package termstatus

import (
	"fmt"
	"io"
	"os"
)

const (
	posixMoveCursorHome = "\r"
	posixMoveCursorUp   = "\x1b[1A"
	posixClearLine      = "\x1b[2K"
)

// posixClearLines will clear the current line and the n lines above.
// Afterwards the cursor is positioned at the start of the first cleared line.
func posixClearLines(wr io.Writer, fd uintptr, n int) {
	// clear current line
	_, err := wr.Write([]byte(posixMoveCursorHome + posixClearLine))
	if err != nil {
		fmt.Fprintf(os.Stderr, "write failed: %v\n", err)
		return
	}

	for ; n > 0; n-- {
		// clear current line and move on line up
		_, err := wr.Write([]byte(posixMoveCursorUp + posixClearLine))
		if err != nil {
			fmt.Fprintf(os.Stderr, "write failed: %v\n", err)
			return
		}
	}
}