feat(debug): highlight current line (#5957)

Add new theme highlight keys, for setting the colour of the breakpoint
character and the current line at which execution has been paused at.
The two new keys are `ui.highlight.frameline` and `ui.debug.breakpoint`.
Highlight according to those keys, both the line at which debugging
is paused at and the breakpoint indicator.

Add an indicator for the current line at which execution is paused
at, themed by the `ui.debug.active` theme scope. Update various themes
to showcase how the new functionality works.

Better icons are dependent on #2869, and as such will be handled in the
future, once it lands.

Closes: #5952

Signed-off-by: Filip Dutescu <filip.dutescu@gmail.com>

15 files changed, 98 insertions, 53 deletions

diff --git a/book/src/themes.md b/book/src/themes.md
index 7accb67f..56d0372c 100644
--- a/book/src/themes.md
+++ b/book/src/themes.md
@@ -278,8 +278,11 @@ These scopes are used for theming the editor interface:
 | `ui.cursor.primary.normal`        |                                                                                                |
 | `ui.cursor.primary.insert`        |                                                                                                |
 | `ui.cursor.primary.select`        |                                                                                                |
+| `ui.debug.breakpoint`             | Breakpoint indicator, found in the gutter                                                      |
+| `ui.debug.active`                 | Indicator for the line at which debugging execution is paused at, found in the gutter          |
 | `ui.gutter`                       | Gutter                                                                                         |
 | `ui.gutter.selected`              | Gutter for the line the cursor is on                                                           |
+| `ui.highlight.frameline`          | Line at which debugging execution is paused at                                                 |
 | `ui.linenr`                       | Line numbers                                                                                   |
 | `ui.linenr.selected`              | Line number for the line the cursor is on                                                      |
 | `ui.statusline`                   | Statusline                                                                                     |
diff --git a/helix-dap/src/client.rs b/helix-dap/src/client.rs
index ff727d00..7efb72d8 100644
--- a/helix-dap/src/client.rs
+++ b/helix-dap/src/client.rs
@@ -512,4 +512,10 @@ impl Client {
 
         self.call::<requests::SetExceptionBreakpoints>(args)
     }
+
+    pub fn current_stack_frame(&self) -> Option<&StackFrame> {
+        self.stack_frames
+            .get(&self.thread_id?)?
+            .get(self.active_frame?)
+    }
 }
diff --git a/helix-term/src/ui/editor.rs b/helix-term/src/ui/editor.rs
index 4cac0fa8..d4b141a0 100644
--- a/helix-term/src/ui/editor.rs
+++ b/helix-term/src/ui/editor.rs
@@ -93,40 +93,6 @@ impl EditorView {
         let mut line_decorations: Vec<Box<dyn LineDecoration>> = Vec::new();
         let mut translated_positions: Vec<TranslatedPosition> = Vec::new();
 
-        // DAP: Highlight current stack frame position
-        let stack_frame = editor.debugger.as_ref().and_then(|debugger| {
-            if let (Some(frame), Some(thread_id)) = (debugger.active_frame, debugger.thread_id) {
-                debugger
-                    .stack_frames
-                    .get(&thread_id)
-                    .and_then(|bt| bt.get(frame))
-            } else {
-                None
-            }
-        });
-        if let Some(frame) = stack_frame {
-            if doc.path().is_some()
-                && frame
-                    .source
-                    .as_ref()
-                    .and_then(|source| source.path.as_ref())
-                    == doc.path()
-            {
-                let line = frame.line - 1; // convert to 0-indexing
-                let style = theme.get("ui.highlight");
-                let line_decoration = move |renderer: &mut TextRenderer, pos: LinePos| {
-                    if pos.doc_line != line {
-                        return;
-                    }
-                    renderer
-                        .surface
-                        .set_style(Rect::new(area.x, pos.visual_line, area.width, 1), style);
-                };
-
-                line_decorations.push(Box::new(line_decoration));
-            }
-        }
-
         if is_focused && config.cursorline {
             line_decorations.push(Self::cursorline_decorator(doc, view, theme))
         }
@@ -135,6 +101,23 @@ impl EditorView {
             Self::highlight_cursorcolumn(doc, view, surface, theme, inner, &text_annotations);
         }
 
