diff --git a/erasing.go b/erasing.go
new file mode 100644
index 0000000..e58de5d
--- /dev/null
+++ b/erasing.go
@@ -0,0 +1,20 @@
+package main
+
+import "github.com/c-bata/go-prompt-toolkit/prompt"
+
+func main() {
+	l := 20
+	out := prompt.NewVT100Writer()
+	for i := 0; i < l; i++ {
+		out.CursorGoTo(i, 0)
+		out.WriteStr("XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX")
+	}
+
+
+	out.CursorGoTo(5, 10)
+	out.EraseLine()
+
+	out.CursorGoTo(l, 0)
+	out.Flush()
+	return
+}
diff --git a/main.go b/main.go
index 5c211c7..de75876 100644
--- a/main.go
+++ b/main.go
@@ -3,18 +3,18 @@ package main
 import (
 	"fmt"
 	"syscall"
+	"os"
+	"os/signal"
 
 	"github.com/c-bata/go-prompt-toolkit/prompt"
 )
 
-func enterAlternateScreen(fd int) {
-	syscall.Write(fd, []byte{0x1b, 0x5b, 0x3f, 0x01, 0x00, 0x04, 0x09, 0x68, 0x1b, 0x5b, 0x48})
-}
-
 func scroll(out *prompt.VT100Writer, lines int) {
 	for i := 0; i < lines; i++ {
 		out.ScrollDown()
-		defer out.ScrollUp()
+	}
+	for i := 0; i < lines; i++ {
+		out.ScrollUp()
 	}
 	return
 }
@@ -23,8 +23,14 @@ func main() {
 	in := prompt.NewVT100Parser()
 	in.Setup()
 	defer in.TearDown()
-	defer fmt.Println("\nexited!")
+	defer fmt.Println("\nGoodbye!")
 	out := prompt.NewVT100Writer()
+
+	renderer := prompt.Render{
+		Prefix: ">>> ",
+		Out:    out,
+	}
+
 	out.SetTitle("はろー")
 	scroll(out, 7)
 	out.Flush()
@@ -32,68 +38,27 @@ func main() {
 	bufCh := make(chan []byte, 128)
 	go readBuffer(bufCh)
 
+	winSizeCh := make(chan *prompt.WinSize, 128)
+	go updateWindowSize(in, winSizeCh)
+
 	buffer := prompt.NewBuffer()
 
 	for {
 		b := <-bufCh
-		if ac := in.GetASCIICode(b); ac == nil {
-			out.EraseDown()
-			out.WriteRaw(b)
+		ac := in.GetASCIICode(b)
+		if ac == nil {
 			buffer.InsertText(string(b), false, true)
-		} else if ac.Key == prompt.Enter || ac.Key == prompt.ControlJ {
 			out.EraseDown()
-			out.WriteStr(buffer.Document().TextAfterCursor())
-
-			out.WriteStr("\n>>> Your input: '")
-			out.WriteStr(buffer.Text())
-			out.WriteStr("' <<<\n")
-			buffer = prompt.NewBuffer()
-		} else if ac.Key == prompt.Left {
-			l := buffer.CursorLeft(1)
-			if l == 0 {
-				continue
-			}
-			out.EraseLine()
-			out.EraseDown()
-			after := buffer.Document().CurrentLine()
-			out.WriteStr(after)
-			out.CursorBackward(len(after) - buffer.CursorPosition)
-		} else if ac.Key == prompt.Right {
-			l := buffer.CursorRight(1)
-			if l == 0 {
-				continue
-			}
-
-			out.CursorForward(l)
 			out.WriteRaw(b)
-			out.EraseDown()
 			after := buffer.Document().TextAfterCursor()
 			out.WriteStr(after)
-		} else if ac.Key == prompt.Backspace {
-			deleted := buffer.DeleteBeforeCursor(1)
-			if deleted == "" {
-				continue
-			}
-			out.CursorBackward(1)
-			out.EraseDown()
-
-			after := buffer.Document().TextAfterCursor()
-			out.WriteStr(after)
-		} else if ac.Key == prompt.Tab || ac.Key == prompt.ControlI {
-		} else if ac.Key == prompt.BackTab {
-		} else if ac.Key == prompt.Right {
-			buffer.CursorRight(1)
-		} else if ac.Key == prompt.ControlT {
-			enterAlternateScreen(syscall.Stdout)
 		} else if ac.Key == prompt.ControlC {
 			out.EraseDown()
 			out.ClearTitle()
 			out.Flush()
 			return
-		} else if ac.Key == prompt.Up || ac.Key == prompt.Down {
 		} else {
-			out.WriteRaw(b)
-			//buffer.InsertText(ac.Key.String(), false, true)
+			prompt.InputHandler(ac, buffer, out)
 		}
 
 		// Display completions
@@ -132,6 +97,8 @@ func main() {
 			out.SetColor("default", "default")
 		}
 
