From 6ab002986a386e5fefd99b8add19bd0bc579fb7b Mon Sep 17 00:00:00 2001
From: Philipp Zerelles <pz@matrix-computer.com>
Date: Tue, 27 Jul 2021 14:54:02 +0200
Subject: [PATCH] Added i18n routes to default template demonstrating alternate
 pages

---
 .../templates/default/i18n.config.js          | 37 +++++++++++++++
 .../templates/default/locales.js              |  1 +
 .../default/src/lib/header/Header.svelte      | 47 +++++++++++++++++--
 .../templates/default/src/lib/i18n.ts         | 26 ++++++++++
 .../templates/default/svelte.config.js        |  5 +-
 5 files changed, 111 insertions(+), 5 deletions(-)
 create mode 100644 packages/create-svelte/templates/default/i18n.config.js
 create mode 100644 packages/create-svelte/templates/default/locales.js
 create mode 100644 packages/create-svelte/templates/default/src/lib/i18n.ts

diff --git a/packages/create-svelte/templates/default/i18n.config.js b/packages/create-svelte/templates/default/i18n.config.js
new file mode 100644
index 000000000000..177f39f81c72
--- /dev/null
+++ b/packages/create-svelte/templates/default/i18n.config.js
@@ -0,0 +1,37 @@
+import locales from './locales.js';
+
+export const defaultLocale = locales[0];
+
+/** @typedef {{
+ *   content: string;
+ *   dynamic: boolean;
+ *   spread: boolean;
+ * }} Part */
+
+/**
+ * Create localized routes prefixed with locale
+ * @param {Part[][]} segments
+ * @param {'page' | 'endpoint'} type
+ * @returns {Part[][][]}
+ */
+export function localizeRoutes(segments, type) {
+	if (type === 'endpoint') return [segments];
+	return locales.map((locale) =>
+		locale === defaultLocale
+			? segments
+			: [
+					[{ content: locale, dynamic: false, spread: false }],
+					...segments.map((segment) => segment.map((part) => translate(part)))
+			  ]
+	);
+}
+
+/**
+ * Translate part of a route segment
+ * @param {Part} part
+ * @returns {Part}
+ */
+function translate(part) {
+	if (part.content === 'about') return { ...part, content: 'ueber' };
+	return part;
+}
diff --git a/packages/create-svelte/templates/default/locales.js b/packages/create-svelte/templates/default/locales.js
new file mode 100644
index 000000000000..0c7c8f3ed840
--- /dev/null
+++ b/packages/create-svelte/templates/default/locales.js
@@ -0,0 +1 @@
+export default ['en', 'de'];
diff --git a/packages/create-svelte/templates/default/src/lib/header/Header.svelte b/packages/create-svelte/templates/default/src/lib/header/Header.svelte
index bab8050a0cb1..a8060c379fad 100644
--- a/packages/create-svelte/templates/default/src/lib/header/Header.svelte
+++ b/packages/create-svelte/templates/default/src/lib/header/Header.svelte
@@ -1,8 +1,21 @@
 <script lang="ts">
 	import { page } from '$app/stores';
 	import logo from './svelte-logo.svg';
+	import { l, localizedPaths, locale as currentLocale, defaultLocale } from '$lib/i18n';
+
+	$: alternatePaths = $localizedPaths($page.path) || {};
+	$: defaultPath = alternatePaths[defaultLocale];
 </script>
 
