added fetchLatestArtifactMetadata() and downloadFile() functions

2 files changed, 81 insertions, 0 deletions

diff --git a/editors/code/src/github/download_file.ts b/editors/code/src/github/download_file.ts
new file mode 100644
index 000000000..f40750be9
--- /dev/null
+++ b/editors/code/src/github/download_file.ts
@@ -0,0 +1,26 @@
+import fetch from "node-fetch";
+import { throttle } from "throttle-debounce";
+import * as fs from "fs";
+
+export async function downloadFile(
+    url: string,
+    destFilePath: fs.PathLike,
+    onProgress: (readBytes: number, totalBytes: number) => void
+): Promise<void> {
+    onProgress = throttle(100, /* noTrailing: */ true, onProgress);
+
+    const response = await fetch(url);
+
+    const totalBytes = Number(response.headers.get('content-length'));
+    let readBytes = 0;
+
+    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))
+    );
+}
diff --git a/editors/code/src/github/fetch_latest_artifact_metadata.ts b/editors/code/src/github/fetch_latest_artifact_metadata.ts
new file mode 100644
index 000000000..52641ca67
--- /dev/null
+++ b/editors/code/src/github/fetch_latest_artifact_metadata.ts
@@ -0,0 +1,55 @@
+import fetch from "node-fetch";
+
+const GITHUB_API_ENDPOINT_URL = "https://api.github.com";
+
+export interface FetchLatestArtifactMetadataOpts {
+    repoName: string;
+    repoOwner: string;
+    artifactFileName: string;
+}
+
+export interface ArtifactMetadata {
+    releaseName: string;
+    releaseDate: Date;
+    downloadUrl: string;
+}
+
+export async function fetchLatestArtifactMetadata(
+    opts: FetchLatestArtifactMetadataOpts
+): Promise<ArtifactMetadata | null> {
+
+    const repoOwner = encodeURIComponent(opts.repoOwner);
+    const repoName  = encodeURIComponent(opts.repoName);
+
+    const apiEndpointPath = `/repos/${repoOwner}/${repoName}/releases/latest`;
+    const requestUrl = GITHUB_API_ENDPOINT_URL + apiEndpointPath;
+
+    // We skip runtime type checks for simplicity (here we cast from `any` to `Release`)
+
+    const response: GithubRelease = await fetch(requestUrl, {
+            headers: { Accept: "application/vnd.github.v3+json" }
+        })
+        .then(res => res.json());
+
+    const artifact = response.assets.find(artifact => artifact.name === opts.artifactFileName);
+
+    return !artifact ? null : {
+        releaseName: response.name,
+        releaseDate: new Date(response.published_at),
+        downloadUrl: artifact.browser_download_url
+    };
+
+    // Noise denotes tremendous amount of data that we are not using here
+    interface GithubRelease {
+        name: string;
+        published_at: Date;
+        assets: Array<{
+            browser_download_url: string;
+
+            [noise: string]: unknown;
+        }>;
+
+        [noise: string]: unknown;
+    }
+
+}