From a245b222dc70f5cf450ba4837b342e4fc9cd7b81 Mon Sep 17 00:00:00 2001
From: Filip Czaplicki <github@starsep.com>
Date: Thu, 8 Feb 2024 21:35:52 +0100
Subject: [PATCH] Generate alternate links for languages

---
 scripts/build_every_lang.sh |  1 +
 vite.config.js              | 14 ++++++++++++++
 2 files changed, 15 insertions(+)

diff --git a/scripts/build_every_lang.sh b/scripts/build_every_lang.sh
index f458003..730eb1f 100755
--- a/scripts/build_every_lang.sh
+++ b/scripts/build_every_lang.sh
@@ -7,6 +7,7 @@ for lang in public/locales/*; do
         continue
     fi
     export VITE_DEFAULT_LANG=$lang
+    export VITE_BASE_URL="/$lang/"
     echo "Generating $lang"
     npm run build -- --outDir "build/$lang" --base "/$lang"
 done
diff --git a/vite.config.js b/vite.config.js
index f188d7d..d827766 100644
--- a/vite.config.js
+++ b/vite.config.js
@@ -20,6 +20,16 @@ const htmlPlugin = async (env) => {
 		...translationsEn,
 		...translationsTarget,
 	};
+	const baseUrl = env.VITE_BASE_URL ?? "";
+	const canonicalLinks = `<link href="${env.VITE_BACKEND_API_URL}${baseUrl}" rel="canonical" />`;
+	const alternateLinks = Object.keys(languages)
+		.map(
+			(lang) =>
+				`\t<link href="${env.VITE_BACKEND_API_URL}/${lang}/" rel="alternate" hreflang="${lang}" />`,
+		)
+		.join("\n");
+	const defaultAlternateLink = `\t<link href="${env.VITE_BACKEND_API_URL}/" rel="alternate" hreflang="x-default" />`;
+	const seoLinks = `${canonicalLinks}\n${alternateLinks}\n${defaultAlternateLink}`;
 	return {
 		name: "html-transform",
 		transformIndexHtml(html) {
@@ -32,6 +42,10 @@ const htmlPlugin = async (env) => {
 				.replace(
 					/<meta content="(.*?)" name="description">/,
 					`<meta content="${meta_description}" name="description">`,
+				)
+				.replace(
+					/<link href="https:\/\/openaedmap.org" rel="canonical" \/>/,
+					seoLinks,
 				);
 		},
 	};