fix(input list): don't leak ansi styling, fuzzy match indicator preserves styles (#16276)

- fixes #16200

# Description

|    | Select           | Fuzzy           |
| -- | ---------------- | --------------- |
| ❌ | ![select-before] | ![fuzzy-before] |
| ✅ | ![select-fixed]  | ![fuzzy-fixed]  |

[select-before]:
8fe9136472/select-before.svg
[select-fixed]:
8fe9136472/select-after.svg
[fuzzy-before]:
8fe9136472/fuzzy-before.svg
[fuzzy-fixed]:
8fe9136472/fuzzy-after.svg

Using a custom `dialoguer::theme::Theme` implementation, how `input
list` renders items are overridden.

Unfortunately, implementing one of the methods requires
`fuzzy_matcher::skim::SkimMatcherV2` which `dialoguer` does not export
by itself.
Had to add an explicit dependency to `fuzzy_matcher`, which we already
depend on through `dialoguer`. Version specification is copied from
`dialoguer`.

# Tests + Formatting
No tests added.
Couldn't find existing tests, not sure how to test this.

---------

Co-authored-by: Bahex <17417311+Bahex@users.noreply.github.com>

Cargo.lock

@@ -3778,6 +3778,7 @@ dependencies = [
  "fancy-regex",
  "filesize",
  "filetime",
+ "fuzzy-matcher",
  "getrandom 0.2.15",
  "human-date-parser",
  "indexmap",

Cargo.toml

@@ -83,6 +83,7 @@ csv = "1.3"
 ctrlc = "3.4"
 devicons = "0.6.12"
 dialoguer = { default-features = false, version = "0.11" }
+fuzzy-matcher = { version = "^0.3.7" }
 digest = { default-features = false, version = "0.10" }
 dirs = "5.0"
 dirs-sys = "0.4"

crates/nu-command/Cargo.toml

@@ -54,6 +54,7 @@ devicons = { workspace = true }
 dialoguer = { workspace = true, default-features = false, features = [
 	"fuzzy-select",
 ] }
+fuzzy-matcher = { workspace = true }
 digest = { workspace = true, default-features = false }
 dtparse = { workspace = true }
 encoding_rs = { workspace = true }

crates/nu-command/src/platform/input/list.rs

@@ -123,14 +123,8 @@ impl Command for InputList {
             });
         }
 
-        // could potentially be used to map the use theme colors at some point
-        // let theme = dialoguer::theme::ColorfulTheme {
-        //     active_item_style: Style::new().fg(Color::Cyan).bold(),
-        //     ..Default::default()
-        // };
-
         let answer: InteractMode = if multi {
-            let multi_select = MultiSelect::new(); //::with_theme(&theme);
+            let multi_select = MultiSelect::with_theme(&NuTheme);
 
             InteractMode::Multi(
                 if let Some(prompt) = prompt {
@@ -146,7 +140,7 @@ impl Command for InputList {
                 })?,
             )
         } else if fuzzy {
-            let fuzzy_select = FuzzySelect::new(); //::with_theme(&theme);
+            let fuzzy_select = FuzzySelect::with_theme(&NuTheme);
 
             InteractMode::Single(
                 if let Some(prompt) = prompt {
@@ -163,7 +157,7 @@ impl Command for InputList {
                 })?,
             )
         } else {
-            let select = Select::new(); //::with_theme(&theme);
+            let select = Select::with_theme(&NuTheme);
             InteractMode::Single(
                 if let Some(prompt) = prompt {
                     select.with_prompt(&prompt)
@@ -255,6 +249,84 @@ impl Command for InputList {
     }
 }
 
+use dialoguer::theme::{SimpleTheme, Theme};
+use nu_ansi_term::ansi::RESET;
+
+// could potentially be used to map the use theme colors at some point
+
+/// Theme for handling already colored items gracefully.
+struct NuTheme;
+
+impl Theme for NuTheme {
+    fn format_select_prompt_item(
+        &self,
+        f: &mut dyn std::fmt::Write,
+        text: &str,
+        active: bool,
+    ) -> std::fmt::Result {
+        SimpleTheme.format_select_prompt_item(f, text, active)?;
+        write!(f, "{RESET}")
+    }
+
+    fn format_multi_select_prompt_item(
+        &self,
+        f: &mut dyn std::fmt::Write,
+        text: &str,
+        checked: bool,
+        active: bool,
+    ) -> std::fmt::Result {
+        SimpleTheme.format_multi_select_prompt_item(f, text, checked, active)?;
+        write!(f, "{RESET}")
+    }
+
+    fn format_sort_prompt_item(
+        &self,
+        f: &mut dyn std::fmt::Write,
+        text: &str,
+        picked: bool,
+        active: bool,
+    ) -> std::fmt::Result {
+        SimpleTheme.format_sort_prompt_item(f, text, picked, active)?;
+        writeln!(f, "{RESET}")
+    }
+
+    fn format_fuzzy_select_prompt_item(
+        &self,
+        f: &mut dyn std::fmt::Write,
+        text: &str,
+        active: bool,
+        highlight_matches: bool,
+        matcher: &fuzzy_matcher::skim::SkimMatcherV2,
+        search_term: &str,
+    ) -> std::fmt::Result {
+        use fuzzy_matcher::FuzzyMatcher;
+        write!(f, "{} ", if active { ">" } else { " " })?;
+
+        if !highlight_matches {
+            return write!(f, "{text}{RESET}");
+        }
+        let Some((_score, indices)) = matcher.fuzzy_indices(text, search_term) else {
+            return write!(f, "{text}{RESET}");
+        };
+        let prefix = nu_ansi_term::Style::new()
+            .italic()
+            .underline()
+            .prefix()
+            .to_string();
+        // HACK: Reset italic and underline, from the `ansi` command, should be moved to `nu_ansi_term`
+        let suffix = "\x1b[23;24m";
+
+        for (idx, c) in text.chars().enumerate() {
+            if indices.contains(&idx) {
+                write!(f, "{prefix}{c}{suffix}")?;
+            } else {
+                write!(f, "{}", c)?;
+            }
+        }
+        write!(f, "{RESET}")
+    }
+}
+
 #[cfg(test)]
 mod test {
     use super::*;