first commit

backend/internal/repository/redeem_cache.go

@@ -0,0 +1,62 @@
+package repository
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"github.com/Wei-Shaw/sub2api/internal/service"
+	"github.com/redis/go-redis/v9"
+)
+
+const (
+	redeemRateLimitKeyPrefix = "redeem:ratelimit:"
+	redeemLockKeyPrefix      = "redeem:lock:"
+	redeemRateLimitDuration  = 24 * time.Hour
+)
+
+// redeemRateLimitKey generates the Redis key for redeem attempt rate limiting.
+func redeemRateLimitKey(userID int64) string {
+	return fmt.Sprintf("%s%d", redeemRateLimitKeyPrefix, userID)
+}
+
+// redeemLockKey generates the Redis key for redeem code locking.
+func redeemLockKey(code string) string {
+	return redeemLockKeyPrefix + code
+}
+
+type redeemCache struct {
+	rdb *redis.Client
+}
+
+func NewRedeemCache(rdb *redis.Client) service.RedeemCache {
+	return &redeemCache{rdb: rdb}
+}
+
+func (c *redeemCache) GetRedeemAttemptCount(ctx context.Context, userID int64) (int, error) {
+	key := redeemRateLimitKey(userID)
+	count, err := c.rdb.Get(ctx, key).Int()
+	if err == redis.Nil {
+		return 0, nil
+	}
+	return count, err
+}
+
+func (c *redeemCache) IncrementRedeemAttemptCount(ctx context.Context, userID int64) error {
+	key := redeemRateLimitKey(userID)
+	pipe := c.rdb.Pipeline()
+	pipe.Incr(ctx, key)
+	pipe.Expire(ctx, key, redeemRateLimitDuration)
+	_, err := pipe.Exec(ctx)
+	return err
+}
+
+func (c *redeemCache) AcquireRedeemLock(ctx context.Context, code string, ttl time.Duration) (bool, error) {
+	key := redeemLockKey(code)
+	return c.rdb.SetNX(ctx, key, 1, ttl).Result()
+}
+
+func (c *redeemCache) ReleaseRedeemLock(ctx context.Context, code string) error {
+	key := redeemLockKey(code)
+	return c.rdb.Del(ctx, key).Err()
+}