+		completions := []string{"select", "insert", "update", "where"}
+		renderer.Render(buffer, completions)
 		scroll(out, 4)
 		out.Flush()
 	}
@@ -146,3 +113,36 @@ func readBuffer(bufCh chan []byte) {
 		}
 	}
 }
+
+func updateWindowSize(in *prompt.VT100Parser, winSizeCh chan *prompt.WinSize) {
+	sigCh := make(chan os.Signal, 1)
+	signal.Notify(
+		sigCh,
+		syscall.SIGHUP,
+		syscall.SIGINT,
+		syscall.SIGTERM,
+		syscall.SIGQUIT,
+		syscall.SIGWINCH,
+	)
+
+	for {
+		s := <-sigCh
+		switch s {
+		// kill -SIGHUP XXXX
+		case syscall.SIGHUP:
+
+			// kill -SIGINT XXXX or Ctrl+c
+		case syscall.SIGINT:
+
+			// kill -SIGTERM XXXX
+		case syscall.SIGTERM:
+
+			// kill -SIGQUIT XXXX
+		case syscall.SIGQUIT:
+
+		case syscall.SIGWINCH:
+			winSizeCh <- in.GetWinSize()
+		default:
+		}
+	}
+}
diff --git a/prompt/completions.go b/prompt/completions.go
new file mode 100644
index 0000000..0c4f39f
--- /dev/null
+++ b/prompt/completions.go
@@ -0,0 +1,24 @@
+package prompt
+
+type Completion struct {
+	// The new string that will be inserted into document.
+	text          string
+	// Position relative to the cursor position where the new text will start.
+	startPosition int
+}
+
+func (c *Completion) NewCompletionFromPosition(position int) *Completion {
+	if position < c.startPosition {
+		panic("position argument must be smaller than start position.")
+	}
+
+	return &Completion{
+		text: c.text[position - c.startPosition:],
+	}
+}
+
+func NewCompletion(text string) *Completion {
+	return &Completion{
+		text: text,
+	}
+}
diff --git a/prompt/input.go b/prompt/input.go
new file mode 100644
index 0000000..1b3b354
--- /dev/null
+++ b/prompt/input.go
@@ -0,0 +1,6 @@
+package prompt
+
+type WinSize struct {
+	Row uint16
+	Col uint16
+}
diff --git a/prompt/key_binding.go b/prompt/key_binding.go
new file mode 100644
index 0000000..20da693
--- /dev/null
+++ b/prompt/key_binding.go
@@ -0,0 +1,63 @@
+package prompt
+
+var InputHandler = defaultHandler
+
+func defaultHandler(ac *ASCIICode, buffer *Buffer, out *VT100Writer) {
+	switch ac.Key {
+	case ControlJ: // this is equivalent with Enter Key.
+		fallthrough
+	case Enter:
+		out.EraseDown()
+		out.WriteStr(buffer.Document().TextAfterCursor())
+
+		out.WriteStr("\n>>> Your input: '")
+		out.WriteStr(buffer.Text())
+		out.WriteStr("' <<<\n")
+		buffer = NewBuffer()
+	case Left:
+		l := buffer.CursorLeft(1)
+		if l == 0 {
+			return
+		}
+		out.EraseLine()
+		out.EraseDown()
+		after := buffer.Document().CurrentLine()
+		out.WriteStr(after)
+		out.CursorBackward(len(after) - buffer.CursorPosition)
+	case Right:
+		l := buffer.CursorRight(1)
+		if l == 0 {
+			return
+		}
+
+		out.CursorForward(l)
+		out.WriteRaw(ac.ASCIICode)
+		out.EraseDown()
+		after := buffer.Document().TextAfterCursor()
+		out.WriteStr(after)
+	case Backspace:
+		deleted := buffer.DeleteBeforeCursor(1)
+		if deleted == "" {
+			return
+		}
+		out.CursorBackward(1)
+		out.EraseDown()
+
+		after := buffer.Document().TextAfterCursor()
+		out.WriteStr(after)
+	case ControlI: // this is equivalent with TabKey.
+		fallthrough
+	case Tab:
+		break
+	case ControlT:
+		break
+		return
+	case Up:
+		break
+	case Down:
+		break
+	default:
+		break
+	}
+	return
+}
diff --git a/prompt/render.go b/prompt/render.go
new file mode 100644
index 0000000..5fa1f03
--- /dev/null
+++ b/prompt/render.go
@@ -0,0 +1,21 @@
+package prompt
+
+type Render struct {
+	Prefix string
+	Out *VT100Writer
+	row uint16
+	col uint16 // sigwinchで送られてくる列数を常に見ながら、prefixのlengthとbufferのcursor positionを比べて、completionの表示位置をずらす
+}
+
+func (r *Render) UpdateWinSize(ws WinSize) {
+	r.row = ws.Row
+	r.col = ws.Col
+	return
+}
+
+func (r *Render) renderCompletion(words []string) {
+	return
+}
+
+func (r *Render) Render(buffer *Buffer, completions []string) {
+}
diff --git a/prompt/vt100_input.go b/prompt/vt100_input.go
index 334a853..7dc1eaa 100644
--- a/prompt/vt100_input.go
+++ b/prompt/vt100_input.go
@@ -53,7 +53,7 @@ func (t *VT100Parser) GetASCIICode(b []byte) *ASCIICode {
 }
 
 // GetWinSize returns winsize struct which is the response of ioctl(2).
-func (t *VT100Parser) GetWinSize() (row, col uint16) {
+func (t *VT100Parser) GetWinSize() *WinSize {
 	ws := &ioctlWinsize{}
 	retCode, _, errno := syscall.Syscall(
 		syscall.SYS_IOCTL,
@@ -64,7 +64,10 @@ func (t *VT100Parser) GetWinSize() (row, col uint16) {
 	if int(retCode) == -1 {
 		panic(errno)
 	}
-	return ws.Row, ws.Col
+	return &WinSize{
+		Row: ws.Row,
+		Col: ws.Col,
+	}
 }
 
 var asciiSequences []*ASCIICode = []*ASCIICode{