Knowledge Article System - Technical Documentation

## System Architecture

### Overview
The KA System is a local desktop application with a client-server architecture:
- **Backend:** Node.js + Express + SQLite (sql.js)
- **Frontend:** React (Vite)
- **Database:** SQLite file-based database

### Components

```
knowledge_article_system/
├── server/                 # Backend
│   ├── server.js          # Express server
│   ├── db.js              # Database functions
│   ├── ka.db              # SQLite database (created at runtime)
│   └── package.json       # Dependencies
│
└── client/                # Frontend
    ├── src/
    │   ├── App.jsx        # Main application component
    │   ├── components/    # UI components
    │   └── App.css        # Styles
    └── package.json       # Dependencies
```

---

## Installation & Setup

### Prerequisites
- Node.js (v16 or higher)
- npm (comes with Node.js)

### First-Time Setup

#### Backend Setup
```bash
cd server
npm install
```

Dependencies installed:
- `express` - Web server framework
- `sql.js` - SQLite database
- `cors` - Cross-origin resource sharing

#### Frontend Setup
```bash
cd client/kb-frontend
npm install
```

Dependencies installed:
- `react` - UI framework
- `vite` - Build tool and dev server
- `react-quill` - Rich text editor (optional, currently using textarea)

### Running the Application

#### Start Backend (Terminal 1)
```bash
cd server
node server.js
```
Server runs on: `http://localhost:9000`

#### Start Frontend (Terminal 2)
```bash
cd client/kb-frontend
npm run dev
```
Frontend runs on: `http://localhost:5173`

---

## API Documentation

### Base URL
```
http://localhost:9000/api
```

### Endpoints

#### Get All Articles
```
GET /api/articles
```
Returns: Array of all articles, ordered by creation date (newest first)

**Response:**
```json
[
  {
    "id": 1,
    "ka_number": "KA001",
    "title": "How to Reset Password",
    "content": "Steps to reset...",
    "created_at": "2024-11-24 12:00:00",
    "updated_at": null
  }
]
```

#### Get Single Article
```
GET /api/articles/:ka_number
```
Parameters: `ka_number` (e.g., "KA001")

Returns: Single article object or 404 if not found

#### Search Articles
```
GET /api/search?q={query}
```
Query Parameters: `q` - search term

Searches across: title, content, and ka_number

Returns: Array of matching articles

#### Create Article
```
POST /api/articles
```
Headers: `Content-Type: application/json`

Body:
```json
{
  "title": "Article Title",
  "content": "Article content..."
}
```

Returns: Newly created article with auto-generated KA number

#### Update Article
```
PUT /api/articles/:ka_number
```
Headers: `Content-Type: application/json`

Body:
```json
{
  "title": "Updated Title",
  "content": "Updated content..."
}
```

Returns: Updated article object

#### Delete Article
```
DELETE /api/articles/:ka_number
```
Returns: Success message

---

## Database Schema

### Articles Table
```sql
CREATE TABLE articles (
  id INTEGER PRIMARY KEY AUTOINCREMENT,
  ka_number TEXT UNIQUE NOT NULL,
  title TEXT NOT NULL,
  content TEXT,
  created_at DATETIME DEFAULT CURRENT_TIMESTAMP,
  updated_at DATETIME
);

CREATE INDEX idx_ka_number ON articles(ka_number);
```

### Fields

| Field | Type | Description |
|-------|------|-------------|
| id | INTEGER | Auto-incrementing primary key |
| ka_number | TEXT | Unique identifier (KA001, KA002, etc.) |
| title | TEXT | Article title (required) |
| content | TEXT | Article content (HTML/text) |
| created_at | DATETIME | Timestamp of creation |
| updated_at | DATETIME | Timestamp of last update |

### KA Number Generation

KA numbers are auto-generated sequentially:
- Format: `KA` + 3-digit number padded with zeros
- Examples: KA001, KA002, ..., KA999
- Logic in `db.js` → `getNextKANumber()`

---

## Code Structure

### Backend (server.js)

**Key Components:**
- Express server initialization
- CORS configuration for frontend access
- JSON body parsing middleware
- API route handlers
- Error handling

**Important:**
- `app.use(express.json())` must be present for POST/PUT requests
- `app.use(cors())` allows frontend to make requests
- Database is initialized before routes are registered

### Database Layer (db.js)

**Functions:**
- `initDb()` - Initialize/load database
- `getAllArticles()` - Fetch all articles
- `getArticle(ka_number)` - Get single article
- `createArticle(title, content)` - Create new article
- `updateArticle(ka_number, title, content)` - Update article
- `deleteArticle(ka_number)` - Delete article
- `searchArticles(query)` - Search articles

**Key Points:**
- Uses prepared statements for security
- Database saved to disk after each write operation
- KA numbers generated automatically

### Frontend (App.jsx)

**State Management:**
- `currentView` - Controls which view to show ('list', 'detail', 'edit')
- `selectedArticle` - Currently selected article
- `articles` - Array of articles for the list view

