Amazon S3 Storage Provider

dotnet add package Zetian
dotnet add package Zetian.Storage.AmazonS3

using Zetian.Server;
using Zetian.Storage.AmazonS3.Extensions;

// Basic S3 setup
var server = new SmtpServerBuilder()
    .Port(25)
    .WithS3Storage(
        "AKIAIOSFODNN7EXAMPLE",
        "wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY",
        "my-smtp-bucket")
    .Build();

await server.StartAsync();

// MinIO, Wasabi, or other S3-compatible services
var server = new SmtpServerBuilder()
    .Port(25)
    .WithS3CompatibleStorage(
        "http://localhost:9000", // MinIO endpoint
        "minioadmin",
        "minioadmin",
        "smtp-messages",
        config =>
        {
            config.ForcePathStyle = true; // Required for MinIO
            config.Region = "us-east-1";
        })
    .Build();

// Wasabi example
var server = new SmtpServerBuilder()
    .Port(25)
    .WithS3CompatibleStorage(
        "https://s3.wasabisys.com",
        "accessKey",
        "secretKey",
        "my-bucket",
        config =>
        {
            config.Region = "us-east-1";
        })
    .Build();

var server = new SmtpServerBuilder()
    .Port(25)
    .WithS3Storage(
        accessKeyId: Environment.GetEnvironmentVariable("AWS_ACCESS_KEY_ID"),
        secretAccessKey: Environment.GetEnvironmentVariable("AWS_SECRET_ACCESS_KEY"),
        bucketName: "smtp-messages",
        config =>
        {
            config.Region = "us-west-2";
            config.KeyPrefix = "emails/";
            
            // Server-side encryption
            config.EnableServerSideEncryption = true;
            config.KmsKeyId = "alias/my-kms-key";
            
            // Versioning
            config.EnableVersioning = true;
            
            // Storage class
            config.StorageClass = S3StorageClass.StandardInfrequentAccess;
            
            // Performance
            config.UseTransferAcceleration = true;
            config.CompressMessageBody = true;
        })
    .Build();

// Lifecycle rules for automatic management
{
  "Rules": [{
    "Id": "ArchiveOldEmails",
    "Status": "Enabled",
    "Transitions": [
      {
        "Days": 30,
        "StorageClass": "STANDARD_IA"
      },
      {
        "Days": 90,
        "StorageClass": "GLACIER"
      },
      {
        "Days": 365,
        "StorageClass": "DEEP_ARCHIVE"
      }
    ],
    "Expiration": {
      "Days": 730
    }
  }]
}

// Apply lifecycle policy
var lifecycleConfig = new LifecycleConfiguration
{
    Rules = new List<LifecycleRule>
    {
        new LifecycleRule
        {
            Id = "EmailArchiving",
            Status = LifecycleRuleStatus.Enabled,
            Transitions = new List<Transition>
            {
                new Transition { Days = 30, StorageClass = S3StorageClass.StandardInfrequentAccess },
                new Transition { Days = 90, StorageClass = S3StorageClass.Glacier }
            }
        }
    }
};

// KMS encryption for sensitive data
var putRequest = new PutObjectRequest
{
    BucketName = "smtp-messages",
    Key = "email-123.eml",
    ServerSideEncryptionMethod = ServerSideEncryptionMethod.AWSKMS,
    ServerSideEncryptionKeyManagementServiceKeyId = "arn:aws:kms:us-west-2:111122223333:key/abc123"
};

// Customer-provided encryption keys
var putRequest = new PutObjectRequest
{
    BucketName = "smtp-messages",
    Key = "email-123.eml",
    ServerSideEncryptionCustomerMethod = ServerSideEncryptionCustomerMethod.AES256,
    ServerSideEncryptionCustomerProvidedKey = "base64-encoded-256-bit-key",
    ServerSideEncryptionCustomerProvidedKeyMD5 = "base64-encoded-md5"
};