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.

2 files changed, 24 insertions, 9 deletions

diff --git a/src/collect_files.rs b/src/collect_files.rs
index 14bf0c3..de577cf 100644
--- a/src/collect_files.rs
+++ b/src/collect_files.rs
@@ -167,7 +167,7 @@ impl Website {
                     let headings = document.blocks.iter()
                         .filter_map(|block| if let Block::Heading { line, level } = block {
                             let name = line.to_string();
-                            let url = make_url_safe(&name);
+                            let url = make_url_safe(strip_appendix(&name));
                             let level = level.to_owned();
                             if !heading_set.insert(url.clone()) {
                                 duplicates.insert(url.clone());
@@ -281,7 +281,8 @@ impl Website {
             if page.full_url == path {
                 let root = from.root();
                 if let Some(heading) = heading {
-                    if !page.headings.iter().any(|h| h.url == make_url_safe(heading)) {
+                    let heading = make_url_safe(strip_appendix(heading));
+                    if !page.headings.iter().any(|h| h.url == heading) {
                         warn!("Page {:?} contains link to nonexistent heading {heading:?} on page {path:?}", from.name());
                     }
                     return Some(format!("{root}{path}.{ext}#{heading}"));
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;
+}