From 87e3cd3df283a6da055488bbea60637713bd1f35 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bla=C5=BE=20Hrastnik?= <blaz@mxxn.io>
Date: Mon, 15 Mar 2021 16:19:31 +0900
Subject: [PATCH] ui: Render diagnostic errors in sideline.

---
 helix-core/src/diagnostic.rs  |  8 +++--
 helix-lsp/src/lib.rs          |  2 +-
 helix-term/src/application.rs |  7 +++--
 helix-term/src/ui/editor.rs   | 59 ++++++++++++++++++++++++++++++++++-
 4 files changed, 69 insertions(+), 7 deletions(-)

diff --git a/helix-core/src/diagnostic.rs b/helix-core/src/diagnostic.rs
index c1a3b4c10..5056c26aa 100644
--- a/helix-core/src/diagnostic.rs
+++ b/helix-core/src/diagnostic.rs
@@ -1,5 +1,3 @@
-use crate::Range;
-
 pub enum Severity {
     Error,
     Warning,
@@ -7,8 +5,12 @@ pub enum Severity {
     Hint,
 }
 
+pub struct Range {
+    pub start: usize,
+    pub end: usize,
+}
 pub struct Diagnostic {
-    pub range: (usize, usize),
+    pub range: Range,
     pub line: usize,
     pub message: String,
     pub severity: Option<Severity>,
diff --git a/helix-lsp/src/lib.rs b/helix-lsp/src/lib.rs
index 0d04b7111..3e4f55ea8 100644
--- a/helix-lsp/src/lib.rs
+++ b/helix-lsp/src/lib.rs
@@ -35,7 +35,7 @@ pub mod util {
     pub fn lsp_pos_to_pos(doc: RopeSlice, pos: lsp::Position) -> usize {
         let line = doc.line_to_char(pos.line as usize);
         let line_start = doc.char_to_utf16_cu(line);
-        doc.utf16_cu_to_char(pos.character as usize + line_start)
+        doc.utf16_cu_to_char(line_start + pos.character as usize)
     }
     pub fn pos_to_lsp_pos(doc: RopeSlice, pos: usize) -> lsp::Position {
         let line = doc.char_to_line(pos);
diff --git a/helix-term/src/application.rs b/helix-term/src/application.rs
index 24b5317bc..c22cf9967 100644
--- a/helix-term/src/application.rs
+++ b/helix-term/src/application.rs
@@ -140,14 +140,17 @@ pub async fn handle_language_server_message(&mut self, call: Option<helix_lsp::C
                                 .into_iter()
                                 .map(|diagnostic| {
                                     use helix_core::diagnostic::Severity::*;
-                                    use helix_core::{diagnostic::Severity, Diagnostic};
+                                    use helix_core::{
+                                        diagnostic::{Range, Severity},
+                                        Diagnostic,
+                                    };
                                     use helix_lsp::{lsp, util::lsp_pos_to_pos};
                                     use lsp::DiagnosticSeverity;
                                     let start = lsp_pos_to_pos(doc, diagnostic.range.start);
                                     let end = lsp_pos_to_pos(doc, diagnostic.range.end);
 
                                     Diagnostic {
-                                        range: (start, end),
+                                        range: Range { start, end },
                                         line: diagnostic.range.start.line as usize,
                                         message: diagnostic.message,
                                         severity: diagnostic.severity.map(
diff --git a/helix-term/src/ui/editor.rs b/helix-term/src/ui/editor.rs
index abdbb7a33..fe4e3439a 100644
--- a/helix-term/src/ui/editor.rs
+++ b/helix-term/src/ui/editor.rs
@@ -56,6 +56,8 @@ pub fn render_view(
         // TODO: this seems to prevent setting style later
         // surface.set_style(viewport, theme.get("ui.background"));
 
+        self.render_diagnostics(&view.doc, area, surface, theme, is_focused);
+
         let area = Rect::new(
             viewport.x,
             viewport.y + viewport.height.saturating_sub(1),
@@ -166,7 +168,8 @@ pub fn render_buffer(
 
                             // ugh,interleave highlight spans with diagnostic spans
                             let is_diagnostic = view.doc.diagnostics.iter().any(|diagnostic| {
-                                diagnostic.range.0 <= char_index && diagnostic.range.1 > char_index
+                                diagnostic.range.start <= char_index
+                                    && diagnostic.range.end > char_index
                             });
 
                             let style = if is_diagnostic {
@@ -316,6 +319,60 @@ pub fn render_buffer(
         }
     }
 
+    pub fn render_diagnostics(
+        &self,
+        doc: &Document,
+        viewport: Rect,
+        surface: &mut Surface,
+        theme: &Theme,
+        is_focused: bool,
+    ) {
+        use helix_core::diagnostic::Severity;
+        use tui::{
+            layout::Alignment,
+            text::Text,
+            widgets::{Paragraph, Widget},
+        };
+
+        let cursor = doc.selection().cursor();
+        let line = doc.text().char_to_line(cursor);
+
+        let diagnostics = doc.diagnostics.iter().filter(|diagnostic| {
+            diagnostic.range.start <= cursor && diagnostic.range.end >= cursor
+        });
+
+        let warning: Style = theme.get("warning");
+        let error: Style = theme.get("error");
+        let info: Style = theme.get("info");
+        let hint: Style = theme.get("hint");
+
+        // Vec::with_capacity(diagnostics.len()); // rough estimate
+        let mut lines = Vec::new();
+        for diagnostic in diagnostics {
+            let text = Text::styled(
+                &diagnostic.message,
+                match diagnostic.severity {
+                    Some(Severity::Error) => error,
+                    Some(Severity::Warning) | None => warning,
+                    Some(Severity::Info) => info,
+                    Some(Severity::Hint) => hint,
+                },
+            );
+            lines.extend(text.lines);
+        }
+
+        let paragraph = Paragraph::new(lines).alignment(Alignment::Right);
+        paragraph.render(
+            Rect::new(
+                viewport.x + viewport.width - 80 - 1,
+                viewport.y as u16 + 1,
+                80,
+                15,
+            ),
+            surface,
+        );
+    }
+
     pub fn render_statusline(
         &self,
         doc: &Document,