// Filename: internal/store/memory_store.go

package store

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

	"github.com/sirupsen/logrus"
)

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

type memoryStoreItem struct {
	value    interface{}
	expireAt time.Time
}

func (item *memoryStoreItem) isExpired() bool {
	return !item.expireAt.IsZero() && time.Now().After(item.expireAt)
}

type zsetMember struct {
	Value string
	Score float64
}

type memoryStore struct {
	items  map[string]*memoryStoreItem
	pubsub map[string][]chan *Message
	mu     sync.RWMutex
	rng    *rand.Rand
	rngMu  sync.Mutex
	logger *logrus.Entry
}

func NewMemoryStore(logger *logrus.Logger) Store {
	store := &memoryStore{
		items:  make(map[string]*memoryStoreItem),
		pubsub: make(map[string][]chan *Message),
		rng:    rand.New(rand.NewSource(time.Now().UnixNano())),
		logger: logger.WithField("component", "store.memory 🗱"),
	}
	go store.startGCollector()
	return store
}

func (s *memoryStore) startGCollector() {
	ticker := time.NewTicker(5 * time.Minute)
	defer ticker.Stop()
	for range ticker.C {
		s.mu.Lock()
		now := time.Now()
		for key, item := range s.items {
			if !item.expireAt.IsZero() && now.After(item.expireAt) {
				delete(s.items, key)
			}
		}
		s.mu.Unlock()
	}
}

// --- [架构修正] 所有方法签名都增加了 context.Context 参数以匹配接口 ---
// --- 内存实现可以忽略该参数，用 _ 接收 ---

func (s *memoryStore) Set(_ context.Context, 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(_ context.Context, key string) ([]byte, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		return nil, ErrNotFound
	}
	if value, ok := item.value.([]byte); ok {
		return value, nil
	}
	return nil, ErrNotFound
}

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

func (s *memoryStore) Exists(_ context.Context, key string) (bool, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	item, ok := s.items[key]
	return ok && !item.isExpired(), nil
}

func (s *memoryStore) SetNX(_ context.Context, key string, value []byte, ttl time.Duration) (bool, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	item, ok := s.items[key]
	if ok && !item.isExpired() {
		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(_ context.Context, key string, fields ...string) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		return nil
	}
	if hash, ok := item.value.(map[string]string); ok {
		for _, field := range fields {
			delete(hash, field)
		}
	}
	return nil
}

func (s *memoryStore) HSet(_ context.Context, key string, values map[string]any) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		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
	}
	for field, value := range values {
		hash[field] = fmt.Sprintf("%v", value)
	}
	return nil
}

func (s *memoryStore) HGetAll(_ context.Context, key string) (map[string]string, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		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(_ context.Context, key, field string, incr int64) (int64, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		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(_ context.Context, key string, values ...any) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		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...)
	return nil
}

func (s *memoryStore) LRem(_ context.Context, key string, count int64, value any) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		return nil
	}
	list, ok := item.value.([]string)
	if !ok {
		return nil
	}
	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
	return nil
}

func (s *memoryStore) SAdd(_ context.Context, key string, members ...any) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		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{}{}
	}
	return nil
}

func (s *memoryStore) SPopN(_ context.Context, key string, count int64) ([]string, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		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)
	}
	s.rngMu.Lock()
	s.rng.Shuffle(len(keys), func(i, j int) { keys[i], keys[j] = keys[j], keys[i] })
	s.rngMu.Unlock()
	for i := int64(0); i < count; i++ {
		poppedKey := keys[i]
		popped = append(popped, poppedKey)
		delete(set, poppedKey)
	}
	return popped, nil
}

func (s *memoryStore) SMembers(_ context.Context, key string) ([]string, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		return []string{}, nil
	}
	set, ok := item.value.(map[string]struct{})
	if !ok {
		return []string{}, nil
	}
	members := make([]string, 0, len(set))
	for member := range set {
		members = append(members, member)
	}
	return members, nil
}

