router.get("/:id/:departTime/:returnTime", [auth, admin], async (req, res) => {
  const trip = await Trip.findById(req.params.id);

  if (!trip) return res.status(404).send("Trip with given ID not found");

  const conflictedDrivers = await Trip.aggregate([
    {
      $unwind: "$drivers"
    },
    {
      $match: {
        _id: { $ne: trip._id },
        $or: [
          {
            departTime: {
              $gte: new Date(req.params.departTime),
              $lte: new Date(req.params.returnTime)
            }
          },
          {
            returnTime: {
              $gte: new Date(req.params.departTime),
              $lte: new Date(req.params.returnTime)
            }
          }
        ]
      }
    },
    {
      $project: {
        _id: "$drivers._id",
        name: "$drivers.name",
        email: "$drivers.email"
      }
    }
  ]);

  const conflictedDriversIdArray = conflictedDrivers.map(driver => {
    return driver._id;
  });

  const availableDrivers = await User.find({
    $and: [{ _id: { $nin: conflictedDriversIdArray } }, { isDriver: true }]
  });
  
  res.send(availableDrivers);
});