From 99e7d3895a977451f63d9123a83d7bdfc3be4126 Mon Sep 17 00:00:00 2001
From: Patrick Auernig <patrick.auernig@mykolab.com>
Date: Thu, 28 Nov 2024 00:33:38 +0100
Subject: [PATCH] feat(tui): Implement fuzzy searching

---
 src/tui.rs | 59 +++++++++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 54 insertions(+), 5 deletions(-)

diff --git a/src/tui.rs b/src/tui.rs
index 1077a7d..77baeca 100644
--- a/src/tui.rs
+++ b/src/tui.rs
@@ -7,6 +7,7 @@ use ratatui::layout::{Constraint, Layout, Rect};
 use ratatui::style::{Color, Style};
 use ratatui::widgets::{Block, Borders, Cell, Paragraph, Row, Table, TableState};
 use ratatui::Frame;
+use tracing::trace;
 use tui_input::{Input, InputRequest};
 
 use crate::state::{clear_selected_project_file, write_selected_project_file};
@@ -61,6 +62,7 @@ impl State {
 }
 
 
+#[tracing::instrument(skip_all)]
 pub fn run(projects: Projects) -> Result<()> {
     clear_selected_project_file()?;
 
@@ -115,7 +117,6 @@ fn handle_key_event(state: &mut State, tx: &mut mpsc::Sender<Message>, event: Ke
             state.search.handle(InputRequest::DeletePrevChar);
             Message::SearchUpdate
         }
-
         (_, _, KeyCode::Enter) => Message::Confirm,
 
         _ => Message::Noop,
@@ -224,11 +225,13 @@ fn draw_list(state: &mut State, frame: &mut Frame, area: Rect) {
 
             let search_value = state.search.value();
 
-            if path_str.contains(search_value) {
-                Some(path_str.to_string())
-            } else {
-                None
+            if search_value.is_empty() {
+                return Some(path_str.to_string());
             }
+
+            let indices = fuzzy_search(search_value, path_str)?;
+            trace!(?search_value, ?path_str, ?indices);
+            Some(path_str.to_string())
         })
         .collect();
 
@@ -245,3 +248,49 @@ fn draw_list(state: &mut State, frame: &mut Frame, area: Rect) {
 
     frame.render_stateful_widget(table, area, &mut state.project_table);
 }
+
+
+fn fuzzy_search(search: &str, text: &str) -> Option<Vec<usize>> {
+    let mut found_indices = Vec::new();
+    let mut start_idx = 0;
+
+    for ch in search.chars() {
+        let remaining = &text[start_idx..];
+
+        let mut found = false;
+
+        for (byte_idx, txt_ch) in remaining.char_indices() {
+            if ch == txt_ch {
+                found_indices.push(start_idx + byte_idx);
+                start_idx += byte_idx + txt_ch.len_utf8();
+                found = true;
+                break;
+            }
+        }
+
+        if !found {
+            return None;
+        }
+    }
+
+    if search.is_empty() {
+        None
+    } else {
+        Some(found_indices)
+    }
+}
+
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn fuzzy_test() {
+        assert_eq!(fuzzy_search("st", "st"), Some(vec![0, 1]));
+        assert_eq!(fuzzy_search("st", "some text"), Some(vec![0, 5]));
+        assert_eq!(fuzzy_search("st", "nothing"), None);
+        assert_eq!(fuzzy_search("st", ""), None);
+        assert_eq!(fuzzy_search("", "nonempty"), None);
+    }
+}