package vault

import (
	"crypto/rand"
	"errors"
	"fmt"
	"math/big"
	"strings"
)

// Diceware returns a diceware password with `length` words in it.
func Diceware(length int) (string, error) {
	words := []string{}
	for i := 0; i < length; i++ {
		// Roll five random dice.
		rolls := ""
		for j := 1; j <= DieCount; j++ {
			roll, _ := rand.Int(rand.Reader, big.NewInt(6))
			rolls += fmt.Sprintf("%d", roll.Int64()+1)
		}

		word, err := findWord(rolls)
		if err != nil {
			return "", err
		}
		words = append(words, word)
	}
	return strings.Join(words, " "), nil
}

// findWord looks up a word based on a dice roll.
func findWord(roll string) (string, error) {
	if word, ok := dict[roll]; ok {
		return word, nil
	}
	return "", errors.New("roll pattern not found? this should not happen")
}