# @gasket/nextjs

Gasket integrations for Next.js apps. Provides several tools:

**AppRouter**

- [request]: Access a request-like object in server components
- [withGasketData][withGasketData2]: HOC to inject Gasket Data into Root Layout

**PageRouter**

- [withGasketData]: HOC to inject Gasket Data into Document
- [withGasketDataProvider]: HOC to provide React Context access to Gasket Data
- [useGasketData]: Hook that enables access to Gasket Data
- [withLocaleInitialProps]: HOC to add current locale with `getInitialProps`

## Installation

```
npm i @gasket/nextjs
```

## App Router

Functions to help integrate Gasket with Next.js App Router.

### request

Get a normalized [GasketRequest] unique to the current request in server components.
This uses the Next.js `cookies()` and `headers()` [dynamic functions]. 

**Signature**

- `await request(params?: object): GasketRequest`

**Props**

- `[query]` - (object) Optional query object

Many GasketActions are designed to be unique to requests.
When using ServerComponents with Next.js, the incoming request object is not
fully accessible.
This function provides a way to get a normalized request-like object
that can be used with GasketActions from ServerComponents.

#### Example

```js
import { request } from '@gasket/nextjs/request';
import gasket from '../gasket.mjs'

export default async function MyPage(props) {
  const req = await request();
  const something = await gasket.actions.getSomething(req);
  
  return <div>{ something.fancy }</div>;
}
```

The `req` will be a [GasketRequest] with headers and cookies.

If a query object is passed in, it will be added to the request object as well.
For server components, dynamic routes params are available via props, and can
be passed to the `request` function to make those path params available as the
query.

```js
import { request } from '@gasket/nextjs/request';
import gasket from '../gasket.mjs'

export default async function MyDynamicRoutePage({ params }) {
  const req = request(params);
  const something = await gasket.actions.getSomething(req);
  
  return <div>{ something.fancy }</div>;
}
```

#### App Router limitations

The App Router does not expose a request object. `request()` assembles a
request-like object from `next/headers`, which has two consequences for the
[GasketRequest] you get back:

- `method` is `undefined`. `next/headers` provides no method, and it is not
  defaulted to `GET` because a Server Action is a `POST` that re-renders server
  components within the same request.
- `getOriginalRequest()` returns the assembled object, not a framework request.
  It is truthy but carries only headers, cookies, and query — so there is no
  `ip` on it. Guard the field you need, not the object:

```js
import { getOriginalRequest } from '@gasket/request';

const ip = getOriginalRequest(req)?.ip;
if (!ip) {
  // No client IP available in this environment
}
```

### Layout withGasketData

Injects Gasket Data into Root Layout for use with the [@gasket/data] package.

**Signature**
- `withGasketData(gasket, options?)(Layout)`

**Props** 
- `gasket` - (object) The Gasket instance
- `[options]` - (object) Optional configuration
  - `index` - (number) Force the script to be inject at a certain child index of the body

#### Example

This is the simplest and most common setup:

```jsx
// app/layout.js
import { withGasketData } from '@gasket/nextjs/layout';
import gasket from '../gasket.js'; 
async function RootLayout({ children }) {
  return (
    <html lang="en">
      <body>
        {children}
      </body>
    </html>
  );
}
export default withGasketData(gasket)(RootLayout);
```

## Page Router

Functions to help integrate Gasket with Next.js Page Router.

### withGasketData

Use this to extend your Next.js Document to automatically inject a script containing the `gasketData` for use with
the [@gasket/data] package.

**Signature**

- `withGasketData(options)(Document)`

**Props**

- `[options]` - (object) Optional configuration
  - `index` - (number) Force the script to be inject at a certain child index of the body

#### Example

This is the simplest and most common setup:

```jsx
// pages/_document.js
import Document from 'next/document';
import { withGasketData } from '@gasket/nextjs/document';
import gasket from '../gasket.js';

export default withGasketData(gasket)(Document);
```

By default this will inject the script in the `<body/>` after the Next.js
`<Main/>` component, but before `<NextScript/>`. This also works for a
[custom Document].

#### Example forced index

However, there may be situations where you want to inject the `gasketData`
script at a particular child index of the `<body/>`. To do so, you can set the
`index` in the decorator options.

```jsx
// pages/_document.js
import Document, {Html, Head, Main, NextScript} from 'next/document'
import { withGasketData } from '@gasket/nextjs/document';
import gasket from '../gasket.js';

class MyDocument extends Document {
    static async getInitialProps(ctx) {
        const initialProps = await Document.getInitialProps(ctx)
        return {...initialProps}
    }

    render() {
        return (
            <Html>
                <Head/>
                <body>
                <Main/>
                <footer>Some custom content</footer>
                <NextScript/>
                </body>
            </Html>
        )
    }
}

export default withGasketData(gasket, {index: 2})(MyDocument);
```

In this example, the `gasketData` script will be injected after the custom
`<footer/>` instead of right after `<Main/>`.

