Refactor

internal/console/input.go

@@ -0,0 +1,95 @@
+package console
+
+import (
+	"io"
+	"os"
+	"unicode/utf8"
+)
+
+type Key int
+
+const (
+	KeyNormal = iota
+	KeyUp
+	KeyDown
+	KeyRight
+	KeyLeft
+)
+
+const RuneEscape rune = 0x1b
+const RuneEnter rune = '\r'
+const RuneBackspace rune = '\b'
+const RuneDelete rune = 0x7f
+
+var buf []rune = make([]rune, 0)
+
+func runeSize(b byte) int {
+	switch {
+	case b&0x80 == 0:
+		return 1
+	case b&0xe0 == 0xc0:
+		return 2
+	case b&0xf0 == 0xe0:
+		return 3
+	case b&0xf8 == 0xf0:
+		return 4
+	default:
+		return -1 // invalid
+	}
+}
+
+func readRune() rune {
+	buf := make([]byte, 1)
+	_, err := io.ReadFull(os.Stdin, buf)
+	if err != nil {
+		panic(err)
+	}
+	expected := runeSize(buf[0])
+	if expected == -1 {
+		panic("Invalid UTF-8 head")
+	}
+	full := make([]byte, expected)
+	full[0] = buf[0]
+	if expected > 1 {
+		_, err := io.ReadFull(os.Stdin, full[1:])
+		if err != nil {
+			panic(err)
+		}
+	}
+	r, size := utf8.DecodeRune(full)
+	if r == utf8.RuneError && size == 1 {
+		panic("Invalid UTF-8 body")
+	}
+	return r
+}
+
+func ReadKey() (Key, rune) {
+	if len(buf) > 0 {
+		r := buf[0]
+		buf = buf[1:]
+		return KeyNormal, r
+	}
+	r := readRune()
+	if r != RuneEscape {
+		return KeyNormal, r
+	}
+	r2 := readRune()
+	if r2 != '[' {
+		buf = append(buf, r2)
+		return KeyNormal, r
+	}
+	r3 := readRune()
+	switch r3 {
+	case 'A':
+		return KeyUp, 0
+	case 'B':
+		return KeyDown, 0
+	case 'C':
+		return KeyRight, 0
+	case 'D':
+		return KeyLeft, 0
+	}
+	buf = append(buf, r2)
+	buf = append(buf, r3)
+	return KeyNormal, r
+}