From cadc1f637f2ca76d693696000455a889f3084447 Mon Sep 17 00:00:00 2001
From: Youwen Wu <youwenw@gmail.com>
Date: Sat, 6 Apr 2024 03:05:16 -0700
Subject: [PATCH] feat: add sticky toc

---
 package.json                               |  1 +
 pnpm-lock.yaml                             | 11 ++++
 src/lib/components/StickyToc.svelte        | 72 ++++++++++++++++++++++
 src/routes/blog/[year]/[slug]/+page.svelte | 37 ++++++++++-
 4 files changed, 120 insertions(+), 1 deletion(-)
 create mode 100644 src/lib/components/StickyToc.svelte

diff --git a/package.json b/package.json
index fbc3bda..4099957 100644
--- a/package.json
+++ b/package.json
@@ -47,6 +47,7 @@
     "@fontsource/geist-sans": "^5.0.2",
     "@fontsource/merriweather": "^5.0.12",
     "@fontsource/zilla-slab": "^5.0.12",
+    "@svelte-put/toc": "^5.0.1",
     "@sveltejs/adapter-vercel": "^5.2.0",
     "bits-ui": "^0.21.2",
     "clsx": "^2.1.0",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index fbb1580..7d46234 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -17,6 +17,9 @@ dependencies:
   '@fontsource/zilla-slab':
     specifier: ^5.0.12
     version: 5.0.12
+  '@svelte-put/toc':
+    specifier: ^5.0.1
+    version: 5.0.1(svelte@4.2.12)
   '@sveltejs/adapter-vercel':
     specifier: ^5.2.0
     version: 5.2.0(@sveltejs/kit@2.5.5)
@@ -890,6 +893,14 @@ packages:
     requiresBuild: true
     optional: true
 
+  /@svelte-put/toc@5.0.1(svelte@4.2.12):
+    resolution: {integrity: sha512-oxDFPM2Y0XmhhXoNDhcPltf8RxhIvtiotFL0PX9NLossTumuAPiLVaDeEsGfBOn+nZK2J1oo9XqJU3NWHDROcw==}
+    peerDependencies:
+      svelte: ^3.55.0 || ^4.0.0
+    dependencies:
+      svelte: 4.2.12
+    dev: false
+
   /@sveltejs/adapter-vercel@5.2.0(@sveltejs/kit@2.5.5):
     resolution: {integrity: sha512-872y13DxKcOBxgnXc4C2YHRw1ow9N1CpUxMH34NYFqCn6PUO6f34qle8v/Byr8sHEC/d+PZIAI3MJs3c8f7TfA==}
     peerDependencies:
diff --git a/src/lib/components/StickyToc.svelte b/src/lib/components/StickyToc.svelte
new file mode 100644
index 0000000..93da107
--- /dev/null
+++ b/src/lib/components/StickyToc.svelte
@@ -0,0 +1,72 @@
+<script lang="ts">
+	import { toclink, type TocStore } from '@svelte-put/toc';
+	import * as Card from '$lib/components/ui/card';
+	import { onMount } from 'svelte';
+
+	export let tocStore: TocStore;
+	export let distanceFromRight: number;
+
+	let el: HTMLElement;
+
+	let hide = false;
+
+	const readjust = () => {
+		el && (el.style.right = `calc(${distanceFromRight - el.clientWidth}px - 20px)`);
+	};
+
+	onMount(() => {
+		readjust();
+	});
+
+	$: readjust();
+
+	$: if (distanceFromRight < 220 && !hide) {
+		hide = true;
+	}
+
+	$: if (distanceFromRight >= 220 && hide) {
+		hide = false;
+	}
+
+	const calcIndent = (el: HTMLElement) => {
+		readjust();
+		if (el.tagName === 'H1' || el.tagName === 'H2') return '0px';
+		if (el.tagName === 'H3') return '1rem';
+		if (el.tagName === 'H4') return '2rem';
+		if (el.tagName === 'H5') return '3rem';
+		if (el.tagName === 'H6') return '4rem';
+		return '0px';
+	};
+
+	const calcTextClasses = (el: HTMLElement) => {
+		if (el.tagName === 'H1') return 'text-lg mb-2';
+		if (el.tagName === 'H2') return 'text-lg my-2';
+		return 'text-sm my-2 text-muted-foreground';
+	};
+</script>
+
+<aside class="fixed top-36 x-4 mx-4" bind:this={el}>
+	<Card.Root>
+		<Card.Header>
+			<Card.Title><h2 class="text-xl">On this page</h2></Card.Title>
+		</Card.Header>
+		<Card.Content>
+			{#if $tocStore.items.size}
+				<ol>
+					{#each $tocStore.items.values() as tocItem}
+						<li
+							style="margin-left: {calcIndent(tocItem.element)}"
+							class={calcTextClasses(tocItem.element)}
+						>
+							<!-- svelte-ignore a11y-missing-attribute a11y-missing-content -->
+							<a
+								use:toclink={{ store: tocStore, tocItem, observe: true }}
+								class="hover:underline"
+							/>
+						</li>
+					{/each}
+				</ol>
+			{/if}
+		</Card.Content>
+	</Card.Root>
+</aside>
diff --git a/src/routes/blog/[year]/[slug]/+page.svelte b/src/routes/blog/[year]/[slug]/+page.svelte
index 5e2bf64..ecec4dd 100644
--- a/src/routes/blog/[year]/[slug]/+page.svelte
+++ b/src/routes/blog/[year]/[slug]/+page.svelte
@@ -5,6 +5,26 @@
 	// import { config } from '$lib/stores/index.js';
 	import { cn } from '$lib/utils.js';
 	import Article from '$lib/components/Blog/Article.svelte';
+	import { toc, createTocStore } from '@svelte-put/toc';
+	import StickyToc from '$lib/components/StickyToc.svelte';
+	import { onMount } from 'svelte';
+
+	let distanceFromRight = 0;
+
+	let mainElement: HTMLElement;
+
+	const handleResize = () => {
+		const screenWidth = window.innerWidth;
+		const mainWidth = mainElement.offsetWidth;
+		distanceFromRight = screenWidth - mainWidth - mainElement.offsetLeft;
+		console.log(distanceFromRight);
+	};
+
+	onMount(() => {
+		handleResize();
+	});
+
+	const tocStore = createTocStore();
 
 	export let data: PageData;
 
@@ -28,6 +48,21 @@
 	<meta name="author" content="Youwen Wu" />
 </svelte:head>
 
-<main class="max-w-4xl md:mx-auto mx-4 mt-8 mb-14">
+<svelte:window on:resize={handleResize} />
+
+<main
+	bind:this={mainElement}
+	class="max-w-4xl mx-auto lg:mx-0 xl:mx-auto px-4 mt-8 mb-14"
+	use:toc={{
+		store: tocStore,
+		observe: true,
+		anchor: {
+			properties: { 'aria-hidden': 'true', 'tab-index': '-1', class: 'hidden' },
+			position: 'before'
+		}
+	}}
+>
 	<Article {doc} />
 </main>
+
+<StickyToc {tocStore} {distanceFromRight} />