Clone all gists using Deno

_clone-all-gists.deno.ts

// Deno v1.0.5
// deno run --allow-net --allow-run --allow-write --unstable _clone-all-gists.deno.ts --user your_username --token your_github_access_token [--directory parent_directory_to_clone_into]
// https://developer.github.com/v3/gists/

import * as path from 'https://deno.land/std@0.56.0/path/mod.ts';
import {parse} from 'https://deno.land/std@0.56.0/flags/mod.ts';
import {writeJson} from 'https://deno.land/std@0.56.0/fs/mod.ts';

type GistMetadata = {
  created_at: string;
  description: string;
  files: {
    [key: string]: {
      filename: string;
      size: number;
    };
  };
  git_pull_url: string;
  html_url: string;
  id: string;
  public: boolean;
  truncated: boolean;
  updated_at: string;
};

const parseLinkHeader = (headerString: string) => {
  const throwUnrecognizedError = () => {
    throw new Error('Unrecognized format');
  };

  const formatPart = (linkPart: string) => {
    let [link, rel] = linkPart.split(';').map(str => str.trim());

    if (!(link.startsWith('<') && link.endsWith('>'))) throwUnrecognizedError();
    if (!(rel.startsWith('rel="') && rel.endsWith('"'))) throwUnrecognizedError();

    link = link.slice(1, -1);
    rel = rel.slice(5, -1);
    const url = new URL(link);

    return [
      rel,
      {...Object.fromEntries(url.searchParams.entries()), _url: url.href},
    ];
  };

  const entries = headerString.split(',').map(part => formatPart(part));
  return Object.fromEntries(entries);
};

const fetchGists = async (username: string, token: string) => {
  const gists: GistMetadata[] = [];

  const options = {
    headers: new Headers({
      Accept: 'application/vnd.github.v3+json',
      Authorization: `Basic ${btoa(`${username}:${token}`)}`,
    }),
    method: 'GET',
  };

  let url = 'https://api.github.com/gists';

  while (url) {
    const response = await fetch(url, options);
    if (!response.ok) throw Object.assign(new Error('Fetch response not OK'), {response});
    const data = await response.json() as GistMetadata[];
    gists.push(...data);
    const links = parseLinkHeader(Object.fromEntries(response.headers).link);
    url = links.next?._url;
  }

  return gists;
};

const cloneGist = async (gist: GistMetadata, parentDirectory: string) => {
  const gistDir = path.join(parentDirectory, gist.id);

  const p = Deno.run({
    cmd: ['git', 'clone', gist.git_pull_url, gistDir],
  });

  const {success} = await p.status();
  if (!success) throw new Error(`Failed to clone ${gist.html_url}`);

  const gistMetaPath = path.join(gistDir, '.gist-meta.json');
  await writeJson(gistMetaPath, gist, {spaces: 2});
};

const main = async () => {
  const args = parse(Deno.args);
  const username = args.user ?? args.u;
  const token = args.token ?? args.t;
  const directory = args.directory ?? args.d;

  if (!(username && token)) throw new Error('username (--user/-u) and token (--token/-t) required');

  const scriptDir = path.dirname(path.fromFileUrl(import.meta.url));
  const parentDir = directory ?? scriptDir;

  const gists = await fetchGists(username, token);

  for (const [index, gist] of gists.entries()) {
    console.log(`\nCloning Gist ${index + 1}/${gists.length}`);
    await cloneGist(gist, parentDir);
  }

  console.log(`\nGists cloned into ${parentDir}`);
};

if (import.meta.main) main();