From 7fb1f05a1e19c38716fbc9153f4839ddcb3d6e51 Mon Sep 17 00:00:00 2001
From: Joseph Montanaro <jfmonty2@gmail.com>
Date: Mon, 4 Sep 2023 22:07:58 -0700
Subject: [PATCH] initial feed implementation

---
 src/lib/Post.svelte                           | 35 ++++---
 src/lib/Sidenote.svelte                       |  4 +-
 src/lib/Toc.svelte                            |  3 -
 src/lib/xml.js                                | 94 +++++++++++++++++++
 src/plugins/remark.js                         | 39 +++++++-
 src/routes/[slug]/+page.js                    |  1 +
 src/routes/_posts/all.js                      | 14 ++-
 ...exposing-docker-containers-to-your-lan.svx |  1 +
 .../_posts/hitchikers-guide-to-mesh-vpns.svx  |  1 +
 .../imagining-a-passwordless-future.svx       |  1 +
 src/routes/_posts/languages-high-and-low.svx  |  1 +
 src/routes/_posts/sidenotes.svx               |  1 +
 src/routes/_posts/simpler-socketio.svx        |  1 +
 ...sufficiently-advanced-technology-magic.svx |  1 +
 src/routes/_posts/vue-vs-svelte.svx           |  1 +
 src/routes/feed/+server.js                    | 49 ++++++++++
 src/routes/posts/+page.svelte                 | 34 ++++---
 17 files changed, 243 insertions(+), 38 deletions(-)
 create mode 100644 src/lib/xml.js
 create mode 100644 src/routes/feed/+server.js

diff --git a/src/lib/Post.svelte b/src/lib/Post.svelte
index 3333314..a51b650 100644
--- a/src/lib/Post.svelte
+++ b/src/lib/Post.svelte
@@ -13,6 +13,9 @@
     export const description = '';
     export const draft = false;
     export let toc = null;
+
+    export let prev = null;
+    export let next = null;
 </script>
 
 <style>
@@ -46,7 +49,6 @@
         grid-column: 2 / 3;
         margin-bottom: 2rem;
         display: flex;
-        justify-content: space-between;
     }
 
     hr {
@@ -101,18 +103,23 @@
     <hr>
 
     <div class="footer">
-        <a href="#">
-            <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1.5" stroke="currentColor" class="w-6 h-6">
-                <path stroke-linecap="round" stroke-linejoin="round" d="M10.5 19.5L3 12m0 0l7.5-7.5M3 12h18" />
-            </svg>
-            Previous
-        </a>
+        {#if prev}
+            <a href="/{prev}" data-sveltekit-preload-data="hover">
+                <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1.5" stroke="currentColor" class="w-6 h-6">
+                    <path stroke-linecap="round" stroke-linejoin="round" d="M10.5 19.5L3 12m0 0l7.5-7.5M3 12h18" />
+                </svg>
+                Previous
+            </a>
+        {/if}
 
-        <a href="#">
-            Next
-            <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1.5" stroke="currentColor" class="w-6 h-6">
-              <path stroke-linecap="round" stroke-linejoin="round" d="M13.5 4.5L21 12m0 0l-7.5 7.5M21 12H3" />
-            </svg>
-        </a>
+        {#if next}
+            <!-- we use margin-left rather than justify-content so it works regardless of whether the "previous" link exists -->
+            <a href="/{next}" style="margin-left: auto;" data-sveltekit-preload-data="hover">
+                Next
+                <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1.5" stroke="currentColor" class="w-6 h-6">
+                  <path stroke-linecap="round" stroke-linejoin="round" d="M13.5 4.5L21 12m0 0l-7.5 7.5M21 12H3" />
+                </svg>
+            </a>
+        {/if}
     </div>
-</div>
\ No newline at end of file
+</div>
diff --git a/src/lib/Sidenote.svelte b/src/lib/Sidenote.svelte
index 8cedb84..959cb3a 100644
--- a/src/lib/Sidenote.svelte
+++ b/src/lib/Sidenote.svelte
@@ -23,7 +23,7 @@
     }
 
