refactored_fellows.js

var teamAndCohortPeerLevels = ['DOA - MONTH ONE','D0B - SIMULATIONS','D0C - SIMULATIONS'];
var peerLevels = ['D1 Jr Consultant','D2 Consultant','D2 Consultant','D2 Consultant'];
var handleError = function(err,res) {
    logger.error(err);
    res.status(500).json(err);
};
var createPeersFromFellows = function(fellows,peers,fellow) {
  _.each(fellows, function(peer) {
    if (peer.uid !== fellow.uid) {
      peers.push(peer);
    }
  })
};
var peers = function(req, res) {
    var peers = [];
    models.Fellow
    .findById(req.params.id)
    .then(function(fellow) {
      if (fellow) {
          if(teamAndCohortPeerLevels.indexOf(fellow.level) != -1) {
              fetchTeamAndCohortPeers(req, res, fellow, peers);
          }
          else if(peerLevels.indexOf(fellow.level) != -1) {
              fetchPeers(req, res, fellow, peers);
          }
      } else {
        res.status(404).json({
          message: 'Fellow does not exist'
        });
      }
    })
    .catch(function(err) {
       handleError(err,res);
    });
  }
};

var fetchTeamAndCohortPeers = function(req, res, fellow, peers) {
  models.Team
  .findById(fellow.team_id, {
    include: [ models.Fellow ]
  })
  .then(function(team) {
    if (team) {
      createPeersFromFellows(team.Fellows,peers,fellow);
      fetchCohortPeers(req, res, fellow, peers);
    }
    else {
      fetchCohortPeers(req, res, fellow, peers);
    }
  })
  .catch(function(err) {
     handleError(err,res);
  });
};


var fetchCohortPeers = function(req, res, fellow, peers) {
  models.Cohort
  .findById(fellow.cohort_id, {
    include: [ models.Fellow ]
  })
  .then(function(cohort) {
    if (cohort) {
      createPeersFromFellows(cohort.Fellows,peers,fellow);
      res.status(200).json(peers);
    }
    else {
      res.status(404).json({
        message: 'Cohort does not exist'
      });
    }
  })
  .catch(function(err) {
      handleError(err,res);
  });
};

var fetchPeers = function(req, res, fellow, peers) {
  var orConditions = [];
  _.each(peerLevels,function(peerLevel){
      var orCondition = {level:peerLevel};
      orConditions.push(orCondition);
  });
  var where = {
    $or: orConditions
  }

  models.Fellow
  .findAll({
    where: where,
    order: 'first_name ASC'
  })
  .then(function(fellows) {
    if (fellows) {
      createPeersFromFellows(fellows,peers,fellow);
      res.status(200).json(peers);
    }
    else {
      res.status(404).json({
        message: 'Peers does not exist'
      });
    }
  })
  .catch(function(err) {
     handleError(err,res);
  });
};