# Accordion

The Accordion component allows you to create collapsible content panels where users can show or hide sections of information. This is useful for organizing large amounts of content in a compact way.

```tsx
import {Accordion} from '@gravity-ui/uikit';
```

## Base example

```tsx
<Accordion>
  <Accordion.Item summary="First Item">Content of the first item</Accordion.Item>
  <Accordion.Item summary="Second Item">Content of the second item</Accordion.Item>
  <Accordion.Item summary="Third Item">Content of the third item</Accordion.Item>
</Accordion>
```

## Controlling state of accordion

You can control the accordion state using the `value` and `onUpdate` properties of the root component, or per item.

Example controlling state from the root component:

```tsx
function ControlledAccordion() {
  const [value, setValue] = React.useState('item1');

  return (
    <Accordion value={value} onUpdate={setValue}>
      <Accordion.Item summary="Settings" value="item1">
        Configure your application settings
      </Accordion.Item>
      <Accordion.Item summary="Notifications" value="item2">
        Manage notification preferences
      </Accordion.Item>
    </Accordion>
  );
}
```

Example controlling state per item by the expanded prop:

```tsx
function ControlledAccordion() {
  const [item1, setItem1] = React.useState(true);
  const [item2, setItem2] = React.useState(false);
  return (
    <Accordion>
      <Accordion.Item summary="Settings" onUpdate={setItem1} value="item1" expanded={item1}>
        Configure your application settings
      </Accordion.Item>
      <Accordion.Item summary="Notifications" onUpdate={setItem2} value="item2" expanded={item2}>
        Manage notification preferences
      </Accordion.Item>
    </Accordion>
  );
}
```

## Size

Use the `size` property to control the `Accordion` size. The default size is `m`.

```tsx
<Accordion size="m">
    <Accordion.Item summary="Medium Size">
        Content for medium accordion
    </Accordion.Item>
</Accordion>
<Accordion size="l">
    <Accordion.Item summary="Large Size">
        Content for large accordion
    </Accordion.Item>
</Accordion>
<Accordion size="xl">
    <Accordion.Item summary="Extra Large Size">
        Content for extra large accordion
    </Accordion.Item>
</Accordion>
```

## View

`solid`: Main view with background (used by default).

`top-bottom`: View with top and bottom borders.

```tsx
<Accordion view="solid">
    <Accordion.Item summary="Solid View">
        Content with solid background
    </Accordion.Item>
    <Accordion.Item summary="Another Item">
        More content
    </Accordion.Item>
</Accordion>
<Accordion view="top-bottom">
    <Accordion.Item summary="Top-Bottom View">
        Content with top-bottom borders
    </Accordion.Item>
    <Accordion.Item summary="Another Item">
        More content
    </Accordion.Item>
</Accordion>
```

## Arrow Position

`end`: Arrow is positioned at the end of the header (used by default).

`start`: Arrow is positioned at the start of the header.

```tsx
<Accordion arrowPosition="end">
    <Accordion.Item summary="Arrow at End">
        Content with arrow at the end
    </Accordion.Item>
</Accordion>
<Accordion arrowPosition="start">
    <Accordion.Item summary="Arrow at Start">
        Content with arrow at the start
    </Accordion.Item>
</Accordion>
```

## Multiple

The `multiple` property allows multiple accordion items to be expanded simultaneously.

```tsx
<Accordion multiple>
  <Accordion.Item summary="First Item">Content of the first item</Accordion.Item>
  <Accordion.Item summary="Second Item">Content of the second item</Accordion.Item>
  <Accordion.Item summary="Third Item">Content of the third item</Accordion.Item>
</Accordion>
```

## Custom Summary

Use the `Accordion.Summary` component to create a custom header.

```tsx
<Accordion>
  <Accordion.Item value="custom">
    <Accordion.Summary>
      {(props) => (
        <Button {...props} view="flat" width="max">
          <Icon data={Settings} size={16} />
          Custom Summary Button
        </Button>
      )}
    </Accordion.Summary>
    Content with custom summary component
  </Accordion.Item>
  <Accordion.Item summary="Regular Summary">Content with regular summary prop</Accordion.Item>
</Accordion>
```

## Disabled State

Individual accordion items can be disabled using the `disabled` property.

```tsx
<Accordion>
  <Accordion.Item summary="Active Item">This item is active and can be expanded</Accordion.Item>
  <Accordion.Item summary="Disabled Item" disabled>
    This item is disabled and cannot be expanded
  </Accordion.Item>
</Accordion>
```

## Properties

### Accordion

| Name          | Description                                        |            Type            |  Default  |
| :------------ | :------------------------------------------------- | :------------------------: | :-------: |
| size          | Accordion size                                     |     `"m"` `"l"` `"xl"`     |   `"m"`   |
| view          | Accordion appearance                               |  `"solid"` `"top-bottom"`  | `"solid"` |
| multiple      | Allow multiple items to be expanded simultaneously |         `boolean`          |  `false`  |
| arrowPosition | Arrow indicator position                           |     `"start"` `"end"`      |  `"end"`  |
| defaultValue  | Default value for uncontrolled state               | `string` `string[]` `null` |           |
| value         | Current value for controlled state                 | `string` `string[]` `null` |           |
| onUpdate      | Callback function called when state changes        |         `Function`         |           |
| ariaLevel     | Heading level for accessibility                    |          `number`          |    `3`    |
| className     | CSS class name                                     |          `string`          |           |
| qa            | HTML `data-qa` attribute, used for testing         |          `string`          |           |

### Accordion.Item

| Name            | Description                                      |       Type        | Default |
| :-------------- | :----------------------------------------------- | :---------------: | :-----: |
| value           | Unique identifier for the item                   |     `string`      |         |
| summary         | Accordion item header                            | `React.ReactNode` |         |
| expanded        | Controlled expanded state                        |     `boolean`     |         |
| defaultExpanded | Default expanded state                           |     `boolean`     |         |
| disabled        | Disables the accordion item                      |     `boolean`     | `false` |
| keepMounted     | Keep content in DOM even when collapsed          |     `boolean`     |         |
| onUpdate        | Callback function called when item state changes |    `Function`     |         |
| className       | CSS class name                                   |     `string`      |         |
| qa              | HTML `data-qa` attribute, used for testing       |     `string`      |         |

### Accordion.Summary

| Name     | Description                                                                             |                      Type                       |                                          Default                                          |
| :------- | :-------------------------------------------------------------------------------------- | :---------------------------------------------: | :---------------------------------------------------------------------------------------: |
| children | Custom summary render function                                                          | `(props, defaultSummary) => React.ReactElement` |                                                                                           |
| qa       | HTML `data-qa` attribute, used for testing. Works only if `qa` passed in Accordion.Item |                    `string`                     | `${accordion-item}-summary` if `qa` passed in Accordion.Item, `disclosure-summary` if not |

## CSS API

| Name                           | Description                               |
| :----------------------------- | :---------------------------------------- |
| `--g-accordion-padding-inline` | Inline (horizontal) padding for accordion |