     .sidenote:before {
-        content: counter(sidenote) " ";
+        content: var(--sidenote-index, counter(sidenote)) " ";
         /* absolute positioning puts it at the top-left corner of the sidenote, overlapping with the content
         (because the sidenote is floated it counts as a positioned parent, I think) */
         position: absolute;
@@ -46,7 +46,7 @@
 
         .sidenote {
             --gap: 2rem;
-            --sidenote-width: min(14rem, calc(50vw - var(--gap) - var(--content-width) / 2));
+            --sidenote-width: min(16rem, calc(50vw - var(--gap) - 1rem - var(--content-width) / 2));
             width: var(--sidenote-width);
             hyphens: auto;
             position: relative;
diff --git a/src/lib/Toc.svelte b/src/lib/Toc.svelte
index 51b9bfc..e7cc127 100644
--- a/src/lib/Toc.svelte
+++ b/src/lib/Toc.svelte
@@ -11,7 +11,6 @@
     let currentSubheadingSlug = null;
 
     function setCurrentHeading() {
-        const start = performance.now();
         for (const h of headings) {
             const yPos = h.getBoundingClientRect().y;
             if (yPos > (window.innerHeight / 3)) {
@@ -25,8 +24,6 @@
                 currentSubheadingSlug = h.id
             }
         }
-        const end = performance.now();
-        console.log(`Elapsed: ${end - start}`);
     }
 
     onMount (() => {
diff --git a/src/lib/xml.js b/src/lib/xml.js
new file mode 100644
index 0000000..260bfc4
--- /dev/null
+++ b/src/lib/xml.js
@@ -0,0 +1,94 @@
+// const Node = {
+//     addChild(child) {
+//         this.children.push(child);
+//         return child;
+//     }
+// }
+
+
+export function tag(name, attrs, children) {
+    return {
+        type: 'tag',
+        tag: name,
+        attrs: attrs || {},
+        children: children || [],
+
+        addTag(name, attrs, children) {
+            const child = tag(name, attrs, children);
+            this.children.push(child);
+            return child;
+        },
+    };
+}
+
+
+export function text(content) {
+    return {
+        type: 'text',
+        text: content,
+    };
+}
+
+
+export function serialize(node, depth) {
+    if (!depth) {
+        depth = 0;
+    }
+
+    const indent = ' '.repeat(depth * 4);
+    let fragments = [];
+
+    // version tag, if this is the top level
+    if (depth === 0) {
+        fragments.push('<?xml version="1.0" encoding="UTF-8"?>\n')
+    }
+
+    fragments.push(`${indent}<${node.tag}`);
+
+    // this happens if there are multiple text nodes within the same parent
+    if (node.type === 'text') {
+        return `${indent}${escape(node.text)}`;
+    }
+
+    if (node.children === undefined) {
+        console.log(node);
+    }
+
+    // opening tag <element attr="value">
+    for (const attr in node.attrs) {
+        fragments.push(` ${attr}="${node.attrs[attr]}"`);
+    }
+    if (node.children.length === 0) {
+        fragments.push(' />');
+        return fragments.join('');
+    }
+    fragments.push('>');
+
+    // if the only child is a single text node, skip recursion and just dump contents directly
+    if (node.children.length === 1 && node.children[0].type === 'text') {
+        const text = escape(node.children[0].text);
+        fragments.push(text);
+    }
+    // otherwise, start a new line for each child node, then recurse
+    else {
+        for (const child of node.children) {
+            fragments.push('\n');
+            fragments.push(serialize(child, depth + 1));
+        }
+        // no need to verify that there were children, we already did that
+        fragments.push(`\n${indent}`);
+    }
+
+    fragments.push(`</${node.tag}>`);
+
+    return fragments.join('');
+}
+
+
+function escape(text) {
+    // we aren't going to bother with escaping attributes, so we won't worry about quotes
+    return text
+        .replaceAll('&', '&amp;')
+        .replaceAll('<', '&gt;')
+        .replaceAll('>', '&lt;');
+}
diff --git a/src/plugins/remark.js b/src/plugins/remark.js
index cbc1d82..1b119c2 100644
--- a/src/plugins/remark.js
+++ b/src/plugins/remark.js
@@ -1,19 +1,48 @@
 import { visit } from 'unist-util-visit';
 import { toString } from 'mdast-util-to-string';
 
