/**
 * Satellizer Node.js Example
 * (c) 2015 Sahat Yalkabov
 * License: MIT
 */

var path = require('path');
var qs = require('querystring');

var async = require('async');
var bcrypt = require('bcryptjs');
var bodyParser = require('body-parser');
var colors = require('colors');
var cors = require('cors');
var express = require('express');
var logger = require('morgan');
var jwt = require('jwt-simple');
var moment = require('moment');
var mongoose = require('mongoose');
var request = require('request');

var config = require('./config');

var userSchema = new mongoose.Schema({
  email: { type: String, unique: true, lowercase: true },
  password: { type: String, select: false },
  displayName: String,
  picture: String,
  bitbucket: String,
  facebook: String,
  foursquare: String,
  google: String,
  github: String,
  instagram: String,
  linkedin: String,
  live: String,
  yahoo: String,
  twitter: String,
  twitch: String
});

userSchema.pre('save', function(next) {
  var user = this;
  if (!user.isModified('password')) {
    return next();
  }
  bcrypt.genSalt(10, function(err, salt) {
    bcrypt.hash(user.password, salt, function(err, hash) {
      user.password = hash;
      next();
    });
  });
});

userSchema.methods.comparePassword = function(password, done) {
  bcrypt.compare(password, this.password, function(err, isMatch) {
    done(err, isMatch);
  });
};

var User = mongoose.model('User', userSchema);

mongoose.connect(config.MONGO_URI);
mongoose.connection.on('error', function(err) {
  console.log('Error: Could not connect to MongoDB. Did you forget to run `mongod`?'.red);
});

var app = express();

app.set('port', process.env.NODE_PORT || 3000);
app.set('host', process.env.NODE_IP || 'localhost');
app.use(cors());
app.use(logger('dev'));
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({ extended: true }));

// Force HTTPS on Heroku
if (app.get('env') === 'production') {
  app.use(function(req, res, next) {
    var protocol = req.get('x-forwarded-proto');
    protocol == 'https' ? next() : res.redirect('https://' + req.hostname + req.url);
  });
}
app.use(express.static(path.join(__dirname, '../../client')));

/*
 |--------------------------------------------------------------------------
 | Login Required Middleware
 |--------------------------------------------------------------------------
 */
function ensureAuthenticated(req, res, next) {
  if (!req.header('Authorization')) {
    return res.status(401).send({ message: 'Please make sure your request has an Authorization header' });
  }
  var token = req.header('Authorization').split(' ')[1];

  var payload = null;
  try {
    payload = jwt.decode(token, config.TOKEN_SECRET);
  }
  catch (err) {
    return res.status(401).send({ message: err.message });
  }

  if (payload.exp <= moment().unix()) {
    return res.status(401).send({ message: 'Token has expired' });
  }
  req.user = payload.sub;
  next();
}

/*
 |--------------------------------------------------------------------------
 | Generate JSON Web Token
 |--------------------------------------------------------------------------
 */
function createJWT(user) {
  var payload = {
    sub: user._id,
    iat: moment().unix(),
    exp: moment().add(14, 'days').unix()
  };
  return jwt.encode(payload, config.TOKEN_SECRET);
}

/*
 |--------------------------------------------------------------------------
 | GET /api/me
 |--------------------------------------------------------------------------
 */
app.get('/api/me', ensureAuthenticated, function(req, res) {
  User.findById(req.user, function(err, user) {
    res.send(user);
  });
});

/*
 |--------------------------------------------------------------------------
 | PUT /api/me
 |--------------------------------------------------------------------------
 */
app.put('/api/me', ensureAuthenticated, function(req, res) {
  User.findById(req.user, function(err, user) {
    if (!user) {
      return res.status(400).send({ message: 'User not found' });
    }
    user.displayName = req.body.displayName || user.displayName;
    user.email = req.body.email || user.email;
    user.save(function(err) {
      res.status(200).end();
    });
  });
});


