package cache

import (
	"fmt"
)

// 缓存键前缀常量
const (
	// 帖子相关
	PrefixPostList = "posts:list"
	PrefixPost     = "posts:detail"
	// HotRankZSet 热门榜（有序集合，member=post_id，score=归一化热度，仅存 TopN）
	HotRankZSet = "posts:hot:zset"
	// HotRankTopIDs 热门榜有序 post_id 列表（JSON []string，供分层缓存本地层命中）
	HotRankTopIDs = "posts:hot:top_ids"

	// 会话相关
	PrefixConversationList   = "conversations:list"
	PrefixConversationDetail = "conversations:detail"

	// 群组相关
	PrefixGroupMembers = "groups:members"
	PrefixGroupInfo    = "groups:info"

	// 未读数相关
	PrefixUnreadSystem       = "unread:system"
	PrefixUnreadConversation = "unread:conversation"
	PrefixUnreadDetail       = "unread:detail"
		
	// 已读位置相关（OpenIM 风格：缓存 hasReadSeq，用于 O(1) 未读数计算）
	PrefixUserReadSeq = "user_read_seq"

	// 用户相关
	PrefixUserInfo = "users:info"
	PrefixUserMe   = "users:me"

	// 频道相关（全量列表一条缓存，供 /channels、帖子 channel 填充共用）
	PrefixChannelsAllList = "channels:all_list"

	// 消息缓存相关
	keyPrefixMsgHash       = "msg_hash"   // 消息详情 Hash
	keyPrefixMsgIndex      = "msg_index"  // 消息索引 Sorted Set
	keyPrefixMsgCount      = "msg_count"  // 消息计数
	keyPrefixMsgSeq        = "msg_seq"    // Seq 计数器
	keyPrefixMsgPage       = "msg_page"   // 分页缓存
	keyPrefixMsgIdempotent = "msg_idem"   // 消息幂等键

	// 帖子创建幂等键前缀（clientRequestID -> 已创建的 postID）
	keyPrefixPostIdempotent = "post_idem"
)

// PostListKey 生成帖子列表缓存键
// postType: 帖子类型 (hot, follow, latest)
// page: 页码
// pageSize: 每页数量
// userID: 用户维度（仅在个性化列表如 follow 场景使用）
// HotRankZSetKey 热门榜 Redis ZSET 逻辑键（仅存 TopN，会经 normalizeKey 加前缀）
func HotRankZSetKey() string {
	return HotRankZSet
}

// HotRankTopIDsKey 热门榜 Top 顺序 ID 列表键（会经 normalizeKey 加前缀）
func HotRankTopIDsKey() string {
	return HotRankTopIDs
}

func HotRankZSetChannelKey(channelID string) string {
	return fmt.Sprintf("%s:ch:%s", HotRankZSet, channelID)
}

func HotRankTopIDsChannelKey(channelID string) string {
	return fmt.Sprintf("%s:ch:%s", HotRankTopIDs, channelID)
}

func PostListKey(postType string, userID string, page, pageSize int) string {
	if userID == "" {
		return fmt.Sprintf("%s:%s:%d:%d", PrefixPostList, postType, page, pageSize)
	}
	return fmt.Sprintf("%s:%s:%s:%d:%d", PrefixPostList, postType, userID, page, pageSize)
}

// PostDetailKey 生成帖子详情缓存键
func PostDetailKey(postID string) string {
	return fmt.Sprintf("%s:%s", PrefixPost, postID)
}

// ConversationListKey 生成会话列表缓存键
func ConversationListKey(userID string, page, pageSize int) string {
	return fmt.Sprintf("%s:%s:%d:%d", PrefixConversationList, userID, page, pageSize)
}


// GroupMembersKey 生成群组成员缓存键
func GroupMembersKey(groupID string, page, pageSize int) string {
	return fmt.Sprintf("%s:%s:page:%d:size:%d", PrefixGroupMembers, groupID, page, pageSize)
}



// UnreadSystemKey 生成系统消息未读数缓存键
func UnreadSystemKey(userID string) string {
	return fmt.Sprintf("%s:%s", PrefixUnreadSystem, userID)
}

// UnreadConversationKey 生成会话未读总数缓存键
func UnreadConversationKey(userID string) string {
	return fmt.Sprintf("%s:%s", PrefixUnreadConversation, userID)
}

