Serve localized donation page

Signed-off-by: Alexander Borsuk <me@alex.bio>

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.

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);
+}

functions/tsconfig.json

@@ -0,0 +1,8 @@
+{
+  "compilerOptions": {
+    "target": "esnext",
+    "module": "esnext",
+    "lib": ["esnext"],
+    "types": ["@cloudflare/workers-types"]
+  }
+}

static/_routes.json

@@ -0,0 +1,5 @@
+{
+  "version": 1,
+  "include": ["/donate", "/donate/"],
+  "exclude": []
+}