Markdown render challenge descriptions (Closes mousetail#21)

lang-runner/src/run.rs

@@ -171,7 +171,7 @@ async fn run_lang(
     }
 
     let data = serde_json::to_string(&RunnerInput { lang, code, judge })
-        .map_err(|e| RunProcessError::SerializationFailed(e))?;
+        .map_err(RunProcessError::SerializationFailed)?;
     stdin.write_all(data.as_bytes()).await?;
 
     let output = child.output().await?;

main-server/Cargo.toml

@@ -22,3 +22,4 @@ oauth2 = "5.0.0-rc.1"
 tower-sessions = "0.13.0"
 tower-http = { version = "0.6.1", features = ["catch-panic", "fs"] }
 serde_json = "1.0.128"
+markdown-it = "0.6.1"

main-server/src/auto_output_format.rs

@@ -18,7 +18,10 @@ use serde::Deserialize;
 use serde::{de::DeserializeOwned, Serialize};
 use tera::{escape_html, to_value, Context, Tera, Value};
 
-use crate::models::account::Account;
+use crate::{
+    markdown::MarkdownFilter,
+    models::account::Account,
+};
 
 #[derive(Serialize)]
 pub struct HtmlContext {
@@ -214,6 +217,7 @@ impl<T: Serialize> AutoOutputFormat<T> {
                 tera.autoescape_on(vec![".html.jinja", ".xml.jinja", ".html", ".xml"]);
                 tera.register_function("languages", get_langs);
                 tera.register_function("modules", load_assets);
+                tera.register_filter("markdown", MarkdownFilter);
                 tera
             })
         });

main-server/src/controllers/challenges.rs

@@ -101,7 +101,7 @@ pub async fn new_challenge(
             )
                 .fetch_one(&pool)
                 .await
-                .map_err(|e| Error::DatabaseError(e))?;
+                .map_err(Error::DatabaseError)?;
 
             Ok(Redirect::temporary(&format!("/challenge/{row}")).into_response())
         }

main-server/src/main.rs

@@ -2,6 +2,7 @@ mod auto_output_format;
 mod controllers;
 mod error;
 mod file_session_storage;
+mod markdown;
 mod models;
 mod session;
 mod test_solution;

main-server/src/markdown.rs

@@ -0,0 +1,51 @@
+use std::cell::OnceCell;
+
+use markdown_it::{plugins::cmark::inline::link::Link, MarkdownIt};
+use tera::Filter;
+
+thread_local! {
+    static MARKDOWN: OnceCell<MarkdownIt> = const { OnceCell::new() };
+}
+
+pub fn render_markdown(source: &str) -> String {
+    MARKDOWN.with(|markdown| {
+        let parser = markdown.get_or_init(|| {
+            let mut parser = markdown_it::MarkdownIt::new();
+            markdown_it::plugins::cmark::add(&mut parser);
+            markdown_it::plugins::extra::add(&mut parser);
+            parser
+        });
+
+        let mut ast = parser.parse(source);
+
+        // TODO: this is probbly better with a plugin
+        ast.walk_mut(|e, _index| {
+            if e.is::<Link>() {
+                e.attrs.push(("rel", "nofollow noopener".to_owned()));
+            }
+        });
+        ast.render()
+    })
+}
+
+pub struct MarkdownFilter;
+
+impl Filter for MarkdownFilter {
+    fn is_safe(&self) -> bool {
+        true
+    }
+
+    fn filter(
+        &self,
+        value: &tera::Value,
+        args: &std::collections::HashMap<String, tera::Value>,
+    ) -> tera::Result<tera::Value> {
+        if !args.is_empty() {
+            return Err(tera::Error::msg("The markdown function takes no arguments"));
+        }
+        let text = value
+            .as_str()
+            .ok_or_else(|| tera::Error::msg("Expected type to be a string"))?;
+        Ok(tera::Value::String(render_markdown(text)))
+    }
+}

main-server/src/models/challenge.rs

@@ -56,7 +56,7 @@ impl ChallengeWithAuthorInfo {
             .bind(id)
             .fetch_optional(pool)
             .await
-            .map_err(|e| Error::DatabaseError(e))?;
+            .map_err(Error::DatabaseError)?;
 
         Ok(challenge)
     }

templates/base/base.html.jinja

@@ -7,6 +7,7 @@
       <meta name="description" value="Yet Another Golf Site" />
       <meta name="keywords" value="code-golf" />
       <meta name="viewport" content="width=device-width, initial-scale=1" />
+      <meta charset="UTF-8" />
     {% endblock head %}
 
     {% block scripts %}

templates/challenge.html.jinja

@@ -5,14 +5,16 @@
   <h1>{{ object.challenge.challenge.name }}</h1>
   <p>
     A challenge by
-    <img src="{{ object.challenge.author_avatar }}&size=18" alt="{{ object.challenge.author_name }} avatar" height="18" />
+    <img src="{{ object.challenge.author_avatar }}&size=18"
+         alt="{{ object.challenge.author_name }} avatar"
+         height="18" />
     {{ object.challenge.author_name }}
     <a href="/challenge/{{ object.challenge.id }}">Edit</a>
   </p>
   <div class="two-column-descripion">
     <div>
       <h3>Descripion</h3>
-      {{ object.challenge.challenge.description }}
+      {{ object.challenge.challenge.description | markdown }}
     </div>
     <div class="leaderboard">
       <h3>Leaderboard</h3>