// Filename: internal/store/memory_store.go (统一存储重构版)

package store

import (
	"fmt"
	"math/rand"
	"sort"
	"sync"
	"time"

	"github.com/sirupsen/logrus"
)

// ensure memoryStore implements Store interface
var _ Store = (*memoryStore)(nil)

// [核心重构] memoryStoreItem 现在是通用容器，可以存储任何类型的值，并自带过期时间
type memoryStoreItem struct {
	value    interface{} // 可以是 []byte, []string, map[string]string, map[string]struct{}, []zsetMember
	expireAt time.Time
}

// isExpired 检查一个条目是否已过期
func (item *memoryStoreItem) isExpired() bool {
	return !item.expireAt.IsZero() && time.Now().After(item.expireAt)
}

// zsetMember 保持不变
type zsetMember struct {
	Value string
	Score float64
}

// [核心重构] memoryStore 现在使用一个统一的 map 来存储所有数据
type memoryStore struct {
	items  map[string]*memoryStoreItem // 指向 item 的指针，以便原地修改
	pubsub map[string][]chan *Message
	mu     sync.RWMutex
	logger *logrus.Entry
}

// NewMemoryStore [核心重構] 構造函數也被簡化了
func NewMemoryStore(logger *logrus.Logger) Store {
	return &memoryStore{
		items:  make(map[string]*memoryStoreItem),
		pubsub: make(map[string][]chan *Message),
		logger: logger.WithField("component", "store.memory 🗱"),
	}
}

// [核心重构] getItem 是一个新的内部辅助函数，它封装了获取、检查过期和删除的通用逻辑
func (s *memoryStore) getItem(key string, lockForWrite bool) *memoryStoreItem {
	if !lockForWrite {
		// 如果是读操作，先用读锁检查
		s.mu.RLock()
		item, ok := s.items[key]
		if !ok || item.isExpired() {
			s.mu.RUnlock()
			// 如果不存在或已过期，需要尝试获取写锁来删除它
			if ok { // 只有在确定 item 存在但已过期时才需要删除
				s.mu.Lock()
				// 再次检查，防止在获取写锁期间状态已改变
				if item, ok := s.items[key]; ok && item.isExpired() {
					delete(s.items, key)
				}
				s.mu.Unlock()
			}
			return nil // 无论如何都返回 nil
		}
		s.mu.RUnlock()
		return item
	}

	// 对于写操作，直接使用写锁
	item, ok := s.items[key]
	if ok && item.isExpired() {
		delete(s.items, key)
		return nil
	}
	return item
}

// --- 所有接口方法现在都基于新的统一结构重写 ---

func (s *memoryStore) Set(key string, value []byte, ttl time.Duration) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	var expireAt time.Time
	if ttl > 0 {
		expireAt = time.Now().Add(ttl)
	}
	s.items[key] = &memoryStoreItem{value: value, expireAt: expireAt}
	return nil
}

func (s *memoryStore) Get(key string) ([]byte, error) {
	item := s.getItem(key, false)
	if item == nil {
		return nil, ErrNotFound
	}
	if value, ok := item.value.([]byte); ok {
		return value, nil
	}
	return nil, ErrNotFound // Type mismatch, treat as not found
}

func (s *memoryStore) Del(keys ...string) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	for _, key := range keys {
		delete(s.items, key)
	}
	return nil
}

func (s *memoryStore) delNoLock(keys ...string) {
	for _, key := range keys {
		delete(s.items, key)
	}
}

func (s *memoryStore) Exists(key string) (bool, error) {
	return s.getItem(key, false) != nil, nil
}

func (s *memoryStore) SetNX(key string, value []byte, ttl time.Duration) (bool, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if item := s.getItem(key, true); item != nil {
		return false, nil
	}
	var expireAt time.Time
	if ttl > 0 {
		expireAt = time.Now().Add(ttl)
	}
	s.items[key] = &memoryStoreItem{value: value, expireAt: expireAt}
	return true, nil
}

func (s *memoryStore) Close() error { return nil }

func (s *memoryStore) HDel(key string, fields ...string) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	item := s.getItem(key, true)
	if item == nil {
		return nil
	}
	if hash, ok := item.value.(map[string]string); ok {
		for _, field := range fields {
			delete(hash, field)
		}
	}
	return nil
}

func (s *memoryStore) HSet(key string, values map[string]any) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.hSetNoLock(key, values)
	return nil
}

