feat: 添加灵感瀑布流 Redis 会话缓存操作

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/pkg/database/redis.go

@@ -11,7 +11,8 @@ import (
 )
 
 const (
-    BlacklistKeyPrefix = "blacklist:token:"
+    BlacklistKeyPrefix       = "blacklist:token:"
+    InspirationFlowKeyPrefix = "inspiration_flow:"
 )
 
 // RedisClient Redis 客户端单例
@@ -134,4 +135,117 @@ func RemoveFromBlacklist(ctx context.Context, token string) error {
 
     key := BlacklistKeyPrefix + tokenToHash(token)
     return RedisClient.Del(ctx, key).Err()
+}
+
+// InspirationFlowCacheEntry 单个展品缓存数据
+type InspirationFlowCacheEntry struct {
+    AssetID       int64  `json:"asset_id"`
+    Name          string `json:"name"`
+    CoverURL      string `json:"cover_url"`
+    LikeCount     int32  `json:"like_count"`
+    OwnerNickname string `json:"owner_nickname"`
+    Span          int32  `json:"span"`
+    MaterialType  string `json:"material_type"`
+}
+
+// InspirationFlowCache 会话缓存结构
+type InspirationFlowCache struct {
+    DisplayedIDs []int64                       `json:"displayed_ids"` // 已展示ID列表
+    History      map[int64]InspirationFlowCacheEntry `json:"history"`     // 历史数据详情
+}
+
+// InspirationFlowKey 生成灵感瀑布流缓存 Key
+func InspirationFlowKey(starID int64, sessionID string) string {
+    return fmt.Sprintf("%s%d:%s", InspirationFlowKeyPrefix, starID, sessionID)
+}
+
+// GetInspirationFlowCache 获取灵感瀑布流会话缓存
+func GetInspirationFlowCache(ctx context.Context, starID int64, sessionID string) (*InspirationFlowCache, error) {
+    if RedisClient == nil {
+        return nil, fmt.Errorf("redis client is not initialized")
+    }
+
+    key := InspirationFlowKey(starID, sessionID)
+    data, err := RedisClient.Get(ctx, key).Result()
+    if err == redis.Nil {
+        return &InspirationFlowCache{
+            DisplayedIDs: []int64{},
+            History:      make(map[int64]InspirationFlowCacheEntry),
+        }, nil
+    }
+    if err != nil {
+        return nil, err
+    }
+
+    var cache InspirationFlowCache
+    if err := json.Unmarshal([]byte(data), &cache); err != nil {
+        return nil, err
+    }
+    return &cache, nil
+}
+
+// SaveInspirationFlowCache 保存灵感瀑布流会话缓存
+func SaveInspirationFlowCache(ctx context.Context, starID int64, sessionID string, cache *InspirationFlowCache, ttl time.Duration) error {
+    if RedisClient == nil {
+        return fmt.Errorf("redis client is not initialized")
+    }
+
+    key := InspirationFlowKey(starID, sessionID)
+    data, err := json.Marshal(cache)
+    if err != nil {
+        return err
+    }
+
+    return RedisClient.Set(ctx, key, data, ttl).Err()
+}
+
+// AddToInspirationFlowCache 添加展品到会话缓存
+func AddToInspirationFlowCache(ctx context.Context, starID int64, sessionID string, entry InspirationFlowCacheEntry, ttl time.Duration) error {
+    cache, err := GetInspirationFlowCache(ctx, starID, sessionID)
+    if err != nil {
+        return err
+    }
+
+    // 检查是否已存在
+    for _, id := range cache.DisplayedIDs {
+        if id == entry.AssetID {
+            return nil // 已存在，跳过
+        }
+    }
+
+    // 添加到已展示列表
+    cache.DisplayedIDs = append(cache.DisplayedIDs, entry.AssetID)
+    // 添加到历史详情
+    if cache.History == nil {
+        cache.History = make(map[int64]InspirationFlowCacheEntry)
+    }
+    cache.History[entry.AssetID] = entry
+
+    return SaveInspirationFlowCache(ctx, starID, sessionID, cache, ttl)
+}
+
+// GetHistoryPage 获取历史数据的某一页
+func GetHistoryPage(cache *InspirationFlowCache, offset, limit int) []InspirationFlowCacheEntry {
+    if cache == nil || cache.History == nil {
+        return []InspirationFlowCacheEntry{}
+    }
+
+    // 按展示顺序反向遍历（最新展示的在前面）
+    items := make([]InspirationFlowCacheEntry, 0)
+    for i := len(cache.DisplayedIDs) - 1; i >= 0; i-- {
+        if entry, ok := cache.History[cache.DisplayedIDs[i]]; ok {
+            items = append(items, entry)
+        }
+    }
+
+    // 分页
+    start := offset
+    end := offset + limit
+    if start >= len(items) {
+        return []InspirationFlowCacheEntry{}
+    }
+    if end > len(items) {
+        end = len(items)
+    }
+    return items[start:end]
 }