From bb3e6998e641f25f3f73d0805522b451c18ac633 Mon Sep 17 00:00:00 2001
From: woojiq <122799969+woojiq@users.noreply.github.com>
Date: Mon, 4 Sep 2023 00:12:38 +0300
Subject: [PATCH] Fix find commands for buffers with non-LF line-endings
 (#8111)

---
 helix-term/src/commands.rs        | 69 +++++++++++++++++++++++++++----
 helix-term/tests/test/movement.rs | 39 +++++++++++++++++
 2 files changed, 101 insertions(+), 7 deletions(-)

diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index 31ea75814..6e3fb9397 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -1251,6 +1251,65 @@ fn extend_next_long_word_end(cx: &mut Context) {
     extend_word_impl(cx, movement::move_next_long_word_end)
 }
 
+/// Separate branch to find_char designed only for <ret> char.
+//
+// This is necessary because the one document can have different line endings inside. And we
+// cannot predict what character to find when <ret> is pressed. On the current line it can be `lf`
+// but on the next line it can be `crlf`. That's why [`find_char_impl`] cannot be applied here.
+fn find_char_line_ending(
+    cx: &mut Context,
+    count: usize,
+    direction: Direction,
+    inclusive: bool,
+    extend: bool,
+) {
+    let (view, doc) = current!(cx.editor);
+    let text = doc.text().slice(..);
+
+    let selection = doc.selection(view.id).clone().transform(|range| {
+        let cursor = range.cursor(text);
+        let cursor_line = range.cursor_line(text);
+
+        // Finding the line where we're going to find <ret>. Depends mostly on
+        // `count`, but also takes into account edge cases where we're already at the end
+        // of a line or the beginning of a line
+        let find_on_line = match direction {
+            Direction::Forward => {
+                let on_edge = line_end_char_index(&text, cursor_line) == cursor;
+                let line = cursor_line + count - 1 + (on_edge as usize);
+                if line >= text.len_lines() - 1 {
+                    return range;
+                } else {
+                    line
+                }
+            }
+            Direction::Backward => {
+                let on_edge = text.line_to_char(cursor_line) == cursor && !inclusive;
+                let line = cursor_line as isize - (count as isize - 1 + on_edge as isize);
+                if line <= 0 {
+                    return range;
+                } else {
+                    line as usize
+                }
+            }
+        };
+
+        let pos = match (direction, inclusive) {
+            (Direction::Forward, true) => line_end_char_index(&text, find_on_line),
+            (Direction::Forward, false) => line_end_char_index(&text, find_on_line) - 1,
+            (Direction::Backward, true) => line_end_char_index(&text, find_on_line - 1),
+            (Direction::Backward, false) => text.line_to_char(find_on_line),
+        };
+
+        if extend {
+            range.put_cursor(text, pos, true)
+        } else {
+            Range::point(range.cursor(text)).put_cursor(text, pos, true)
+        }
+    });
+    doc.set_selection(view.id, selection);
+}
+
 fn find_char(cx: &mut Context, direction: Direction, inclusive: bool, extend: bool) {
     // TODO: count is reset to 1 before next key so we move it into the closure here.
     // Would be nice to carry over.
@@ -1264,13 +1323,9 @@ fn find_char(cx: &mut Context, direction: Direction, inclusive: bool, extend: bo
             KeyEvent {
                 code: KeyCode::Enter,
                 ..
-            } =>
-            // TODO: this isn't quite correct when CRLF is involved.
-            // This hack will work in most cases, since documents don't
-            // usually mix line endings.  But we should fix it eventually
-            // anyway.
-            {
-                doc!(cx.editor).line_ending.as_str().chars().next().unwrap()
+            } => {
+                find_char_line_ending(cx, count, direction, inclusive, extend);
+                return;
             }
 
             KeyEvent {
diff --git a/helix-term/tests/test/movement.rs b/helix-term/tests/test/movement.rs
index 9a48cdbcb..e3c2668da 100644
--- a/helix-term/tests/test/movement.rs
+++ b/helix-term/tests/test/movement.rs
@@ -513,3 +513,42 @@ async fn select_mode_tree_sitter_prev_function_goes_backwards_to_object() -> any
 
     Ok(())
 }
+
+#[tokio::test(flavor = "multi_thread")]
+async fn find_char_line_ending() -> anyhow::Result<()> {
+    test((
+        helpers::platform_line(indoc! {
+            "\
+            one
+            #[|t]#wo
+            three"
+        }),
+        "T<ret>gll2f<ret>",
+        helpers::platform_line(indoc! {
+            "\
+            one
+            two#[
+            |]#three"
+        }),
+    ))
+    .await?;
+
+    test((
+        helpers::platform_line(indoc! {
+            "\
+            #[|o]#ne
+            two
+            three"
+        }),
+        "f<ret>2t<ret>ghT<ret>F<ret>",
+        helpers::platform_line(indoc! {
+            "\
+            one#[|
+            t]#wo
+            three"
+        }),
+    ))
+    .await?;
+
+    Ok(())
+}