+        // Set DAP highlights, if needed.
+        if let Some(frame) = editor.current_stack_frame() {
+            let dap_line = frame.line.saturating_sub(1) as usize;
+            let style = theme.get("ui.highlight.frameline");
+            let line_decoration = move |renderer: &mut TextRenderer, pos: LinePos| {
+                if pos.doc_line != dap_line {
+                    return;
+                }
+                renderer.surface.set_style(
+                    Rect::new(inner.x, inner.y + pos.visual_line, inner.width, 1),
+                    style,
+                );
+            };
+
+            line_decorations.push(Box::new(line_decoration));
+        }
+
         let mut highlights =
             Self::doc_syntax_highlights(doc, view.offset.anchor, inner.height, theme);
         let overlay_highlights = Self::overlay_syntax_highlights(
@@ -422,6 +405,7 @@ impl EditorView {
         let primary_selection_scope = theme
             .find_scope_index_exact("ui.selection.primary")
             .unwrap_or(selection_scope);
+
         let base_cursor_scope = theme
             .find_scope_index_exact("ui.cursor")
             .unwrap_or(selection_scope);
diff --git a/helix-view/src/editor.rs b/helix-view/src/editor.rs
index ee535b5c..c939aa5c 100644
--- a/helix-view/src/editor.rs
+++ b/helix-view/src/editor.rs
@@ -10,6 +10,7 @@ use crate::{
     view::ViewPosition,
     Align, Document, DocumentId, View, ViewId,
 };
+use dap::StackFrame;
 use helix_vcs::DiffProviderRegistry;
 
 use futures_util::stream::select_all::SelectAll;
@@ -1652,6 +1653,12 @@ impl Editor {
             doc.restore_cursor = false;
         }
     }
+
+    pub fn current_stack_frame(&self) -> Option<&StackFrame> {
+        self.debugger
+            .as_ref()
+            .and_then(|debugger| debugger.current_stack_frame())
+    }
 }
 
 fn try_restore_indent(doc: &mut Document, view: &mut View) {
diff --git a/helix-view/src/gutter.rs b/helix-view/src/gutter.rs
index 36e8e16a..3ecae919 100644
--- a/helix-view/src/gutter.rs
+++ b/helix-view/src/gutter.rs
@@ -2,7 +2,7 @@ use std::fmt::Write;
 
 use crate::{
     editor::GutterType,
-    graphics::{Color, Style, UnderlineStyle},
+    graphics::{Style, UnderlineStyle},
     Document, Editor, Theme, View,
 };
 
@@ -245,9 +245,9 @@ pub fn breakpoints<'doc>(
     theme: &Theme,
     _is_focused: bool,
 ) -> GutterFn<'doc> {
-    let warning = theme.get("warning");
     let error = theme.get("error");
     let info = theme.get("info");
+    let breakpoint_style = theme.get("ui.debug.breakpoint");
 
     let breakpoints = doc.path().and_then(|path| editor.breakpoints.get(path));
 
@@ -265,30 +265,52 @@ pub fn breakpoints<'doc>(
                 .iter()
                 .find(|breakpoint| breakpoint.line == line)?;
 
-            let mut style = if breakpoint.condition.is_some() && breakpoint.log_message.is_some() {
+            let style = if breakpoint.condition.is_some() && breakpoint.log_message.is_some() {
                 error.underline_style(UnderlineStyle::Line)
             } else if breakpoint.condition.is_some() {
                 error
             } else if breakpoint.log_message.is_some() {
                 info
             } else {
-                warning
+                breakpoint_style
             };
 
-            if !breakpoint.verified {
-                // Faded colors
-                style = if let Some(Color::Rgb(r, g, b)) = style.fg {
-                    style.fg(Color::Rgb(
-                        ((r as f32) * 0.4).floor() as u8,
-                        ((g as f32) * 0.4).floor() as u8,
-                        ((b as f32) * 0.4).floor() as u8,
-                    ))
-                } else {
-                    style.fg(Color::Gray)
-                }
-            };
+            let sym = if breakpoint.verified { "●" } else { "◯" };
+            write!(out, "{}", sym).unwrap();
+            Some(style)
+        },
+    )
+}
+
+fn execution_pause_indicator<'doc>(
+    editor: &'doc Editor,
+    doc: &'doc Document,
+    theme: &Theme,
+    is_focused: bool,
+) -> GutterFn<'doc> {
+    let style = theme.get("ui.debug.active");
+    let current_stack_frame = editor.current_stack_frame();
+    let frame_line = current_stack_frame.map(|frame| frame.line - 1);
+    let frame_source_path = current_stack_frame.map(|frame| {
+        frame
+            .source
+            .as_ref()
+            .and_then(|source| source.path.as_ref())
+    });
+    let should_display_for_current_doc =
+        doc.path().is_some() && frame_source_path.unwrap_or(None) == doc.path();
+
+    Box::new(
+        move |line: usize, _selected: bool, first_visual_line: bool, out: &mut String| {
+            if !first_visual_line
+                || !is_focused
+                || line != frame_line?
+                || !should_display_for_current_doc
+            {
+                return None;
+            }
 
