# xterm.js Upgrade Documentation

## Overview

This document describes the upgrade of xterm.js from version 3.14.5 to 5.5.0 (latest).

## Changes Made

### 1. Package Dependencies

**Before (package.json):**
```json
{
  "dependencies": {
    "xterm": "^3.14.5"
  }
}
```

**After (package.json):**
```json
{
  "dependencies": {
    "@xterm/xterm": "^5.3.0",
    "@xterm/addon-fit": "^0.10.0"
  }
}
```

**Installed Versions:**
- `@xterm/xterm`: 5.5.0
- `@xterm/addon-fit`: 0.10.0

### 2. Package Namespace Change

xterm.js moved from the `xterm` package to the scoped `@xterm/xterm` package. The old package is now deprecated.

### 3. Addon System Overhaul

**Old Addon System (v3.x):**
- Addons loaded via `<script>` tags from `/dist/addons/*/`
- Applied using `Terminal.applyAddon(addonName)`
- Methods added directly to Terminal prototype
- Example: `term.fit()` after applying fit addon

**New Addon System (v5.x):**
- Addons are separate npm packages under `@xterm/addon-*`
- Loaded using `term.loadAddon(new AddonClass())`
- Implements `ITerminalAddon` interface
- Methods accessed through addon instance
- Example: `fitAddon.fit()` instead of `term.fit()`

### 4. Terminado Protocol Addon

Created a custom `TerminadoAddon` class compatible with xterm 5.x that implements the Terminado WebSocket protocol.

**Location:** `static/terminado-addon.js` (also copied to `node_modules/` for serving)

**Features:**
- Implements modern `ITerminalAddon` interface
- Handles bidirectional communication over WebSocket
- Supports JSON message format: `["stdin", data]`, `["stdout", data]`, `["set_size", rows, cols]`
- Buffered output for better performance
- Automatic cleanup on dispose
- Public methods: `attach()`, `detach()`, `sendSize()`, `sendCommand()`

**API Usage:**
```javascript
const terminadoAddon = new TerminadoAddon();
term.loadAddon(terminadoAddon);

// Attach to WebSocket
terminadoAddon.attach(socket, bidirectional=true, buffered=true);

// Send size update
terminadoAddon.sendSize(rows, cols);

// Send command
terminadoAddon.sendCommand("socktop -P local\r");

// Detach when done
terminadoAddon.detach();
```

### 5. HTML Template Updates

**File:** `templates/term.html`

**Script Loading Changes:**
```html
<!-- OLD (v3.x) -->
<link rel="stylesheet" href="/static/xterm/dist/xterm.css" />
<script src="/static/xterm/dist/xterm.js"></script>
<script src="/static/xterm/dist/addons/attach/attach.js"></script>
<script src="/static/xterm/dist/addons/terminado/terminado.js"></script>
<script src="/static/xterm/dist/addons/fit/fit.js"></script>
<script src="/static/xterm/dist/addons/search/search.js"></script>

<!-- NEW (v5.x) -->
<link rel="stylesheet" href="/static/@xterm/xterm/css/xterm.css" />
<script src="/static/@xterm/xterm/lib/xterm.js"></script>
<script src="/static/@xterm/addon-fit/lib/addon-fit.js"></script>
<script src="/static/terminado-addon.js"></script>
```

**JavaScript API Changes:**
```javascript
// OLD (v3.x)
if (typeof Terminal !== 'undefined' && typeof Terminal.applyAddon === 'function') {
  Terminal.applyAddon(terminado);
  Terminal.applyAddon(fit);
}
var term = new Terminal();
term.open(terminalContainer);
term.terminadoAttach(sock);
term.fit();

// NEW (v5.x)
var term = new Terminal();
var fitAddon = new FitAddon.FitAddon();
term.loadAddon(fitAddon);
var terminadoAddon = new TerminadoAddon();
term.loadAddon(terminadoAddon);
term.open(terminalContainer);
fitAddon.fit();
terminadoAddon.attach(sock, true, true);
```

### 6. Rust Backend

**No changes required** - The Rust backend (`src/server.rs`, `src/lib.rs`, `src/terminado.rs`) continues to work without modification because:
- The Terminado protocol remains unchanged
- WebSocket communication is the same
- PTY handling is identical

## Migration Guide

### For Developers Using This Project

1. **Update npm packages:**
   ```bash
   npm install
   ```

2. **Copy custom addon to node_modules:**
   ```bash
   cp static/terminado-addon.js node_modules/
   ```

3. **Build and run:**
   ```bash
   cargo build
   cargo run
   ```

4. **Access the terminal:**
   Open `http://localhost:8082/` in your browser

### For Projects Forking This Code

If you're building a similar project, here's what you need to know:

1. **Use scoped packages:** Install `@xterm/xterm` instead of `xterm`
2. **Install addon packages separately:** Each addon is now its own npm package
3. **Implement ITerminalAddon:** Custom addons must implement the modern interface:
   ```javascript
   class MyAddon {
     activate(terminal) { /* ... */ }
     dispose() { /* ... */ }
   }
   ```
4. **Update your HTML:** Change script paths to point to new locations
5. **Refactor addon usage:** Replace `applyAddon()` with `loadAddon()`

## Breaking Changes from v3.x to v5.x

1. **No backward compatibility:** The old addon API is completely removed
2. **Package names changed:** Must use `@xterm/*` scoped packages
3. **Addon methods moved:** Methods like `fit()` now belong to addon instances
4. **File locations changed:** Scripts moved from `dist/` to `lib/` or `css/`
5. **No global addon objects:** Addons no longer register themselves globally

## Benefits of Upgrading

1. **Modern API:** Cleaner, more maintainable code structure
2. **Better TypeScript support:** Improved type definitions
3. **Performance improvements:** Better rendering and memory management
4. **Security updates:** Patches for known vulnerabilities
5. **Active development:** v3.x is no longer maintained
6. **New features:** Access to all features added since v3.x
7. **Better addon ecosystem:** Separate packages allow independent versioning

## Testing

A test file is provided to verify the upgrade: `test_xterm.html`

Open it in a browser (served via a local web server) to verify:
- xterm.js loads correctly
- FitAddon works properly
- Terminal renders and accepts input
- Modern API is functional

## Known Issues

None at this time. The upgrade was successful with no breaking changes to functionality.

## Resources

- [xterm.js Official Documentation](https://xtermjs.org/)
- [xterm.js GitHub Repository](https://github.com/xtermjs/xterm.js)
- [Migration Guide (v3 to v4)](https://github.com/xtermjs/xterm.js/blob/master/MIGRATION.md)
- [Addon API Documentation](https://github.com/xtermjs/xterm.js/tree/master/addons)

## Future Considerations

1. **Additional addons:** Consider adding more xterm addons:
   - `@xterm/addon-search`: Search functionality
   - `@xterm/addon-web-links`: Clickable URLs
   - `@xterm/addon-webgl`: WebGL renderer for better performance
   - `@xterm/addon-unicode11`: Full Unicode 11 support

2. **WebAssembly backend:** xterm.js v5.x supports WebAssembly for improved performance

3. **Ligature support:** New versions support font ligatures for better code display

4. **Image support:** Experimental support for inline images (Sixel protocol)

## Conclusion

The upgrade to xterm.js 5.5.0 was successful. All original functionality is preserved, the codebase is now more maintainable, and we have access to the latest features and security updates.