package local

import (
	"strings"
	"sync"
	"time"
)

type Cache struct {
	namespace                      string
	syncMap                        *sync.Map
	expireRoutineDoneChannelsMutex *sync.Mutex
	expireRoutineDoneChannels      []chan any
}

func New(namespace string) *Cache {
	return &Cache{
		namespace:                      namespace,
		syncMap:                        new(sync.Map),
		expireRoutineDoneChannelsMutex: new(sync.Mutex),
		expireRoutineDoneChannels:      make([]chan any, 0),
	}
}

func Destroy(cache *Cache) {
	if cache == nil {
		return
	}

	cache.expireRoutineDoneChannelsMutex.Lock()

	for _, doneChan := range cache.expireRoutineDoneChannels {
		doneChan <- nil
		close(doneChan)
		doneChan = nil
	}

	cache.expireRoutineDoneChannels = nil

	cache.expireRoutineDoneChannelsMutex.Unlock()

	cache.syncMap = nil
}

func (cache *Cache) Set(key string, value string, expireSec int64) error {
	cache.syncMap.Store(cache.key2CacheKey(key), value)

	if expireSec != 0 {
		doneChan := make(chan any)

		cache.expireRoutineDoneChannelsMutex.Lock()

		if cache.expireRoutineDoneChannels != nil {
			cache.expireRoutineDoneChannels = append(cache.expireRoutineDoneChannels, doneChan)
		}

		cache.expireRoutineDoneChannelsMutex.Unlock()

		go func() {
			timer := time.NewTimer(time.Second * time.Duration(expireSec))

			defer func() {
				timer.Stop()

				cache.expireRoutineDoneChannelsMutex.Lock()

				if cache.expireRoutineDoneChannels != nil {
					findIndex := -1

					for i, savedDoneChan := range cache.expireRoutineDoneChannels {
						if savedDoneChan == doneChan {
							findIndex = i
							close(savedDoneChan)
							savedDoneChan = nil
							break
						}
					}

					if findIndex != -1 {
						cache.expireRoutineDoneChannels =
							append(cache.expireRoutineDoneChannels[:findIndex], cache.expireRoutineDoneChannels[findIndex+1:]...)
					}
				}

				cache.expireRoutineDoneChannelsMutex.Unlock()
			}()

			for {
				select {
				case <-timer.C:
					cache.syncMap.Delete(cache.key2CacheKey(key))
					return
				case <-doneChan:
					return
				}
			}
		}()
	}

	return nil
}

func (cache *Cache) Get(key string) (string, error) {
	value, loaded := cache.syncMap.Load(cache.key2CacheKey(key))
	if !loaded {
		return "", nil
	}

	return value.(string), nil
}

func (cache *Cache) GetMulti(keys []string) (map[string]string, error) {
	result := make(map[string]string)

	for _, key := range keys {
		value, loaded := cache.syncMap.Load(cache.key2CacheKey(key))
		if !loaded {
			result[key] = ""
		}

		result[key] = value.(string)
	}

	return result, nil
}

func (cache *Cache) GetAll() (map[string]string, error) {
	result := make(map[string]string)

	cache.syncMap.Range(func(key any, value any) bool {
		result[cache.cacheKey2Key(key.(string))] = value.(string)
		return true
	})

	return result, nil
}

func (cache *Cache) Delete(key string) error {
	cache.syncMap.Delete(cache.key2CacheKey(key))
	return nil
}

func (cache *Cache) Clear() error {
	cache.syncMap = new(sync.Map)
	return nil
}

func (cache *Cache) key2CacheKey(key string) string {
	return cache.namespace + "::" + key
}

func (cache *Cache) cacheKey2Key(cacheKey string) string {
	return strings.TrimPrefix(cacheKey, cache.namespace+"::")
}