func (s *memoryStore) hSetNoLock(key string, values map[string]any) {
	item := s.getItem(key, true)
	if item == nil {
		item = &memoryStoreItem{value: make(map[string]string)}
		s.items[key] = item
	}
	hash, ok := item.value.(map[string]string)
	if !ok { // If key exists but is not a hash, create a new hash
		hash = make(map[string]string)
		item.value = hash
	}
	for field, value := range values {
		hash[field] = fmt.Sprintf("%v", value)
	}
}

func (s *memoryStore) HGetAll(key string) (map[string]string, error) {
	item := s.getItem(key, false)
	if item == nil {
		return make(map[string]string), nil
	}
	if hash, ok := item.value.(map[string]string); ok {
		result := make(map[string]string, len(hash))
		for k, v := range hash {
			result[k] = v
		}
		return result, nil
	}
	return make(map[string]string), nil
}

func (s *memoryStore) HIncrBy(key, field string, incr int64) (int64, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.hIncrByNoLock(key, field, incr)
}

func (s *memoryStore) hIncrByNoLock(key, field string, incr int64) (int64, error) {
	item := s.getItem(key, true)
	if item == nil {
		item = &memoryStoreItem{value: make(map[string]string)}
		s.items[key] = item
	}
	hash, ok := item.value.(map[string]string)
	if !ok {
		hash = make(map[string]string)
		item.value = hash
	}
	var currentVal int64
	if valStr, ok := hash[field]; ok {
		fmt.Sscanf(valStr, "%d", &currentVal)
	}
	newVal := currentVal + incr
	hash[field] = fmt.Sprintf("%d", newVal)
	return newVal, nil
}

func (s *memoryStore) LPush(key string, values ...any) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.lPushNoLock(key, values...)
	return nil
}

func (s *memoryStore) lPushNoLock(key string, values ...any) {
	item := s.getItem(key, true)
	if item == nil {
		item = &memoryStoreItem{value: make([]string, 0)}
		s.items[key] = item
	}
	list, ok := item.value.([]string)
	if !ok {
		list = make([]string, 0)
	}
	stringValues := make([]string, len(values))
	for i, v := range values {
		stringValues[i] = fmt.Sprintf("%v", v)
	}
	item.value = append(stringValues, list...)
}

func (s *memoryStore) LRem(key string, count int64, value any) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.lRemNoLock(key, count, value)
	return nil
}
func (s *memoryStore) lRemNoLock(key string, count int64, value any) {
	item := s.getItem(key, true)
	if item == nil {
		return
	}
	list, ok := item.value.([]string)
	if !ok {
		return
	}
	valToRemove := fmt.Sprintf("%v", value)
	newList := make([]string, 0, len(list))
	removedCount := int64(0)
	for _, v := range list {
		if v == valToRemove && (count == 0 || removedCount < count) {
			removedCount++
		} else {
			newList = append(newList, v)
		}
	}
	item.value = newList
}
func (s *memoryStore) SAdd(key string, members ...any) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.sAddNoLock(key, members...)
	return nil
}

func (s *memoryStore) sAddNoLock(key string, members ...any) {
	item := s.getItem(key, true)
	if item == nil {
		item = &memoryStoreItem{value: make(map[string]struct{})}
		s.items[key] = item
	}
	set, ok := item.value.(map[string]struct{})
	if !ok {
		set = make(map[string]struct{})
		item.value = set
	}
	for _, member := range members {
		set[fmt.Sprintf("%v", member)] = struct{}{}
	}
}
func (s *memoryStore) SPopN(key string, count int64) ([]string, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	item := s.getItem(key, true)
	if item == nil {
		return []string{}, nil
	}
	set, ok := item.value.(map[string]struct{})
	if !ok || len(set) == 0 {
		return []string{}, nil
	}
	if int64(len(set)) < count {
		count = int64(len(set))
	}
	popped := make([]string, 0, count)
	keys := make([]string, 0, len(set))
	for k := range set {
		keys = append(keys, k)
	}
	rand.Shuffle(len(keys), func(i, j int) { keys[i], keys[j] = keys[j], keys[i] })
	for i := int64(0); i < count; i++ {
		poppedKey := keys[i]
		popped = append(popped, poppedKey)
		delete(set, poppedKey)
	}
	return popped, nil
}
func (s *memoryStore) SMembers(key string) ([]string, error) {
	item := s.getItem(key, false)
	if item == nil {
		return []string{}, nil
	}
	set, ok := item.value.(map[string]struct{})
	if !ok {
		return []string{}, nil
	}
	s.mu.RLock() // Lock needed for iterating map
	defer s.mu.RUnlock()
	members := make([]string, 0, len(set))
	for member := range set {
		members = append(members, member)
	}
	return members, nil
}
func (s *memoryStore) SRem(key string, members ...any) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.sRemNoLock(key, members...)
	return nil
}
func (s *memoryStore) sRemNoLock(key string, members ...any) {
	item := s.getItem(key, true)
	if item == nil {
		return
	}
	set, ok := item.value.(map[string]struct{})
	if !ok {
		return
	}
	for _, member := range members {
		delete(set, fmt.Sprintf("%v", member))
	}
}

