package store

import (
	"fmt"
	"sync"

	"github.com/google/uuid"
)

type IDer interface {
	GetID() string
	SetID(string)
}

type Hasher interface {
	GetHash() string
}

type Storable interface {
	IDer
	Hasher
}

type Storer[T Storable] interface {
	Create(T) (T, error)
	ReadAll() []T
	Read(string) (T, error)
	Update(T, string) (T, error)
	Delete(string) (T, error)
}

type FilterStorer[T Storable] interface {
	Storer[T]

	Filter([]T, func(T) bool) []T
}

type Store[T Storable] struct {
	ids    map[string]T
	hashes map[string]T

	lock sync.RWMutex
}

type FilterStore[T Storable] struct {
	*Store[T]
}

func NewFilterStore[T Storable]() *FilterStore[T] {
	return &FilterStore[T]{NewStore[T]()}
}

func (fs *FilterStore[T]) Filter(slice []T, f func(T) bool) []T {
	result := make([]T, 0)

	for _, item := range slice {
		if f(item) {
			result = append(result, item)
		}
	}

	return result
}

func NewStore[T Storable]() *Store[T] {
	store := new(Store[T])

	store.ids = make(map[string]T)
	store.hashes = make(map[string]T)

	return store
}

func (s *Store[T]) Create(entity T) (T, error) {
	s.lock.Lock()
	defer s.lock.Unlock()

	if hash := entity.GetHash(); hash != "" {
		storedEntity, ok := s.hashes[hash]
		if ok {
			return storedEntity, nil
		}
		s.hashes[hash] = entity
	}

	id := entity.GetID()

	if id == "" {
		id = uuid.New().String()
	}

	entity.SetID(id)
	s.ids[id] = entity

	return entity, nil
}

func (s *Store[T]) ReadAll() []T {
	s.lock.Lock()
	defer s.lock.Unlock()

	result := make([]T, 0)

	for _, v := range s.ids {
		result = append(result, v)
	}

	return result
}

func (s *Store[T]) Read(id string) (T, error) {
	s.lock.RLock()
	defer s.lock.RUnlock()

	entity, ok := s.ids[id]
	if !ok {
		return entity, fmt.Errorf("Entity with ID %s was not found in the store.", id)
	}

	return entity, nil

}

func (s *Store[T]) Update(entity T, id string) (T, error) {
	sEntity, err := s.Read(id)
	if err != nil {
		return sEntity, err
	}

	s.lock.Lock()
	defer s.lock.Unlock()

	entity.SetID(id)
	s.ids[id] = entity

	if hash := entity.GetHash(); hash != "" {
		s.hashes[hash] = entity
	}

	return entity, nil
}

func (s *Store[T]) Delete(id string) (T, error) {
	sEntity, err := s.Read(id)
	if err != nil {
		return sEntity, err
	}

	s.lock.Lock()
	defer s.lock.Unlock()

	delete(s.ids, id)

	if hash := sEntity.GetHash(); hash != "" {
		delete(s.hashes, hash)
	}

	return sEntity, nil
}