package sha256

import (
	"crypto/sha256"
	"fmt"
	"sort"
	"strings"

	"git.andreafazzi.eu/andrea/probo/client"
	"git.andreafazzi.eu/andrea/probo/hasher"
)

var DefaultSHA256HashingFn = func(text string) string {
	return fmt.Sprintf("%x", sha256.Sum256([]byte(text)))
}

type Default256Hasher struct {
	hashFn hasher.HashFunc
}

func NewDefault256Hasher(hashFn hasher.HashFunc) *Default256Hasher {
	return &Default256Hasher{hashFn}
}

func (h *Default256Hasher) QuizHashes(quiz *client.Quiz) []string {
	result := make([]string, 0)

	result = append(result, h.QuestionHash(quiz.Question))

	for _, a := range quiz.Answers {
		result = append(result, h.AnswerHash(a))
	}

	result = append(result, h.Calculate(result))

	return result
}

func (h *Default256Hasher) QuestionHash(question *client.Question) string {
	return h.hashFn(question.Text)
}

func (h *Default256Hasher) AnswerHash(answer *client.Answer) string {
	return h.hashFn(answer.Text)
}

func (h *Default256Hasher) Calculate(hashes []string) string {
	orderedHashes := make([]string, len(hashes))

	copy(orderedHashes, hashes)
	sort.Strings(orderedHashes)

	return h.hashFn(strings.Join(orderedHashes, ""))
}