From 9133ab55d05669b46e2e7002f23ad42bccb9ae12 Mon Sep 17 00:00:00 2001
From: "Luke I. Wilson" <thelukaswils@gmail.com>
Date: Wed, 24 Mar 2021 11:40:18 -0500
Subject: [PATCH] Bounds check delete regions in rope buffer

---
 ui/buffer/rope.go      | 12 +++++++++++-
 ui/buffer/rope_test.go | 19 ++++++++++++++++---
 ui/textedit.go         |  1 +
 3 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/ui/buffer/rope.go b/ui/buffer/rope.go
index f8855ce..9d9a2f2 100644
--- a/ui/buffer/rope.go
+++ b/ui/buffer/rope.go
@@ -114,7 +114,17 @@ func (b *RopeBuffer) Insert(line, col int, value []byte) {
 // Remove deletes any characters between startLine, startCol, and endLine,
 // endCol, inclusive bounds.
 func (b *RopeBuffer) Remove(startLine, startCol, endLine, endCol int) {
-	(*rope.Node)(b).Remove(b.pos(startLine, startCol), b.pos(endLine, endCol)+1)
+	start := b.pos(startLine, startCol)
+	end := b.pos(endLine, endCol) + 1
+
+	if len := (*rope.Node)(b).Len(); end >= len {
+		end = len
+		if start > end {
+			start = end
+		}
+	}
+
+	(*rope.Node)(b).Remove(start, end)
 }
 
 // Returns the number of occurrences of 'sequence' in the buffer, within the range
diff --git a/ui/buffer/rope_test.go b/ui/buffer/rope_test.go
index 0b3d46c..5a8e14b 100644
--- a/ui/buffer/rope_test.go
+++ b/ui/buffer/rope_test.go
@@ -4,16 +4,29 @@ import "testing"
 
 func TestRopeInserting(t *testing.T) {
 	var buf Buffer = NewRopeBuffer([]byte("some"))
-	buf.Insert(0, 4, []byte(" text")) // Insert " text" after "some"
+	buf.Insert(0, 4, []byte(" text\n")) // Insert " text" after "some"
 	buf.Insert(0, 0, []byte("with\n\t"))
-	// "with\n\tsome text"
+	//with
+	//	some text
+	//
 
 	buf.Remove(0, 4, 1, 5) // Delete from line 0, col 4, to line 1, col 6 "\n\tsome "
 
-	if str := string(buf.Bytes()); str != "withtext" {
+	if str := string(buf.Bytes()); str != "withtext\n" {
 		t.Errorf("string does not match \"withtext\", got %#v", str)
 		t.Fail()
 	}
+
+	//withtext
+	//
+
+	// Note the inclusive bounds and pointing to last line, first column.
+	buf.Remove(0, 0, 1, 0) // Delete all of the buffer
+
+	if str := string(buf.Bytes()); str != "" {
+		t.Errorf("string does not math \"\", got %#v", str)
+		t.Fail()
+	}
 }
 
 func TestRopeBounds(t *testing.T) {
diff --git a/ui/textedit.go b/ui/textedit.go
index cc0419a..a3faebd 100644
--- a/ui/textedit.go
+++ b/ui/textedit.go
@@ -302,6 +302,7 @@ func (t *TextEdit) getColumnWidth() int {
 // If the returned string is empty, then nothing was selected. The slice returned may or may not
 // be a copy of the buffer, so do not write to it.
 func (t *TextEdit) GetSelectedBytes() []byte {
+	// TODO: there's a bug with copying text
 	if t.selectMode {
 		return t.Buffer.Slice(t.selection.StartLine, t.selection.StartCol, t.selection.EndLine, t.selection.EndCol)
 	}