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import { Meta } from '@storybook/blocks';

<Meta title="Docs/Storybook Structure" />

# LUI Storybook Code Organization

`apps/lightning-ui-docs/.storybook`

| Folder            |          File           | Purpose                                                           |
| ----------------- | :---------------------: | :---------------------------------------------------------------- |
| addons            |                         |                                                                   |
|                   |      constants.js       | constants for addons                                              |
| addons/components |                         |                                                                   |
|                   |        index.js         |                                                                   |
|                   |      NumberRow.js       |                                                                   |
|                   |        Table.js         |                                                                   |
|                   |       TableRow.js       |                                                                   |
| addons/decorators |                         |                                                                   |
|                   |    withLightning.js     | decorator for Lightning to work in Storybook                      |
| addons/panels     |                         |                                                                   |
|                   | ComponentStylesPanel.js | Lightning Custom Component Style Panel                            |
|                   |   GridOverlayPanel.js   | Lighting Custom Grid Overlay Panel                                |
|                   |      ThemePanel.js      | Lightning Custom Theme Panel                                      |
| addons/toolbars   |                         |                                                                   |
|                   |       Announce.js       | turn on Announce feature                                          |
|                   |      StageColor.js      | stage color toggle                                                |
|                   |    ThemeDownload.js     | download a theme                                                  |
|                   |     ThemePicker.js      | select a theme                                                    |
| utils             |                         |                                                                   |
|                   |       helpers.js        | helper functions for Storybook config                             |
|                   |    registerEvent.js     | event listeners for Storybook config                              |
|                   |      themeUtils.js      | utility functions for Lightning Theming to work in Storybook      |
| /                 |                         |                                                                   |
|                   |        brand.png        | Lightning logo for Storybook theme                                |
|                   |         main.js         | controls server behavior                                          |
|                   |    manager-head.html    |                                                                   |
|                   |        manger.js        | sets Storybook UI options and themes, and registers custom addons |
|                   |    preview-head.html    |                                                                   |
|                   |       preview.js        | controls rendering of stories                                     |
|                   |        theme.js         | theme for Storybook UI                                            |

### useArgs

There may be cases throughout our Stories where we want one control to affect the value of another control, or a user interaction with the component to update the value of a control.

This can be achieved through Storybook's `useArgs` hook and `updateArgs` method. For more information, check out the documentation [here](https://storybook.js.org/docs/vue/addons/addons-api#useargs).

`useArgs` is a hook that is a part of the Storybook API that allows **args** to be read or updated.

Specifically, `useArgs` has a method called `updateArgs` that can be used to update an arg when it changes value.

Below is an example of how to use `updateArgs` along with the value property:

```js
import { useArgs } from '@storybook/manager-api';

const [{ value }, updateArgs] = useArgs();

// update arg control when value changes
onChange(value) {
  updateArgs({ value });
}
```

For example, in our [Slider component](?path=/docs/components-slider--docs), when in the `focused` mode, if a user hits left or right on their keyboard, the value of the Slider changes accordingly. However, the Storybook control for the current `value` never updates. This puts the component and the control out of sync. The next time the user updates a control, the value will be reapplied, wiping out whatever was set via the keyboard interaction.

To keep the Slider control in sync, we used the `updateArgs` method. In Slider.js, the component emits a signal called "onChange" whenever its value is updated:

```js
this.signal('onChange', this.value, this);
```

In Slider.stories.js, our component intercepts the signal:

```js
Slider: {
  type: Slider,
  value: value,
  signals: {
    onChange: true
  }
}
```

That signal gets mapped to a new method local to our story that then calls the `updateArgs` method

```js
onChange(value) {
  updateArgs({ value })
}
```

This `updateArgs` method is what then updates the value control in Storybook to match the value of the component (the one set by the user when hitting left and right).
