1 files changed, 34 insertions, 0 deletions

diff --git a/editors/code/src/installation/download_file.ts b/editors/code/src/installation/download_file.ts
new file mode 100644
index 000000000..b51602ef9
--- /dev/null
+++ b/editors/code/src/installation/download_file.ts
@@ -0,0 +1,34 @@
+import fetch from "node-fetch";
+import * as fs from "fs";
+import { strict as assert } from "assert";
+
+/**
+ * Downloads file from `url` and stores it at `destFilePath`.
+ * `onProgress` callback is called on recieveing each chunk of bytes
+ * to track the progress of downloading, it gets the already read and total
+ * amount of bytes to read as its parameters.
+ */
+export async function downloadFile(
+    url: string,
+    destFilePath: fs.PathLike,
+    onProgress: (readBytes: number, totalBytes: number) => void
+): Promise<void> {
+    const response = await fetch(url);
+
+    const totalBytes = Number(response.headers.get('content-length'));
+    assert(!Number.isNaN(totalBytes), "Sanity check of content-length protocol");
+
+    let readBytes = 0;
+
+    console.log("Downloading file of", totalBytes, "bytes size from", url, "to", destFilePath);
+
+    return new Promise<void>((resolve, reject) => response.body
+        .on("data", (chunk: Buffer) => {
+            readBytes += chunk.length;
+            onProgress(readBytes, totalBytes);
+        })
+        .on("end", resolve)
+        .on("error", reject)
+        .pipe(fs.createWriteStream(destFilePath))
+    );
+}