Dynamically register which CSS files are needed.

src/context/blog_post_page.rs

@@ -1,3 +1,5 @@
+use std::collections::HashSet;
+
 use serde::Serialize;
 
 use super::render_context::RenderContext;
@@ -51,34 +53,6 @@ render!(
     render_context,
     {
         push_file!(render_context, &original.page.src, {
-            let css_files = vec![
-                get_web_path(
-                    render_context.config,
-                    render_context.output_root_directory,
-                    render_context.output_file,
-                    "stylesheet/reset.css",
-                )?,
-                get_web_path(
-                    render_context.config,
-                    render_context.output_root_directory,
-                    render_context.output_file,
-                    "stylesheet/main.css",
-                )?,
-                get_web_path(
-                    render_context.config,
-                    render_context.output_root_directory,
-                    render_context.output_file,
-                    "stylesheet/language_nix.css",
-                )?,
-            ];
-            let js_files = vec![get_web_path(
-                render_context.config,
-                render_context.output_root_directory,
-                render_context.output_file,
-                "blog_post.js",
-            )?];
-            let global_settings =
-                GlobalSettings::new(original.page.title.clone(), css_files, js_files);
             let page_header = PageHeader::new(
                 render_context.config.get_site_title().map(str::to_string),
                 Some(get_web_path(
@@ -120,6 +94,46 @@ render!(
                 ret
             };
 
+            let mut css_files = vec![
+                get_web_path(
+                    render_context.config,
+                    render_context.output_root_directory,
+                    render_context.output_file,
+                    "stylesheet/reset.css",
+                )?,
+                get_web_path(
+                    render_context.config,
+                    render_context.output_root_directory,
+                    render_context.output_file,
+                    "stylesheet/main.css",
+                )?,
+            ];
+            let additional_css_files = render_context
+                .dependency_manager
+                .lock()
+                .unwrap()
+                .list_css()?
+                .map(|css_name| {
+                    get_web_path(
+                        render_context.config,
+                        render_context.output_root_directory,
+                        render_context.output_file,
+                        format!("stylesheet/{}", css_name),
+                    )
+                })
+                .collect::<Result<HashSet<_>, _>>()?;
+            css_files.extend(additional_css_files.into_iter());
+
+            let js_files = vec![get_web_path(
+                render_context.config,
+                render_context.output_root_directory,
+                render_context.output_file,
+                "blog_post.js",
+            )?];
+
+            let global_settings =
+                GlobalSettings::new(original.page.title.clone(), css_files, js_files);
+
             let ret = RenderBlogPostPage {
                 global_settings,
                 page_header: Some(page_header),

src/context/blog_stream.rs

@@ -1,3 +1,5 @@
+use std::collections::HashSet;
+
 use serde::Serialize;
 
 use super::macros::render;
@@ -49,37 +51,6 @@ render!(
     original,
     render_context,
     {
-        let css_files = vec![
-            get_web_path(
-                render_context.config,
-                render_context.output_root_directory,
-                render_context.output_file,
-                "stylesheet/reset.css",
-            )?,
-            get_web_path(
-                render_context.config,
-                render_context.output_root_directory,
-                render_context.output_file,
-                "stylesheet/main.css",
-            )?,
-            get_web_path(
-                render_context.config,
-                render_context.output_root_directory,
-                render_context.output_file,
-                "stylesheet/language_nix.css",
-            )?,
-        ];
-        let js_files = vec![get_web_path(
-            render_context.config,
-            render_context.output_root_directory,
-            render_context.output_file,
-            "blog_post.js",
-        )?];
-        let global_settings = GlobalSettings::new(
-            render_context.config.get_site_title().map(str::to_string),
-            css_files,
-            js_files,
-        );
         let page_header = PageHeader::new(
             render_context.config.get_site_title().map(str::to_string),
             Some(get_web_path(
@@ -111,6 +82,49 @@ render!(
             None
         };
 
+        let mut css_files = vec![
+            get_web_path(
+                render_context.config,
+                render_context.output_root_directory,
+                render_context.output_file,
+                "stylesheet/reset.css",
+            )?,
+            get_web_path(
+                render_context.config,
+                render_context.output_root_directory,
+                render_context.output_file,
+                "stylesheet/main.css",
+            )?,
+        ];
+        let additional_css_files = render_context
+            .dependency_manager
+            .lock()
+            .unwrap()
+            .list_css()?
+            .map(|css_name| {
+                get_web_path(
+                    render_context.config,
+                    render_context.output_root_directory,
+                    render_context.output_file,
+                    format!("stylesheet/{}", css_name),
+                )
+            })
+            .collect::<Result<HashSet<_>, _>>()?;
+        css_files.extend(additional_css_files.into_iter());
+
+        let js_files = vec![get_web_path(
+            render_context.config,
+            render_context.output_root_directory,
+            render_context.output_file,
+            "blog_post.js",
+        )?];
+
+        let global_settings = GlobalSettings::new(
+            render_context.config.get_site_title().map(str::to_string),
+            css_files,
+            js_files,
+        );
+
         Ok(RenderBlogStream {
             global_settings,
             page_header: Some(page_header),

