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/*! * Module dependencies. */
'use strict';
const MongooseConnection = require('../../connection');const STATES = require('../../connectionstate');const immediate = require('../../helpers/immediate');const setTimeout = require('../../helpers/timers').setTimeout;
/** * A [node-mongodb-native](https://github.com/mongodb/node-mongodb-native) connection implementation. * * @inherits Connection * @api private */
function NativeConnection() {  MongooseConnection.apply(this, arguments);  this._listening = false;}
/** * Expose the possible connection states. * @api public */
NativeConnection.STATES = STATES;
/*! * Inherits from Connection. */
Object.setPrototypeOf(NativeConnection.prototype, MongooseConnection.prototype);
/** * Switches to a different database using the same connection pool. * * Returns a new connection object, with the new db. If you set the `useCache` * option, `useDb()` will cache connections by `name`. * * **Note:** Calling `close()` on a `useDb()` connection will close the base connection as well. * * @param {String} name The database name * @param {Object} [options] * @param {Boolean} [options.useCache=false] If true, cache results so calling `useDb()` multiple times with the same name only creates 1 connection object. * @param {Boolean} [options.noListener=false] If true, the new connection object won't listen to any events on the base connection. This is better for memory usage in cases where you're calling `useDb()` for every request. * @return {Connection} New Connection Object * @api public */
NativeConnection.prototype.useDb = function(name, options) {  // Return immediately if cached  options = options || {};  if (options.useCache && this.relatedDbs[name]) {    return this.relatedDbs[name];  }
  // we have to manually copy all of the attributes...  const newConn = new this.constructor();  newConn.name = name;  newConn.base = this.base;  newConn.collections = {};  newConn.models = {};  newConn.replica = this.replica;  newConn.config = Object.assign({}, this.config, newConn.config);  newConn.name = this.name;  newConn.options = this.options;  newConn._readyState = this._readyState;  newConn._closeCalled = this._closeCalled;  newConn._hasOpened = this._hasOpened;  newConn._listening = false;  newConn._parent = this;
  newConn.host = this.host;  newConn.port = this.port;  newConn.user = this.user;  newConn.pass = this.pass;
  // First, when we create another db object, we are not guaranteed to have a  // db object to work with. So, in the case where we have a db object and it  // is connected, we can just proceed with setting everything up. However, if  // we do not have a db or the state is not connected, then we need to wait on  // the 'open' event of the connection before doing the rest of the setup  // the 'connected' event is the first time we'll have access to the db object
  const _this = this;
  newConn.client = _this.client;
  if (this.db && this._readyState === STATES.connected) {    wireup();  } else {    this.once('connected', wireup);  }
  function wireup() {    newConn.client = _this.client;    const _opts = {};    if (options.hasOwnProperty('noListener')) {      _opts.noListener = options.noListener;    }    newConn.db = _this.client.db(name, _opts);    newConn.onOpen();  }
  newConn.name = name;
  // push onto the otherDbs stack, this is used when state changes  if (options.noListener !== true) {    this.otherDbs.push(newConn);  }  newConn.otherDbs.push(this);
  // push onto the relatedDbs cache, this is used when state changes  if (options && options.useCache) {    this.relatedDbs[newConn.name] = newConn;    newConn.relatedDbs = this.relatedDbs;  }
  return newConn;};
/** * Closes the connection * * @param {Boolean} [force] * @param {Function} [fn] * @return {Connection} this * @api private */
NativeConnection.prototype.doClose = function(force, fn) {  if (this.client == null) {    immediate(() => fn());    return this;  }
  let skipCloseClient = false;  if (force != null && typeof force === 'object') {    skipCloseClient = force.skipCloseClient;    force = force.force;  }
  if (skipCloseClient) {    immediate(() => fn());    return this;  }
  this.client.close(force, (err, res) => {    // Defer because the driver will wait at least 1ms before finishing closing    // the pool, see https://github.com/mongodb-js/mongodb-core/blob/a8f8e4ce41936babc3b9112bf42d609779f03b39/lib/connection/pool.js#L1026-L1030.    // If there's queued operations, you may still get some background work    // after the callback is called.    setTimeout(() => fn(err, res), 1);  });  return this;};

/*! * Module exports. */
module.exports = NativeConnection;