feat: add feed cache implementation and integrate with channel handler

internal/rss/cache.go

@@ -0,0 +1,99 @@
+package rss
+
+import (
+	"context"
+	"sync"
+	"time"
+
+	"go.uber.org/fx"
+	"go.uber.org/zap"
+)
+
+type FeedCache struct {
+	logger     *zap.Logger
+	feedsCache map[string]*RSSFeed
+	mu         sync.Mutex
+}
+
+func NewFeedCache(logger *zap.Logger) *FeedCache {
+	return &FeedCache{logger: logger, feedsCache: map[string]*RSSFeed{}, mu: sync.Mutex{}}
+}
+
+func (c *FeedCache) SetFeedToFeedCache(channelId string, feed *RSSFeed) {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	c.feedsCache[channelId] = feed
+}
+
+func (c *FeedCache) GetFeedFromFeedCache(channelId string, limit int) *RSSFeed {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	if feed, ok := c.feedsCache[channelId]; ok {
+		feedBuildTime, err := time.Parse("Mon, 02 Jan 2006 15:04 -0700", feed.Channel.LastBuildDate)
+		if err != nil || time.Since(feedBuildTime) > time.Minute*15 {
+			delete(c.feedsCache, channelId)
+			return nil
+		}
+
+		if len(feed.Channel.Items) >= limit {
+			feedCopy := *feed
+			feedCopy.Channel.Items = feed.Channel.Items[len(feed.Channel.Items)-limit:]
+			c.logger.Debug("Cache hit on channel ID", zap.String("channelId", channelId))
+			return &feedCopy
+		}
+		return nil
+	}
+	return nil
+}
+
+func (c *FeedCache) CleanupFeedCache() {
+	c.mu.Lock()
+	defer c.mu.Unlock()
+
+	for channelId, feed := range c.feedsCache {
+		feedBuildTime, _ := time.Parse("Mon, 02 Jan 2006 15:04 MST", feed.Channel.LastBuildDate)
+		if time.Since(feedBuildTime) > time.Minute*15 {
+			delete(c.feedsCache, channelId)
+		}
+
+	}
+
+}
+
+func RegisterFeedCacheCleanup(lc fx.Lifecycle, logger *zap.Logger, f *FeedCache) {
+	var ticker *time.Ticker
+	var stopChan chan struct{}
+
+	lc.Append(fx.Hook{
+		OnStart: func(ctx context.Context) error {
+			logger.Info("Starting feed cache cleanup task", zap.Duration("interval", 30*time.Minute))
+			ticker = time.NewTicker(20 * time.Minute)
+			stopChan = make(chan struct{})
+			go func() {
+				for {
+					select {
+					case <-ticker.C:
+						logger.Info("Running feed cache cleanup")
+						f.CleanupFeedCache()
+						logger.Info("Feed cache cleanup completed")
+					case <-stopChan:
+						return
+					}
+				}
+			}()
+			return nil
+		},
+		OnStop: func(ctx context.Context) error {
+			logger.Info("Stopping feed cache cleanup task")
+			if ticker != nil {
+				ticker.Stop()
+			}
+			if stopChan != nil {
+				close(stopChan)
+			}
+			return nil
+		},
+	})
+}