Tool to clone all open PRs of a GitHub repo into a subdirectory.

clone-open-prs

#!/usr/bin/env node
// -*- javascript -*-

/**
 * Tool to clone all open PRs of a GitHub repo into a subdirectory.
 *
 * Usage:
 * 
 *     clone-open-prs USER/REPO DIR
 *
 * USER/REPO is the GitHub username and repo name, and DIR is the output
 * directory name, which must not already exist.
 *
 * For each PR, creates a subdirectory under DIR, clones the corresponding head
 * repo into it, and resets it to the PR's head SHA hash.
 *
 */

//------------------------------------------------------------------------------

var spawnSync = require('child_process').spawnSync;
var fs = require('fs');
var https = require('https');
var path = require('path');

var API_HOST = 'api.github.com';

//------------------------------------------------------------------------------

/**
 * Gets all open pulls for `repo` from GitHub.
 */
function getPulls(repo, callback) {
  https.request({
    host: API_HOST,
    path: '/repos/' + repo + '/pulls?state=open',
    headers: {
      'User-Agent': 'node.js'
    }
  }, function (response) {
    var data = [];
    response.on('data', function (chunk) {
      data.push(chunk);
    });
    response.on('end', function() {
      var pulls = JSON.parse(data.join(''));
      callback(pulls);
    });
  }).end();
}

/**
 * Clones a git repo with URL `repo` into `dir` and resets it to SHA `hash`.
 */
function cloneRepoHash(repo, hash, dir) {
  var clone = spawnSync('git', ['clone', repo, dir]); 
  if (clone.status !== 0) {
    console.warn('failed to clone repo: ' + repo);
    return false;
  } 

  var reset = spawnSync('git', ['reset', '--hard', hash], {cwd: dir});
  if (reset.status !== 0) {
    console.warn('failed to reset ' + dir + ' to hash: ' + hash);
    return false;
  }

  return true;
}

//------------------------------------------------------------------------------

if (process.argv.length != 4) {
  console.error('usage: clone-open-prs REPONAME OUTDIR');
  process.exit(2);
}
var repo = process.argv[2];
var outDir = process.argv[3];

fs.mkdirSync(outDir, function (err) {
  if (err) {
    console.log('failed to create ' + outDir + ': ' + err);
    process.exit(1);
  }
});

getPulls(repo, function (pulls) { 
  for (var i = 0; i < pulls.length; ++i) {
    var pull = pulls[i];
    var number = pull.number;
    var username = pull.user.login;
    var repoUrl = pull.head.repo.git_url;
    var hash = pull.head.sha;

    // The clone goes here.
    var subdir = path.join(outDir, username + '-' + number);

    cloneRepoHash(repoUrl, hash, subdir);
  }
});