package cli

import (
	"bufio"
	"fmt"
	"io"
	"os"
	"strings"
)

// Confirm asks the user the yes/no question prompt on stdin and reports whether
// they answered yes. "y" and "yes" confirm, "n" and "no" refuse, in any case;
// anything else asks again. It exits the program if stdin can't be read.
func Confirm(out io.Writer, in io.Reader, prompt string) bool {
	reader := bufio.NewReader(in)

	for {
		_, err := fmt.Fprintf(out, "%s [y/n]: ", prompt)
		if err != nil {
			fmt.Fprintf(os.Stderr, "error asking question: %s\n", err)
			os.Exit(1)
		}

		response, err := reader.ReadString('\n')
		if err != nil {
			fmt.Fprintf(os.Stderr, "error reading answer: %s\n", err)
			os.Exit(1)
		}

		response = strings.ToLower(strings.TrimSpace(response))

		switch response {
		case "y", "yes":
			return true
		case "n", "no":
			return false
		}
	}
}