import {
type NextFetchEvent,
type NextRequest,
NextResponse,
} from 'next/server';
/**
* Utility to combine multiple Next.js middlewares into one.
*
* It executes middlewares in order, merges headers, and correctly handles
* redirects and rewrites.
*
* @example
* import { multipleMiddlewares, intlayerMiddleware } from "next-intlayer/middleware";
* import { NextResponse } from "next/server";
*
* const authMiddleware = (req: NextRequest) => {
* if (!req.cookies.get("token")) {
* return NextResponse.redirect(new URL("/login", req.url));
* }
* return NextResponse.next();
* };
*
* export default multipleMiddlewares([
* intlayerMiddleware,
* authMiddleware,
* ]);
*
* @param middlewares - An array of middleware functions to execute in order.
* @returns A single middleware function that runs all provided middlewares.
*/
export const multipleMiddlewares =
(
middlewares: ((
req: NextRequest,
event?: NextFetchEvent,
response?: NextResponse
) => NextResponse | Promise<NextResponse>)[]
) =>
async (req: NextRequest, event?: NextFetchEvent, response?: NextResponse) => {
// Array to store middleware headers
const middlewareHeader = [];
// Loop through middleware functions
for (const middleware of middlewares) {
// Execute middleware function and await the result
const result = await middleware(req, event, response);
// Check if the result is not okay and return it
if (!result.ok) {
return result;
}
// Push middleware headers to the array
middlewareHeader.push(result.headers);
}
// Merge all the headers to check if there is a redirection or rewrite
const mergedHeaders = new Headers();
// Merge all the custom headers added by the middlewares
const transmittedHeaders = new Headers();
// Merge headers
middlewareHeader.forEach((header) => {
for (const [key, value] of header.entries()) {
mergedHeaders.append(key, value);
// check if it's a custom header added by one of the middlewares
if (key.startsWith('x-middleware-request-')) {
// remove the prefix to get the original key
const fixedKey = key.replace('x-middleware-request-', '');
// add the original key to the transmitted headers
transmittedHeaders.append(fixedKey, value);
}
}
});
// Look for the 'x-middleware-request-redirect' header
const redirect = mergedHeaders.get('x-middleware-request-redirect');
// If a redirection is required based on the middleware headers
if (redirect) {
// Perform the redirection
return NextResponse.redirect(new URL(redirect, req.url), {
status: 307, // Temporary redirect
});
}
// Look for the 'x-middleware-rewrite' header
const rewrite = mergedHeaders.get('x-middleware-rewrite');
if (rewrite) {
// Perform the rewrite
return NextResponse.rewrite(new URL(rewrite, req.url), {
request: {
headers: transmittedHeaders,
},
});
}
// Default: continue to next middleware
return NextResponse.next({
request: {
headers: transmittedHeaders,
},
});
};
