feat(risk-control): add content moderation audit

backend/internal/repository/content_moderation_hash_cache.go

@@ -0,0 +1,71 @@
+package repository
+
+import (
+	"context"
+	"strings"
+
+	"github.com/Wei-Shaw/sub2api/internal/service"
+	"github.com/redis/go-redis/v9"
+)
+
+const contentModerationFlaggedHashSetKey = "content_moderation:flagged_hashes"
+
+type contentModerationHashCache struct {
+	rdb *redis.Client
+}
+
+func NewContentModerationHashCache(rdb *redis.Client) service.ContentModerationHashCache {
+	return &contentModerationHashCache{rdb: rdb}
+}
+
+func (c *contentModerationHashCache) RecordFlaggedInputHash(ctx context.Context, inputHash string) error {
+	inputHash = strings.TrimSpace(inputHash)
+	if c == nil || c.rdb == nil || inputHash == "" {
+		return nil
+	}
+	return c.rdb.SAdd(ctx, contentModerationFlaggedHashSetKey, inputHash).Err()
+}
+
+func (c *contentModerationHashCache) HasFlaggedInputHash(ctx context.Context, inputHash string) (bool, error) {
+	inputHash = strings.TrimSpace(inputHash)
+	if c == nil || c.rdb == nil || inputHash == "" {
+		return false, nil
+	}
+	return c.rdb.SIsMember(ctx, contentModerationFlaggedHashSetKey, inputHash).Result()
+}
+
+func (c *contentModerationHashCache) DeleteFlaggedInputHash(ctx context.Context, inputHash string) (bool, error) {
+	inputHash = strings.TrimSpace(inputHash)
+	if c == nil || c.rdb == nil || inputHash == "" {
+		return false, nil
+	}
+	deleted, err := c.rdb.SRem(ctx, contentModerationFlaggedHashSetKey, inputHash).Result()
+	if err != nil {
+		return false, err
+	}
+	return deleted > 0, nil
+}
+
+func (c *contentModerationHashCache) ClearFlaggedInputHashes(ctx context.Context) (int64, error) {
+	if c == nil || c.rdb == nil {
+		return 0, nil
+	}
+	deleted, err := c.rdb.SCard(ctx, contentModerationFlaggedHashSetKey).Result()
+	if err != nil {
+		return 0, err
+	}
+	if deleted == 0 {
+		return 0, nil
+	}
+	if err := c.rdb.Del(ctx, contentModerationFlaggedHashSetKey).Err(); err != nil {
+		return 0, err
+	}
+	return deleted, nil
+}
+
+func (c *contentModerationHashCache) CountFlaggedInputHashes(ctx context.Context) (int64, error) {
+	if c == nil || c.rdb == nil {
+		return 0, nil
+	}
+	return c.rdb.SCard(ctx, contentModerationFlaggedHashSetKey).Result()
+}