/*
 |--------------------------------------------------------------------------
 | Log in with Email
 |--------------------------------------------------------------------------
 */
app.post('/auth/login', function(req, res) {
  User.findOne({ email: req.body.email }, '+password', function(err, user) {
    if (!user) {
      return res.status(401).send({ message: 'Invalid email and/or password' });
    }
    user.comparePassword(req.body.password, function(err, isMatch) {
      if (!isMatch) {
        return res.status(401).send({ message: 'Invalid email and/or password' });
      }
      res.send({ token: createJWT(user) });
    });
  });
});

/*
 |--------------------------------------------------------------------------
 | Create Email and Password Account
 |--------------------------------------------------------------------------
 */
app.post('/auth/signup', function(req, res) {
  User.findOne({ email: req.body.email }, function(err, existingUser) {
    if (existingUser) {
      return res.status(409).send({ message: 'Email is already taken' });
    }
    var user = new User({
      displayName: req.body.displayName,
      email: req.body.email,
      password: req.body.password
    });
    user.save(function(err, result) {
      if (err) {
        res.status(500).send({ message: err.message });
      }
      res.send({ token: createJWT(result) });
    });
  });
});

/*
 |--------------------------------------------------------------------------
 | Login with Google
 |--------------------------------------------------------------------------
 */
app.post('/auth/google', function(req, res) {
  var accessTokenUrl = 'https://accounts.google.com/o/oauth2/token';
  var peopleApiUrl = 'https://www.googleapis.com/plus/v1/people/me/openIdConnect';
  var params = {
    code: req.body.code,
    client_id: req.body.clientId,
    client_secret: config.GOOGLE_SECRET,
    redirect_uri: req.body.redirectUri,
    grant_type: 'authorization_code'
  };

  // Step 1. Exchange authorization code for access token.
  request.post(accessTokenUrl, { json: true, form: params }, function(err, response, token) {
    var accessToken = token.access_token;
    var headers = { Authorization: 'Bearer ' + accessToken };

    // Step 2. Retrieve profile information about the current user.
    request.get({ url: peopleApiUrl, headers: headers, json: true }, function(err, response, profile) {
      if (profile.error) {
        return res.status(500).send({message: profile.error.message});
      }
      // Step 3a. Link user accounts.
      if (req.header('Authorization')) {
        User.findOne({ google: profile.sub }, function(err, existingUser) {
          if (existingUser) {
            return res.status(409).send({ message: 'There is already a Google account that belongs to you' });
          }
          var token = req.header('Authorization').split(' ')[1];
          var payload = jwt.decode(token, config.TOKEN_SECRET);
          User.findById(payload.sub, function(err, user) {
            if (!user) {
              return res.status(400).send({ message: 'User not found' });
            }
            user.google = profile.sub;
            user.picture = user.picture || profile.picture.replace('sz=50', 'sz=200');
            user.displayName = user.displayName || profile.name;
            user.save(function() {
              var token = createJWT(user);
              res.send({ token: token });
            });
          });
        });
      } else {
        // Step 3b. Create a new user account or return an existing one.
        User.findOne({ google: profile.sub }, function(err, existingUser) {
          if (existingUser) {
            return res.send({ token: createJWT(existingUser) });
          }
          var user = new User();
          user.google = profile.sub;
          user.picture = profile.picture.replace('sz=50', 'sz=200');
          user.displayName = profile.name;
          user.save(function(err) {
            var token = createJWT(user);
            res.send({ token: token });
          });
        });
      }
    });
  });
});

/*
 |--------------------------------------------------------------------------
 | Login with GitHub
 |--------------------------------------------------------------------------
 */
app.post('/auth/github', function(req, res) {
  var accessTokenUrl = 'https://github.com/login/oauth/access_token';
  var userApiUrl = 'https://api.github.com/user';
  var params = {
    code: req.body.code,
    client_id: req.body.clientId,
    client_secret: config.GITHUB_SECRET,
    redirect_uri: req.body.redirectUri
  };

  // Step 1. Exchange authorization code for access token.
  request.get({ url: accessTokenUrl, qs: params }, function(err, response, accessToken) {
    accessToken = qs.parse(accessToken);
    var headers = { 'User-Agent': 'Satellizer' };