+import fs from 'node:fs';
 
 // build table of contents and inject into frontmatter
 export function localRemark() {
     return (tree, vfile) => {
         let toc = [];
+        let description = null;
         
-        visit(tree, 'heading', node => {
-            toc.push({
-                text: toString(node),
-                depth: node.depth,
-            });
+        visit(tree, ['heading', 'paragraph'], node => {
+            // build table of contents and inject into frontmatter
+            if (node.type === 'heading') {
+                toc.push({
+                    text: toString(node),
+                    depth: node.depth,
+                });
+            }
+
+            // inject description (first 25 words of the first paragraph)
+            if (node.type === 'paragraph' && description === null) {
+                description = summarize(node);
+            }
         });
 
         vfile.data.fm.toc = toc;
+        vfile.data.fm.description = description;
     }
 }
+
+
+// convert paragraph to single string after stripping everything between html tags
+function summarize(par) {
+    let newChildren = [];
+    let push = true;
+    for (const child of par.children) {
+        if (child.type === 'html') {
+            push = !push;
+            continue;
+        }
+        if (push) {
+            newChildren.push(child);
+        }
+    }
+
+    return toString({type: 'paragraph', children: newChildren});
+}
diff --git a/src/routes/[slug]/+page.js b/src/routes/[slug]/+page.js
index 23528ff..ee82b83 100644
--- a/src/routes/[slug]/+page.js
+++ b/src/routes/[slug]/+page.js
@@ -12,6 +12,7 @@ export async function load({ url, params, data }) {
     }
     catch (err) {
         // throw error(404, `Not found: ${url.pathname}`);
+        console.log(err);
         throw err;
     }
 }
diff --git a/src/routes/_posts/all.js b/src/routes/_posts/all.js
index 4678683..d1f8925 100644
--- a/src/routes/_posts/all.js
+++ b/src/routes/_posts/all.js
@@ -1,4 +1,3 @@
-import { writable } from 'svelte/store';
 import { dev } from '$app/environment';
 const posts = import.meta.globEager('./*.svx');
 
@@ -16,6 +15,19 @@ for (const path in posts) {
     postData.push(posts[path].metadata);
 }
 
