From 7ef25e55e4bf2bca44f48c8fdd07e71a414045f5 Mon Sep 17 00:00:00 2001
From: Matthew Bessette <blade30912@gmail.com>
Date: Mon, 14 Feb 2022 06:23:39 +0000
Subject: [PATCH] Add 'archive-bundler.service.ts'

---
 archive-bundler.service.ts | 111 +++++++++++++++++++++++++++++++++++++
 1 file changed, 111 insertions(+)
 create mode 100644 archive-bundler.service.ts

diff --git a/archive-bundler.service.ts b/archive-bundler.service.ts
new file mode 100644
index 0000000..5925905
--- /dev/null
+++ b/archive-bundler.service.ts
@@ -0,0 +1,111 @@
+import { Injectable, Logger } from '@nestjs/common';
+import { Readable, Writable } from 'stream';
+import { S3Service } from '../s3/s3.service';
+import { BufferManager } from '../utils/buffer.manager';
+import * as archiver from 'archiver';
+import { CompletedPart } from '@aws-sdk/client-s3';
+
+const MAX_CHUNK_SIZE = 1024 * 1024 * 5;
+
+@Injectable()
+export class ArchiveBundlerService {
+
+  private readonly logger = new Logger(ArchiveBundlerService.name);
+
+  constructor(
+    private readonly s3Service: S3Service,
+  ) { }
+
+  async generateZipFromKeys(bucket: string, keys: string[], archiveKey: string): Promise<void> {
+
+    const archiveTransformer = archiver('zip', {
+      zlib: { level: 9 },
+    });
+
+    const { UploadId } = await this.s3Service.createMultiPartUpload({
+      Bucket: bucket,
+      Key: archiveKey,
+    });
+
+    let partNumber = 1;
+    const completedParts: CompletedPart[] = [];
+    const bufferManager = new BufferManager(MAX_CHUNK_SIZE);
+
+    const eventDataHandler = async (data: Buffer, final: boolean = false) => {
+
+      if (bufferManager.hasRoom(data) && !final) {
+        bufferManager.append(data);
+        return;
+      }
+
+      console.log(`Currently at ${process.memoryUsage().heapUsed / 1024 / 1024} MB RAM`);
+
+      const eventPartNumber = partNumber++;
+      const Body = bufferManager.appendAndGetCompletedBuffer(data);
+
+      const { ETag } = await this.s3Service.uploadPart({
+        UploadId,
+        Body,
+        Bucket: bucket,
+        Key: archiveKey,
+        PartNumber: eventPartNumber,
+        ContentLength: Body.length,
+      });
+
+      completedParts.push({
+        ETag,
+        PartNumber: eventPartNumber,
+      });
+    };
+
+    const writableStream = new Writable({
+      write: async (record, _, callback) => {
+        await eventDataHandler(record);
+        callback();
+      },
+    });
+
+    archiveTransformer.pipe(writableStream);
+
+    archiveTransformer.on('warning', (err) => {
+      this.logger.warn(err);
+    });
+
+    for (const key of keys) {
+
+      const fileNameParts = key.split('/');
+      const fileName = fileNameParts[fileNameParts.length - 1];
+
+      console.log(`Reading ${key} into ${fileName}`);
+
+      const { Body } = await this.s3Service.getObject({
+        Bucket: bucket,
+        Key: key,
+      });
+
+      const readStream = Body as Readable;
+
+      archiveTransformer.append(readStream, { name: fileName });
+    }
+
+    archiveTransformer.finalize();
+
+    return await new Promise((resolve) => {
+      writableStream.on('finish', async () => {
+
+        await eventDataHandler(Buffer.alloc(0), true);
+
+        await this.s3Service.completeMultiPartUpload({
+          UploadId,
+          Bucket: bucket,
+          Key: archiveKey,
+          MultipartUpload: {
+            Parts: completedParts,
+          },
+        });
+
+        resolve();
+      });
+    });
+  }
+}