-            let sym = if breakpoint.verified { "▲" } else { "⊚" };
+            let sym = "▶";
             write!(out, "{}", sym).unwrap();
             Some(style)
         },
@@ -304,9 +326,11 @@ pub fn diagnostics_or_breakpoints<'doc>(
 ) -> GutterFn<'doc> {
     let mut diagnostics = diagnostic(editor, doc, view, theme, is_focused);
     let mut breakpoints = breakpoints(editor, doc, view, theme, is_focused);
+    let mut execution_pause_indicator = execution_pause_indicator(editor, doc, theme, is_focused);
 
     Box::new(move |line, selected, first_visual_line: bool, out| {
-        breakpoints(line, selected, first_visual_line, out)
+        execution_pause_indicator(line, selected, first_visual_line, out)
+            .or_else(|| breakpoints(line, selected, first_visual_line, out))
             .or_else(|| diagnostics(line, selected, first_visual_line, out))
     })
 }
diff --git a/runtime/themes/acme.toml b/runtime/themes/acme.toml
index e1d66ff8..65092474 100644
--- a/runtime/themes/acme.toml
+++ b/runtime/themes/acme.toml
@@ -12,6 +12,8 @@
 "ui.virtual.ruler" = { bg = "acme_bar_bg" }
 "ui.cursor.match" = {bg="acme_bar_bg"}
 "ui.cursor" = {bg="cursor", fg="white"}
+"ui.debug" = {fg="orange"}
+"ui.highlight.frameline" = {bg="#da8581"}
 "string" = "red"
 "comment" = "green"
 "ui.help" = {fg="black", bg="acme_bg"}
diff --git a/runtime/themes/autumn.toml b/runtime/themes/autumn.toml
index 1430e0a8..4474b0d4 100644
--- a/runtime/themes/autumn.toml
+++ b/runtime/themes/autumn.toml
@@ -26,6 +26,8 @@
 "ui.cursor.primary" = { fg = "my_white", modifiers = ["reversed"] }
 "ui.cursorline.primary" = { bg = "my_black" }
 "ui.cursorline.secondary" = { bg = "my_black" }
+"ui.highlight.frameline" = { bg = "#8b6904" }
+"ui.debug" = { fg = "my_yellow1", bg = "my_gray0" }
 "ui.text" = "my_white"
 "operator" = "my_white"
 "ui.text.focus" = "my_white"
diff --git a/runtime/themes/ayu_dark.toml b/runtime/themes/ayu_dark.toml
index 37060a24..211d423f 100644
--- a/runtime/themes/ayu_dark.toml
+++ b/runtime/themes/ayu_dark.toml
@@ -61,6 +61,8 @@
 "diagnostic.error"= { underline = { color = "red", style="curl"} }
 "ui.bufferline" = { fg = "gray", bg = "background" }
 "ui.bufferline.active" = { fg = "foreground", bg = "dark_gray" }
+"ui.debug" = { fg = "orange", bg = "background" }
+"ui.highlight.frameline" = { bg = "#0067a3" }
 
 "special" = "orange"
 
diff --git a/runtime/themes/ayu_light.toml b/runtime/themes/ayu_light.toml
index 58b25484..4b0ba1db 100644
--- a/runtime/themes/ayu_light.toml
+++ b/runtime/themes/ayu_light.toml
@@ -61,6 +61,8 @@
 "diagnostic.error"= { underline = { color = "red", style = "curl" } }
 "ui.bufferline" = { fg = "gray", bg = "background" }
 "ui.bufferline.active" = { fg = "foreground", bg = "dark_gray" }
+"ui.debug" = { fg = "orange", bg = "background" }
+"ui.highlight.frameline" = { bg = "#cfe0f2" }
 
