package memory

import (
	"fmt"
	"sync"

	"git.andreafazzi.eu/andrea/probo/client"
	"git.andreafazzi.eu/andrea/probo/hasher"
	"git.andreafazzi.eu/andrea/probo/models"
	"github.com/google/uuid"
)

type MemoryProboCollectorStore struct {
	quizzes map[string]*models.Quiz

	questionsHashes map[string]*models.Question
	answersHashes   map[string]*models.Answer
	quizzesHashes   map[string]*models.Quiz

	hasher hasher.Hasher

	// A mutex is used to synchronize read/write access to the map
	lock sync.RWMutex
}

func NewMemoryProboCollectorStore(hasher hasher.Hasher) *MemoryProboCollectorStore {
	s := new(MemoryProboCollectorStore)

	s.hasher = hasher

	s.questionsHashes = make(map[string]*models.Question)
	s.answersHashes = make(map[string]*models.Answer)
	s.quizzesHashes = make(map[string]*models.Quiz)

	s.quizzes = make(map[string]*models.Quiz)

	return s
}

func (s *MemoryProboCollectorStore) getQuizFromHash(hash string) *models.Quiz {
	s.lock.RLock()
	defer s.lock.RUnlock()

	quiz, ok := s.quizzesHashes[hash]
	if ok {
		return quiz
	}

	return nil
}

func (s *MemoryProboCollectorStore) getQuizFromID(id string) *models.Quiz {
	s.lock.RLock()
	defer s.lock.RUnlock()

	quiz, ok := s.quizzes[id]
	if ok {
		return quiz
	}

	return nil
}

func (s *MemoryProboCollectorStore) getQuestionFromHash(hash string) *models.Question {
	s.lock.RLock()
	defer s.lock.RUnlock()

	question, ok := s.questionsHashes[hash]
	if ok {
		return question
	}

	return nil
}

func (s *MemoryProboCollectorStore) getAnswerFromHash(hash string) *models.Answer {
	s.lock.RLock()
	defer s.lock.RUnlock()

	answer, ok := s.answersHashes[hash]
	if ok {
		return answer
	}

	return nil
}

func (s *MemoryProboCollectorStore) createQuizFromHash(id string, hash string, quiz *models.Quiz) *models.Quiz {
	s.lock.Lock()
	defer s.lock.Unlock()

	quiz.ID = id

	s.quizzesHashes[hash] = quiz
	s.quizzes[id] = quiz

	return quiz
}

func (s *MemoryProboCollectorStore) createQuestionFromHash(hash string, question *models.Question) *models.Question {
	s.lock.Lock()
	defer s.lock.Unlock()

	s.questionsHashes[hash] = question

	return question
}

func (s *MemoryProboCollectorStore) createAnswerFromHash(hash string, answer *models.Answer) *models.Answer {
	s.lock.Lock()
	defer s.lock.Unlock()

	s.answersHashes[hash] = answer

	return answer
}

func (s *MemoryProboCollectorStore) ReadAllQuizzes() ([]*models.Quiz, error) {
	result := make([]*models.Quiz, 0)
	for id := range s.quizzes {
		result = append(result, s.getQuizFromID(id))
	}
	return result, nil
}

func (s *MemoryProboCollectorStore) createOrUpdateQuiz(r *client.CreateUpdateQuizRequest, id string) (*models.Quiz, error) {
	hashes := s.hasher.QuizHashes(r.Quiz)
	quizHash := hashes[len(hashes)-1]

	quiz := s.getQuizFromHash(quizHash)
	if quiz != nil { // Quiz is already present in the store
		return quiz, nil
	}

	if id != "" {
		quiz = s.getQuizFromID(id)
		if quiz == nil { // Quiz is already present in the store
			return nil, fmt.Errorf("Quiz ID %v doesn't exist in the store!", id)
		}
	} else {
		id = uuid.New().String()
		quiz = new(models.Quiz)
	}

	questionHash := hashes[0]
	q := s.getQuestionFromHash(questionHash)
	if q == nil { // if the question is not in the store then we should add it
		q = s.createQuestionFromHash(questionHash, &models.Question{
			ID:   uuid.New().String(),
			Text: r.Quiz.Question.Text,
		})
	}

	// Populate Question field
	quiz.Question = q
	for i, answer := range r.Quiz.Answers {
		answerHash := hashes[i+1]
		a := s.getAnswerFromHash(answerHash)
		if a == nil { // if the answer is not in the store add it
			a = s.createAnswerFromHash(answerHash, &models.Answer{
				ID:   uuid.New().String(),
				Text: answer.Text,
			})
		}
		if answer.Correct {
			quiz.Correct = a
		}
		quiz.Answers = append(quiz.Answers, a)
	}

	return s.createQuizFromHash(id, quizHash, quiz), nil
}

func (s *MemoryProboCollectorStore) CreateQuiz(r *client.CreateUpdateQuizRequest) (*models.Quiz, error) {
	return s.createOrUpdateQuiz(r, "")
}

func (s *MemoryProboCollectorStore) UpdateQuiz(r *client.CreateUpdateQuizRequest, id string) (*models.Quiz, error) {
	return s.createOrUpdateQuiz(r, id)
}