+
+let ids = new Set();
+for (const postMeta of postData) {
+    if (postMeta.uuid === undefined) {
+        throw(`Missing UUID for post: ${postMeta.title}`);
+    }
+    if (ids.has(postMeta.uuid)) {
+        throw(`Duplicate UUID in post: ${postMeta.title}`);
+    }
+    ids.add(postMeta.uuid);
+}
+
+
 postData.sort((a, b) => {
     // sorting in reverse, so we flip the intuitive order
     if (a.date > b.date) return -1;
diff --git a/src/routes/_posts/exposing-docker-containers-to-your-lan.svx b/src/routes/_posts/exposing-docker-containers-to-your-lan.svx
index 7f3de8d..f19dc46 100644
--- a/src/routes/_posts/exposing-docker-containers-to-your-lan.svx
+++ b/src/routes/_posts/exposing-docker-containers-to-your-lan.svx
@@ -2,6 +2,7 @@
 title: Exposing Docker Containers to your LAN
 description: If, for some strange reason, you should want to do such a thing.
 date: 2022-03-21
+uuid: 81715fb3-990e-487e-9662-fed7b7d02943
 ---
 <script>
     import Sidenote from '$lib/Sidenote.svelte';
diff --git a/src/routes/_posts/hitchikers-guide-to-mesh-vpns.svx b/src/routes/_posts/hitchikers-guide-to-mesh-vpns.svx
index d84d2d8..209b539 100644
--- a/src/routes/_posts/hitchikers-guide-to-mesh-vpns.svx
+++ b/src/routes/_posts/hitchikers-guide-to-mesh-vpns.svx
@@ -2,6 +2,7 @@
 title: The Hitchiker's Guide to Mesh VPNs
 description: The golden age of VPNery is upon us.
 date: 2022-03-17
+uuid: fc6930ef-979c-4851-bc5a-c0e1b1698061
 ---
 <script>
     import Sidenote from '$lib/Sidenote.svelte';
diff --git a/src/routes/_posts/imagining-a-passwordless-future.svx b/src/routes/_posts/imagining-a-passwordless-future.svx
index f77a9d6..ed574e4 100644
--- a/src/routes/_posts/imagining-a-passwordless-future.svx
+++ b/src/routes/_posts/imagining-a-passwordless-future.svx
@@ -4,6 +4,7 @@ description: Can we replace passwords with something more user-friendly?
 date: 2021-04-30
 draft: true
 dropcap: false
+uuid: 696020b3-1513-42a8-b346-634d40f0e9d9
 ---
 <script>
     import Sidenote from '$lib/Sidenote.svelte';
diff --git a/src/routes/_posts/languages-high-and-low.svx b/src/routes/_posts/languages-high-and-low.svx
index 6db7e60..236378c 100644
--- a/src/routes/_posts/languages-high-and-low.svx
+++ b/src/routes/_posts/languages-high-and-low.svx
@@ -2,6 +2,7 @@
 title: 'Languages: High and Low'
 description: How high is up?
 date: 2022-08-19
+uuid: 89ae4194-7785-4fac-a841-8bcf5a5a3a2e
 draft: true
 ---
 
diff --git a/src/routes/_posts/sidenotes.svx b/src/routes/_posts/sidenotes.svx
index 914e4a9..f3092ae 100644
--- a/src/routes/_posts/sidenotes.svx
+++ b/src/routes/_posts/sidenotes.svx
@@ -2,6 +2,7 @@
 title: Sidenotes
 description: An entirely-too-detailed dive into how I implemented sidenotes for this blog.
 date: 2023-08-14
+uuid: c514c46e-92f3-4078-a76b-e1dafd5f7e07
 ---
 <script>
     import Sidenote from '$lib/Sidenote.svelte';
diff --git a/src/routes/_posts/simpler-socketio.svx b/src/routes/_posts/simpler-socketio.svx
index bb592ad..d272241 100644
--- a/src/routes/_posts/simpler-socketio.svx
+++ b/src/routes/_posts/simpler-socketio.svx
@@ -2,6 +2,7 @@
 title: Let's Design A Simpler SocketIO
 date: 2021-10-16
 description: SocketIO is packed with features. But do we really need all of them all the time?
+uuid: 95cde7e7-9293-4fab-a0b4-fc6ab7da08c8
 draft: true
 ---
 
