From b511a1a64e9076a040baf3c02a1587c40d0ec172 Mon Sep 17 00:00:00 2001
From: Ben Bridle <bridle.benjamin@gmail.com>
Date: Wed, 22 Jan 2025 12:47:06 +1300
Subject: Remove 'appendix' from the links of appendix headings

If a heading is prefixed with 'Appendix #:', the link to that heading
will not include that prefix. This is to make it possible to rearrange
appendices in a document without breaking existing links.
---
 src/generate_html.rs | 28 +++++++++++++++++++++-------
 1 file changed, 21 insertions(+), 7 deletions(-)

(limited to 'src/generate_html.rs')

diff --git a/src/generate_html.rs b/src/generate_html.rs
index e531854..0f520aa 100644
--- a/src/generate_html.rs
+++ b/src/generate_html.rs
@@ -111,10 +111,13 @@ pub fn document_to_html(document: &MarkdownDocument, page: &Page, website: &Webs
     let root = page.root();
     for block in &document.blocks {
         match block {
-            Block::Heading { level, line } => match level {
-                Level::Heading1 => tag!("h1", line, format!("id='{}'", make_url_safe(&line_to_html!(line)))),
-                Level::Heading2 => tag!("h2", line, format!("id='{}'", make_url_safe(&line_to_html!(line)))),
-                Level::Heading3 => tag!("h3", line, format!("id='{}'", make_url_safe(&line_to_html!(line)))),
+            Block::Heading { level, line } => {
+                let id = make_url_safe(strip_appendix(&line_to_html!(line)));
+                match level {
+                    Level::Heading1 => tag!("h1", line, format!("id='{id}'")),
+                    Level::Heading2 => tag!("h2", line, format!("id='{id}'")),
+                    Level::Heading3 => tag!("h3", line, format!("id='{id}'")),
+                }
             }
             Block::Paragraph(line) => tag!("p", line),
             Block::Math(content) => html!("<div class='math'>{}</div>", sanitize_text(content, false)),
@@ -269,8 +272,8 @@ fn line_to_html(line: &Line, page: &Page, website: &Website) -> String {
                 let text = &sanitize_text(text, false); html.push_str(&format!("<span class='math'>{text}</span>")) }
             Token::InternalLink(name) => {
                 let (class, label, path) = match name.split_once('#') {
-                    Some(("", heading)) => ("heading", heading, format!("#{heading}")),
-                    Some((page, heading)) => ("page", heading, format!("{page}.html#{heading}")),
+                    Some(("", heading)) => ("heading", heading, format!("#{}", strip_appendix(heading))),
+                    Some((page, heading)) => ("page", heading, format!("{page}.html#{}", strip_appendix(heading))),
                     _ => ("page", name.as_str(), format!("{name}.html")),
                 };
                 let mut path = make_url_safe(&path);
@@ -287,7 +290,7 @@ fn line_to_html(line: &Line, page: &Page, website: &Website) -> String {
                 }
                 // Check that the heading exists.
                 if class == "heading" {
-                    let heading = path.strip_prefix('#').unwrap().to_string();
+                    let heading = path.strip_prefix('#').unwrap();
                     if !page.headings.iter().any(|h| h.url == heading) {
                         warn!("Page {from:?} contains link to nonexistent internal heading {heading:?}");
                     }
@@ -371,3 +374,14 @@ fn sanitize_text(text: &str, fancy: bool) -> String {
     }
     return output;
 }
+
+
+/// Remove a 'Appendix #: ' prefix from a string.
+pub fn strip_appendix(text: &str) -> &str {
+    if let Some((prefix, name)) = text.split_once(": ") {
+        if prefix.starts_with("Appendix") {
+            return name;
+        }
+    }
+    return text;
+}
-- 
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