Resilient APIs & Cloud Systems Engineered on AWS

import { SESClient, SendEmailCommand } from "@aws-sdk/client-ses";
import { S3Client, PutObjectCommand } from "@aws-sdk/client-s3";
import { getSignedUrl } from "@aws-sdk/s3-request-presigner";

// 1. Initialize AWS SES Client with connection pooling
export const sesClient = new SESClient({
  region: process.env.AWS_REGION || "ap-south-1",
  credentials: {
    accessKeyId: process.env.AWS_ACCESS_KEY_ID!,
    secretAccessKey: process.env.AWS_SECRET_ACCESS_KEY!,
  },
});

// 2. High-throughput transactional email dispatch with SNS bounce tracking
export async function sendTransactionalEmail({
  to,
  subject,
  htmlBody,
}: {
  to: string;
  subject: string;
  htmlBody: string;
}) {
  const command = new SendEmailCommand({
    Source: "Dendrite Notifications <notifications@dendritetechnologies.in>",
    Destination: { ToAddresses: [to] },
    Message: {
      Subject: { Data: subject, Charset: "UTF-8" },
      Body: { Html: { Data: htmlBody, Charset: "UTF-8" } },
    },
    // Triggers automated real-time SNS bounce & complaint webhook reconciliation
    ConfigurationSetName: "production-transactional-alerts",
  });

  return await sesClient.send(command);
}

// 3. Generate short-lived S3 Presigned Upload URL (Direct Client-to-S3 Streaming)
const s3Client = new S3Client({ region: process.env.AWS_REGION || "ap-south-1" });

export async function createPresignedUploadUrl(fileName: string, mimeType: string) {
  const key = `uploads/${Date.now()}-${fileName}`;
  const command = new PutObjectCommand({
    Bucket: process.env.AWS_S3_BUCKET_NAME || "dendrite-vault-prod",
    Key: key,
    ContentType: mimeType,
    ServerSideEncryption: "AES256",
  });

  // Client gets 60 seconds to stream file directly to S3 (zero server RAM saturation)
  const uploadUrl = await getSignedUrl(s3Client, command, { expiresIn: 60 });
  return { uploadUrl, key };
}