 "special" = "orange"
 
diff --git a/runtime/themes/ayu_mirage.toml b/runtime/themes/ayu_mirage.toml
index 4c1f8fa6..5afe0acd 100644
--- a/runtime/themes/ayu_mirage.toml
+++ b/runtime/themes/ayu_mirage.toml
@@ -61,6 +61,8 @@
 "diagnostic.error"= { underline = { color = "red", style = "curl" } }
 "ui.bufferline" = { fg = "gray", bg = "background" }
 "ui.bufferline.active" = { fg = "foreground", bg = "dark_gray" }
+"ui.debug" = { fg = "orange", bg = "background" }
+"ui.highlight.frameline" = { bg = "#0067a3" }
 
 "special" = "orange"
 
diff --git a/runtime/themes/dracula.toml b/runtime/themes/dracula.toml
index 8bde4708..b08357db 100644
--- a/runtime/themes/dracula.toml
+++ b/runtime/themes/dracula.toml
@@ -25,6 +25,8 @@
 "ui.cursor.primary" = { fg = "background", bg = "cyan", modifiers = ["dim"] }
 "ui.cursorline.primary" = { bg = "background_dark" }
 "ui.help" = { fg = "foreground", bg = "background_dark" }
+"ui.debug" = { fg = "red" }
+"ui.highlight.frameline" = { fg = "black", bg = "red" }
 "ui.linenr" = { fg = "comment" }
 "ui.linenr.selected" = { fg = "foreground" }
 "ui.menu" = { fg = "foreground", bg = "background_dark" }
diff --git a/runtime/themes/dracula_at_night.toml b/runtime/themes/dracula_at_night.toml
index 9f10ec90..b2e3b9a9 100644
--- a/runtime/themes/dracula_at_night.toml
+++ b/runtime/themes/dracula_at_night.toml
@@ -25,6 +25,8 @@
 "ui.cursor.match" = { fg = "green", modifiers = ["underlined"] }
 "ui.cursor.primary" = { fg = "background", bg = "cyan", modifiers = ["dim"] }
 "ui.help" = { fg = "foreground", bg = "background_dark" }
+"ui.debug" = { fg = "red" }
+"ui.highlight.frameline" = { fg = "black", bg = "red" }
 "ui.linenr" = { fg = "comment" }
 "ui.linenr.selected" = { fg = "foreground" }
 "ui.menu" = { fg = "foreground", bg = "background_dark" }
diff --git a/runtime/themes/onedark.toml b/runtime/themes/onedark.toml
index 81ca0463..6df5f797 100644
--- a/runtime/themes/onedark.toml
+++ b/runtime/themes/onedark.toml
@@ -64,6 +64,7 @@
 "ui.cursorline.primary" = { bg = "light-black" }
 
 "ui.highlight" = { bg = "gray" }
+"ui.highlight.frameline" = { bg = "#97202a" }
 
 "ui.linenr" = { fg = "linenr" }
 "ui.linenr.selected" = { fg = "white" }
@@ -84,6 +85,8 @@
 "ui.menu.selected" = { fg = "black", bg = "blue" }
 "ui.menu.scroll" = { fg = "white", bg = "light-gray" }
 
+"ui.debug" = { fg = "red" }
+
 [palette]
 
 yellow = "#E5C07B"
diff --git a/runtime/themes/onedarker.toml b/runtime/themes/onedarker.toml
index 33f900cc..7169fd02 100644
--- a/runtime/themes/onedarker.toml
+++ b/runtime/themes/onedarker.toml
@@ -78,6 +78,8 @@
 "ui.text.focus" = { fg = "white", bg = "light-black", modifiers = ["bold"] }
 
 "ui.help" = { fg = "white", bg = "gray" }
+"ui.debug" = { fg = "red" }
+"ui.highlight.frameline" = { bg = "#97202a" }
 "ui.popup" = { bg = "gray" }
 "ui.window" = { fg = "gray" }
 "ui.menu" = { fg = "white", bg = "gray" }
diff --git a/theme.toml b/theme.toml
index b67eaecc..dd1a5d88 100644
--- a/theme.toml
+++ b/theme.toml
@@ -69,7 +69,9 @@ label = "honey"
 "ui.cursor" = { modifiers = ["reversed"] }
 "ui.cursorline.primary" = { bg = "bossanova" }
 "ui.highlight" = { bg = "bossanova" }
-
+"ui.highlight.frameline" = { bg = "#634450" }
+"ui.debug" = { fg = "#634450" }
+"ui.debug.breakpoint" = { fg = "apricot" }
 "ui.menu" = { fg = "lavender", bg = "revolver" }
 "ui.menu.selected" = { fg = "revolver", bg = "white" }
 "ui.menu.scroll" = { fg = "lavender", bg = "comet" }