package main

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

type packageFlags struct {
	dryRun bool
}

func parsePackageFlags(args []string) (packageFlags, string, error) {
	flags := packageFlags{}
	var pkg string
	for _, arg := range args {
		if arg == "--dry-run" {
			flags.dryRun = true
			continue
		}
		if strings.HasPrefix(arg, "-") {
			return flags, "", fmt.Errorf("unknown flag %q", arg)
		}
		if pkg != "" {
			return flags, "", errors.New("too many arguments")
		}
		pkg = arg
	}
	if pkg == "" {
		return flags, "", errors.New("missing package")
	}
	return flags, pkg, nil
}

var stdinReader *bufio.Reader

func newReader() *bufio.Reader {
	if stdinReader == nil {
		stdinReader = bufio.NewReader(os.Stdin)
	}
	return stdinReader
}

func promptWithDefault(label, def string) (string, error) {
	reader := newReader()
	if def != "" {
		fmt.Printf("%s [%s]: ", label, def)
	} else {
		fmt.Printf("%s: ", label)
	}

	text, err := reader.ReadString('\n')
	if err != nil {
		return "", err
	}
	text = strings.TrimSpace(text)
	if text == "" {
		return def, nil
	}
	return text, nil
}

func promptYesNo(message string, def bool) (bool, error) {
	reader := newReader()
	defLabel := "y/N"
	if def {
		defLabel = "Y/n"
	}
	fmt.Printf("%s [%s]: ", message, defLabel)
	text, err := reader.ReadString('\n')
	if err != nil {
		return false, err
	}
	text = strings.TrimSpace(strings.ToLower(text))
	if text == "" {
		return def, nil
	}
	return text == "y" || text == "yes", nil
}