// finds a subscription using protocol, endpoint and topic_arn (which is a key in sns subscription)
func findSubscriptionByNonID(d *schema.ResourceData, snsconn *sns.SNS) (*sns.Subscription, error) {
	protocol := d.Get("protocol").(string)
	endpoint := d.Get("endpoint").(string)
	topic_arn := d.Get("topic_arn").(string)

	req := &sns.ListSubscriptionsByTopicInput{
		TopicArn: aws.String(topic_arn),
	}

	for {

		res, err := snsconn.ListSubscriptionsByTopic(req)

		if err != nil {
			return nil, fmt.Errorf("Error fetching subscripitions for topic %s : %s", topic_arn, err)
		}

		for _, subscription := range res.Subscriptions {
			log.Printf("[DEBUG] check subscription with EndPoint %s, Protocol %s,  topicARN %s and SubscriptionARN %s", *subscription.Endpoint, *subscription.Protocol, *subscription.TopicArn, *subscription.SubscriptionArn)
			if *subscription.Endpoint == endpoint && *subscription.Protocol == protocol && *subscription.TopicArn == topic_arn && !subscriptionHasPendingConfirmation(subscription.SubscriptionArn) {
				return subscription, nil
			}
		}

		// if there are more than 100 subscriptions then go to the next 100 otherwise return nil
		if res.NextToken != nil {
			req.NextToken = res.NextToken
		} else {
			return nil, nil
		}
	}
}
func subscribeToSNSTopic(d *schema.ResourceData, snsconn *sns.SNS) (output *sns.SubscribeOutput, err error) {
	protocol := d.Get("protocol").(string)
	endpoint := d.Get("endpoint").(string)
	topic_arn := d.Get("topic_arn").(string)
	endpoint_auto_confirms := d.Get("endpoint_auto_confirms").(bool)
	confirmation_timeout_in_minutes := d.Get("confirmation_timeout_in_minutes").(int)

	if strings.Contains(protocol, "http") && !endpoint_auto_confirms {
		return nil, fmt.Errorf("Protocol http/https is only supported for endpoints which auto confirms!")
	}

	log.Printf("[DEBUG] SNS create topic subscription: %s (%s) @ '%s'", endpoint, protocol, topic_arn)

	req := &sns.SubscribeInput{
		Protocol: aws.String(protocol),
		Endpoint: aws.String(endpoint),
		TopicArn: aws.String(topic_arn),
	}

	output, err = snsconn.Subscribe(req)
	if err != nil {
		return nil, fmt.Errorf("Error creating SNS topic: %s", err)
	}

	log.Printf("[DEBUG] Finished subscribing to topic %s with subscription arn %s", topic_arn, *output.SubscriptionArn)

	if strings.Contains(protocol, "http") && subscriptionHasPendingConfirmation(output.SubscriptionArn) {

		log.Printf("[DEBUG] SNS create topic subscription is pending so fetching the subscription list for topic : %s (%s) @ '%s'", endpoint, protocol, topic_arn)

		err = resource.Retry(time.Duration(confirmation_timeout_in_minutes)*time.Minute, func() *resource.RetryError {

			subscription, err := findSubscriptionByNonID(d, snsconn)

			if subscription != nil {
				output.SubscriptionArn = subscription.SubscriptionArn
				return nil
			}

			if err != nil {
				return resource.RetryableError(
					fmt.Errorf("Error fetching subscriptions for SNS topic %s: %s", topic_arn, err))
			}

			return resource.RetryableError(
				fmt.Errorf("Endpoint (%s) did not autoconfirm the subscription for topic %s", endpoint, topic_arn))
		})

		if err != nil {
			return nil, err
		}
	}

	log.Printf("[DEBUG] Created new subscription! %s", *output.SubscriptionArn)
	return output, nil
}
func subscribeToSNSTopic(d *schema.ResourceData, snsconn *sns.SNS) (output *sns.SubscribeOutput, err error) {
	protocol := d.Get("protocol").(string)
	endpoint := d.Get("endpoint").(string)
	topic_arn := d.Get("topic_arn").(string)

	log.Printf("[DEBUG] SNS create topic subscription: %s (%s) @ '%s'", endpoint, protocol, topic_arn)

	req := &sns.SubscribeInput{
		Protocol: aws.String(protocol),
		Endpoint: aws.String(endpoint),
		TopicArn: aws.String(topic_arn),
	}

	output, err = snsconn.Subscribe(req)
	if err != nil {
		return nil, fmt.Errorf("Error creating SNS topic: %s", err)
	}

	log.Printf("[DEBUG] Created new subscription!")
	return output, nil
}