How to use the passport.protocols function in passport

* The former sets up an endpoint (/auth/:provider) for redirecting a user to a
 * third-party provider for authentication, while the latter sets up a callback
 * endpoint (/auth/:provider/callback) for receiving the response from the
 * third-party provider. All you have to do is define in the configuration which
 * third-party providers you'd like to support. It's that easy!
 *
 * Behind the scenes, the service stores all the data it needs within "Passports".
 * These contain all the information required to associate a local user with a
 * profile from a third-party provider. This even holds true for the good ol'
 * password authentication scheme – the Authentication Service takes care of
 * encrypting passwords and storing them in Passports, allowing you to keep your
 * User model free of bloat.
 */

// Load authentication protocols
passport.protocols = require('./protocols');

/**
 * Connect a third-party profile to a local user
 *
 * This is where most of the magic happens when a user is authenticating with a
 * third-party provider. What it does, is the following:
 *
 *   1. Given a provider and an identifier, find a matching Passport.
 *   2. From here, the logic branches into two paths.
 *
 *     - A user is not currently logged in:
 *       1. If a Passport wasn't found, just return 401
 *       2. If a Passport was found, get the user associated with the passport.
 *
 *     - A user is currently logged in:
 *       1. If a Passport wasn't found, just return 401

* Behind the scenes, the service stores all the data it needs within "Passports".
 * These contain all the information required to associate a local user with a
 * profile from a third-party provider. This even holds true for the good ol'
 * password authentication scheme – the Authentication Service takes care of
 * encrypting passwords and storing them in Passports, allowing you to keep your
 * User model free of bloat.
 */

// Module dependencies
var passport = require('passport');
var path = require('path');
var url = require('url');
var _ = require('lodash');

// Load authentication protocols
passport.protocols = require('./protocols');

/**
 * Connect a third-party profile to a local user
 *
 * This is where most of the magic happens when a user is authenticating with a
 * third-party provider. What it does, is the following:
 *
 *   1. Given a provider and an identifier, find a matching Passport.
 *   2. From here, the logic branches into two paths.
 *
 *     - A user is not currently logged in:
 *       1. If a Passport wasn't found, just return 401
 *       2. If a Passport was found, get the user associated with the passport.
 *
 *     - A user is currently logged in:
 *       1. If a Passport wasn't found, just return 401

* The former sets up an endpoint (/auth/:provider) for redirecting a user to a
 * third-party provider for authentication, while the latter sets up a callback
 * endpoint (/auth/:provider/callback) for receiving the response from the
 * third-party provider. All you have to do is define in the configuration which
 * third-party providers you'd like to support. It's that easy!
 *
 * Behind the scenes, the service stores all the data it needs within "Pass-
 * ports". These contain all the information required to associate a local user
 * with a profile from a third-party provider. This even holds true for the good
 * ol' password authentication scheme – the Authentication Service takes care of
 * encrypting passwords and storing them in Passports, allowing you to keep your
 * User model free of bloat.
 */

// Load authentication protocols
passport.protocols = require('./protocols');

/**
 * Connect a third-party profile to a local user
 *
 * This is where most of the magic happens when a user is authenticating with a
 * third-party provider. What it does, is the following:
 *
 *   1. Given a provider and an identifier, find a matching Passport.
 *   2. From here, the logic branches into two paths.
 *
 *     - A user is not currently logged in:
 *       1. If a Passport wasn't found, create a new user as well as a new
 *          Passport that will be assigned to the user.
 *       2. If a Passport was found, get the user associated with the passport.
 *
 *     - A user is currently logged in:

* The former sets up an endpoint (/auth/:provider) for redirecting a user to a
 * third-party provider for authentication, while the latter sets up a callback
 * endpoint (/auth/:provider/callback) for receiving the response from the
 * third-party provider. All you have to do is define in the configuration which
 * third-party providers you'd like to support. It's that easy!
 *
 * Behind the scenes, the service stores all the data it needs within "Pass-
 * ports". These contain all the information required to associate a local user
 * with a profile from a third-party provider. This even holds true for the good
 * ol' password authentication scheme – the Authentication Service takes care of
 * encrypting passwords and storing them in Passports, allowing you to keep your
 * User model free of bloat.
 */

// Load authentication protocols
passport.protocols = require('./protocols');

/**
 * Connect a third-party profile to a local user
 *
 * This is where most of the magic happens when a user is authenticating with a
 * third-party provider. What it does, is the following:
 *
 *   1. Given a provider and an identifier, find a mathcing Passport.
 *   2. From here, the logic branches into two paths.
 *
 *     - A user is not currently logged in:
 *       1. If a Passport wassn't found, create a new user as well as a new
 *          Passport that will be assigned to the user.
 *       2. If a Passport was found, get the user associated with the passport.
 *
 *     - A user is currently logged in:

* The former sets up an endpoint (/auth/:provider) for redirecting a user to a
 * third-party provider for authentication, while the latter sets up a callback
 * endpoint (/auth/:provider/callback) for receiving the response from the
 * third-party provider. All you have to do is define in the configuration which
 * third-party providers you'd like to support. It's that easy!
 *
 * Behind the scenes, the service stores all the data it needs within "Pass-
 * ports". These contain all the information required to associate a local user
 * with a profile from a third-party provider. This even holds true for the good
 * ol' password authentication scheme – the Authentication Service takes care of
 * encrypting passwords and storing them in Passports, allowing you to keep your
 * User model free of bloat.
 */

// Load authentication protocols
passport.protocols = require('./protocols');

