From f898e5d7e54c57294f14f7056531ecd2ec6e1d79 Mon Sep 17 00:00:00 2001
From: Alexander Borsuk <me@alex.bio>
Date: Sun, 20 Nov 2022 19:16:32 +0100
Subject: [PATCH] Serve localized donation page

Signed-off-by: Alexander Borsuk <me@alex.bio>
---
 README.md               |  2 ++
 functions/donate.ts     | 39 +++++++++++++++++++++++++++++++++++++++
 functions/tsconfig.json |  8 ++++++++
 static/_routes.json     |  5 +++++
 4 files changed, 54 insertions(+)
 create mode 100644 functions/donate.ts
 create mode 100644 functions/tsconfig.json
 create mode 100644 static/_routes.json

diff --git a/README.md b/README.md
index e93090d8..cd09ae44 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,8 @@ This website is build with [Zola](https://www.getzola.org/) and Cloudflare Pages
 
 Use `zola serve` for a local preview or `zola build` to generate static site in the `public` folder.
 
+To test Clouldflare Functions locally, use `npx wrangler pages dev public` after doing `zola build`.
+
 `npm i && npm run format` will pretty-format Markdown and scss.
 
 Upgrade npm dependencies with `npm run upgrade`, make sure that you have installed `npm-check-updates` package.
diff --git a/functions/donate.ts b/functions/donate.ts
new file mode 100644
index 00000000..08d27314
--- /dev/null
+++ b/functions/donate.ts
@@ -0,0 +1,39 @@
+// Redirects users from the default en donate page to the appropriate localized version.
+interface Env {
+	KV: KVNamespace;
+}
+
+// TODO: Detect if donation page already has translation in resources automatically,
+// without hard-coded list
+const localizedLanguages = ['ru', 'it', 'tr'];
+
+// To parse accept-language like this:
+// fr-CH, fr;q=0.9, en;q=0.8, de;q=0.7, *;q=0.5
+// en-AU,en;q=0.8,be;q=0.6,ru;q=0.4,uk;q=0.2
+const langCodeRegex = /[a-z]{2}/g;
+
+// Returns user's preferred languages: ["en", "be", "ru"]
+function extractLanguageList(acceptLanguage: string): string[] {
+  const langs = acceptLanguage.match(langCodeRegex);
+  return [...new Set(langs)];  // Filter duplicates.
+}
+
+// Should be invoked only for /donate or /donate/ routes
+export const onRequest: PagesFunction<Env> = async (context) => {
+  console.log('Donate handler hit url:' + context.request.url);
+
+  const acceptLanguage = context.request.headers.get('accept-language');
+  if (acceptLanguage) {
+    // Is there a localized version?
+    const languages = extractLanguageList(acceptLanguage);
+    const filtered = localizedLanguages.filter(lang => languages.includes(lang));
+    if (filtered.length) {
+      const url = new URL(context.request.url);
+      console.log('Old pathname: ' + url.pathname);
+      url.pathname = '/' + filtered[0] + url.pathname;
+      return context.env.ASSETS.fetch(url);
+    }
+  }
+  // Return default en version.
+  return context.env.ASSETS.fetch(context.request.url);
+}
diff --git a/functions/tsconfig.json b/functions/tsconfig.json
new file mode 100644
index 00000000..da95421c
--- /dev/null
+++ b/functions/tsconfig.json
@@ -0,0 +1,8 @@
+{
+  "compilerOptions": {
+    "target": "esnext",
+    "module": "esnext",
+    "lib": ["esnext"],
+    "types": ["@cloudflare/workers-types"]
+  }
+}
diff --git a/static/_routes.json b/static/_routes.json
new file mode 100644
index 00000000..8cc07033
--- /dev/null
+++ b/static/_routes.json
@@ -0,0 +1,5 @@
+{
+  "version": 1,
+  "include": ["/donate", "/donate/"],
+  "exclude": []
+}