func (s *memoryStore) SRandMember(key string) (string, error) {
	item := s.getItem(key, false)
	if item == nil {
		return "", ErrNotFound
	}
	set, ok := item.value.(map[string]struct{})
	if !ok || len(set) == 0 {
		return "", ErrNotFound
	}
	s.mu.RLock()
	defer s.mu.RUnlock()
	members := make([]string, 0, len(set))
	for member := range set {
		members = append(members, member)
	}
	if len(members) == 0 {
		return "", ErrNotFound
	}
	return members[rand.Intn(len(members))], nil
}
func (s *memoryStore) Rotate(key string) (string, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	item := s.getItem(key, true)
	if item == nil {
		return "", ErrNotFound
	}
	list, ok := item.value.([]string)
	if !ok || len(list) == 0 {
		return "", ErrNotFound
	}
	val := list[len(list)-1]
	item.value = append([]string{val}, list[:len(list)-1]...)
	return val, nil
}
func (s *memoryStore) LIndex(key string, index int64) (string, error) {
	item := s.getItem(key, false)
	if item == nil {
		return "", ErrNotFound
	}
	list, ok := item.value.([]string)
	if !ok {
		return "", ErrNotFound
	}
	s.mu.RLock()
	defer s.mu.RUnlock()
	l := int64(len(list))
	if index < 0 {
		index += l
	}
	if index < 0 || index >= l {
		return "", ErrNotFound
	}
	return list[index], nil
}

// Zset methods... (ZAdd, ZRange, ZRem)
func (s *memoryStore) ZAdd(key string, members map[string]float64) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	item := s.getItem(key, true)
	if item == nil {
		item = &memoryStoreItem{value: make([]zsetMember, 0)}
		s.items[key] = item
	}
	zset, ok := item.value.([]zsetMember)
	if !ok {
		zset = make([]zsetMember, 0)
	}
	for memberVal, score := range members {
		found := false
		for i := range zset {
			if zset[i].Value == memberVal {
				zset[i].Score = score
				found = true
				break
			}
		}
		if !found {
			zset = append(zset, zsetMember{Value: memberVal, Score: score})
		}
	}
	sort.Slice(zset, func(i, j int) bool {
		if zset[i].Score == zset[j].Score {
			return zset[i].Value < zset[j].Value
		}
		return zset[i].Score < zset[j].Score
	})
	item.value = zset
	return nil
}
func (s *memoryStore) ZRange(key string, start, stop int64) ([]string, error) {
	item := s.getItem(key, false)
	if item == nil {
		return []string{}, nil
	}
	zset, ok := item.value.([]zsetMember)
	if !ok {
		return []string{}, nil
	}
	s.mu.RLock()
	defer s.mu.RUnlock()
	l := int64(len(zset))
	if start < 0 {
		start += l
	}
	if stop < 0 {
		stop += l
	}
	if start < 0 {
		start = 0
	}
	if start > stop || start >= l {
		return []string{}, nil
	}
	if stop >= l {
		stop = l - 1
	}
	result := make([]string, 0, stop-start+1)
	for i := start; i <= stop; i++ {
		result = append(result, zset[i].Value)
	}
	return result, nil
}
func (s *memoryStore) ZRem(key string, members ...any) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	item := s.getItem(key, true)
	if item == nil {
		return nil
	}
	zset, ok := item.value.([]zsetMember)
	if !ok {
		return nil
	}
	membersToRemove := make(map[string]struct{}, len(members))
	for _, m := range members {
		membersToRemove[fmt.Sprintf("%v", m)] = struct{}{}
	}
	newZSet := make([]zsetMember, 0, len(zset))
	for _, z := range zset {
		if _, exists := membersToRemove[z.Value]; !exists {
			newZSet = append(newZSet, z)
		}
	}
	item.value = newZSet
	return nil
}
func (s *memoryStore) PopAndCycleSetMember(mainKey, cooldownKey string) (string, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	mainItem := s.getItem(mainKey, true)
	if mainItem == nil || len(mainItem.value.(map[string]struct{})) == 0 {
		cooldownItem := s.getItem(cooldownKey, true)
		if cooldownItem == nil {
			return "", ErrNotFound
		}
		// "Rename" by moving value and deleting old key
		s.items[mainKey] = cooldownItem
		delete(s.items, cooldownKey)
		mainItem = cooldownItem
	}
	mainSet, ok := mainItem.value.(map[string]struct{})
	if !ok || len(mainSet) == 0 {
		return "", ErrNotFound // Should not happen after cycle logic
	}
	var popped string
	for k := range mainSet {
		popped = k
		break
	}
	delete(mainSet, popped)
	return popped, nil
}

