Passport Slack strategy

 /* 
 This gist shows a modification of the basic Oauth2 Passport strategy, to be suitable for Slack platform
 
 Module dependencies.
 */
var util = require('util')
var OAuth2Strategy = require('passport-oauth2').Strategy

/**
 * `Strategy` constructor.
 *
 * The Slack authentication strategy authenticates requests by delegating
 * to Slack using the OAuth 2.0 protocol.
 *
 * Applications must supply a `verify` callback which accepts an `accessToken`,
 * `refreshToken` and service-specific `profile`, and then calls the `done`
 * callback supplying a `user`, which should be set to `false` if the
 * credentials are not valid.  If an exception occured, `err` should be set.
 *
 * Options:
 *   - `clientID`      your Slack application's client id
 *   - `clientSecret`  your Slack application's client secret
 *   - `callbackURL`   URL to which Slack will redirect the user after granting authorization
 *   - `scope`         array of permission scopes to request, for example:
 *                     'identify', 'channels:read', 'chat:write:user', 'client', or 'admin'
 *                     full set of scopes: https://api.slack.com/docs/oauth-scopes
 *
 * Examples:
 *
 *     passport.use(new SlackStrategy({
 *         clientID: '123-456-789',
 *         clientSecret: 'shhh-its-a-secret'
 *         callbackURL: 'https://www.example.net/auth/slack/callback',
 *         scope: 'identify channels:read chat:write:user client admin'
 *       },
 *       function(accessToken, refreshToken, profile, done) {
 *         User.findOrCreate(..., function (err, user) {
 *           done(err, user);
 *         });
 *       }
 *     ));
 *
 * @param {Object} options
 * @param {Function} verify
 * @api public
 */
function Strategy (options, verify) {
  options = options || {}
  options.authorizationURL = options.authorizationURL || 'https://slack.com/oauth/authorize'
  options.tokenURL = options.tokenURL || 'https://slack.com/api/oauth.access'
  options.scope = options.scope || 'identity.basic'
  this.profileUrl = options.profileUrl || 'https://slack.com/api/users.identity'
  this._team = options.team

  OAuth2Strategy.call(this, options, verify)
  this.name = options.name || 'slack'
  this._oauth2.setAccessTokenName('token')
}

/**
 * Inherit from `OAuth2Strategy`.
 */
util.inherits(Strategy, OAuth2Strategy)

/**
 * Retrieve user profile from Slack.
 *
 * This function constructs a normalized profile, with the following properties:
 *
 *   - `provider`         always set to `slack`
 *   - `id`               the user's ID
 *   - `displayName`      the user's username
 *
 *  as well as additional properties
 *   - `team_id`          the team's ID
 *
 * @param {String} accessToken
 * @param {Function} done
 * @api protected
 */
Strategy.prototype.userProfile = function (accessToken, done) {
  this._oauth2.get(this.profileUrl, accessToken, function (err, body) {
    if (err) {
      return done(err)
    }
    else {
      try {
        var json = JSON.parse(body)
        // console.log("results from identity", json)
        var profile = {
          provider: 'slack'
        }
        if (json.ok) {
          profile.team_id = json.team.id
          profile.id = json.user.id
          profile.displayName = json.user.name
        }
        else {
          console.log(json)
        }
        return done(null, profile)
      }
      catch (e) {
        console.log(e)
        return done(e)
      }
    }
  })
}

/**
 * Expose `Strategy`.
 */
module.exports = Strategy