/**
 * Connect a third-party profile to a local user
 *
 * This is where most of the magic happens when a user is authenticating with a
 * third-party provider. What it does, is the following:
 *
 *   1. Given a provider and an identifier, find a matching Passport.
 *   2. From here, the logic branches into two paths.
 *
 *     - A user is not currently logged in:
 *       1. If a Passport wasn't found, create a new user as well as a new
 *          Passport that will be assigned to the user.
 *       2. If a Passport was found, get the user associated with the passport.
 *
 *     - A user is currently logged in:

* The former sets up an endpoint (/auth/:provider) for redirecting a user to a
   * third-party provider for authentication, while the latter sets up a callback
   * endpoint (/auth/:provider/callback) for receiving the response from the
   * third-party provider. All you have to do is define in the configuration which
   * third-party providers you'd like to support. It's that easy!
   *
   * Behind the scenes, the service stores all the data it needs within "Pass-
   * ports". These contain all the information required to associate a local user
   * with a profile from a third-party provider. This even holds true for the good
   * ol' password authentication scheme – the Authentication Service takes care of
   * encrypting passwords and storing them in Passports, allowing you to keep your
   * User model free of bloat.
   */

  // Load authentication protocols
  passport.protocols = require('./protocols');

  /**
   * Connect a third-party profile to a local user
   *
   * This is where most of the magic happens when a user is authenticating with a
   * third-party provider. What it does, is the following:
   *
   *   1. Given a provider and an identifier, find a matching Passport.
   *   2. From here, the logic branches into two paths.
   *
   *     - A user is not currently logged in:
   *       1. If a Passport wassn't found, create a new user as well as a new
   *          Passport that will be assigned to the user.
   *       2. If a Passport was found, get the user associated with the passport.
   *
   *     - A user is currently logged in:

* The former sets up an endpoint (/auth/:provider) for redirecting a user to a
 * third-party provider for authentication, while the latter sets up a callback
 * endpoint (/auth/:provider/callback) for receiving the response from the
 * third-party provider. All you have to do is define in the configuration which
 * third-party providers you'd like to support. It's that easy!
 *
 * Behind the scenes, the service stores all the data it needs within "Pass-
 * ports". These contain all the information required to associate a local user
 * with a profile from a third-party provider. This even holds true for the good
 * ol' password authentication scheme – the Authentication Service takes care of
 * encrypting passwords and storing them in Passports, allowing you to keep your
 * User model free of bloat.
 */

// Load authentication protocols
passport.protocols = require('./protocols');

/**
 * Connect a third-party profile to a local user
 *
 * This is where most of the magic happens when a user is authenticating with a
 * third-party provider. What it does, is the following:
 *
 *   1. Given a provider and an identifier, find a matching Passport.
 *   2. From here, the logic branches into two paths.
 *
 *     - A user is not currently logged in:
 *       1. If a Passport wasn't found, create a new user as well as a new
 *          Passport that will be assigned to the user.
 *       2. If a Passport was found, get the user associated with the passport.
 *
 *     - A user is currently logged in:

* The former sets up an endpoint (/auth/:provider) for redirecting a user to a
 * third-party provider for authentication, while the latter sets up a callback
 * endpoint (/auth/:provider/callback) for receiving the response from the
 * third-party provider. All you have to do is define in the configuration which
 * third-party providers you'd like to support. It's that easy!
 *
 * Behind the scenes, the service stores all the data it needs within "Pass-
 * ports". These contain all the information required to associate a local user
 * with a profile from a third-party provider. This even holds true for the good
 * ol' password authentication scheme – the Authentication Service takes care of
 * encrypting passwords and storing them in Passports, allowing you to keep your
 * User model free of bloat.
 */

// Load authentication protocols
passport.protocols = require('./protocols');

/**
 * Connect a third-party profile to a local user
 *
 * This is where most of the magic happens when a user is authenticating with a
 * third-party provider. What it does, is the following:
 *
 *   1. Given a provider and an identifier, find a matching Passport.
 *   2. From here, the logic branches into two paths.
 *
 *     - A user is not currently logged in:
 *       1. If a Passport wasn't found, create a new user as well as a new
 *          Passport that will be assigned to the user.
 *       2. If a Passport was found, get the user associated with the passport.
 *
 *     - A user is currently logged in:

* The former sets up an endpoint (/auth/:provider) for redirecting a user to a
 * third-party provider for authentication, while the latter sets up a callback
 * endpoint (/auth/:provider/callback) for receiving the response from the
 * third-party provider. All you have to do is define in the configuration which
 * third-party providers you'd like to support. It's that easy!
 *
 * Behind the scenes, the service stores all the data it needs within "Pass-
 * ports". These contain all the information required to associate a local user
 * with a profile from a third-party provider. This even holds true for the good
 * ol' password authentication scheme – the Authentication Service takes care of
 * encrypting passwords and storing them in Passports, allowing you to keep your
 * User model free of bloat.
 */

// Load authentication protocols
passport.protocols = require('./protocols');

/**
 * Connect a third-party profile to a local user
 *
 * This is where most of the magic happens when a user is authenticating with a
 * third-party provider. What it does, is the following:
 *
 *   1. Given a provider and an identifier, find a mathcing Passport.
 *   2. From here, the logic branches into two paths.
 *
 *     - A user is not currently logged in:
 *       1. If a Passport wassn't found, create a new user as well as a new
 *          Passport that will be assigned to the user.
 *       2. If a Passport was found, get the user associated with the passport.
 *
 *     - A user is currently logged in: