transformations

/*
    We are implementing a `view` that must consume
    some external service (which we've mocked below). The service returns
    data that needs to be sanitized for client consumption -- in the
    below example it includes sensitive information like SSN, email, etc.... The
    exercises work through simple sanitizations, to slightly more complex
    ones, before asking that the interviewee try to define a general approach
    to solving the problem.
*/
var _ = require('lodash');

var externalService = function(projectName){
    // Mock; in real life we use some information
    // about the project to, say, read from a
    // particular URL.
    return {
        'project': 'Sanitization Project',
        'users': [
            {
                'username': 'z',
                'email': '[email protected]',
                'ssn': '111223333',
                'apiKeys': [
                    {
                        'codename': 'tugboat',
                        'code': 'la8dfh47',
                    },
                    {
                        'codename': 'titanic',
                        'code': 'dg810fj3',
                    },
                ]
            },
            {
                'username': 'bk',
                'email': '[email protected]',
                'ssn': '889900000',
                'apiKeys': [],
            }
        ],
    };
};


function last4(obj, key) {
  const ssnReplaceChars = '*****';
  const ssnLast4 = obj[key].substring(5);
  obj[key] = `${ssnReplaceChars}${ssnLast4}`;
}

function strip(obj, key) {
  delete obj[key];
}



var sanitize = function(response){
  //const blacklisted = ['ssn', 'code'];
  
    if (_.isObject(response)) {
      for (let key in response.keys()) {
        if (definition.hasOwnProperty(key)) {
          definition[key](response, key);
        }
        sanitize(response[key]);
          // value = transformations[transformation](value, key, response);
      }
    }
    if (_.isArray(response)) {
      _.map(response, sanitize);
    }
  
  return response;
};


var view = function(projectName){
    response = externalService(projectName);
    sanitize(response);
  return response;
};

var response = view('part 0');


// Part 4:
//
// Seems like this is getting to be a common occurrence -- let's
// make it easier on ourselves. Any time you see key, do value.
var definition = {
  ssn: 'last4',
  email: 'strip',
  code: 'strip'
};

response = view('part 4');

console.assert(response.users[0].ssn == '*****3333', 'last 4');
console.assert(response.users[1].ssn == '*****0000', 'last 4');
console.assert(!response.users[0].email, 'stripped email');
console.assert(!response.users[1].email, 'stripped email');
console.assert(!response.users[0].apiKeys[0].code, 'stripped first code');
console.assert(!response.users[0].apiKeys[1].code, 'stripped second code');

console.info('part 4 done!');


// Part 4 solution
var transformations = {
  'last-4': function(value){
    return value.replace(/^.{5}/, '*****')
  },
  'domain-only': function(value){
    return '****@' + value.split('@')[1];
  },
  'strip': function(value, key, response){
    delete response[key];
  }
};

var sanitize = function(response){
  if(_.isObject(response)){
    _.forEach(response, function(value, key){
      var transformation = definition[key];
      if(transformation){
        value = transformations[transformation](value, key, response);
      }
      if(!_.isUndefined(value)){
        response[key] = value;
        sanitize(value);
      }
    });
  }
  else if(_.isArray(response)){
    _.map(response, sanitize);
  }
  return;
};