// SPDX-License-Identifier: MIT

//go:build !windows

package main

import (
	"bufio"
	"errors"
	"fmt"
	"io"
	"os"
	"os/exec"
	"strings"
)

// readPassword asks on the terminal, with typing hidden. It reads the
// terminal itself rather than standard input, so a command whose input is a
// pipe still asks the person at the keyboard.
func readPassword(prompt string) (string, error) {
	tty, err := os.OpenFile("/dev/tty", os.O_RDWR, 0)
	if err != nil {
		return "", errNoTerminal
	}
	defer tty.Close()

	saved, err := stty(tty, "-g")
	if err != nil {
		return "", errNoTerminal
	}
	if _, err := stty(tty, "-echo"); err != nil {
		return "", errNoTerminal
	}
	restore := func() { _, _ = stty(tty, strings.TrimSpace(saved)) }
	stop := onInterrupt(func() {
		restore()
		fmt.Fprintln(tty)
	})
	defer stop()
	defer restore()

	fmt.Fprint(tty, prompt)
	line, err := bufio.NewReader(tty).ReadString('\n')
	fmt.Fprintln(tty)
	if err != nil && !(errors.Is(err, io.EOF) && line != "") {
		return "", fmt.Errorf("could not read the password: %w", err)
	}
	return strings.TrimRight(line, "\r\n"), nil
}

// stty runs the system's stty on the terminal. It is named by its path: every
// system this tool is built for has it there.
func stty(tty *os.File, args ...string) (string, error) {
	cmd := exec.Command("/bin/stty", args...)
	cmd.Stdin = tty
	out, err := cmd.Output()
	return string(out), err
}