+<svelte:head>
+	{#if defaultPath}
+		<link rel="alternate" hreflang="x-default" href={defaultPath} />
+	{/if}
+	{#each Object.entries(alternatePaths) as [locale, path]}
+		<link rel="alternate" hreflang={locale} href={path} />
+	{/each}
+</svelte:head>
+
 <header>
 	<div class="corner">
 		<a href="https://kit.svelte.dev">
@@ -15,9 +28,13 @@
 			<path d="M0,0 L1,2 C1.5,3 1.5,3 2,3 L2,0 Z" />
 		</svg>
 		<ul>
-			<li class:active={$page.path === '/'}><a sveltekit:prefetch href="/">Home</a></li>
-			<li class:active={$page.path === '/about'}><a sveltekit:prefetch href="/about">About</a></li>
-			<li class:active={$page.path === '/todos'}><a sveltekit:prefetch href="/todos">Todos</a></li>
+			<li class:active={$page.path === $l('/')}><a sveltekit:prefetch href={$l('/')}>Home</a></li>
+			<li class:active={$page.path === $l('/about')}>
+				<a sveltekit:prefetch href={$l('/about')}>About</a>
+			</li>
+			<li class:active={$page.path === $l('/todos')}>
+				<a sveltekit:prefetch href={$l('/todos')}>Todos</a>
+			</li>
 		</ul>
 		<svg viewBox="0 0 2 3" aria-hidden="true">
 			<path d="M0,0 L0,3 C0.5,3 0.5,3 1,2 L2,0 Z" />
@@ -26,6 +43,11 @@
 
 	<div class="corner">
 		<!-- TODO put something else here? github link? -->
+		<nav>
+			{#each Object.entries(alternatePaths) as [locale, path]}
+				<a class:active={$currentLocale === locale} href={path}>{locale}</a>
+			{/each}
+		</nav>
 	</div>
 </header>
 
@@ -36,7 +58,7 @@
 	}
 
 	.corner {
-		width: 3em;
+		display: flex;
 		height: 3em;
 	}
 
@@ -46,6 +68,23 @@
 		justify-content: center;
 		width: 100%;
 		height: 100%;
+		text-transform: uppercase;
+	}
+
+	.corner nav a {
+		position: relative;
+	}
+
+	.corner a.active::before {
+		--size: 6px;
+		content: '';
+		width: 0;
+		height: 0;
+		position: absolute;
+		top: 0;
+		left: calc(50% - var(--size));
+		border: var(--size) solid transparent;
+		border-top: var(--size) solid var(--accent-color);
 	}
 
 	.corner img {
diff --git a/packages/create-svelte/templates/default/src/lib/i18n.ts b/packages/create-svelte/templates/default/src/lib/i18n.ts
new file mode 100644
index 000000000000..37ce3b88bb62
--- /dev/null
+++ b/packages/create-svelte/templates/default/src/lib/i18n.ts
@@ -0,0 +1,26 @@
+import { derived } from 'svelte/store';
+import { page } from '$app/stores';
+import { alternates } from '$app/navigation';
+
+import locales from '../../locales';
+
+export const defaultLocale = locales[0];
+
+export const locale = derived(
+	page,
+	(page) => page.path.match(/^\/([a-z]{2})(\/|$)/)?.[1] || defaultLocale
+);
+
+export const localizedPaths = derived(page, (page) => (path: string): Record<string, string> =>
+	alternates(path)?.reduce((result, alt) => {
+		result[alt.match(/^\/([a-z]{2})(\/|$)/)?.[1] || defaultLocale] = alt;
+		return result;
+	}, {})
+);
+
+export const l = derived(
+	[localizedPaths, locale],
+	([localizedPaths, locale]) => (path: string): string => localizedPaths(path)?.[locale] || path
+);
+
+export { l as localize };
diff --git a/packages/create-svelte/templates/default/svelte.config.js b/packages/create-svelte/templates/default/svelte.config.js
index 3315cb538d64..a84d610428d0 100644
--- a/packages/create-svelte/templates/default/svelte.config.js
+++ b/packages/create-svelte/templates/default/svelte.config.js
@@ -1,4 +1,5 @@
 import preprocess from 'svelte-preprocess';
+import { localizeRoutes } from './i18n.config.js';
 
 const adapter = process.env.ADAPTER;
 const options = JSON.parse(process.env.OPTIONS || '{}');
@@ -11,7 +12,9 @@ const config = {
 
 	kit: {
 		// hydrate the <div id="svelte"> element in src/app.html
-		target: '#svelte'
+		target: '#svelte',
+
+		alternateRoutes: localizeRoutes
 	}
 };