    // Step 2. Retrieve profile information about the current user.
    request.get({ url: userApiUrl, qs: accessToken, headers: headers, json: true }, function(err, response, profile) {

      // Step 3a. Link user accounts.
      if (req.header('Authorization')) {
        User.findOne({ github: profile.id }, function(err, existingUser) {
          if (existingUser) {
            return res.status(409).send({ message: 'There is already a GitHub account that belongs to you' });
          }
          var token = req.header('Authorization').split(' ')[1];
          var payload = jwt.decode(token, config.TOKEN_SECRET);
          User.findById(payload.sub, function(err, user) {
            if (!user) {
              return res.status(400).send({ message: 'User not found' });
            }
            user.github = profile.id;
            user.picture = user.picture || profile.avatar_url;
            user.displayName = user.displayName || profile.name;
            user.save(function() {
              var token = createJWT(user);
              res.send({ token: token });
            });
          });
        });
      } else {
        // Step 3b. Create a new user account or return an existing one.
        User.findOne({ github: profile.id }, function(err, existingUser) {
          if (existingUser) {
            var token = createJWT(existingUser);
            return res.send({ token: token });
          }
          var user = new User();
          user.github = profile.id;
          user.picture = profile.avatar_url;
          user.displayName = profile.name;
          user.save(function() {
            var token = createJWT(user);
            res.send({ token: token });
          });
        });
      }
    });
  });
});

/*
|--------------------------------------------------------------------------
| Login with Instagram
|--------------------------------------------------------------------------
*/
app.post('/auth/instagram', function(req, res) {
  var accessTokenUrl = 'https://api.instagram.com/oauth/access_token';

  var params = {
    client_id: req.body.clientId,
    redirect_uri: req.body.redirectUri,
    client_secret: config.INSTAGRAM_SECRET,
    code: req.body.code,
    grant_type: 'authorization_code'
  };

  // Step 1. Exchange authorization code for access token.
  request.post({ url: accessTokenUrl, form: params, json: true }, function(error, response, body) {

    // Step 2a. Link user accounts.
    if (req.header('Authorization')) {
      User.findOne({ instagram: body.user.id }, function(err, existingUser) {
        if (existingUser) {
          return res.status(409).send({ message: 'There is already an Instagram account that belongs to you' });
        }

        var token = req.header('Authorization').split(' ')[1];
        var payload = jwt.decode(token, config.TOKEN_SECRET);

        User.findById(payload.sub, function(err, user) {
          if (!user) {
            return res.status(400).send({ message: 'User not found' });
          }
          user.instagram = body.user.id;
          user.picture = user.picture || body.user.profile_picture;
          user.displayName = user.displayName || body.user.username;
          user.save(function() {
            var token = createJWT(user);
            res.send({ token: token });
          });
        });
      });
    } else {
      // Step 2b. Create a new user account or return an existing one.
      User.findOne({ instagram: body.user.id }, function(err, existingUser) {
        if (existingUser) {
          return res.send({ token: createJWT(existingUser) });
        }

        var user = new User({
          instagram: body.user.id,
          picture: body.user.profile_picture,
          displayName: body.user.username
        });

        user.save(function() {
          var token = createJWT(user);
          res.send({ token: token, user: user });
        });
      });
    }
  });
});

/*
 |--------------------------------------------------------------------------
 | Login with LinkedIn
 |--------------------------------------------------------------------------
 */
app.post('/auth/linkedin', function(req, res) {
  var accessTokenUrl = 'https://www.linkedin.com/uas/oauth2/accessToken';
  var peopleApiUrl = 'https://api.linkedin.com/v1/people/~:(id,first-name,last-name,email-address,picture-url)';
  var params = {
    code: req.body.code,
    client_id: req.body.clientId,
    client_secret: config.LINKEDIN_SECRET,
    redirect_uri: req.body.redirectUri,
    grant_type: 'authorization_code'
  };