This is especially useful if you are somehow nesting or extending the `<Main/>`
and `<NextScript/>` components and the decorator cannot find the right place to inject the script.

---

### withGasketDataProvider

Use this to allow gasket data to be accessed with the `useGasketData` hook. This is SSR
and client side friendly and can be added at the app level or component level.

#### Example

---

```jsx
// pages/_app.js
import { AppProps } from 'next/app';
import { withGasketDataProvider } from '@gasket/nextjs';
import gasket from '../gasket.js';


const Root = ({ Page, pageProps }) => {
  return (
    <Page {...pageProps} />
  );
};

export default withGasketDataProvider(gasket)(Root);
```

### useGasketData

Use this hook to access the gasketData provided by the `withGasketDataProvider` hoc.

#### Example

```jsx
// MyComponent.js
import { useGasketData } from '@gasket/nextjs';


export const MyComponent = (props) => {
  const gasketData = useGasketData();

  return (
    <>
      <div>{gasketData.something}</div>
      <div>{gasketData.here}</div>
    </>
  );
};
```

---

### withLocaleInitialProps

Use this HOC to inject the current locale into your Next.js page or app component props via `getInitialProps`.
Particular useful when used with `withMessagesProvider` from [@gasket/react-intl] to set the locale on the provider.

**Signature**

- `withLocaleInitialProps(gasket)(Component)`

**Props Added**

- `locale` - (string) The resolved locale for the current request

This HOC works by enhancing the wrapped component's `getInitialProps` method to automatically resolve and inject the
current locale based on the request context. It works with both page-level and app-level components.

**Note:** This requires [@gasket/plugin-intl] to be configured in your Gasket app for locale resolution to work properly.

#### Example - Page Component

```jsx
// pages/index.js
import { withLocaleInitialProps } from '@gasket/nextjs';
import gasket from '../gasket.js';

function HomePage({ locale }) {
  return (
    <div>
      <h1>Current locale: {locale}</h1>
      <p>Welcome! This page is rendered in {locale}</p>
    </div>
  );
}

export default withLocaleInitialProps(gasket)(HomePage);
```

#### Example - App Component

```jsx
// pages/_app.js
import { withLocaleInitialProps } from '@gasket/nextjs';
import gasket from '../gasket.js';

function MyApp({ Component, pageProps, locale }) {
  return (
    <div data-locale={locale}>
      <Component {...pageProps} />
    </div>
  );
}

export default withLocaleInitialProps(gasket)(MyApp);
```

#### Example - App Component with withMessagesProvider

```jsx
// pages/_app.js
import { withLocaleInitialProps } from '@gasket/nextjs';
import { withMessagesProvider } from '@gasket/react-intl';
import { IntlProvider } from 'react-intl';
import intlManager from '../path/to/intl.js';
import gasket from '../gasket.js';

const IntlMessagesProvider = withMessagesProvider(intlManager)(IntlProvider);

function MyApp({ Component, pageProps, locale }) {
  return (
    <IntlMessagesProvider locale={locale}>
      <Component {...pageProps} />
    </IntlMessagesProvider>
  );
}

export default withLocaleInitialProps(gasket)(MyApp);
```

## How it works

During server side rendering, lifecycles' data can be added to the gasketData property. When the `withGasketData` hoc is added to a custom Next.js _document, the gasketData is added to the rendered html inside a script tag.

The `withGasketDataProvider` can be added to a Next.js custom _app or react component. This HOC will capture the gasket data from server side gasketData property or the script tag that was rendered to the html. If Next.js is preforming a SSR the data will come from the gasketData property, otherwise the data will come from the script tag. The `withGasketDataProvider` hoc will then create a provider and inject gasket data into a context that can be consumed by the `useGasketData` hook.

The `useGasketData` will provide access to the gasket data within the context of the `withGasketDataProvider`, allowing data to be used within any react component.

> Please see @gasket/data docs for examples on adding data during SSR lifecycle

## License

[MIT](./LICENSE.md)

<!-- LINKS -->

[@gasket/data]: /packages/gasket-data/README.md
[@gasket/plugin-intl]: /packages/gasket-plugin-intl/README.md
[GasketRequest]: /packages/gasket-request/README.md#GasketRequest

[custom Document]: https://nextjs.org/docs/advanced-features/custom-document
[dynamic functions]: https://nextjs.org/docs/app/building-your-application/rendering/server-components#dynamic-functions

[request]: #request
[withGasketData2]: #layout-withgasketdata
[withGasketData]: #withgasketdata
[withGasketDataProvider]: #withgasketdataprovider
[useGasketData]: #usegasketdata
[withLocaleInitialProps]: #withlocaleinitialprops