// UnreadDetailKey 生成单个会话未读数缓存键
func UnreadDetailKey(userID, conversationID string) string {
	return fmt.Sprintf("%s:%s:%s", PrefixUnreadDetail, userID, conversationID)
}


// ChannelsAllListKey 频道全量列表缓存键（含未启用，供 MapByIDs 解析历史帖子 channel）
func ChannelsAllListKey() string {
	return PrefixChannelsAllList
}

// InvalidateChannelList 失效频道列表缓存（管理端增删改频道后调用）
func InvalidateChannelList(c Cache) {
	c.Delete(ChannelsAllListKey())
}

// InvalidatePostList 失效帖子列表缓存
func InvalidatePostList(cache Cache) {
	cache.DeleteByPrefix(PrefixPostList)
}

// InvalidatePostDetail 失效帖子详情缓存
func InvalidatePostDetail(cache Cache, postID string) {
	cache.Delete(PostDetailKey(postID))
}

// InvalidateConversationList 失效会话列表缓存
func InvalidateConversationList(cache Cache, userID string) {
	cache.DeleteByPrefix(PrefixConversationList + ":" + userID + ":")
}


// InvalidateGroupMembers 失效群组成员缓存
func InvalidateGroupMembers(cache Cache, groupID string) {
	cache.DeleteByPrefix(PrefixGroupMembers + ":" + groupID)
}


// InvalidateUnreadSystem 失效系统消息未读数缓存
func InvalidateUnreadSystem(cache Cache, userID string) {
	cache.Delete(UnreadSystemKey(userID))
}

// InvalidateUnreadConversation 失效会话未读数缓存
func InvalidateUnreadConversation(cache Cache, userID string) {
	cache.Delete(UnreadConversationKey(userID))
}

// InvalidateUnreadDetail 失效单个会话未读数缓存
func InvalidateUnreadDetail(cache Cache, userID, conversationID string) {
	cache.Delete(UnreadDetailKey(userID, conversationID))
}


// ============================================================
// 消息缓存 Key 生成函数
// ============================================================

// MessageHashKey 消息详情 Hash key
func MessageHashKey(convID string) string {
	return fmt.Sprintf("%s:%s", keyPrefixMsgHash, convID)
}

// MessageIndexKey 消息索引 Sorted Set key
func MessageIndexKey(convID string) string {
	return fmt.Sprintf("%s:%s", keyPrefixMsgIndex, convID)
}

// MessageCountKey 消息计数 key
func MessageCountKey(convID string) string {
	return fmt.Sprintf("%s:%s", keyPrefixMsgCount, convID)
}

// MessageSeqKey Seq 计数器 key
func MessageSeqKey(convID string) string {
	return fmt.Sprintf("%s:%s", keyPrefixMsgSeq, convID)
}

// MessagePageKey 分页缓存 key
func MessagePageKey(convID string, page, pageSize int) string {
	return fmt.Sprintf("%s:%s:%d:%d", keyPrefixMsgPage, convID, page, pageSize)
}

// InvalidateMessagePages 失效会话消息分页缓存
func InvalidateMessagePages(cache Cache, conversationID string) {
	cache.DeleteByPrefix(fmt.Sprintf("%s:%s:", keyPrefixMsgPage, conversationID))
}

// MessageIdempotentKey 消息幂等键 (clientMsgID -> server MsgID)
func MessageIdempotentKey(senderID, clientMsgID string) string {
	return fmt.Sprintf("%s:%s:%s", keyPrefixMsgIdempotent, senderID, clientMsgID)
}

// PostCreateIdempotentKey 帖子创建幂等键 (userID + clientRequestID -> postID)
// 用于在 SetNX 原子抢占期间识别同一客户端请求的重试，避免重复发帖。
func PostCreateIdempotentKey(userID, clientRequestID string) string {
	return fmt.Sprintf("%s:%s:%s", keyPrefixPostIdempotent, userID, clientRequestID)
}

// UserReadSeqKey 用户已读位置缓存键（OpenIM 风格 SEQ_USER_READ:{convID}:{userID}）
func UserReadSeqKey(convID, userID string) string {
	return fmt.Sprintf("%s:%s:%s", PrefixUserReadSeq, convID, userID)
}