"use strict";

// HTTP status codes by name
const codes = require('./http-codes');

const genericPatch = (req, res, next, modelClass) => {
  if (!req.body || (req.body._id && req.body._id !== req.params.id)) {
    // little bit different as in PUT. :id does not need to be in data, but if the _id and url id must match
    const err = new Error('id of PATCH resource and send JSON body are not equal ' + req.params.id + ' ' +
      req.body._id);
    err.status = codes.notfound;
    next(err);
    return; // prevent node to process this function further after next() has finished.
  }

  req.body.updatedAt = new Date();
  req.body.$inc = {__v: 1};
  if (req.body.hasOwnProperty('__v')) {
    delete req.body.__v;
  }

  // PATCH is easier with mongoose than PUT. You simply update by all data that comes from outside. no need to
  // reset attributes that are missing.
  modelClass.findByIdAndUpdate(req.params.id, req.body, {new: true}, (err, item) => {
    if (err) {
      err.status = codes.wrongrequest;
    } else if (!item) {
      err = new Error('item not found');
      err.status = codes.notfound;
    } else {
      res.locals.items = item;
    }
    next(err);
  });
};

exports.genericPatch = genericPatch;