// Pipeline implementation
type memoryPipeliner struct {
	store *memoryStore
	ops   []func()
}

func (s *memoryStore) Pipeline() Pipeliner {
	return &memoryPipeliner{store: s}
}
func (p *memoryPipeliner) Exec() error {
	p.store.mu.Lock()
	defer p.store.mu.Unlock()
	for _, op := range p.ops {
		op()
	}
	return nil
}

// [核心修正] Expire 现在可以正确地为任何 key 设置过期时间
func (p *memoryPipeliner) Expire(key string, expiration time.Duration) {
	p.ops = append(p.ops, func() {
		// This must be called within Exec's lock
		item := p.store.getItem(key, true)
		if item != nil {
			item.expireAt = time.Now().Add(expiration)
		}
	})
}

// All other pipeliner methods...
func (p *memoryPipeliner) HSet(key string, values map[string]any) {
	p.ops = append(p.ops, func() { p.store.hSetNoLock(key, values) })
}
func (p *memoryPipeliner) HIncrBy(key, field string, incr int64) {
	p.ops = append(p.ops, func() { p.store.hIncrByNoLock(key, field, incr) })
}
func (p *memoryPipeliner) Del(keys ...string) {
	p.ops = append(p.ops, func() { p.store.delNoLock(keys...) })
}
func (p *memoryPipeliner) SAdd(key string, members ...any) {
	p.ops = append(p.ops, func() { p.store.sAddNoLock(key, members...) })
}
func (p *memoryPipeliner) SRem(key string, members ...any) {
	p.ops = append(p.ops, func() { p.store.sRemNoLock(key, members...) })
}
func (p *memoryPipeliner) LPush(key string, values ...any) {
	p.ops = append(p.ops, func() { p.store.lPushNoLock(key, values...) })
}
func (p *memoryPipeliner) LRem(key string, count int64, value any) {
	p.ops = append(p.ops, func() { p.store.lRemNoLock(key, count, value) })
}

// Pub/Sub implementation (remains unchanged as it's a separate system)
type memorySubscription struct {
	store       *memoryStore
	channelName string
	msgChan     chan *Message
}

func (ms *memorySubscription) Channel() <-chan *Message { return ms.msgChan }
func (ms *memorySubscription) Close() error {
	return ms.store.removeSubscriber(ms.channelName, ms.msgChan)
}
func (s *memoryStore) Publish(channel string, message []byte) error {
	s.mu.RLock()
	defer s.mu.RUnlock()
	subscribers, ok := s.pubsub[channel]
	if !ok {
		return nil
	}
	msg := &Message{Channel: channel, Payload: message}
	for _, ch := range subscribers {
		select {
		case ch <- msg:
		case <-time.After(100 * time.Millisecond):
			s.logger.Warnf("Could not publish to a subscriber on channel '%s' within 100ms", channel)
		}
	}
	return nil
}
func (s *memoryStore) Subscribe(channel string) (Subscription, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	msgChan := make(chan *Message, 10)
	sub := &memorySubscription{store: s, channelName: channel, msgChan: msgChan}
	s.pubsub[channel] = append(s.pubsub[channel], msgChan)
	return sub, nil
}
func (s *memoryStore) removeSubscriber(channelName string, msgChan chan *Message) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	subscribers, ok := s.pubsub[channelName]
	if !ok {
		return nil
	}
	newSubscribers := make([]chan *Message, 0)
	for _, ch := range subscribers {
		if ch != msgChan {
			newSubscribers = append(newSubscribers, ch)
		}
	}
	if len(newSubscribers) == 0 {
		delete(s.pubsub, channelName)
	} else {
		s.pubsub[channelName] = newSubscribers
	}
	close(msgChan)
	return nil
}