From 79a70c316ebb7091cfbeb13cd56f6084602276d0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=9A=D0=B8=D1=80=D0=B8=D0=BB=D0=BB=20=D0=A1=D1=8B=D1=81?=
 =?UTF-8?q?=D0=BE=D0=B5=D0=B2?= <k.sysoev@me.com>
Date: Sat, 21 Oct 2023 21:35:06 +0800
Subject: [PATCH] Improve stability for inserting symbols

---
 pkg/cli/content.go      | 60 ++++++++++++++++++++++++-----------------
 pkg/cli/content_test.go | 27 +++++++++++--------
 2 files changed, 51 insertions(+), 36 deletions(-)

diff --git a/pkg/cli/content.go b/pkg/cli/content.go
index 71011be..1cf6aa8 100644
--- a/pkg/cli/content.go
+++ b/pkg/cli/content.go
@@ -72,7 +72,8 @@ func (c *Content) Clear() string {
 		return ""
 	}
 
-	output := LineClear + "\r"
+	output := c.MoveToEnd()
+	output += LineClear + "\r"
 
 	for i := 0; i < len(c.text); i++ {
 		if c.text[i] == '\n' {
@@ -127,42 +128,51 @@ func (c *Content) RemoveSymbol() string {
 }
 
 func (c *Content) InsertSymbol(symbol rune) string {
+	if c.pos < 0 || c.pos > len(c.text) {
+		return ""
+	}
+
+	if c.pos == len(c.text) {
+		c.text = append(c.text, symbol)
+		c.pos++
+
+		return string(symbol)
+	}
+
 	buffer := make([]rune, c.pos, len(c.text)+1)
 	copy(buffer, c.text[:c.pos])
 	buffer = append(buffer, symbol)
-	output := ""
-
-	if symbol == '\n' && c.pos < len(c.text) {
-		endOfLine := lastIndexOf(c.text, c.pos, '\n')
-		if endOfLine == -1 {
-			endOfLine = len(c.text)
-		}
+	buffer = append(buffer, c.text[c.pos:]...)
+	c.pos++
+	c.text = buffer
 
-		for i := c.pos; i <= endOfLine; i++ {
-			output += string(' ')
-		}
+	if symbol != '\n' && c.text[c.pos] == '\n' {
+		return string(symbol)
 	}
 
-	output += string(symbol)
+	startCurrentLine, lines := c.GetLinesAfterPosition(c.pos - 1)
+
+	if symbol != '\n' {
+		// here probably i have a room for optimization
+		endCurrentLine := startCurrentLine + len(lines[0])
+		return LineClear + "\r" + string(c.text[startCurrentLine:endCurrentLine]) + "\r" + string(c.text[startCurrentLine:c.pos])
+	}
 
-	if c.pos < len(c.text) {
-		buffer = append(buffer, c.text[c.pos:]...)
-		moveCursor := ""
+	output := ""
 
-		for i := c.pos; i < len(c.text); i++ {
-			if c.text[i] != '\n' {
-				output += string(c.text[i])
-				moveCursor += "\b"
-			} else {
-				break
-			}
+	for i := 0; i < len(lines); i++ {
+		output += LineClear + "\r" + lines[i]
+		if i < len(lines)-1 {
+			output += "\n"
 		}
+	}
 
-		output += moveCursor
+	// Move cursor back to position
+	for i := 2; i < len(lines); i++ {
+		output += LineUp
 	}
 
-	c.text = buffer
-	c.pos++
+	output += "\r"
 
 	return output
 }
diff --git a/pkg/cli/content_test.go b/pkg/cli/content_test.go
index 64d2240..037249d 100644
--- a/pkg/cli/content_test.go
+++ b/pkg/cli/content_test.go
@@ -350,6 +350,7 @@ func TestContent_InsertSymbol(t *testing.T) {
 		contentAfter string
 		symbol       rune
 		pos          int
+		posAfter     int
 	}{
 		{
 			name:         "insert at the end",
@@ -358,36 +359,34 @@ func TestContent_InsertSymbol(t *testing.T) {
 			pos:          11,
 			output:       "!",
 			contentAfter: "hello world!",
+			posAfter:     12,
 		},
 		{
-			// This test is not really correct, but it is how it works now
-			// TODO: fix this test
 			name:         "insert at the beginning",
 			input:        "hello world",
 			symbol:       '>',
 			pos:          0,
-			output:       ">hello world\b\b\b\b\b\b\b\b\b\b\b",
+			output:       "\x1b[2K\r>hello world\r>",
 			contentAfter: ">hello world",
+			posAfter:     1,
 		},
 		{
-			// This test is not really correct, but it is how it works now
-			// TODO: fix this test
 			name:         "insert in the middle",
 			input:        "hello world",
 			symbol:       ',',
 			pos:          5,
-			output:       ", world\b\b\b\b\b\b",
+			output:       "\x1b[2K\rhello, world\rhello,",
 			contentAfter: "hello, world",
+			posAfter:     6,
 		},
 		{
-			// This test is not really correct, but it is how it works now
-			// TODO: fix this test
 			name:         "insert newline in the middle",
 			input:        "hello\nworld",
 			symbol:       '\n',
 			pos:          4,
-			output:       "        \no\b",
+			output:       "\x1b[2K\rhell\n\x1b[2K\ro\n\x1b[2K\rworld\x1b[1A\r",
 			contentAfter: "hell\no\nworld",
+			posAfter:     5,
 		},
 		{
 			name:         "insert newline at the end",
@@ -396,6 +395,7 @@ func TestContent_InsertSymbol(t *testing.T) {
 			pos:          11,
 			output:       "\n",
 			contentAfter: "hello world\n",
+			posAfter:     12,
 		},
 		{
 			// This test is not really correct, but it is how it works now
@@ -404,8 +404,9 @@ func TestContent_InsertSymbol(t *testing.T) {
 			input:        "hello\nworld",
 			symbol:       '\n',
 			pos:          0,
-			output:       "            \nhello\b\b\b\b\b",
+			output:       "\x1b[2K\r\n\x1b[2K\rhello\n\x1b[2K\rworld\x1b[1A\r",
 			contentAfter: "\nhello\nworld",
+			posAfter:     1,
 		},
 	}
 
@@ -427,7 +428,11 @@ func TestContent_InsertSymbol(t *testing.T) {
 			}
 
 			if string(content.text) != tt.contentAfter {
-				t.Errorf("expected text to be '%s', but got '%s'", tt.contentAfter, string(content.text))
+				t.Errorf("expected text to be '%q', but got '%q'", tt.contentAfter, string(content.text))
+			}
+
+			if content.pos != tt.posAfter {
+				t.Errorf("expected position to be '%d', but got '%d'", tt.posAfter, content.pos)
 			}
 		})
 	}