refactor: split update service responsibilities

src/main/services/update/update-storage-client.ts

@@ -0,0 +1,57 @@
+import * as fs from 'fs'
+import * as path from 'path'
+import { GetObjectCommand, S3Client } from '@aws-sdk/client-s3'
+import type { UpdateConfig } from '../../types/config.schema'
+
+export class UpdateStorageClient {
+  private client: S3Client
+  private bucket: string
+
+  constructor(config: UpdateConfig) {
+    this.bucket = config.bucket
+    this.client = new S3Client({
+      region: config.region,
+      endpoint: config.endpoint,
+      credentials: {
+        accessKeyId: config.accessKey,
+        secretAccessKey: config.secretKey
+      },
+      forcePathStyle: true
+    })
+  }
+
+  async readText(key: string): Promise<string> {
+    const response = await this.client.send(
+      new GetObjectCommand({
+        Bucket: this.bucket,
+        Key: key
+      })
+    )
+
+    const chunks: Buffer[] = []
+    for await (const chunk of response.Body as AsyncIterable<Uint8Array>) {
+      chunks.push(Buffer.from(chunk))
+    }
+    return Buffer.concat(chunks).toString('utf-8')
+  }
+
+  async downloadToFile(key: string, destination: string): Promise<void> {
+    const response = await this.client.send(
+      new GetObjectCommand({
+        Bucket: this.bucket,
+        Key: key
+      })
+    )
+
+    await fs.promises.mkdir(path.dirname(destination), { recursive: true })
+    const output = fs.createWriteStream(destination)
+    const body = response.Body as NodeJS.ReadableStream
+
+    await new Promise<void>((resolve, reject) => {
+      body.on('error', reject)
+      output.on('error', reject)
+      output.on('finish', resolve)
+      body.pipe(output)
+    })
+  }
+}