  // Step 1. Exchange authorization code for access token.
  request.post(accessTokenUrl, { form: params, json: true }, function(err, response, body) {
    if (response.statusCode !== 200) {
      return res.status(response.statusCode).send({ message: body.error_description });
    }
    var params = {
      oauth2_access_token: body.access_token,
      format: 'json'
    };

    // Step 2. Retrieve profile information about the current user.
    request.get({ url: peopleApiUrl, qs: params, json: true }, function(err, response, profile) {

      // Step 3a. Link user accounts.
      if (req.header('Authorization')) {
        User.findOne({ linkedin: profile.id }, function(err, existingUser) {
          if (existingUser) {
            return res.status(409).send({ message: 'There is already a LinkedIn account that belongs to you' });
          }
          var token = req.header('Authorization').split(' ')[1];
          var payload = jwt.decode(token, config.TOKEN_SECRET);
          User.findById(payload.sub, function(err, user) {
            if (!user) {
              return res.status(400).send({ message: 'User not found' });
            }
            user.linkedin = profile.id;
            user.picture = user.picture || profile.pictureUrl;
            user.displayName = user.displayName || profile.firstName + ' ' + profile.lastName;
            user.save(function() {
              var token = createJWT(user);
              res.send({ token: token });
            });
          });
        });
      } else {
        // Step 3b. Create a new user account or return an existing one.
        User.findOne({ linkedin: profile.id }, function(err, existingUser) {
          if (existingUser) {
            return res.send({ token: createJWT(existingUser) });
          }
          var user = new User();
          user.linkedin = profile.id;
          user.picture = profile.pictureUrl;
          user.displayName = profile.firstName + ' ' + profile.lastName;
          user.save(function() {
            var token = createJWT(user);
            res.send({ token: token });
          });
        });
      }
    });
  });
});

/*
 |--------------------------------------------------------------------------
 | Login with Windows Live
 |--------------------------------------------------------------------------
 */
app.post('/auth/live', function(req, res) {
  async.waterfall([
    // Step 1. Exchange authorization code for access token.
    function(done) {
      var accessTokenUrl = 'https://login.live.com/oauth20_token.srf';
      var params = {
        code: req.body.code,
        client_id: req.body.clientId,
        client_secret: config.WINDOWS_LIVE_SECRET,
        redirect_uri: req.body.redirectUri,
        grant_type: 'authorization_code'
      };
      request.post(accessTokenUrl, { form: params, json: true }, function(err, response, accessToken) {
        done(null, accessToken);
      });
    },
    // Step 2. Retrieve profile information about the current user.
    function(accessToken, done) {
      var profileUrl = 'https://apis.live.net/v5.0/me?access_token=' + accessToken.access_token;
      request.get({ url: profileUrl, json: true }, function(err, response, profile) {
        done(err, profile);
      });
    },
    function(profile) {
      // Step 3a. Link user accounts.
      if (req.header('Authorization')) {
        User.findOne({ live: profile.id }, function(err, user) {
          if (user) {
            return res.status(409).send({ message: 'There is already a Windows Live account that belongs to you' });
          }
          var token = req.header('Authorization').split(' ')[1];
          var payload = jwt.decode(token, config.TOKEN_SECRET);
          User.findById(payload.sub, function(err, existingUser) {
            if (!existingUser) {
              return res.status(400).send({ message: 'User not found' });
            }
            existingUser.live = profile.id;
            existingUser.displayName = existingUser.displayName || profile.name;
            existingUser.save(function() {
              var token = createJWT(existingUser);
              res.send({ token: token });
            });
          });
        });
      } else {
        // Step 3b. Create a new user or return an existing account.
        User.findOne({ live: profile.id }, function(err, user) {
          if (user) {
            return res.send({ token: createJWT(user) });
          }
          var newUser = new User();
          newUser.live = profile.id;
          newUser.displayName = profile.name;
          newUser.save(function() {
            var token = createJWT(newUser);
            res.send({ token: token });
          });
        });
      }
    }
  ]);
});

