package lru

import (
	"container/list"
	_ "gitee.com/timedb/wheatCache/conf"
	"gitee.com/timedb/wheatCache/pkg/errorx"
	"gitee.com/timedb/wheatCache/pkg/event"
	"gitee.com/timedb/wheatCache/pkg/structure"
	"gitee.com/timedb/wheatCache/pkg/util"
	"github.com/spf13/viper"
	"sync/atomic"
)


type keyBaseValue struct {
	key string
	val structure.KeyBaseInterface
}

type singleCache struct {
	maxsize   int64 //最大的长度
	clearSize int64 // 清理长度
	nowSize   int64 // 现在的长度
	li        *list.List
	lruMap    map[string]*list.Element

	lruDriver   event.DriverInterface
	lruConsumer event.ConsumerInterface
	lruProduce  event.ProduceInterface // 发送清理事件
}

func (lru *singleCache) UpdateLruLength(length int64) {
	atomic.AddInt64(&lru.nowSize, length)
}

// NewLRUCache lru初始化
func NewLRUCache() *singleCache {
	maxSize := viper.GetString("lruCache.maxSize")
	clearSize := viper.GetString("lruCache.clearSize")
	maxDriver := viper.GetInt("lruCache.eventDriverSize")
	lruDriver := event.NewDriver(maxDriver)

	return &singleCache{
		maxsize:     util.ParseSizeToBit(maxSize),
		clearSize:   util.ParseSizeToBit(clearSize),
		nowSize:     0,
		li:          list.New(),
		lruMap:      make(map[string]*list.Element),
		lruDriver:   lruDriver,
		lruConsumer: event.NewConsumer(lruDriver),
		lruProduce:  event.NewProduce(lruDriver),
	}
}

// RetDriver 获取驱动
func (lru *singleCache) RetDriver() event.DriverInterface {
	return lru.lruDriver
}

//Add 增加
func (lru *singleCache) Add(key string, val structure.KeyBaseInterface) {

	keyBaseVal := &keyBaseValue{
		key: key,
		val: val,
	}
	if elVal, ok := lru.lruMap[key]; ok {
		lru.li.MoveToFront(elVal)
		elVal.Value = keyBaseVal
		return
	}
	valEl := lru.li.PushFront(keyBaseVal)
	lru.lruMap[key] = valEl
}

// Get 查找key对应的value
func (lru *singleCache) Get(key string) (structure.KeyBaseInterface, bool) {

	if lru.lruMap == nil {
		return nil, false
	}
	if elVal, ok := lru.lruMap[key]; ok {
		lru.li.MoveToFront(elVal)
		return elVal.Value.(*keyBaseValue).val, true
	}
	return nil, false
}

//Del 删除机制
func (lru *singleCache) Del() error {
	if lru.lruMap == nil {
		return errorx.New("lru is nil")
	}
	data := lru.li.Back()
	delete(lru.lruMap, data.Value.(*keyBaseValue).key)
	lru.li.Remove(data)
	return nil
}