# `navigationAutomat`

> **Source File**: [`src/automats/navigationAutomat.js`](file:///home/seb/src/dashfront/src/automats/navigationAutomat.js)  
> **Registration Key**: `'navigation'` (`Automat.get('navigation')` / `window.__AUTOMATS__.get('navigation')`)

---

## 1. Overview & Purpose

`navigationAutomat` tracks the user's most recently visited delivery document path and article SKU. When navigating across main sidebar sections (for example, switching from `/lieferung` to `/artikel` and back), it enables the navigation system to restore the user's active context instead of resetting them back to the root list page.

### Core Responsibilities
- **Context Preservation**: Remembers the exact active subpath (e.g. `/lieferung/42` or `/lieferung/neu`) and article SKU (e.g. `'SKU-8910'`).
- **Seamless Multitasking**: Users working on a delivery who need to quickly check an article warehouse stock can navigate to `/artikel` and return to `/lieferung` without losing their spot.
- **Session-Scoped History**: In-memory state (`persist: false`) kept during active application usage.

---

## 2. State Structure

```ts
interface NavigationState {
  /** Last delivery path visited, e.g. '/lieferung/19' or '/lieferung/neu'. */
  lastDeliveryPath: string | null;
  /** Last article SKU visited, e.g. '10042'. */
  lastArticleSku: string | null;
}
```

### Initial State
```js
const initialState = {
  lastDeliveryPath: null,
  lastArticleSku: null,
};
```

---

## 3. Configuration & Options

```js
new Automat(initialState, actions, {
  name: 'navigation',
  persist: false,
});
```

- **`name`**: `'navigation'`
- **`persist`**: `false`

---

## 4. Actions & Methods

Actions are exported both on `navigationAutomat.actions` and as standalone named functions:

### `setLastDeliveryPath(path: string | null): void`
Stores the full delivery route path (e.g. `'/lieferung/19'`, `'/lieferung/neu'`).

### `setLastArticleSku(sku: string | null): void`
Stores the SKU of the article currently being edited or viewed.

### `clearNavigation(): void`
Resets both `lastDeliveryPath` and `lastArticleSku` to `null`.

---

## 5. Usage Examples

### A. Recording Active SKU in `ArtikelSkuPage`

```jsx
import { PureComponent } from 'react';
import { setLastArticleSku } from '../automats/navigationAutomat';

export class ArtikelSkuPage extends PureComponent {
  componentDidMount() {
    setLastArticleSku(this.props.sku);
  }

  componentDidUpdate(prevProps) {
    if (prevProps.sku !== this.props.sku) {
      setLastArticleSku(this.props.sku);
    }
  }

  render() {
    return <div>Artikel Detail für SKU {this.props.sku}</div>;
  }
}
```

### B. Dynamic Navigation Link in `src/nav.js`

```js
import navigationAutomat from './automats/navigationAutomat';

export function getDeliveryNavPath() {
  const lastPath = navigationAutomat.state.lastDeliveryPath;
  return lastPath || '/lieferung';
}

export function getArticleNavPath() {
  const lastSku = navigationAutomat.state.lastArticleSku;
  return lastSku ? `/artikel/${encodeURIComponent(lastSku)}` : '/artikel';
}
```

---

## 6. Best Practices & Gotchas

1. **Path Formatting**: Always pass normalized route paths to `setLastDeliveryPath` (with leading slash).
2. **Clear on Logout**: If resetting application state on logout, call `clearNavigation()`.