nikoksr/notify

package amazonsns

import (
    "context"
    "fmt"

    "github.com/aws/aws-sdk-go-v2/aws"
    "github.com/aws/aws-sdk-go-v2/config"
    "github.com/aws/aws-sdk-go-v2/credentials"
    "github.com/aws/aws-sdk-go-v2/service/sns"
)

// snsSendMessageAPI Basic interface to send messages through SNS.
//
//go:generate mockery --name=snsSendMessageAPI --output=. --case=underscore --inpackage
type snsSendMessageAPI interface {
    SendMessage(ctx context.Context,
        params *sns.PublishInput,
        optFns ...func(*sns.Options)) (*sns.PublishOutput, error)
}

// snsSendMessageClient Client specific for SNS using aws sdk v2.
type snsSendMessageClient struct {
    client *sns.Client
}

// SendMessage Client specific for SNS using aws sdk v2.
func (s snsSendMessageClient) SendMessage(ctx context.Context,
    params *sns.PublishInput,
    optFns ...func(*sns.Options),
) (*sns.PublishOutput, error) {
    return s.client.Publish(ctx, params, optFns...)
}

// AmazonSNS Basic structure with SNS information.
type AmazonSNS struct {
    sendMessageClient snsSendMessageAPI
    queueTopics       []string
}

// New creates a new AmazonSNS.
func New(accessKeyID, secretKey, region string) (*AmazonSNS, error) {
    credProvider := credentials.NewStaticCredentialsProvider(accessKeyID, secretKey, "")
    cfg, err := config.LoadDefaultConfig(
        context.Background(),
        config.WithCredentialsProvider(credProvider),
        config.WithRegion(region),
    )
    if err != nil {
        return nil, err
    }
    client := sns.NewFromConfig(cfg)
    return &AmazonSNS{
        sendMessageClient: snsSendMessageClient{client: client},
    }, nil
}

// AddReceivers takes queue urls and adds them to the internal topics
// list. The Send method will send a given message to all those
// Topics.
func (s *AmazonSNS) AddReceivers(queues ...string) {
    s.queueTopics = append(s.queueTopics, queues...)
}

// Send message to everyone on all topics.
func (s AmazonSNS) Send(ctx context.Context, subject, message string) error {
    // For each topic
    for _, topic := range s.queueTopics {
        // Create new input with subject, message and the specific topic
        input := &sns.PublishInput{
            Subject:  aws.String(subject),
            Message:  aws.String(message),
            TopicArn: aws.String(topic),
        }
        // Send the message
        _, err := s.sendMessageClient.SendMessage(ctx, input)
        if err != nil {
            return fmt.Errorf("send message using Amazon SNS to ARN TOPIC %q: %w", topic, err)
        }
    }
    return nil
}