1 files changed, 59 insertions, 0 deletions
diff --git a/cwriter/writer.go b/cwriter/writer.go
new file mode 100644
index 0000000..23a72d3
--- /dev/null
+++ b/cwriter/writer.go
@@ -0,0 +1,59 @@
+package cwriter
+
+import (
+	"bytes"
+	"errors"
+	"io"
+	"os"
+	"strconv"
+)
+
+// https://github.com/dylanaraps/pure-sh-bible#cursor-movement
+const (
+	escOpen  = "\x1b["
+	cuuAndEd = "A\x1b[J"
+)
+
+// ErrNotTTY not a TeleTYpewriter error.
+var ErrNotTTY = errors.New("not a terminal")
+
+// New returns a new Writer with defaults.
+func New(out io.Writer) *Writer {
+	w := &Writer{
+		Buffer: new(bytes.Buffer),
+		out:    out,
+		termSize: func(_ int) (int, int, error) {
+			return -1, -1, ErrNotTTY
+		},
+	}
+	if f, ok := out.(*os.File); ok {
+		w.fd = int(f.Fd())
+		if IsTerminal(w.fd) {
+			w.terminal = true
+			w.termSize = func(fd int) (int, int, error) {
+				return GetSize(fd)
+			}
+		}
+	}
+	bb := make([]byte, 16)
+	w.ew = escWriter(bb[:copy(bb, []byte(escOpen))])
+	return w
+}
+
+// IsTerminal tells whether underlying io.Writer is terminal.
+func (w *Writer) IsTerminal() bool {
+	return w.terminal
+}
+
+// GetTermSize returns WxH of underlying terminal.
+func (w *Writer) GetTermSize() (width, height int, err error) {
+	return w.termSize(w.fd)
+}
+
+type escWriter []byte
+
+func (b escWriter) ansiCuuAndEd(out io.Writer, n int) error {
+	b = strconv.AppendInt(b, int64(n), 10)
+	_, err := out.Write(append(b, []byte(cuuAndEd)...))
+	return err
+}