/*
 |--------------------------------------------------------------------------
 | Login with Facebook
 |--------------------------------------------------------------------------
 */
app.post('/auth/facebook', function(req, res) {
  var fields = ['id', 'email', 'first_name', 'last_name', 'link', 'name'];
  var accessTokenUrl = 'https://graph.facebook.com/v2.5/oauth/access_token';
  var graphApiUrl = 'https://graph.facebook.com/v2.5/me?fields=' + fields.join(',');
  var params = {
    code: req.body.code,
    client_id: req.body.clientId,
    client_secret: config.FACEBOOK_SECRET,
    redirect_uri: req.body.redirectUri
  };

  // Step 1. Exchange authorization code for access token.
  request.get({ url: accessTokenUrl, qs: params, json: true }, function(err, response, accessToken) {
    if (response.statusCode !== 200) {
      return res.status(500).send({ message: accessToken.error.message });
    }

    // Step 2. Retrieve profile information about the current user.
    request.get({ url: graphApiUrl, qs: accessToken, json: true }, function(err, response, profile) {
      if (response.statusCode !== 200) {
        return res.status(500).send({ message: profile.error.message });
      }
      if (req.header('Authorization')) {
        User.findOne({ facebook: profile.id }, function(err, existingUser) {
          if (existingUser) {
            return res.status(409).send({ message: 'There is already a Facebook account that belongs to you' });
          }
          var token = req.header('Authorization').split(' ')[1];
          var payload = jwt.decode(token, config.TOKEN_SECRET);
          User.findById(payload.sub, function(err, user) {
            if (!user) {
              return res.status(400).send({ message: 'User not found' });
            }
            user.facebook = profile.id;
            user.picture = user.picture || 'https://graph.facebook.com/v2.3/' + profile.id + '/picture?type=large';
            user.displayName = user.displayName || profile.name;
            user.save(function() {
              var token = createJWT(user);
              res.send({ token: token });
            });
          });
        });
      } else {
        // Step 3. Create a new user account or return an existing one.
        User.findOne({ facebook: profile.id }, function(err, existingUser) {
          if (existingUser) {
            var token = createJWT(existingUser);
            return res.send({ token: token });
          }
          var user = new User();
          user.facebook = profile.id;
          user.picture = 'https://graph.facebook.com/' + profile.id + '/picture?type=large';
          user.displayName = profile.name;
          user.save(function() {
            var token = createJWT(user);
            res.send({ token: token });
          });
        });
      }
    });
  });
});

/*
 |--------------------------------------------------------------------------
 | Login with Yahoo
 |--------------------------------------------------------------------------
 */
app.post('/auth/yahoo', function(req, res) {
  var accessTokenUrl = 'https://api.login.yahoo.com/oauth2/get_token';
  var clientId = req.body.clientId;
  var clientSecret = config.YAHOO_SECRET;
  var formData = {
    code: req.body.code,
    redirect_uri: req.body.redirectUri,
    grant_type: 'authorization_code'
  };
  var headers = { Authorization: 'Basic ' + new Buffer(clientId + ':' + clientSecret).toString('base64') };

  // Step 1. Exchange authorization code for access token.
  request.post({ url: accessTokenUrl, form: formData, headers: headers, json: true }, function(err, response, body) {
    var socialApiUrl = 'https://social.yahooapis.com/v1/user/' + body.xoauth_yahoo_guid + '/profile?format=json';
    var headers = { Authorization: 'Bearer ' + body.access_token };

    // Step 2. Retrieve profile information about the current user.
    request.get({ url: socialApiUrl, headers: headers, json: true }, function(err, response, body) {

