feat:添加热榜功能并添加了增加热度的方法。

backend/internal/feed/service.go

@@ -6,6 +6,7 @@ import (
 	rediscache "feedsystem_video_go/internal/redis"
 	"feedsystem_video_go/internal/video"
 	"fmt"
+	"strconv"
 	"time"
 )
 
@@ -229,6 +230,114 @@ func (f *FeedService) ListByFollowing(ctx context.Context, limit int, latestBefo
 	return resp, nil
 }
 
+func (f *FeedService) ListByPopularity(ctx context.Context, limit int, reqAsOf int64, offset int, viewerAccountID uint, latestPopularity int64, latestBefore time.Time, latestIDBefore uint) (ListByPopularityResponse, error) {
+	// Redis 热榜（稳定分页：as_of + offset）
+	if f.cache != nil {
+		asOf := time.Now().UTC().Truncate(time.Minute)
+		if reqAsOf > 0 {
+			asOf = time.Unix(reqAsOf, 0).UTC().Truncate(time.Minute)
+		}
+
+		const win = 60
+		keys := make([]string, 0, win)
+		for i := 0; i < win; i++ {
+			keys = append(keys, "hot:video:1m:"+asOf.Add(-time.Duration(i)*time.Minute).Format("200601021504"))
+		}
+
+		dest := "hot:video:merge:1m:" + asOf.Format("200601021504") // 快照key：同一个as_of页内复用
+		opCtx, cancel := context.WithTimeout(ctx, 80*time.Millisecond)
+		defer cancel()
+
+		exists, _ := f.cache.Exists(opCtx, dest)
+		if !exists {
+			_ = f.cache.ZUnionStore(opCtx, dest, keys, "SUM")
+			_ = f.cache.Expire(opCtx, dest, 2*time.Minute) // 给翻页留时间
+		}
+
+		start := int64(offset)
+		stop := start + int64(limit) - 1
+		members, err := f.cache.ZRevRange(opCtx, dest, start, stop)
+		if err == nil && len(members) == 0 {
+			if offset > 0 {
+				return ListByPopularityResponse{
+					VideoList:  []FeedVideoItem{},
+					AsOf:       asOf.Unix(),
+					NextOffset: offset,
+					HasMore:    false,
+				}, nil
+			}
+		}
+		if err == nil && len(members) > 0 {
+			ids := make([]uint, 0, len(members))
+			for _, m := range members {
+				u, err := strconv.ParseUint(m, 10, 64)
+				if err == nil && u > 0 {
+					ids = append(ids, uint(u))
+				}
+			}
+
+			videos, err := f.repo.GetByIDs(ctx, ids)
+			if err == nil {
+				byID := make(map[uint]*video.Video, len(videos))
+				for _, v := range videos {
+					byID[v.ID] = v
+				}
+				ordered := make([]*video.Video, 0, len(ids))
+				for _, id := range ids {
+					if v := byID[id]; v != nil {
+						ordered = append(ordered, v)
+					}
+				}
+				items, err := f.buildFeedVideos(ctx, ordered, viewerAccountID)
+				if err != nil {
+					return ListByPopularityResponse{}, err
+				}
+				resp := ListByPopularityResponse{
+					VideoList:  items,
+					AsOf:       asOf.Unix(),
+					NextOffset: offset + len(items),
+					HasMore:    len(items) == limit,
+				}
+				if len(ordered) > 0 {
+					last := ordered[len(ordered)-1]
+					nextPopularity := last.Popularity
+					nextBefore := last.CreateTime
+					nextID := last.ID
+					resp.NextLatestPopularity = &nextPopularity
+					resp.NextLatestBefore = &nextBefore
+					resp.NextLatestIDBefore = &nextID
+				}
+				return resp, nil
+			}
+		}
+	}
+
+	videos, err := f.repo.ListByPopularity(ctx, limit, latestPopularity, latestBefore, latestIDBefore)
+	if err != nil {
+		return ListByPopularityResponse{}, err
+	}
+	items, err := f.buildFeedVideos(ctx, videos, viewerAccountID)
+	if err != nil {
+		return ListByPopularityResponse{}, err
+	}
+	resp := ListByPopularityResponse{
+		VideoList:  items,
+		AsOf:       0,
+		NextOffset: 0,
+		HasMore:    len(items) == limit,
+	}
+	if len(videos) > 0 {
+		last := videos[len(videos)-1]
+		nextPopularity := last.Popularity
+		nextBefore := last.CreateTime
+		nextID := last.ID
+		resp.NextLatestPopularity = &nextPopularity
+		resp.NextLatestBefore = &nextBefore
+		resp.NextLatestIDBefore = &nextID
+	}
+	return resp, nil
+}
+
 func (f *FeedService) buildFeedVideos(ctx context.Context, videos []*video.Video, viewerAccountID uint) ([]FeedVideoItem, error) {
 	feedVideos := make([]FeedVideoItem, 0, len(videos))
 	videoIDs := make([]uint, len(videos))