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-rw-r--r--web/blog/default.nix63
-rw-r--r--web/blog/fragments.nix96
2 files changed, 159 insertions, 0 deletions
diff --git a/web/blog/default.nix b/web/blog/default.nix
new file mode 100644
index 000000000000..f55c33a63a54
--- /dev/null
+++ b/web/blog/default.nix
@@ -0,0 +1,63 @@
+# This creates the static files that make up my blog from the Markdown
+# files in this repository.
+#
+# All blog posts are rendered from Markdown by cheddar.
+{ depot, lib, pkgs, ... }@args:
+
+with depot.nix.yants;
+
+let
+  inherit (builtins) readFile;
+  inherit (depot.nix) renderMarkdown;
+  inherit (depot.web) atom-feed;
+  inherit (lib) singleton;
+
+  # Type definition for a single blog post.
+  post = struct "blog-post" {
+    key = string;
+    title = string;
+    date = int;
+
+    # Optional time at which this post was last updated.
+    updated = option int;
+
+    # Path to the Markdown file containing the post content.
+    content = path;
+
+    # Should this post be included in the index? (defaults to true)
+    listed = option bool;
+
+    # Is this a draft? (adds a banner indicating that the link should
+    # not be shared)
+    draft = option bool;
+
+    # Previously each post title had a numeric ID. For these numeric
+    # IDs, redirects are generated so that old URLs stay compatible.
+    oldKey = option string;
+  };
+
+  # Rendering fragments for the HTML version of the blog.
+  fragments = import ./fragments.nix args;
+
+  # Functions for generating feeds for these blogs using //web/atom-feed.
+  toFeedEntry = { baseUrl, ... }: defun [ post atom-feed.entry ] (post: rec {
+    id = "${baseUrl}/${post.key}";
+    title = post.title;
+    content = readFile (renderMarkdown post.content);
+    published = post.date;
+    updated = post.updated or post.date;
+
+    links = singleton {
+      rel = "alternate";
+      href = id;
+    };
+  });
+in
+{
+  inherit post toFeedEntry;
+  inherit (fragments) renderPost;
+
+  # Helper function to determine whether a post should be included in
+  # listings (on homepages, feeds, ...)
+  includePost = post: !(fragments.isDraft post) && !(fragments.isUnlisted post);
+}
diff --git a/web/blog/fragments.nix b/web/blog/fragments.nix
new file mode 100644
index 000000000000..19d62fa4744d
--- /dev/null
+++ b/web/blog/fragments.nix
@@ -0,0 +1,96 @@
+# This file defines various fragments of the blog, such as the header
+# and footer, as functions that receive arguments to be templated into
+# them.
+#
+# An entire post is rendered by `renderPost`, which assembles the
+# fragments together in a runCommand execution.
+{ depot, lib, pkgs, ... }:
+
+let
+  inherit (builtins) filter map hasAttr replaceStrings;
+  inherit (pkgs) runCommandNoCC writeText;
+  inherit (depot.nix) renderMarkdown;
+
+  staticUrl = "https://static.tvl.fyi/${depot.web.static.drvHash}";
+
+  # Generate a post list for all listed, non-draft posts.
+  isDraft = post: (hasAttr "draft" post) && post.draft;
+  isUnlisted = post: (hasAttr "listed" post) && !post.listed;
+
+  escape = replaceStrings [ "<" ">" "&" "'" ] [ "&lt;" "&gt;" "&amp;" "&#39;" ];
+
+  header = name: title: ''
+    <!DOCTYPE html>
+    <head>
+      <meta charset="utf-8">
+      <meta name="viewport" content="width=device-width, initial-scale=1">
+      <meta name="description" content="${escape name}">
+      <link rel="stylesheet" type="text/css" href="${staticUrl}/tvl.css" media="all">
+      <link rel="icon" type="image/webp" href="/static/favicon.webp">
+      <link rel="alternate" type="application/atom+xml" title="Atom Feed" href="https://tvl.fyi/feed.atom">
+      <title>${escape name}: ${escape title}</title>
+    </head>
+    <body class="light">
+      <header>
+        <h1><a class="blog-title" href="/">${escape name}</a> </h1>
+        <hr>
+      </header>
+  '';
+
+  fullFooter = content: ''
+      <hr>
+      <footer>
+        ${content}
+      </footer>
+    </body>
+  '';
+
+  draftWarning = writeText "draft.html" ''
+    <p class="cheddar-callout cheddar-warning">
+      <b>Note:</b> This post is a <b>draft</b>! Please do not share
+      the link to it without asking first.
+    </p>
+    <hr>
+  '';
+
+  unlistedWarning = writeText "unlisted.html" ''
+    <p class="cheddar-callout cheddar-warning">
+      <b>Note:</b> This post is <b>unlisted</b>! Please do not share
+      the link to it without asking first.
+    </p>
+    <hr>
+  '';
+
+  renderPost = { name, footer, ... }: post: runCommandNoCC "${post.key}.html" { } ''
+    cat ${writeText "header.html" (header name post.title)} > $out
+
+    # Write the post title & date
+    echo '<article><h2 class="inline">${escape post.title}</h2>' >> $out
+    echo '<aside class="date">' >> $out
+    date --date="@${toString post.date}" '+%Y-%m-%d' >> $out
+    ${
+      if post ? updated
+      then ''date --date="@${toString post.updated}" '+ (updated %Y-%m-%d)' >> $out''
+      else ""
+    }
+    echo '</aside>' >> $out
+
+    ${
+      # Add a warning to draft/unlisted posts to make it clear that
+      # people should not share the post.
+
+      if (isDraft post) then "cat ${draftWarning} >> $out"
+      else if (isUnlisted post) then "cat ${unlistedWarning} >> $out"
+      else "# Your ads could be here?"
+    }
+
+    # Write the actual post through cheddar's about-filter mechanism
+    cat ${renderMarkdown post.content} >> $out
+    echo '</article>' >> $out
+
+    cat ${writeText "footer.html" (fullFooter footer)} >> $out
+  '';
+in
+{
+  inherit isDraft isUnlisted renderPost;
+}