src/context/dependency.rs

@@ -7,6 +7,7 @@ use super::RenderContext;
 #[derive(Debug)]
 pub(crate) enum Dependency {
     StaticFile { absolute_path: PathBuf },
+    CssFile { name: String },
 }
 
 impl Dependency {
@@ -40,6 +41,11 @@ impl Dependency {
                 }
                 Ok(())
             }
+            Dependency::CssFile { name } => {
+                // We don't do anything because the CSS files are already copied into the output from natter's default environment.
+                // TODO: When we add support for CSS outside the default environment, we should add support for dynamically picking which ones to copy here.
+                Ok(())
+            }
         }
     }
 }

src/context/dependency_manager.rs

@@ -65,4 +65,20 @@ impl DependencyManager {
         std::mem::swap(&mut self.dependencies, &mut dependencies);
         dependencies
     }
+
+    pub(crate) fn include_css<N>(&mut self, name: N) -> Result<(), CustomError>
+    where
+        std::string::String: From<N>,
+    {
+        self.dependencies
+            .push(Dependency::CssFile { name: name.into() });
+        Ok(())
+    }
+
+    pub(crate) fn list_css(&self) -> Result<impl Iterator<Item = &String>, CustomError> {
+        Ok(self.dependencies.iter().filter_map(|dep| match dep {
+            Dependency::CssFile { name } => Some(name),
+            _ => None,
+        }))
+    }
 }

src/context/page.rs

@@ -1,3 +1,5 @@
+use std::collections::HashSet;
+
 use super::footnote_definition::RenderRealFootnoteDefinition;
 use super::macros::render;
 use super::render_context::RenderContext;
@@ -30,33 +32,6 @@ pub(crate) struct RenderPage {
 
 render!(RenderPage, IPage, original, render_context, {
     push_file!(render_context, &original.src, {
-        let css_files = vec![
-            get_web_path(
-                render_context.config,
-                render_context.output_root_directory,
-                render_context.output_file,
-                "stylesheet/reset.css",
-            )?,
-            get_web_path(
-                render_context.config,
-                render_context.output_root_directory,
-                render_context.output_file,
-                "stylesheet/main.css",
-            )?,
-            get_web_path(
-                render_context.config,
-                render_context.output_root_directory,
-                render_context.output_file,
-                "stylesheet/language_nix.css",
-            )?,
-        ];
-        let js_files = vec![get_web_path(
-            render_context.config,
-            render_context.output_root_directory,
-            render_context.output_file,
-            "blog_post.js",
-        )?];
-        let global_settings = GlobalSettings::new(original.title.clone(), css_files, js_files);
         let page_header = PageHeader::new(
             render_context.config.get_site_title().map(str::to_string),
             Some(get_web_path(
@@ -98,6 +73,45 @@ render!(RenderPage, IPage, original, render_context, {
             ret
         };
 
+        let mut css_files = vec![
+            get_web_path(
+                render_context.config,
+                render_context.output_root_directory,
+                render_context.output_file,
+                "stylesheet/reset.css",
+            )?,
+            get_web_path(
+                render_context.config,
+                render_context.output_root_directory,
+                render_context.output_file,
+                "stylesheet/main.css",
+            )?,
+        ];
+        let additional_css_files = render_context
+            .dependency_manager
+            .lock()
+            .unwrap()
+            .list_css()?
+            .map(|css_name| {
+                get_web_path(
+                    render_context.config,
+                    render_context.output_root_directory,
+                    render_context.output_file,
+                    format!("stylesheet/{}", css_name),
+                )
+            })
+            .collect::<Result<HashSet<_>, _>>()?;
+        css_files.extend(additional_css_files.into_iter());
+
+        let js_files = vec![get_web_path(
+            render_context.config,
+            render_context.output_root_directory,
+            render_context.output_file,
+            "blog_post.js",
+        )?];
+
+        let global_settings = GlobalSettings::new(original.title.clone(), css_files, js_files);
+
         let ret = RenderPage {
             global_settings,
             page_header: Some(page_header),

src/context/src_block.rs

@@ -34,7 +34,7 @@ pub(crate) enum RenderSrcSegment {
     HighlightEnd,
 }
 
-render!(RenderSrcBlock, ISrcBlock, original, _render_context, {
+render!(RenderSrcBlock, ISrcBlock, original, render_context, {
     let lines = original
         .lines
         .iter()
@@ -55,6 +55,16 @@ render!(RenderSrcBlock, ISrcBlock, original, _render_context, {
             RenderSrcLine { children }
         })
         .collect();
+    match original.language.as_ref().map(String::as_str) {
+        Some("nix") => {
+            render_context
+                .dependency_manager
+                .lock()
+                .unwrap()
+                .include_css("language_nix.css")?;
+        }
+        _ => {}
+    };
     Ok(RenderSrcBlock {
         lines,
         language: original.language.clone(),