add line numbers

cmd/goedit/main.go

@@ -149,21 +149,36 @@ func (m Model) View() string {
 
 	b.WriteString("Text Editor (Ctrl+C or Esc to quit)\n\n")
 
+	contentHeight := m.height - 4
+	lineNumWidth := len(fmt.Sprintf("%d", len(m.lines))) + 1
+
 	for i, line := range m.lines {
+		if i >= contentHeight {
+			break
+		}
+
+		lineNum := fmt.Sprintf("%*d ", lineNumWidth, i+1)
+
 		if i == m.row {
 			if m.col == 0 {
-				b.WriteString("█" + line + "\n")
+				b.WriteString(lineNum + "█" + line + "\n")
 			} else if m.col >= len(line) {
-				b.WriteString(line + "█\n")
+				b.WriteString(lineNum + line + "█\n")
 			} else {
-				b.WriteString(line[:m.col] + "█" + line[m.col:] + "\n")
+				b.WriteString(lineNum + line[:m.col] + "█" + line[m.col:] + "\n")
 			}
 		} else {
-			b.WriteString(line + "\n")
+			b.WriteString(lineNum + line + "\n")
 		}
 	}
 
-	b.WriteString(fmt.Sprintf("\nRow: %d, Col: %d", m.row+1, m.col+1))
+	for i := len(m.lines); i < contentHeight; i++ {
+		b.WriteString("\n")
+	}
+
+	statusBar := fmt.Sprintf("%d:%d", m.row+1, m.col+1)
+	padding := strings.Repeat(" ", m.width-len(statusBar))
+	b.WriteString(padding + statusBar)
 
 	return b.String()
 }