feat: add desktop repo (#1071)

packages/desktop/app/javascripts/Main/Packages/Networking.ts

@@ -0,0 +1,75 @@
+import { IncomingMessage, net } from 'electron'
+import fs from 'fs'
+import path from 'path'
+import { pipeline as pipelineFn } from 'stream'
+import { promisify } from 'util'
+import { MessageType } from '../../../../test/TestIpcMessage'
+import { ensureDirectoryExists } from '../Utils/FileUtils'
+import { handleTestMessage } from '../Utils/Testing'
+import { isTesting } from '../Utils/Utils'
+
+const pipeline = promisify(pipelineFn)
+
+if (isTesting()) {
+  handleTestMessage(MessageType.GetJSON, getJSON)
+  handleTestMessage(MessageType.DownloadFile, downloadFile)
+}
+
+/**
+ * Downloads a file to the specified destination.
+ * @param filePath path to the saved file (will be created if it does
+ * not exist)
+ */
+export async function downloadFile(url: string, filePath: string): Promise<void> {
+  await ensureDirectoryExists(path.dirname(filePath))
+  const response = await get(url)
+  await pipeline(
+    /**
+     * IncomingMessage doesn't implement *every* property of ReadableStream
+     * but still all the ones that pipeline needs
+     * @see https://www.electronjs.org/docs/api/incoming-message
+     */
+    response as any,
+    fs.createWriteStream(filePath),
+  )
+}
+
+export async function getJSON<T>(url: string): Promise<T | undefined> {
+  const response = await get(url)
+  let data = ''
+  return new Promise((resolve, reject) => {
+    response
+      .on('data', (chunk) => {
+        data += chunk
+      })
+      .on('error', reject)
+      .on('end', () => {
+        try {
+          const parsed = JSON.parse(data)
+          resolve(parsed)
+        } catch (error) {
+          resolve(undefined)
+        }
+      })
+  })
+}
+
+export function get(url: string): Promise<IncomingMessage> {
+  const enum Method {
+    Get = 'GET',
+  }
+  const enum RedirectMode {
+    Follow = 'follow',
+  }
+
+  return new Promise<IncomingMessage>((resolve, reject) => {
+    const request = net.request({
+      url,
+      method: Method.Get,
+      redirect: RedirectMode.Follow,
+    })
+    request.on('response', resolve)
+    request.on('error', reject)
+    request.end()
+  })
+}