package memory

import (
	"errors"
	"fmt"
	"strings"
	"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
	collections     map[string]*models.Collection
	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)
	s.collections = make(map[string]*models.Collection)

	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) getCollectionFromID(id string) *models.Collection {
	s.lock.RLock()
	defer s.lock.RUnlock()

	collection, ok := s.collections[id]
	if ok {
		return collection
	}

	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
	quiz.Hash = hash

	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) deleteQuiz(id string) (*models.Quiz, error) {
	s.lock.Lock()
	defer s.lock.Unlock()

	quiz := s.quizzes[id]
	if quiz == nil {
		return nil, fmt.Errorf("Trying to delete a quiz that doesn't exist in memory (ID: %v)", id)
	}

	s.quizzes[id] = nil
	s.quizzesHashes[quiz.Hash] = nil

	return quiz, nil

}

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) ReadQuizByHash(hash string) (*models.Quiz, error) {
	quiz := s.getQuizFromHash(hash)
	if quiz == nil {
		return nil, fmt.Errorf("Quiz with hash %s was not found in the store.", hash)
	}
	return quiz, nil
}

func (s *MemoryProboCollectorStore) CalculateQuizHash(quiz *client.Quiz) string {
	hashes := s.hasher.QuizHashes(quiz)
	return hashes[len(hashes)-1]
}

func (s *MemoryProboCollectorStore) parseTextForTags(text string, tags *[]*models.Tag) string {

	// Trim the following chars
	trimChars := "*:.,/\\@()[]{}<>"

	// Split the text into words
	words := strings.Fields(text)

	for _, word := range words {
		// If the word starts with '#', it is considered as a tag
		if strings.HasPrefix(word, "#") {
			// Check if the tag already exists in the tags slice
			exists := false
			for _, tag := range *tags {
				if tag.Name == word {
					exists = true
					break
				}
			}

			// If the tag does not exist in the tags slice, add it
			if !exists {
				*tags = append(*tags, &models.Tag{Name: strings.TrimRight(word, trimChars)})
			}
		}
	}

	return text
}

func (s *MemoryProboCollectorStore) createOrUpdateQuiz(r *client.CreateUpdateQuizRequest, id string) (*models.Quiz, bool, error) {
	if r.Quiz == nil {
		return nil, false, errors.New("A request was made passing a nil quiz object")
	}
	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, false, nil
	}

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

	if quiz.Tags == nil {
		quiz.Tags = make([]*models.Tag, 0)
	}

	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: s.parseTextForTags(r.Quiz.Question.Text, &quiz.Tags),
		})
	}

	// Populate Question field
	quiz.Question = q

	// Reset answer slice
	quiz.Answers = make([]*models.Answer, 0)

	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: s.parseTextForTags(answer.Text, &quiz.Tags),
			})
		}
		if answer.Correct {
			quiz.Correct = a
		}
		quiz.Answers = append(quiz.Answers, a)
	}

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

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

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

func (s *MemoryProboCollectorStore) DeleteQuiz(id string) (*models.Quiz, error) {
	return s.deleteQuiz(id)
}

func (s *MemoryProboCollectorStore) CreateCollection(r *client.CreateUpdateCollectionRequest) (*models.Collection, error) {
	q, _, err := s.createOrUpdateCollection(r, "")
	return q, err
}

func (s *MemoryProboCollectorStore) UpdateCollection(r *client.CreateUpdateCollectionRequest, id string) (*models.Collection, bool, error) {
	return s.createOrUpdateCollection(r, id)
}

func (s *MemoryProboCollectorStore) ReadCollectionByID(id string) (*models.Collection, error) {
	collection := s.getCollectionFromID(id)
	if collection == nil {
		return nil, fmt.Errorf("Collection ID %v not found in the store", collection.ID)
	}
	return collection, nil
}

func (s *MemoryProboCollectorStore) createOrUpdateCollection(r *client.CreateUpdateCollectionRequest, id string) (*models.Collection, bool, error) {
	var collection *models.Collection

	if r.Collection == nil {
		return nil, false, errors.New("A request was made passing a nil collection object")
	}

	if id != "" { // we're updating a collection
		collection = s.getCollectionFromID(id)
		if collection == nil { // Quiz is not present in the store
			return nil, false, fmt.Errorf("Collection ID %v doesn't exist in the store!", id)
		}
	} else {
		id = uuid.New().String()
		collection = new(models.Collection)
	}

	collection.Name = r.Collection.Name
	collection.Query = r.Collection.Query

	collection.IDs = s.query(collection.Query)

	return s.createCollectionFromID(id, collection), true, nil
}

func (s *MemoryProboCollectorStore) query(query string) []string {
	s.lock.Lock()
	defer s.lock.Unlock()

	result := make([]string, 0)

	for id, quiz := range s.quizzes {
		for _, tag := range quiz.Tags {
			if query == tag.Name {
				result = append(result, id)
				break
			}
		}
	}

	return result
}

func (s *MemoryProboCollectorStore) createCollectionFromID(id string, collection *models.Collection) *models.Collection {
	s.lock.Lock()
	defer s.lock.Unlock()

	collection.ID = id

	s.collections[id] = collection

	return collection
}