**Key Functions:**
- `handleSearch()` - Search or load all articles
- `handleArticleClick()` - View article details
- `handleEdit()` - Switch to edit mode
- `handleSave()` - Save new or updated article
- `handleDelete()` - Delete article
- `handleCreateNew()` - Create new article

**Component Tree:**
```
App
├── Header
├── SearchBar (list view)
├── ArticleList (list view)
├── ArticleDetail (detail view)
└── ArticleEditor (edit view)
```

---

## Maintenance

### Database Backup

**Manual Backup:**
```bash
# Stop the server first
cp server/ka.db server/ka.db.backup-$(date +%Y%m%d)
```

**Automated Backup Script (Linux/Mac):**
```bash
#!/bin/bash
# save as backup-ka.sh

SOURCE="./server/ka.db"
DEST="./backups/ka.db.$(date +%Y%m%d-%H%M%S)"

mkdir -p backups
cp $SOURCE $DEST
echo "Backup created: $DEST"

# Keep only last 30 backups
ls -t backups/ka.db.* | tail -n +31 | xargs rm -f
```

**Windows Backup Script:**
```batch
@echo off
REM save as backup-ka.bat

set SOURCE=server\ka.db
set DEST=backups\ka.db.%date:~-4,4%%date:~-10,2%%date:~-7,2%

if not exist backups mkdir backups
copy %SOURCE% %DEST%
echo Backup created: %DEST%
```

### Database Restore

1. Stop the backend server
2. Replace `server/ka.db` with backup file
3. Restart the server

### Troubleshooting

**Server won't start:**
- Check port 9000 is available
- Verify npm dependencies installed
- Check for syntax errors in server.js

**Frontend won't connect:**
- Verify backend is running on port 9000
- Check CORS is enabled in server.js
- Clear browser cache

**Database corruption:**
- Restore from backup
- If no backup, delete ka.db and restart (creates new empty database)

**Search not working:**
- Check database has articles
- Verify search endpoint in server.js
- Check browser console for errors

---

## Deployment

### Building for Production

#### Backend
Use `pkg` to create executable:
```bash
npm install -g pkg
cd server
pkg server.js
```

Creates executables:
- `server-win.exe` (Windows)
- `server-linux` (Linux)
- `server-macos` (macOS)

#### Frontend
Build static files:
```bash
cd client/kb-frontend
npm run build
```

Output in `dist/` folder - can be served by any static file server.

### Distribution

COMING SOON

---

## Future Enhancements

Potential features for Week 2+:
- Rich text editor improvements
- Article categories/tags
- Attachment support (screenshots, logs)
- Version history
- Export to PDF
- Article templates
- User tracking (who created/edited)
- Dark mode
- Keyboard shortcuts

---

## Security Considerations

**Current State:**
- No authentication (local use only)
- No input sanitization for XSS
- SQL injection protected by prepared statements

**For Production Use:**
- Add user authentication
- Implement role-based access control
- Sanitize HTML content from editor
- Add rate limiting
- Use HTTPS
- Validate all inputs

---

## Performance

**Current Performance:**
- Handles hundreds of articles easily
- Search is fast with ka_number index
- No pagination needed for small teams

**If Database Grows:**
- Add pagination to article list
- Implement full-text search (SQLite FTS5)
- Add more indexes
- Consider caching frequently accessed articles

---

## Testing

### Manual Testing Checklist

**Backend:**
- [ ] Server starts without errors
- [ ] All API endpoints return correct data
- [ ] Create article returns new article with KA number
- [ ] Update article modifies existing article
- [ ] Delete article removes from database
- [ ] Search returns relevant results

**Frontend:**
- [ ] Article list displays all articles
- [ ] Search updates results correctly
- [ ] Clicking article shows detail view
- [ ] Edit button opens editor with current data
- [ ] Save button updates article
- [ ] Cancel button returns without saving
- [ ] Delete button removes article after confirmation
- [ ] Create new article generates KA number

### API Testing with curl

```bash
# Create article
curl -X POST http://localhost:9000/api/articles \
  -H "Content-Type: application/json" \
  -d '{"title":"Test","content":"Test content"}'

# Get all articles
curl http://localhost:9000/api/articles

# Search
curl "http://localhost:9000/api/search?q=test"

# Update article
curl -X PUT http://localhost:9000/api/articles/KA001 \
  -H "Content-Type: application/json" \
  -d '{"title":"Updated","content":"New content"}'

# Delete article
curl -X DELETE http://localhost:9000/api/articles/KA001
```

---

## Version History

### v0.0.1 (MVP) - Week 1
**Features:**
- Basic CRUD operations (Create, Read, Update, Delete)
- Search functionality (title, content, KA number)
- Auto-generated KA numbers
- Simple text editor (textarea)
- Responsive layout
- Local SQLite database

**Known Limitations:**
- No rich text editing (plain text/basic HTML only)
- No authentication
- No version history
- No attachments
- No categories/tags

---

## Support

For issues or questions:
- Check this documentation
- Review USER_GUIDE.md for usage questions
- Contact: Matt Taylor (developer)

---

## License

MIT License