Line movement and inserting is working

main.go

@@ -26,8 +26,92 @@ const (
 	BackSpace rune = 127
 )
 
-func readKey() (rune, error) {
+type Buffer struct {
+	buf []rune
+	cursor int
+}
+
+func (lb Buffer) String() string {
+	return string(lb.buf)
+}
+
+func (lb *Buffer) AddChar(c rune, echo bool) {
+	if lb.cursor == len(lb.buf) {
+		lb.buf = append(lb.buf, c)
+		lb.cursor++
+		if echo {
+			fmt.Printf("%c", c)
+		}
+	} else {
+		lb.buf = append(lb.buf[:lb.cursor+1], lb.buf[lb.cursor:]...)
+		lb.buf[lb.cursor] = c
+		lb.cursor++
+		if echo {
+			s := string(lb.buf[lb.cursor-1:])
+			fmt.Printf("%s\033[%dD", s, len(s)-1)
+		}
+	}
+}
+
+func (lb *Buffer) controlInput(c rune) {
+	switch c {
+	case BackSpace:
+		lb.cursor--
+		fmt.Printf("%c", BackSpace)
+	case LeftArrow:
+		if lb.cursor > 0 {
+			lb.cursor--
+			fmt.Print("\033[1D")
+		}
+	case RightArrow:
+		if lb.cursor < len(lb.buf) {
+			lb.cursor++
+			fmt.Print("\033[1C")
+		}
+	}
+}
+
+func (lb *Buffer) seedContent(s string) {
+	for _, r := range s {
+		lb.AddChar(r, false)
+	}
+}
+
+func GetText(prompt string, content string, endChar rune, includeEndChar bool) string {
+	b := Buffer{make([]rune, 0, (len(content)+1)*2), 0}
+	b.seedContent(content)
+
+	fmt.Print(prompt)
+	fmt.Print(b.String())
+
+	var ch rune
+	var err error
 	reader := bufio.NewReader(os.Stdin)
+
+	for {
+		ch, err = readKey(reader)
+		if err != nil {
+			continue
+		}
+		if ch == endChar {
+			if includeEndChar {
+				b.AddChar(ch, true)
+			}
+			break
+		}
+
+		if isControl(ch) {
+			b.controlInput(ch)
+		} else {
+			b.AddChar(ch, true)
+		}
+
+	}
+	return b.String()
+}
+
+
+func readKey(reader *bufio.Reader) (rune, error) {
 	char, _, err := reader.ReadRune()
 	if err != nil {
 		return 0, err
@@ -57,11 +141,11 @@ func readKey() (rune, error) {
 			char = PageUp
 		case escSeq == "\033[6~":
 			char = PageDown
-		case IsHomeKey(escSeq):
+		case isHomeKey(escSeq):
 			char = Home
-		case IsEndKey(escSeq):
+		case isEndKey(escSeq):
 			char = End
-		case escSeq == "\033[3~" || escSeq == "\033[P":
+		case isDeleteKey(escSeq):
 			char = Delete
 		default:
 			fmt.Printf("Odd sequence: %s\n", escSeq[1:])
@@ -70,7 +154,25 @@ func readKey() (rune, error) {
 	return char, nil
 }
 
-func IsHomeKey(seq string) bool {
+func isControl(c rune) bool {
+	switch c {
+		case UpArrow, DownArrow, RightArrow, LeftArrow, PageUp, PageDown, Home, End, Delete, BackSpace, CarriageReturn, NewLine, Escape:
+			return true
+		default:
+			return false
+	}
+}
+
+func isDeleteKey(seq string) bool {
+	switch seq {
+	case "\033[3~", "\033[P":
+		return true
+	default:
+		return false
+	}
+}
+
+func isHomeKey(seq string) bool {
 	switch seq {
 	case "\033[1~", "\033[7~", "\033[H", "\033OH":
 		return true
@@ -79,7 +181,7 @@ func IsHomeKey(seq string) bool {
 	}
 }
 
-func IsEndKey(seq string) bool {
+func isEndKey(seq string) bool {
 	switch seq {
 	case "\033[4~", "\033[8~", "\033[F", "\033OF":
 		return true
@@ -120,17 +222,11 @@ func PrintKey(k rune) {
 
 func main() {
 	termios.SetCharMode()
+	defer termios.Restore()
+	str := "Hi"
 
 	for {
-		k, e := readKey()
-		if e != nil {
-			fmt.Println(e.Error())
-			continue
-		}
-		PrintKey(k)
-		if k == NewLine || k == CarriageReturn {
-			break
-		}
+		fmt.Print("\n")
+		str = GetText("> ", str, '\n', false)
 	}
-	termios.Restore()
 }