      // Step 3a. Link user accounts.
      if (req.header('Authorization')) {
        User.findOne({ yahoo: body.profile.guid }, function(err, existingUser) {
          if (existingUser) {
            return res.status(409).send({ message: 'There is already a Yahoo account that belongs to you' });
          }
          var token = req.header('Authorization').split(' ')[1];
          var payload = jwt.decode(token, config.TOKEN_SECRET);
          User.findById(payload.sub, function(err, user) {
            if (!user) {
              return res.status(400).send({ message: 'User not found' });
            }
            user.yahoo = body.profile.guid;
            user.displayName = user.displayName || body.profile.nickname;
            user.save(function() {
              var token = createJWT(user);
              res.send({ token: token });
            });
          });
        });
      } else {
        // Step 3b. Create a new user account or return an existing one.
        User.findOne({ yahoo: body.profile.guid }, function(err, existingUser) {
          if (existingUser) {
            return res.send({ token: createJWT(existingUser) });
          }
          var user = new User();
          user.yahoo = body.profile.guid;
          user.displayName = body.profile.nickname;
          user.save(function() {
            var token = createJWT(user);
            res.send({ token: token });
          });
        });
      }
    });
  });
});

/*
 |--------------------------------------------------------------------------
 | Login with Twitter
 |--------------------------------------------------------------------------
 */
app.post('/auth/twitter', function(req, res) {
  var requestTokenUrl = 'https://api.twitter.com/oauth/request_token';
  var accessTokenUrl = 'https://api.twitter.com/oauth/access_token';
  var profileUrl = 'https://api.twitter.com/1.1/users/show.json?screen_name=';

  // Part 1 of 2: Initial request from Satellizer.
  if (!req.body.oauth_token || !req.body.oauth_verifier) {
    var requestTokenOauth = {
      consumer_key: config.TWITTER_KEY,
      consumer_secret: config.TWITTER_SECRET,
      callback: req.body.redirectUri
    };

    // Step 1. Obtain request token for the authorization popup.
    request.post({ url: requestTokenUrl, oauth: requestTokenOauth }, function(err, response, body) {
      var oauthToken = qs.parse(body);

      // Step 2. Send OAuth token back to open the authorization screen.
      res.send(oauthToken);
    });
  } else {
    // Part 2 of 2: Second request after Authorize app is clicked.
    var accessTokenOauth = {
      consumer_key: config.TWITTER_KEY,
      consumer_secret: config.TWITTER_SECRET,
      token: req.body.oauth_token,
      verifier: req.body.oauth_verifier
    };

    // Step 3. Exchange oauth token and oauth verifier for access token.
    request.post({ url: accessTokenUrl, oauth: accessTokenOauth }, function(err, response, accessToken) {

      accessToken = qs.parse(accessToken);

      var profileOauth = {
        consumer_key: config.TWITTER_KEY,
        consumer_secret: config.TWITTER_SECRET,
        oauth_token: accessToken.oauth_token
      };

      // Step 4. Retrieve profile information about the current user.
      request.get({
        url: profileUrl + accessToken.screen_name,
        oauth: profileOauth,
        json: true
      }, function(err, response, profile) {

        // Step 5a. Link user accounts.
        if (req.header('Authorization')) {
          User.findOne({ twitter: profile.id }, function(err, existingUser) {
            if (existingUser) {
              return res.status(409).send({ message: 'There is already a Twitter account that belongs to you' });
            }

            var token = req.header('Authorization').split(' ')[1];
            var payload = jwt.decode(token, config.TOKEN_SECRET);

            User.findById(payload.sub, function(err, user) {
              if (!user) {
                return res.status(400).send({ message: 'User not found' });
              }

              user.twitter = profile.id;
              user.displayName = user.displayName || profile.name;
              user.picture = user.picture || profile.profile_image_url.replace('_normal', '');
              user.save(function(err) {
                res.send({ token: createJWT(user) });
              });
            });
          });
        } else {
          // Step 5b. Create a new user account or return an existing one.
          User.findOne({ twitter: profile.id }, function(err, existingUser) {
            if (existingUser) {
              return res.send({ token: createJWT(existingUser) });
            }

            var user = new User();
            user.twitter = profile.id;
            user.displayName = profile.name;
            user.picture = profile.profile_image_url.replace('_normal', '');
            user.save(function() {
              res.send({ token: createJWT(user) });
            });
          });
        }
      });
    });
  }
});

