From 5945815d978da07d0970502d481c17ef02525c4d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bla=C5=BE=20Hrastnik?= <blaz@mxxn.io>
Date: Thu, 1 Oct 2020 18:44:12 +0900
Subject: [PATCH] Fix cursor rendering & placement on append mode.

---
 helix-core/src/state.rs    |  3 +++
 helix-term/src/editor.rs   | 12 +++++++++++-
 helix-view/src/commands.rs | 15 ++++++++++++++-
 3 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/helix-core/src/state.rs b/helix-core/src/state.rs
index c17e9c90..36ca221c 100644
--- a/helix-core/src/state.rs
+++ b/helix-core/src/state.rs
@@ -20,6 +20,8 @@ pub struct State {
     pub selection: Selection,
     pub mode: Mode,
 
+    pub restore_cursor: bool,
+
     //
     pub syntax: Option<Syntax>,
 }
@@ -46,6 +48,7 @@ impl State {
             selection: Selection::single(0, 0),
             mode: Mode::Normal,
             syntax: None,
+            restore_cursor: false,
         }
     }
 
diff --git a/helix-term/src/editor.rs b/helix-term/src/editor.rs
index 23ecbea9..a3bc8b3b 100644
--- a/helix-term/src/editor.rs
+++ b/helix-term/src/editor.rs
@@ -127,7 +127,7 @@ impl Editor {
                     .ranges()
                     .iter()
                     // TODO: limit selection to one in viewport
-                    .filter(|range| !range.is_empty()) // && range.overlaps(&Range::new(start, end + 1))
+                    // .filter(|range| !range.is_empty()) // && range.overlaps(&Range::new(start, end + 1))
                     .copied()
                     .collect();
 
@@ -178,6 +178,7 @@ impl Editor {
                                     let grapheme = Cow::from(grapheme);
                                     let width = grapheme_width(&grapheme) as u16;
 
+                                    // TODO: this should really happen as an after pass
                                     let style = if visible_selections
                                         .iter()
                                         .any(|range| range.contains(char_index))
@@ -188,6 +189,15 @@ impl Editor {
                                         style
                                     };
 
+                                    let style = if visible_selections
+                                        .iter()
+                                        .any(|range| range.head == char_index)
+                                    {
+                                        style.clone().bg(Color::Rgb(255, 255, 255))
+                                    } else {
+                                        style
+                                    };
+
                                     // TODO: paint cursor heads except primary
 
                                     self.surface.set_string(
diff --git a/helix-view/src/commands.rs b/helix-view/src/commands.rs
index 2b2f1239..93ec2632 100644
--- a/helix-view/src/commands.rs
+++ b/helix-view/src/commands.rs
@@ -186,6 +186,7 @@ pub fn insert_mode(view: &mut View, _count: usize) {
 // inserts at the end of each selection
 pub fn append_mode(view: &mut View, _count: usize) {
     view.state.mode = Mode::Insert;
+    view.state.restore_cursor = true;
 
     // TODO: as transaction
     let text = &view.state.doc.slice(..);
@@ -268,8 +269,20 @@ pub fn open_below(view: &mut View, _count: usize) {
 // O inserts a new line before each line with a selection
 
 pub fn normal_mode(view: &mut View, _count: usize) {
-    // TODO: if leaving append mode, move cursor back by 1
     view.state.mode = Mode::Normal;
+
+    // if leaving append mode, move cursor back by 1
+    if view.state.restore_cursor {
+        let text = &view.state.doc.slice(..);
+        view.state.selection = view.state.selection.transform(|range| {
+            Range::new(
+                range.from(),
+                graphemes::prev_grapheme_boundary(text, range.to()),
+            )
+        });
+
+        view.state.restore_cursor = false;
+    }
 }
 
 // TODO: insert means add text just before cursor, on exit we should be on the last letter.