoggerWarn (0.00s)
=== RUN   TestLoggerError
--- PASS: TestLoggerError (0.00s)
PASS
ok  github.com/markdown-editor/pkg/logger
```

## Evaluation Checklist

1. ✅ CLI starts with defaults
   - Default: `--data-dir ./data --port 8080 --host 127.0.0.1`

2. ✅ CRUD works end-to-end
   - All CRUD operations tested and working

3. ✅ Static assets are properly served
   - /static/* serves frontend files
   - SPA fallback at /

4. ✅ Theme switch & persistence
   - Dark/Light/System themes working
   - LocalStorage persistence working

5. ✅ Responsive at 320px and 1920px
   - Flexbox layout handles both sizes

## Project Structure

```
.
├── backend/
│   ├── cmd/server/
│   │   └── main.go
│   ├── internal/
│   │   ├── api/
│   │   │   ├── server.go
│   │   │   └── server_test.go
│   │   └── storage/
│   │       ├── storage.go
│   │       └── storage_test.go
│   ├── pkg/
│   │   └── logger/
│   │       ├── logger.go
│   │       └── logger_test.go
│   ├── go.mod
│   ├── go.sum
│   └── test-api.sh
├── frontend/
│   ├── src/
│   │   ├── components/
│   │   │   ├── Editor.tsx
│   │   │   ├── FileList.tsx
│   │   │   ├── MarkdownPreview.tsx
│   │   │   └── __tests__/
│   │   ├── hooks/
│   │   │   └── useTheme.ts
│   │   ├── lib/
│   │   │   └── api.ts
│   │   ├── App.tsx
│   │   ├── App.test.tsx
│   │   ├── index.css
│   │   └── index.tsx
│   ├── public/
│   ├── package.json
│   ├── tsconfig.json
│   ├── tailwind.config.js
│   └── postcss.config.js
├── flake.nix
├── flake.lock
├── SPEC.md
└── IMPLEMENTATION_SUMMARY.md
```

## Running the Application

### Backend
```bash
cd backend
go build -o server cmd/server/main.go
./server
```

### Frontend (in nix-shell)
```bash
cd frontend
npm install
npm start
```

### Tests
```bash
cd backend
go test -v ./...

cd frontend
npm test
```

## API Endpoints

- `GET /api/files` - List all markdown files (returns array of filenames)
- `GET /api/files/:filename` - Get file content (returns markdown content)
- `POST /api/files` - Create new file (body: {"name": "file.md", "content": "..."})
- `PUT /api/files/:filename` - Update file (body: {"content": "..."})
- `DELETE /api/files/:filename` - Delete file
- `/` - Serve frontend (SPA fallback)
- `/static/*` - Serve static assets

## Features Implemented

- ✅ Markdown editor with live preview
- ✅ File management (list, create, open, save, delete)
- ✅ Three themes (Dark, Light, System)
- ✅ Responsive design
- ✅ REST API with CRUD operations
- ✅ Comprehensive logging
- ✅ JSON error responses
- ✅ Static asset serving
- ✅ Test coverage