ui: add SearchView and SearchQueryState

Introduce a new view for searching for notes.

Fixes: https://linear.app/damus/issue/DECK-510/initial-search-query-view
Signed-off-by: William Casarin <jb55@jb55.com>

crates/notedeck_columns/src/ui/search/state.rs

@@ -0,0 +1,63 @@
+use crate::timeline::TimelineTab;
+use notedeck::debouncer::Debouncer;
+use std::time::Duration;
+
+#[derive(Debug, Eq, PartialEq)]
+pub enum SearchState {
+    Typing,
+    Searched,
+    New,
+}
+
+/// Search query state that exists between frames
+#[derive(Debug)]
+pub struct SearchQueryState {
+    /// This holds our search query while we're updating it
+    pub string: String,
+
+    /// When the debouncer timer elapses, we execute the search and mark
+    /// our state as searchd. This will make sure we don't try to search
+    /// again next frames
+    pub state: SearchState,
+
+    /// When was the input updated? We use this to debounce searches
+    pub debouncer: Debouncer,
+
+    /// The search results
+    pub notes: TimelineTab,
+}
+
+impl Default for SearchQueryState {
+    fn default() -> Self {
+        SearchQueryState::new()
+    }
+}
+
+impl SearchQueryState {
+    pub fn new() -> Self {
+        Self {
+            string: "".to_string(),
+            state: SearchState::New,
+            notes: TimelineTab::default(),
+            debouncer: Debouncer::new(Duration::from_millis(200)),
+        }
+    }
+
+    pub fn should_search(&self) -> bool {
+        self.state == SearchState::Typing && self.debouncer.should_act()
+    }
+
+    /// Mark the search as updated. This will update our debouncer and clear
+    /// the searched flag, enabling us to search again. This should be
+    /// called when the search box changes
+    pub fn mark_updated(&mut self) {
+        self.state = SearchState::Typing;
+        self.debouncer.bounce();
+    }
+
+    /// Call this when you are about to do a search so that we don't try
+    /// to search again next frame
+    pub fn mark_searched(&mut self, state: SearchState) {
+        self.state = state;
+    }
+}