func (s *memoryStore) SRem(_ context.Context, key string, members ...any) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		return nil
	}
	set, ok := item.value.(map[string]struct{})
	if !ok {
		return nil
	}
	for _, member := range members {
		delete(set, fmt.Sprintf("%v", member))
	}
	return nil
}

func (s *memoryStore) SRandMember(_ context.Context, key string) (string, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		return "", ErrNotFound
	}
	set, ok := item.value.(map[string]struct{})
	if !ok || len(set) == 0 {
		return "", ErrNotFound
	}
	members := make([]string, 0, len(set))
	for member := range set {
		members = append(members, member)
	}
	if len(members) == 0 {
		return "", ErrNotFound
	}
	s.rngMu.Lock()
	n := s.rng.Intn(len(members))
	s.rngMu.Unlock()
	return members[n], nil
}

func (s *memoryStore) Rotate(_ context.Context, key string) (string, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		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(_ context.Context, key string, index int64) (string, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		return "", ErrNotFound
	}
	list, ok := item.value.([]string)
	if !ok {
		return "", ErrNotFound
	}
	l := int64(len(list))
	if index < 0 {
		index += l
	}
	if index < 0 || index >= l {
		return "", ErrNotFound
	}
	return list[index], nil
}

func (s *memoryStore) ZAdd(_ context.Context, key string, members map[string]float64) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		item = &memoryStoreItem{value: make([]zsetMember, 0)}
		s.items[key] = item
	}
	zset, ok := item.value.([]zsetMember)
	if !ok {
		zset = make([]zsetMember, 0)
	}
	membersMap := make(map[string]float64, len(zset))
	for _, z := range zset {
		membersMap[z.Value] = z.Score
	}
	for memberVal, score := range members {
		membersMap[memberVal] = score
	}
	newZSet := make([]zsetMember, 0, len(membersMap))
	for val, score := range membersMap {
		newZSet = append(newZSet, zsetMember{Value: val, Score: score})
	}
	sort.Slice(newZSet, func(i, j int) bool {
		if newZSet[i].Score == newZSet[j].Score {
			return newZSet[i].Value < newZSet[j].Value
		}
		return newZSet[i].Score < newZSet[j].Score
	})
	item.value = newZSet
	return nil
}
func (s *memoryStore) ZRange(_ context.Context, key string, start, stop int64) ([]string, error) {
	s.mu.RLock()
	defer s.mu.RUnlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		return []string{}, nil
	}
	zset, ok := item.value.([]zsetMember)
	if !ok {
		return []string{}, nil
	}
	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(_ context.Context, key string, members ...any) error {
	s.mu.Lock()
	defer s.mu.Unlock()
	item, ok := s.items[key]
	if !ok || item.isExpired() {
		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(_ context.Context, mainKey, cooldownKey string) (string, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	mainItem, mainOk := s.items[mainKey]
	var mainSet map[string]struct{}
	if mainOk && !mainItem.isExpired() {
		mainSet, mainOk = mainItem.value.(map[string]struct{})
		mainOk = mainOk && len(mainSet) > 0
	} else {
		mainOk = false
	}
	if !mainOk {
		cooldownItem, cooldownOk := s.items[cooldownKey]
		if !cooldownOk || cooldownItem.isExpired() {
			return "", ErrNotFound
		}
		cooldownSet, cooldownSetOk := cooldownItem.value.(map[string]struct{})
		if !cooldownSetOk || len(cooldownSet) == 0 {
			return "", ErrNotFound
		}
		s.items[mainKey] = cooldownItem
		delete(s.items, cooldownKey)
		mainSet = cooldownSet
	}
	var popped string
	for k := range mainSet {
		popped = k
		break
	}
	delete(mainSet, popped)
	cooldownItem, cooldownOk := s.items[cooldownKey]
	if !cooldownOk || cooldownItem.isExpired() {
		cooldownItem = &memoryStoreItem{value: make(map[string]struct{})}
		s.items[cooldownKey] = cooldownItem
	}
	cooldownSet, ok := cooldownItem.value.(map[string]struct{})
	if !ok {
		cooldownSet = make(map[string]struct{})
		cooldownItem.value = cooldownSet
	}
	cooldownSet[popped] = struct{}{}
	return popped, nil
}

