constructRecommendations.js

/**
 * Constructs GitHub recommendation database. Based on followers of a project
 * attemtps to find related proejcts. This program saves results into `out` folder
 *
 * Usage:
 *   node constructRecommendations.js ./db/followers ./db/stars
 *
 * Where:
 *   - followers: leveldb database name with indexed followers (produced by followersIndexer)
 *   - stars: leveldb database name with indexed stars (produced by starsIndexer)
 */
var fs = require('fs');
var saveRecommendation = require('./lib/saveRecommendation');
var findRelated = require('./lib/findRelated');

if (!checkInput()) {
  printHelp();
  return -1;
}

fs.mkdirSync('./out');
fs.mkdirSync('./projects');

// we will iterate over each project:
var projectsDB = openDB(process.argv[2]);
var starsDB = openDB(process.argv[3]);
processProjects();

function processProjects() {
  var projects = [];
  projectsDB.forEach(constructRecommendations)
    .then(writeProjectsFile);

  function constructRecommendations(projectName, followers) {
    console.log('Processing', projectName);
    starsDB.getAllKeyValues(followers)
      .then(function (usersDB) {
        console.log('Loaded projects starred by followers of ' + projectName);
        var related = findRelated(followers, usersDB);
        saveRecommendation(projectName, related);
        projects.push(projectName);
      });
  }

  function writeProjectsFile() {
    var projectsFile ='./projects/projects.json';
    console.log('Saving projects file to', projectsFile);
    fs.writeFileSync(projectsFile, JSON.stringify(projects));
  }
}

function openDB(name) {
  console.log('Opening ' + name + '...');
  return require('./lib/ldb')(name);
}

function loadFullDBInMemory(name) {
  var db = openDB(name);
  var records = Object.create(null);
  var totalRead = 0;

  return db.forEach(readRecord).then(returnRecords);

  function readRecord(key, value) {
    records[key] = value;
    totalRead += 1;
  }

  function returnRecords() {
    console.log('Loaded ' + totalRead + ' records');
    return records;
  }
}

function checkInput() {
  console.log('Checking command arguments');

  console.log('Followers database:', process.argv[2]);
  if (!fs.existsSync(process.argv[2])) {
   console.log('Followers database is missing' + name);
   return;
  }

  console.log('Stars database:', process.argv[3]);
  if (!fs.existsSync(process.argv[3])) {
   console.log('Stars database is missing' + name);
   return;
  }

  if (fs.existsSync('./out')) {
    // just to make sure we do not overwrite old stuff.
    console.log('Output folder `./out` is present. Please remove it to proceed.');
    return;
  }

  return true; // all is good
}

function printHelp() {
  [
'--------------------------------------------------------------------------',
'Constructs GitHub recommendation database. Based on followers of a project',
'attemtps to find related proejcts. This program saves results into `out` folder',
'',
'Usage:',
'  node constructRecommendations.js ./db/followers ./db/stars',
'',
'Where:',
'  - followers: leveldb database name with indexed followers (produced by followersIndexer)',
'  - stars: leveldb database name with indexed stars (produced by starsIndexer)']
.forEach(function (line) { console.log(line); });
}