package cli

import (
	"bufio"
	"fmt"
	"os"
	"reflect"

	"github.com/alecthomas/kong"
)

var _ kong.Mapper = (*PasswordMapper)(nil)

type PasswordMapper struct {
}

func (p PasswordMapper) Decode(ctx *kong.DecodeContext, target reflect.Value) error {
	token := ctx.Scan.Pop()
	switch v := token.Value.(type) {
	case []byte:
		target.SetBytes(v)
	case string:
		if len(v) == 0 {
			return nil
		}

		if v == "-" {
			scanner := bufio.NewScanner(os.Stdin)
			if scanner.Scan() {
				target.SetBytes(scanner.Bytes())
				return nil
			} else {
				return fmt.Errorf("failed to read password from stdin: %v", scanner.Err())
			}
		}

		target.SetBytes([]byte(v))
	default:
		return fmt.Errorf("expected bool but got %q (%T)", token.Value, token.Value)
	}

	return nil
}