read-repo-url.js

const url = require("url");
const fetch = require("node-fetch");
const { safeJoin } = require("safe-join");

// supported repo host types
const GITHUB = Symbol("GITHUB");
// const BITBUCKET = Symbol('BITBUCKET')
// const GITLAB = Symbol('GITLAB')

/**
 * Takes a url like https://github.com/netlify-labs/all-the-functions/tree/master/functions/9-using-middleware
 * and returns https://api.github.com/repos/netlify-labs/all-the-functions/contents/functions/9-using-middleware
 */
async function readRepoURL(_url) {
  const URL = url.parse(_url);
  const repoHost = validateRepoURL(_url);
  if (repoHost !== GITHUB)
    throw new Error("only github repos are supported for now");
  const [owner_and_repo, contents_path] = parseRepoURL(repoHost, URL);
  const folderContents = await getRepoURLContents(
    repoHost,
    owner_and_repo,
    contents_path
  );
  return folderContents;
}

async function getRepoURLContents(repoHost, owner_and_repo, contents_path) {
  // naive joining strategy for now
  if (repoHost === GITHUB) {
    // https://developer.github.com/v3/repos/contents/#get-contents
    const APIURL = safeJoin(
      "https://api.github.com/repos",
      owner_and_repo,
      "contents",
      contents_path
    );
    return fetch(APIURL)
      .then(x => x.json())
      .catch(
        error => console.error("Error occurred while fetching ", APIURL, error) // eslint-disable-line no-console
      );
  }
  throw new Error("unsupported host ", repoHost);
}

function validateRepoURL(_url) {
  const URL = url.parse(_url);
  if (URL.host !== "github.com") return null;
  // other validation logic here
  return GITHUB;
}
function parseRepoURL(repoHost, URL) {
  // naive splitting strategy for now
  if (repoHost === GITHUB) {
    // https://developer.github.com/v3/repos/contents/#get-contents
    const [owner_and_repo, contents_path] = URL.path.split("/tree/master"); // what if it's not master? note that our contents retrieval may assume it is master
    return [owner_and_repo, contents_path];
  }
  throw new Error("unsupported host ", repoHost);
}

module.exports = {
  readRepoURL,
  validateRepoURL
};