/*
 |--------------------------------------------------------------------------
 | Login with Foursquare
 |--------------------------------------------------------------------------
 */
app.post('/auth/foursquare', function(req, res) {
  var accessTokenUrl = 'https://foursquare.com/oauth2/access_token';
  var profileUrl = 'https://api.foursquare.com/v2/users/self';
  var formData = {
    code: req.body.code,
    client_id: req.body.clientId,
    client_secret: config.FOURSQUARE_SECRET,
    redirect_uri: req.body.redirectUri,
    grant_type: 'authorization_code'
  };

  // Step 1. Exchange authorization code for access token.
  request.post({ url: accessTokenUrl, form: formData, json: true }, function(err, response, body) {
    var params = {
      v: '20140806',
      oauth_token: body.access_token
    };

    // Step 2. Retrieve information about the current user.
    request.get({ url: profileUrl, qs: params, json: true }, function(err, response, profile) {
      profile = profile.response.user;

      // Step 3a. Link user accounts.
      if (req.header('Authorization')) {
        User.findOne({ foursquare: profile.id }, function(err, existingUser) {
          if (existingUser) {
            return res.status(409).send({ message: 'There is already a Foursquare account that belongs to you' });
          }
          var token = req.header('Authorization').split(' ')[1];
          var payload = jwt.decode(token, config.TOKEN_SECRET);
          User.findById(payload.sub, function(err, user) {
            if (!user) {
              return res.status(400).send({ message: 'User not found' });
            }
            user.foursquare = profile.id;
            user.picture = user.picture || profile.photo.prefix + '300x300' + profile.photo.suffix;
            user.displayName = user.displayName || profile.firstName + ' ' + profile.lastName;
            user.save(function() {
              var token = createJWT(user);
              res.send({ token: token });
            });
          });
        });
      } else {
        // Step 3b. Create a new user account or return an existing one.
        User.findOne({ foursquare: profile.id }, function(err, existingUser) {
          if (existingUser) {
            var token = createJWT(existingUser);
            return res.send({ token: token });
          }
          var user = new User();
          user.foursquare = profile.id;
          user.picture = profile.photo.prefix + '300x300' + profile.photo.suffix;
          user.displayName = profile.firstName + ' ' + profile.lastName;
          user.save(function() {
            var token = createJWT(user);
            res.send({ token: token });
          });
        });
      }
    });
  });
});

/*
 |--------------------------------------------------------------------------
 | Login with Twitch
 |--------------------------------------------------------------------------
 */
app.post('/auth/twitch', function(req, res) {
  var accessTokenUrl = 'https://api.twitch.tv/kraken/oauth2/token';
  var profileUrl = 'https://api.twitch.tv/kraken/user';
  var formData = {
    code: req.body.code,
    client_id: req.body.clientId,
    client_secret: config.TWITCH_SECRET,
    redirect_uri: req.body.redirectUri,
    grant_type: 'authorization_code'
  };

  // Step 1. Exchange authorization code for access token.
  request.post({ url: accessTokenUrl, form: formData, json: true }, function(err, response, accessToken) {
   var params = {
     oauth_token: accessToken.access_token
   };

    // Step 2. Retrieve information about the current user.
    request.get({ url: profileUrl, qs: params, json: true }, function(err, response, profile) {
      // Step 3a. Link user accounts.
      if (req.header('Authorization')) {
        User.findOne({ twitch: profile._id }, function(err, existingUser) {
          if (existingUser) {
            return res.status(409).send({ message: 'There is already a Twitch account that belongs to you' });
          }
          var token = req.header('Authorization').split(' ')[1];
          var payload = jwt.decode(token, config.TOKEN_SECRET);
          User.findById(payload.sub, function(err, user) {
            if (!user) {
              return res.status(400).send({ message: 'User not found' });
            }
            user.twitch = profile._id;
            user.picture = user.picture || profile.logo;
            user.displayName = user.name || profile.name;
            user.email = user.email || profile.email;
            user.save(function() {
              var token = createJWT(user);
              res.send({ token: token });
            });
          });
        });
      } else {
        // Step 3b. Create a new user account or return an existing one.
        User.findOne({ twitch: profile._id }, function(err, existingUser) {
          if (existingUser) {
            var token = createJWT(existingUser);
            return res.send({ token: token });
          }
          var user = new User();
          user.twitch = profile._id;
          user.picture = profile.logo;
          user.displayName = profile.name;
          user.email = profile.email;
          user.save(function() {
            var token = createJWT(user);
            res.send({ token: token });
          });
        });
      }
    });
  });
});

