feat: introduce streamers that handle the stream and anonymization from github

src/core/source/GitHubBase.ts

@@ -0,0 +1,27 @@
+import { Readable } from "stream";
+
+import AnonymizedFile from "../AnonymizedFile";
+import { Tree } from "../types";
+import { SourceBase } from "./Source";
+
+export interface GitHubBaseData {
+  getToken: () => string | Promise<string>;
+  repoId: string;
+  organization: string;
+  repoName: string;
+  commit: string;
+}
+
+export default abstract class GitHubBase implements SourceBase {
+  abstract type: "GitHubDownload" | "GitHubStream" | "Zip";
+  accessToken: string | undefined;
+
+  constructor(readonly data: GitHubBaseData) {}
+
+  abstract getFileContent(
+    file: AnonymizedFile,
+    progress?: (status: string) => void
+  ): Promise<Readable>;
+
+  abstract getFiles(progress?: (status: string) => void): Promise<Tree>;
+}