server: add unread field to tag query.

Optionally fill out unread, as it's expensive.

server/src/graphql.rs

@@ -6,6 +6,7 @@ use async_graphql::{
 };
 use log::info;
 use notmuch::Notmuch;
+use rayon::prelude::*;
 
 pub struct QueryRoot;
 
@@ -36,6 +37,7 @@ struct Tag {
     name: String,
     fg_color: String,
     bg_color: String,
+    unread: usize,
 }
 
 #[Object]
@@ -129,15 +131,21 @@ impl QueryRoot {
         let nm = ctx.data_unchecked::<Notmuch>();
         Ok(nm
             .tags()?
-            .into_iter()
+            .into_par_iter()
             .map(|tag| {
                 let mut hasher = DefaultHasher::new();
                 tag.hash(&mut hasher);
                 let hex = format!("#{:06x}", hasher.finish() % (1 << 24));
+                let unread = if ctx.look_ahead().field("unread").exists() {
+                    nm.count(&format!("tag:{tag} is:unread")).unwrap_or(0)
+                } else {
+                    0
+                };
                 Tag {
                     name: tag,
                     fg_color: "white".to_string(),
                     bg_color: hex,
+                    unread,
                 }
             })
             .collect())