/*
 |--------------------------------------------------------------------------
 | Login with Bitbucket
 |--------------------------------------------------------------------------
 */
app.post('/auth/bitbucket', function(req, res) {
  var accessTokenUrl = 'https://bitbucket.org/site/oauth2/access_token';
  var userApiUrl = 'https://bitbucket.org/api/2.0/user';
  var emailApiUrl = 'https://bitbucket.org/api/2.0/user/emails';

  var headers = {
    Authorization: 'Basic ' + new Buffer(req.body.clientId + ':' + config.BITBUCKET_SECRET).toString('base64')
  };

  var formData = {
    code: req.body.code,
    redirect_uri: req.body.redirectUri,
    grant_type: 'authorization_code'
  };

  // Step 1. Exchange authorization code for access token.
  request.post({ url: accessTokenUrl, form: formData, headers: headers, json: true }, function(err, response, body) {
    if (body.error) {
      return res.status(400).send({ message: body.error_description });
    }
    
    var params = {
      access_token: body.access_token
    };

    // Step 2. Retrieve information about the current user.
    request.get({ url: userApiUrl, qs: params, json: true }, function(err, response, profile) {

      // Step 2.5. Retrieve current user's email.
      request.get({ url: emailApiUrl, qs: params, json: true }, function(err, response, emails) {
        var email = emails.values[0].email;

        // Step 3a. Link user accounts.
        if (req.header('Authorization')) {
          User.findOne({ bitbucket: profile.uuid }, function(err, existingUser) {
            if (existingUser) {
              return res.status(409).send({ message: 'There is already a Bitbucket account that belongs to you' });
            }
            var token = req.header('Authorization').split(' ')[1];
            var payload = jwt.decode(token, config.TOKEN_SECRET);
            User.findById(payload.sub, function(err, user) {
              if (!user) {
                return res.status(400).send({ message: 'User not found' });
              }
              user.bitbucket = profile.uuid;
              user.email = user.email || email;
              user.picture = user.picture || profile.links.avatar.href;
              user.displayName = user.displayName || profile.display_name;
              user.save(function() {
                var token = createJWT(user);
                res.send({ token: token });
              });
            });
          });
        } else {
          // Step 3b. Create a new user account or return an existing one.
          User.findOne({ bitbucket: profile.id }, function(err, existingUser) {
            if (existingUser) {
              var token = createJWT(existingUser);
              return res.send({ token: token });
            }
            var user = new User();
            user.bitbucket = profile.uuid;
            user.email = email;
            user.picture = profile.links.avatar.href;
            user.displayName = profile.display_name;
            user.save(function() {
              var token = createJWT(user);
              res.send({ token: token });
            });
          });
        }
      });
    });
  });
});

/*
 |--------------------------------------------------------------------------
 | Unlink Provider
 |--------------------------------------------------------------------------
 */
app.post('/auth/unlink', ensureAuthenticated, function(req, res) {
  var provider = req.body.provider;
  var providers = ['facebook', 'foursquare', 'google', 'github', 'instagram',
    'linkedin', 'live', 'twitter', 'twitch', 'yahoo'];

  if (providers.indexOf(provider) === -1) {
    return res.status(400).send({ message: 'Unknown OAuth Provider' });
  }

  User.findById(req.user, function(err, user) {
    if (!user) {
      return res.status(400).send({ message: 'User Not Found' });
    }
    user[provider] = undefined;
    user.save(function() {
      res.status(200).end();
    });
  });
});

/*
 |--------------------------------------------------------------------------
 | Start the Server
 |--------------------------------------------------------------------------
 */
app.listen(app.get('port'), app.get('host'), function() {
  console.log('Express server listening on port ' + app.get('port'));
});