feat: getting presigned url of the uploaded attachment

packages/server/src/services/Attachments/GetAttachmentPresignedUrl.ts

@@ -0,0 +1,27 @@
+import { GetObjectCommand } from '@aws-sdk/client-s3';
+import { getSignedUrl } from '@aws-sdk/s3-request-presigner';
+import { s3 } from '@/lib/S3/S3';
+import { Service } from 'typedi';
+
+@Service()
+export class getAttachmentPresignedUrl {
+  /**
+   * Retrieves the presigned url of the given attachment key.
+   * @param {string} key 
+   * @returns {Promise<string?>}
+   */
+  async getPresignedUrl(key: string) {
+    const params = {
+      Bucket: process.env.AWS_BUCKET,
+      Key: key,
+      Expires: 60 * 5, // 5 minutes
+    };
+    const command = new GetObjectCommand({
+      Bucket: process.env.AWS_BUCKET,
+      Key: key,
+    });
+    const signedUrl = await getSignedUrl(s3, command, { expiresIn: 300 });
+
+    return signedUrl;
+  }
+}