From c5c55978794036437402febea8b259f9e544f615 Mon Sep 17 00:00:00 2001
From: Michael Davis <mcarsondavis@gmail.com>
Date: Thu, 4 Apr 2024 12:26:39 -0400
Subject: [PATCH] Reset all changes overlapped by primary sel in
 ':reset-diff-change'

This is useful for resetting multiple changes at once. For example you
might use 'maf' or even '%' to select a larger region and reset all
changes within.

The original behavior of resetting the change on the current line is
retained when the primary selection is 1-width since we look for chunks
in the line range of the primary selection.
---
 helix-term/src/commands/typed.rs | 46 ++++++++++++++++----------------
 helix-vcs/src/diff.rs            | 18 +++++++++++++
 2 files changed, 41 insertions(+), 23 deletions(-)

diff --git a/helix-term/src/commands/typed.rs b/helix-term/src/commands/typed.rs
index 5d7057da6b39b..92c4ce1b22bbc 100644
--- a/helix-term/src/commands/typed.rs
+++ b/helix-term/src/commands/typed.rs
@@ -2304,37 +2304,37 @@ fn reset_diff_change(
 
     let diff = handle.load();
     let doc_text = doc.text().slice(..);
-    let line = doc.selection(view.id).primary().cursor_line(doc_text);
-
-    let Some(hunk_idx) = diff.hunk_at(line as u32, true) else {
-        bail!("There is no change at the cursor")
-    };
-    let hunk = diff.nth_hunk(hunk_idx);
+    let (start_line, end_line) = doc.selection(view.id).primary().line_range(doc_text);
     let diff_base = diff.diff_base();
-    let before_start = diff_base.line_to_char(hunk.before.start as usize);
-    let before_end = diff_base.line_to_char(hunk.before.end as usize);
-    let text: Tendril = diff
-        .diff_base()
-        .slice(before_start..before_end)
-        .chunks()
-        .collect();
-    let anchor = doc_text.line_to_char(hunk.after.start as usize);
+    let mut changes = 0;
+
     let transaction = Transaction::change(
         doc.text(),
-        [(
-            anchor,
-            doc_text.line_to_char(hunk.after.end as usize),
-            (!text.is_empty()).then_some(text),
-        )]
-        .into_iter(),
+        diff.hunks_in_range(start_line as u32, end_line as u32)
+            .map(|hunk| {
+                changes += 1;
+                let start = diff_base.line_to_char(hunk.before.start as usize);
+                let end = diff_base.line_to_char(hunk.before.end as usize);
+                let text: Tendril = diff_base.slice(start..end).chunks().collect();
+                (
+                    doc_text.line_to_char(hunk.after.start as usize),
+                    doc_text.line_to_char(hunk.after.end as usize),
+                    Some(text).filter(|t| !t.is_empty()),
+                )
+            }),
     );
+    if changes == 0 {
+        bail!("There is no change under the primary selection");
+    }
+
     drop(diff); // make borrow check happy
     doc.apply(&transaction, view.id);
-    // select inserted text
-    let text_len = before_end - before_start;
-    doc.set_selection(view.id, Selection::single(anchor, anchor + text_len));
     doc.append_changes_to_history(view);
     view.ensure_cursor_in_view(doc, scrolloff);
+    cx.editor.set_status(format!(
+        "Reset {changes} change{}",
+        if changes == 1 { "" } else { "s" }
+    ));
     Ok(())
 }
 
diff --git a/helix-vcs/src/diff.rs b/helix-vcs/src/diff.rs
index c72deb7ea7f37..eee77b8b33685 100644
--- a/helix-vcs/src/diff.rs
+++ b/helix-vcs/src/diff.rs
@@ -259,6 +259,24 @@ impl Diff<'_> {
         }
     }
 
+    /// Iterates over all hunks that overlap with the given line range.
+    pub fn hunks_in_range(&self, start_line: u32, end_line: u32) -> impl Iterator<Item = &Hunk> {
+        let hunk_range = if self.inverted {
+            |hunk: &Hunk| hunk.before.clone()
+        } else {
+            |hunk: &Hunk| hunk.after.clone()
+        };
+
+        let first = self
+            .diff
+            .hunks
+            .partition_point(|hunk| hunk_range(hunk).end < start_line);
+
+        self.diff.hunks[first..]
+            .iter()
+            .take_while(move |hunk| hunk_range(hunk).start <= end_line)
+    }
+
     pub fn hunk_at(&self, line: u32, include_removal: bool) -> Option<u32> {
         let hunk_range = if self.inverted {
             |hunk: &Hunk| hunk.before.clone()