diff --git a/src/routes/_posts/sufficiently-advanced-technology-magic.svx b/src/routes/_posts/sufficiently-advanced-technology-magic.svx
index 2699c21..f072148 100644
--- a/src/routes/_posts/sufficiently-advanced-technology-magic.svx
+++ b/src/routes/_posts/sufficiently-advanced-technology-magic.svx
@@ -2,6 +2,7 @@
 title: Sufficiently Advanced Technology Is Often Distinguishable From Magic
 description: I see what Arthur C. Clarke was getting at, but I don't think I agree.
 date: 2022-05-14
+uuid: 84636766-eb78-4060-a98d-593d8d5b55c9
 draft: true
 ---
 <script>
diff --git a/src/routes/_posts/vue-vs-svelte.svx b/src/routes/_posts/vue-vs-svelte.svx
index b19dd62..580fc45 100644
--- a/src/routes/_posts/vue-vs-svelte.svx
+++ b/src/routes/_posts/vue-vs-svelte.svx
@@ -2,6 +2,7 @@
 title: Thoughts on Vue vs Svelte
 description: They're more similar than they are different, but they say the most bitter enemies are those who have the fewest differences.
 date: 2023-06-29
+uuid: 8280f0e0-6bf5-43a2-9eac-b8c2508cca29
 ---
 <script>
     import Sidenote from '$lib/Sidenote.svelte';
diff --git a/src/routes/feed/+server.js b/src/routes/feed/+server.js
new file mode 100644
index 0000000..536106e
--- /dev/null
+++ b/src/routes/feed/+server.js
@@ -0,0 +1,49 @@
+import { tag, text, serialize } from '$lib/xml.js';
+import { postData } from '../_posts/all.js';
+
+
+export function GET() {
+    return new Response(renderFeed(), {
+        headers: {'Content-Type': 'text/xml'}
+    });
+}
+
+
+function renderFeed() {
+    const feed = tag('feed', {xmlns: 'http://www.w3.org/2005/Atom'});
+
+    feed.addTag('id', {}, [text('https://blog.jfmonty2.com')])
+    feed.addTag('title', {}, [text("Joe's Blog")]);
+    feed.addTag('link', {href: 'https://blog.jfmonty2.com/'});
+
+    const lastUpdate = iso(postData[0].updated || postData[0].date);
+    feed.addTag('updated', {}, [text(lastUpdate)]);
+
+    const author = feed.addTag('author');
+    author.addTag('name', {}, [text('Joseph Montanaro')]);
+
+    for (const post of postData) {
+        const entry = feed.addTag('entry');
+        entry.addTag('title', {}, [text(post.title)]);
+        entry.addTag('link', {rel: 'alternate', href: `https://blog.jfmonty2.com/${post.slug}`});
+        entry.addTag('id', {}, [text(post.uuid)]);
+
+        const publishedDate = iso(post.date);
+        entry.addTag('published', {}, [text(publishedDate)])
+        const updatedDate = iso(post.updated || post.date);
+        entry.addTag('updated', {}, [text(updatedDate)]);
+
+        entry.addTag('content', {type: 'html'}, [text(renderDescription(post))]);
+    }
+    return serialize(feed);
+}
+
+
+function renderDescription(post) {
+    return `<p>${post.description} <a href="https://blog.jfmonty2.com/${post.slug}">Read more</a></p>`;
+}
+
+
+function iso(datetimeStr) {
+    return new Date(datetimeStr).toISOString();
+}
diff --git a/src/routes/posts/+page.svelte b/src/routes/posts/+page.svelte
index 095aa6e..879f4c4 100644
--- a/src/routes/posts/+page.svelte
+++ b/src/routes/posts/+page.svelte
@@ -6,14 +6,13 @@
 <style>
     #posts {
         /*text-align:  center;*/
-        max-width:  24rem;
-        margin-left:  auto;
-        margin-right:  auto;
+        max-width:  var(--content-width);
+        margin:  0 auto;
     }
 
-    .post {
-        border-bottom: 2px solid #eee;
-        margin-top: 1rem;
+    hr {
+        margin: 2rem 0;
+        border-color: #eee;
     }
 
     .post-date {
@@ -38,9 +37,14 @@
         text-decoration: underline;
     }
 
-    h3 {
-        display: inline;
-        margin:  0;
+    h2 {
+        font-size: 1.25rem;
+        margin-top: 0.5rem;
+        margin-bottom: 0.75rem;
+    }
+
+    h2 a {
+        color: currentcolor;
     }
 </style>
 
@@ -50,18 +54,22 @@
 
 <div id="posts">
     <h1 style:text-align="center">All Posts</h1>
-    {#each postData as post}
+    {#each postData as post, idx}
         <div class="post">
             <div class="post-date">{new Date(post.date).toISOString().split('T')[0]}</div>
-            <div>
+            <h2>
                 <a data-sveltekit-preload-data="hover" class="post-link" href="/{post.slug}">
-                    <h3>{post.title}<h3>
+                    {post.title}
                 </a>
                 {#if post.draft}
                     <span class="draft-notice">Draft</span>
                 {/if}
-            </div>
+            </h2>
             <p>{post.description}</p>
         </div>
+
+        {#if idx < postData.length - 1}
+        <hr>
+        {/if}
     {/each}
 </div>