Merge pull request #1 from balena-io/handle-path-redirects

Handle path redirects

src/handler.ts

@@ -1,55 +1,72 @@
 // eslint-disable-next-line no-undef
-declare const REDIRECT_KV: KVNamespace
+declare const REDIRECT_KV: KVNamespace;
 
 export async function handleRequest(request: Request): Promise<Response> {
-	const url = new URL(request.url)
-	const path = url.pathname
-	const fullUrl = url.host + url.pathname
+	const requestUrl = new URL(request.url);
+	const requestPath = requestUrl.pathname;
+	const requestRootPath = `${requestUrl.host}/`;
 
-	// Get the matching target URL by first checking against the full url and then the path
-	const target = await REDIRECT_KV.get(fullUrl) || await REDIRECT_KV.get(path)
+	// Get the matching target URL by first checking against the full url then host and then the path
+	const target =
+		(await REDIRECT_KV.get(`${requestUrl.host}${requestUrl.pathname}`)) ||
+		(await REDIRECT_KV.get(requestRootPath)) ||
+		(await REDIRECT_KV.get(requestPath));
 
-	if (!target || target === '404') {
+	if (!target || target === "404") {
 		// Optionally redirect to custom page on 404
-		const errorRedirect = await REDIRECT_KV.get(`${ url.host }/404`) || await REDIRECT_KV.get('404')
-
-		if (errorRedirect === 'pass') {
+		const errorRedirect =
+			(await REDIRECT_KV.get(`${requestUrl.host}/404`)) ||
+			(await REDIRECT_KV.get("404"));
 
+		if (errorRedirect === "pass") {
 			// Pass the original request along
-			return fetch(request)
-
+			return fetch(request);
 		} else if (errorRedirect) {
-
 			// Redirect to the specified error page
-			return Response.redirect(errorRedirect, 301)
-
+			return Response.redirect(errorRedirect, 301);
 		}
 
 		// Return normal 404 error
-		return new Response('Sorry, page not found.', {
+		return new Response("Sorry, page not found.", {
 			status: 404,
-			statusText: 'page not found'
-		})
+			statusText: "page not found",
+		});
 	}
 
 	// Pass the original request along
-	if (target === 'pass') {
-		return fetch(request)
+	if (target === "pass") {
+		return fetch(request);
 	}
 
 	/*
 		Combine source and target URL search parameters (target params overwrite source params)
 		Note: CF worker does not support url.searchParams.forEach
 	*/
-	const targetUrl = new URL(target)
-	Array.from(url.searchParams).forEach(([ key, val ]) => {
-		if (targetUrl.searchParams.has(key) === false) {
-			targetUrl.searchParams.set(key, val)
-		}
-	})
 
-	const redirectTo = targetUrl.toString()
+	// Construct URL class from target (value from KV) so we can easily manipulate it
+	const targetUrl = new URL(target);
+	// Default to using targetUrl path
+	let redirectPath = targetUrl.pathname;
+	// Check if the request has a path though
+	if (!emptyPath(requestPath) && emptyPath(targetUrl.pathname)) {
+		// Since request has a path but target does not, use requestPath
+		redirectPath = requestPath;
+	}
+
+	// Construct a redirect url using target host and redirect path
+	const redirectUrl = new URL(
+		`${targetUrl.protocol}//${targetUrl.host}${redirectPath}`
+	);
+	Array.from(requestUrl.searchParams).forEach(([key, val]) => {
+		if (redirectUrl.searchParams.has(key) === false) {
+			redirectUrl.searchParams.set(key, val);
+		}
+	});
 
 	// Redirect to the target URL
-	return Response.redirect(redirectTo, 301)
-}
+	return Response.redirect(redirectUrl, 301);
+}
+
+function emptyPath(path: string): boolean {
+	return path === "/";
+}