notecache: add initial in-memory notecache

This is useful for things like relative time strings and other
transient note cache state

Signed-off-by: William Casarin <jb55@jb55.com>

src/app.rs

@@ -3,6 +3,7 @@ use crate::error::Error;
 use crate::fonts::setup_gossip_fonts;
 use crate::frame_history::FrameHistory;
 use crate::images::fetch_img;
+use crate::notecache::NoteCache;
 use crate::timeline;
 use crate::ui::padding;
 use crate::Result;
@@ -97,6 +98,7 @@ pub struct Damus {
     compose: String,
     initial_filter: Vec<enostr::Filter>,
 
+    note_cache: HashMap<NoteKey, NoteCache>,
     pool: RelayPool,
 
     timelines: Vec<Timeline>,
@@ -449,6 +451,7 @@ impl Damus {
             state: DamusState::Initializing,
             pool: RelayPool::new(),
             img_cache: HashMap::new(),
+            note_cache: HashMap::new(),
             initial_filter,
             n_panels: 1,
             timelines: vec![Timeline::new()],
@@ -457,6 +460,12 @@ impl Damus {
             frame_history: FrameHistory::default(),
         }
     }
+
+    pub fn get_note_cache_mut(&mut self, note_ref: &NoteRef) -> &mut NoteCache {
+        self.note_cache
+            .entry(note_ref.key)
+            .or_insert_with(|| NoteCache::new(note_ref.created_at))
+    }
 }
 
 fn render_pfp(ui: &mut egui::Ui, img_cache: &mut ImageCache, url: &str) {

src/lib.rs

@@ -11,6 +11,7 @@ mod filter;
 mod ui;
 mod timecache;
 mod time;
+mod notecache;
 mod frame_history;
 mod timeline;
 

src/notecache.rs

@@ -0,0 +1,17 @@
+use crate::time::time_ago_since;
+use crate::timecache::TimeCached;
+use std::time::Duration;
+
+pub struct NoteCache {
+    reltime: TimeCached<String>,
+}
+
+impl NoteCache {
+    pub fn new(created_at: u64) -> Self {
+        let reltime = TimeCached::new(
+            Duration::from_secs(1),
+            Box::new(move || time_ago_since(created_at)),
+        );
+        NoteCache { reltime }
+    }
+}