# ThemeSwitcher

## Overview

Theme toggle with three options: system, light, dark. Uses a controlled/uncontrolled API and avoids hydration mismatch by rendering only after mount.

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## Props

| Prop           | Type             | Default     | Description        |
| -------------- | ---------------- | ----------- | ------------------ | ----------- | -------------------------------- |
| `value`        | `"light"         | "dark"      | "system"`          | `undefined` | Controlled theme value.          |
| `onChange`     | `(theme: "light" | "dark"      | "system") => void` | `undefined` | Called when theme changes.       |
| `defaultValue` | `"light"         | "dark"      | "system"`          | `"system"`  | Initial value when uncontrolled. |
| `className`    | `string`         | `undefined` | Container classes. |

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## Behavior

- **SSR safe**: Renders `null` until mounted to prevent hydration mismatch.
- **Active state**: Highlights the active option with a rounded background.
- **Control**: Works in both controlled (`value`/`onChange`) and uncontrolled (`defaultValue`) modes.

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## Examples

### Default (uncontrolled)

```tsx
import { ThemeSwitcher } from "laif-ds";

export function DefaultTheme() {
  return <ThemeSwitcher defaultValue="system" />;
}
```

### Controlled

```tsx
import * as React from "react";
import { ThemeSwitcher } from "laif-ds";

export function ControlledTheme() {
  const [theme, setTheme] = React.useState<"light" | "dark" | "system">(
    "system",
  );
  return (
    <div className="flex flex-col items-start gap-2">
      <ThemeSwitcher value={theme} onChange={setTheme} />
      <div className="text-d-muted-foreground text-sm">
        Current theme: <span className="font-medium">{theme}</span>
      </div>
    </div>
  );
}
```

### Custom styling

```tsx
<ThemeSwitcher defaultValue="system" className="h-10 w-32 p-2" />
```

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## Notes

- **Icons**: The component renders icons internally; no configuration required.
- **Persistence**: Persisting theme choice is up to the app (e.g., localStorage + class on `html`).