From abdf79099ee4a261bdfff6e2536f78167360d85d Mon Sep 17 00:00:00 2001
From: Mylloon <kennel.anri@tutanota.com>
Date: Sun, 16 Jun 2024 15:31:44 +0200
Subject: [PATCH] wip: quick and dumb implementation of toc

---
 src/misc/markdown.rs | 105 ++++++++++++++++++++++++++++++++++++++++---
 src/routes/blog.rs   |   3 +-
 2 files changed, 99 insertions(+), 9 deletions(-)

diff --git a/src/misc/markdown.rs b/src/misc/markdown.rs
index d0fe36e..599ee58 100644
--- a/src/misc/markdown.rs
+++ b/src/misc/markdown.rs
@@ -1,8 +1,10 @@
 use crate::misc::date::Date;
 use base64::engine::general_purpose;
 use base64::Engine;
-use comrak::nodes::{AstNode, NodeValue};
-use comrak::{format_html, parse_document, Arena, ComrakOptions, ListStyleType, Options};
+use comrak::nodes::{AstNode, NodeCode, NodeMath, NodeValue};
+use comrak::{
+    format_html, parse_document, Anchorizer, Arena, ComrakOptions, ListStyleType, Options,
+};
 use lol_html::html_content::ContentType;
 use lol_html::{element, rewrite_str, HtmlRewriter, RewriteStrSettings, Settings};
 use ramhorns::Content;
@@ -19,7 +21,7 @@ pub struct FileMetadataBlog {
     pub description: Option<String>,
     pub publish: Option<bool>,
     pub tags: Option<Vec<Tag>>,
-    pub toc: Option<bool>,
+    pub toc: Option<String>,
 }
 
 /// A tag, related to post blog
@@ -333,10 +335,15 @@ pub fn get_metadata<'a>(root: &'a AstNode<'a>, mtype: &TypeFileMetadata) -> File
         .find_map(|node| match &node.data.borrow().value {
             // Extract metadata from frontmatter
             NodeValue::FrontMatter(text) => Some(match mtype {
-                TypeFileMetadata::Blog => FileMetadata {
-                    blog: Some(deserialize_metadata(text)),
-                    ..FileMetadata::default()
-                },
+                TypeFileMetadata::Blog => {
+                    let mut metadata: FileMetadataBlog = deserialize_metadata(text);
+                    metadata.toc = toc_to_html(&generate_toc(root));
+
+                    FileMetadata {
+                        blog: Some(metadata),
+                        ..FileMetadata::default()
+                    }
+                }
                 TypeFileMetadata::Contact => {
                     let mut metadata: FileMetadataContact = deserialize_metadata(text);
 
@@ -503,3 +510,87 @@ fn mail_obfuscation(html: &str) -> (String, bool) {
         (new_html, modified)
     }
 }
+
+#[derive(Debug)]
+struct TOCEntry {
+    id: String,
+    title: String,
+    depth: u8,
+}
+
+fn generate_toc<'a>(root: &'a AstNode<'a>) -> Vec<TOCEntry> {
+    /// See <https://github.com/kivikakk/comrak/blob/b67d406d3b101b93539c37a1ca75bff81ff8c149/src/html.rs#L446>
+    fn collect_text<'a>(node: &'a AstNode<'a>, output: &mut String) {
+        match node.data.borrow().value {
+            NodeValue::Text(ref literal)
+            | NodeValue::Code(NodeCode { ref literal, .. })
+            | NodeValue::Math(NodeMath { ref literal, .. }) => {
+                *output = literal.to_string();
+            }
+            _ => {
+                for n in node.children() {
+                    if !output.is_empty() {
+                        break;
+                    }
+
+                    collect_text(n, output);
+                }
+            }
+        }
+    }
+
+    let mut toc = vec![];
+
+    let mut anchorizer = Anchorizer::new();
+
+    // Collect headings first to avoid mutable borrow conflicts
+    let headings: Vec<_> = root
+        .children()
+        .filter_map(|node| {
+            if let NodeValue::Heading(ref nch) = &node.data.borrow().value {
+                Some((*nch, node))
+            } else {
+                None
+            }
+        })
+        .collect();
+
+    // Now process each heading
+    for (nch, node) in headings {
+        let mut title = String::with_capacity(20);
+        collect_text(node, &mut title);
+
+        toc.push(TOCEntry {
+            id: anchorizer.anchorize(title.clone()),
+            title,
+            depth: nch.level,
+        });
+    }
+
+    toc
+}
+
+fn toc_to_html(toc: &[TOCEntry]) -> Option<String> {
+    if toc.is_empty() {
+        return None;
+    }
+
+    let mut html = Vec::with_capacity(20 + 20 * toc.len());
+
+    html.extend_from_slice(b"<ul>");
+
+    for entry in toc {
+        // TODO: Use depth
+        html.extend_from_slice(
+            format!(
+                "<li><a href=\"{}\">{} (dbg/depth/{})</a></li>",
+                entry.id, entry.title, entry.depth
+            )
+            .as_bytes(),
+        );
+    }
+
+    html.extend_from_slice(b"</ul>");
+
+    Some(String::from_utf8(html).unwrap())
+}
diff --git a/src/routes/blog.rs b/src/routes/blog.rs
index 252dc72..a97a2c7 100644
--- a/src/routes/blog.rs
+++ b/src/routes/blog.rs
@@ -255,8 +255,7 @@ fn get_post(
                 None => default.2,
             },
             match &data.metadata.info.blog.as_ref().unwrap().toc {
-                // TODO: Generate TOC
-                Some(true) => String::new(),
+                Some(toc) => toc.into(),
                 _ => default.3,
             },
         ),