Refactor highlighting

src/routes.rs

     }
 }
 
+fn format_gist(filetype: Option<String>, body: String) -> String {
+    filetype.map_or(
+        format!("<pre class='plaintext'>{}</pre>", body),
+        |filetype| {
+            let ps = SyntaxSet::load_defaults_newlines();
+            let ts = ThemeSet::load_defaults();
+            ps.find_syntax_by_extension(&filetype).map_or(
+                format!("<pre class='plaintext'>{}</pre>", body),
+                |syntax| {
+                    highlighted_html_for_string(&body, &ps, syntax, &ts.themes["Solarized (light)"])
+                },
+            )
+        },
+    )
+}
+
 #[get("/")]
 pub fn index(connection: DbConn) -> Result<Json<Vec<Gist>>, Status> {
     gists::all(&connection)
 
 #[get("/gists/<id>")]
 pub fn show_gist(id: i32, connection: DbConn) -> Template {
-    let gist = match gists::get(&connection, id) {
+    let result = match gists::get(&connection, id) {
         Ok(gist) => Some(gist),
         Err(_) => None,
     };
-    let mut context = HashMap::new();
 
-    match gist {
-        Some(g) => {
-            let body = match g.filetype {
-                Some(filetype) => {
-                    let ps = SyntaxSet::load_defaults_newlines();
-                    let ts = ThemeSet::load_defaults();
-                    let syntax = ps.find_syntax_by_extension(&filetype);
+    let (title, body) = result.map_or(
+        (
+            String::from("404 - Gist not found"),
+            format!("<h3'>{}</h3>", "Gist not found"),
+        ),
+        |gist| (gist.title, format_gist(gist.filetype, gist.body)),
+    );
 
-                    match syntax {
-                        Some(s) => highlighted_html_for_string(
-                            &g.body,
-                            &ps,
-                            s,
-                            &ts.themes["Solarized (light)"],
-                        ),
-                        None => format!("<pre class='plaintext'>{}</pre>", g.body),
-                    }
-                }
-                None => format!("<pre class='plaintext'>{}</pre>", g.body),
-            };
-            context.insert("title", g.title.clone());
-            context.insert("body", body);
-        }
-        None => {
-            context.insert("title", "404".to_string());
-            context.insert("body", "<h3>Gist not found</h3>".to_string());
-        }
-    }
+    let mut context: HashMap<&str, String> = HashMap::new();
+    context.insert("title", title);
+    context.insert("body", body);
 
     Template::render("gists/show", &context)
 }