//Simple caching library with expiration capabilities
package cache2go

import (
	"sync"

	"github.com/cgrates/cgrates/config"
)

const (
	PREFIX_LEN   = 4
	KIND_ADD     = "ADD"
	KIND_REM     = "REM"
	KIND_PRF     = "PRF"
	DOUBLE_CACHE = true
)

var (
	mux   sync.RWMutex
	cache cacheStore
	cfg   *config.CacheConfig
	// transaction stuff
	transactionBuffer []*transactionItem
	transactionMux    sync.Mutex
	transactionON     = false
	transactionLock   = false
)

type transactionItem struct {
	key   string
	value interface{}
	kind  string
}

func init() {
	NewCache(nil)
}

func NewCache(cacheCfg *config.CacheConfig) {
	cfg = cacheCfg
	cache = newLruStore()
}

func BeginTransaction() {
	transactionMux.Lock()
	transactionLock = true
	transactionON = true
}

func RollbackTransaction() {
	transactionBuffer = nil
	transactionLock = false
	transactionON = false
	transactionMux.Unlock()
}

func CommitTransaction() {
	transactionON = false
	// apply all transactioned items
	mux.Lock()
	for _, item := range transactionBuffer {
		switch item.kind {
		case KIND_REM:
			RemKey(item.key)
		case KIND_PRF:
			RemPrefixKey(item.key)
		case KIND_ADD:
			Set(item.key, item.value)
		}
	}
	mux.Unlock()
	transactionBuffer = nil
	transactionLock = false
	transactionMux.Unlock()
}

// The function to be used to cache a key/value pair when expiration is not needed
func Set(key string, value interface{}) {
	if !transactionLock {
		mux.Lock()
		defer mux.Unlock()
	}
	if !transactionON {
		cache.Put(key, value)
		//log.Println("ADD: ", key)
	} else {
		transactionBuffer = append(transactionBuffer, &transactionItem{key: key, value: value, kind: KIND_ADD})
	}
}

// The function to extract a value for a key that never expire
func Get(key string) (interface{}, bool) {
	mux.RLock()
	defer mux.RUnlock()
	return cache.Get(key)
}

func RemKey(key string) {
	if !transactionLock {
		mux.Lock()
		defer mux.Unlock()
	}
	if !transactionON {
		cache.Delete(key)
	} else {
		transactionBuffer = append(transactionBuffer, &transactionItem{key: key, kind: KIND_REM})
	}
}

func RemPrefixKey(prefix string) {
	if !transactionLock {
		mux.Lock()
		defer mux.Unlock()
	}
	if !transactionON {
		cache.DeletePrefix(prefix)
	} else {
		transactionBuffer = append(transactionBuffer, &transactionItem{key: prefix, kind: KIND_PRF})
	}
}

// Delete all keys from cache
func Flush() {
	mux.Lock()
	defer mux.Unlock()
	cache = newLruStore()
}

func CountEntries(prefix string) (result int) {
	mux.RLock()
	defer mux.RUnlock()
	return cache.CountEntriesForPrefix(prefix)
}

func GetEntriesKeys(prefix string) (keys []string) {
	mux.RLock()
	defer mux.RUnlock()
	return cache.GetKeysForPrefix(prefix)
}