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

func (s *memoryStore) Pipeline(_ context.Context) 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
}

func (p *memoryPipeliner) Expire(key string, expiration time.Duration) {
	capturedKey := key
	p.ops = append(p.ops, func() {
		if item, ok := p.store.items[capturedKey]; ok {
			item.expireAt = time.Now().Add(expiration)
		}
	})
}
func (p *memoryPipeliner) Del(keys ...string) {
	capturedKeys := make([]string, len(keys))
	copy(capturedKeys, keys)
	p.ops = append(p.ops, func() {
		for _, key := range capturedKeys {
			delete(p.store.items, key)
		}
	})
}
func (p *memoryPipeliner) SAdd(key string, members ...any) {
	capturedKey := key
	capturedMembers := make([]any, len(members))
	copy(capturedMembers, members)
	p.ops = append(p.ops, func() {
		item, ok := p.store.items[capturedKey]
		if !ok || item.isExpired() {
			item = &memoryStoreItem{value: make(map[string]struct{})}
			p.store.items[capturedKey] = item
		}
		set, ok := item.value.(map[string]struct{})
		if !ok {
			set = make(map[string]struct{})
			item.value = set
		}
		for _, member := range capturedMembers {
			set[fmt.Sprintf("%v", member)] = struct{}{}
		}
	})
}
func (p *memoryPipeliner) SRem(key string, members ...any) {
	capturedKey := key
	capturedMembers := make([]any, len(members))
	copy(capturedMembers, members)
	p.ops = append(p.ops, func() {
		item, ok := p.store.items[capturedKey]
		if !ok || item.isExpired() {
			return
		}
		set, ok := item.value.(map[string]struct{})
		if !ok {
			return
		}
		for _, member := range capturedMembers {
			delete(set, fmt.Sprintf("%v", member))
		}
	})
}
func (p *memoryPipeliner) LPush(key string, values ...any) {
	capturedKey := key
	capturedValues := make([]any, len(values))
	copy(capturedValues, values)
	p.ops = append(p.ops, func() {
		item, ok := p.store.items[capturedKey]
		if !ok || item.isExpired() {
			item = &memoryStoreItem{value: make([]string, 0)}
			p.store.items[capturedKey] = item
		}
		list, ok := item.value.([]string)
		if !ok {
			list = make([]string, 0)
		}
		stringValues := make([]string, len(capturedValues))
		for i, v := range capturedValues {
			stringValues[i] = fmt.Sprintf("%v", v)
		}
		item.value = append(stringValues, list...)
	})
}
func (p *memoryPipeliner) LRem(key string, count int64, value any)     {}
func (p *memoryPipeliner) HSet(key string, values map[string]any)      {}
func (p *memoryPipeliner) HIncrBy(key, field string, incr int64)       {}
func (p *memoryPipeliner) ZAdd(key string, members map[string]float64) {}
func (p *memoryPipeliner) ZRem(key string, members ...any)             {}

type memorySubscription struct {
	store       *memoryStore
	channelName string
	msgChan     chan *Message
}

func (ms *memorySubscription) Channel() <-chan *Message { return ms.msgChan }
func (ms *memorySubscription) ChannelName() string      { return ms.channelName }
func (ms *memorySubscription) Close() error {
	return ms.store.removeSubscriber(ms.channelName, ms.msgChan)
}
func (s *memoryStore) Publish(_ context.Context, 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(_ context.Context, 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
}