Adding Frontmatter Reader: Support summary card (OG. Twitter)

Cargo.toml

@@ -35,6 +35,9 @@ shlex = "1.3.0"
 tempfile = "3.4.0"
 toml = "0.5.11" # Do not update, see https://github.com/rust-lang/mdBook/issues/2037
 topological-sort = "0.2.2"
+gray_matter = "0.2" #Fronmatter
+serde_yaml = "0.9"
+
 
 # Watch feature
 notify = { version = "6.1.1", optional = true }

src/renderer/html_handlebars/hbs_renderer.rs

@@ -19,6 +19,23 @@ use once_cell::sync::Lazy;
 use regex::{Captures, Regex};
 use serde_json::json;
 
+use gray_matter::engine::YAML;
+use gray_matter::Matter;
+use serde::Deserialize;
+
+fn extract_frontmatter(content: &str) -> Option<&str> {
+    let start = content.find("---")? + 3; // Find the end of the first `---` + 3 to move past it
+    let end = content[start..].find("---")? + start; // Find the start of the closing `---`
+    Some(&content[start..end].trim())
+}
+
+#[derive(Deserialize, Debug)]
+struct FrontMatter {
+    title: String,
+    description: String,
+    featured_image_url: String,
+}
+
 #[derive(Default)]
 pub struct HtmlHandlebars;
 
@@ -54,7 +71,45 @@ impl HtmlHandlebars {
                 .insert("git_repository_edit_url".to_owned(), json!(edit_url));
         }
 
-        let content = utils::render_markdown(&ch.content, ctx.html_config.curly_quotes);
+        // Parse frontmatter and prepare content
+        let matter = Matter::<YAML>::new();
+        let parsed = matter.parse(&ch.content);
+        let (content, new_content) = if let Some(data) = parsed.data {
+            debug!("Parsed frontmatter: {:?}", &data);
+            let yaml_str = extract_frontmatter(&ch.content).unwrap_or_default();
+            let front_matter_result: Result<FrontMatter, serde_yaml::Error> =
+                serde_yaml::from_str(yaml_str);
+            // let front_matter_result: Result<FrontMatter, serde_yaml::Error> = serde_yaml::from_str(&ch.content);
+            match front_matter_result {
+                Ok(front_matter) => {
+                    ctx.data.insert("is_frontmatter".to_owned(), json!("true"));
+                    ctx.data
+                        .insert("og_title".to_owned(), json!(front_matter.title));
+                    ctx.data
+                        .insert("og_description".to_owned(), json!(front_matter.description));
+                    ctx.data.insert(
+                        "og_image_url".to_owned(),
+                        json!(front_matter.featured_image_url),
+                    );
+                }
+                Err(e) => {
+                    eprintln!("Frontmatter: Deserialization error: {:?}", e);
+                }
+            }
+
+            // Prepare new content without frontmatter for rendering
+            let new_content = parsed.content.trim_start();
+            (
+                utils::render_markdown(&new_content, ctx.html_config.curly_quotes),
+                Some(new_content),
+            )
+        } else {
+            // No frontmatter, use original content
+            (
+                utils::render_markdown(&ch.content, ctx.html_config.curly_quotes),
+                None,
+            )
+        };
 
         let fixed_content =
             utils::render_markdown_with_path(&ch.content, ctx.html_config.curly_quotes, Some(path));

src/theme/index.hbs

@@ -43,6 +43,33 @@
         <link rel="stylesheet" href="{{ path_to_root }}tomorrow-night.css">
         <link rel="stylesheet" href="{{ path_to_root }}ayu-highlight.css">
 
+        <!-- Open Graph Meta Tags for Social Media Exposure -->
+        {{#if is_frontmatter}}
+        <meta name="title" property="og:title" content="{{ og_title }}">
+        <meta name="description" property="og:description" content="{{ og_description }}">
+        <meta name="twitter:title" content="{{ og_title }}"/>
+        <meta name="twitter:description" content="{{ og_description }}"/>
+        <!-- <meta property="og:url" content="{{ base_url}}"> -->
+        {{else}}
+        <meta name="title" property="og:title" content="mdBook Documentation">
+        <meta name="description" property="og:description" content="Create book from markdown files. Like Gitbook but implemented in Rust">
+        <!-- <meta property="og:url" content="https://www.dedp.online"> -->
+        <meta name="twitter:title" content="mdBook Documentation"/>
+        <meta name="twitter:description" content="Create book from markdown files. Like Gitbook but implemented in Rust"/>
+        {{/if}}
+        {{#if og_image_url}}
+        <meta property="og:image" content="{{ og_image_url }}">
+        <meta name="twitter:image" content="{{ og_image_url }}"/>
+        {{else}}
+        <meta property="og:image" content="https://rust-lang.github.io/mdBook/favicon.png">
+        <meta name="twitter:image" content="https://rust-lang.github.io/mdBook/favicon.png"/>
+        {{/if}}
+
+        <meta name="author" content="mdBook">
+        <meta property="og:type" content="book">
+        <meta name="twitter:card" content="summary_large_image"/>
+        <meta name="twitter:creator" content="@rustlang"/>
+
         <!-- Custom theme stylesheets -->
         {{#each additional_css}}
         <link rel="stylesheet" href="{{ ../path_to_root }}{{ this }}">