Function to fetch a markdown post in Firebase Storage from Cloud Functions (old way)

firebase_functions_fetch_post.ts

/**
 * Retrieve a project's content in markdown format
 * (with accessibility check).
 */
export const fetch = functions
    .region(cloudRegions.eu)
    .https
    .onCall(async (data) => {
      const projectId: string = data.projectId;

      /** Used if the project is a draft or restricted to some members. */
      const jwt: string = data.jwt;

      if (!projectId) {
        throw new functions.https.HttpsError(
            "invalid-argument",
            `The function must be called with one (string) argument 
        "projectId" which is the project to fetch.`,
        );
      }

      // Check this helper function in its dedicated gist.
      // // [firebase_functions_helper_post_acl.ts](https://gist.github.com/rootasjey/6b8594cd4da10822c5029a6997f1b8c6)
      await checkAccessControl({projectId, jwt});

      // Retrieve content (access control OK)
      const projectFile = storage
          .bucket()
          .file(`blog/projects/${projectId}/post.md`);

      let projectContent = "";

      const stream = projectFile.createReadStream();

      stream.on("data", (chunck) => {
        projectContent = projectContent.concat(chunck.toString());
      });

      await new Promise((fulfill) => stream.on("end", fulfill));
      stream.destroy();

      return {project: projectContent};
    });