'use strict';

var shallowClone = require('./utils').shallowClone,
  handleCallback = require('./utils').handleCallback,
  MongoError = require('mongodb-core').MongoError,
  f = require('util').format;

var authenticate = function(client, username, password, options, callback) {
  // Did the user destroy the topology
  if (client.topology && client.topology.isDestroyed())
    return callback(new MongoError('topology was destroyed'));

  // the default db to authenticate against is 'self'
  // if authententicate is called from a retry context, it may be another one, like admin
  var authdb = options.dbName;
  authdb = options.authdb ? options.authdb : authdb;
  authdb = options.authSource ? options.authSource : authdb;

  // Callback
  var _callback = function(err, result) {
    if (client.listeners('authenticated').length > 0) {
      client.emit('authenticated', err, result);
    }

    // Return to caller
    handleCallback(callback, err, result);
  };

  // authMechanism
  var authMechanism = options.authMechanism || '';
  authMechanism = authMechanism.toUpperCase();

  // If classic auth delegate to auth command
  if (authMechanism === 'MONGODB-CR') {
    client.topology.auth('mongocr', authdb, username, password, function(err) {
      if (err) return handleCallback(callback, err, false);
      _callback(null, true);
    });
  } else if (authMechanism === 'PLAIN') {
    client.topology.auth('plain', authdb, username, password, function(err) {
      if (err) return handleCallback(callback, err, false);
      _callback(null, true);
    });
  } else if (authMechanism === 'MONGODB-X509') {
    client.topology.auth('x509', authdb, username, password, function(err) {
      if (err) return handleCallback(callback, err, false);
      _callback(null, true);
    });
  } else if (authMechanism === 'SCRAM-SHA-1') {
    client.topology.auth('scram-sha-1', authdb, username, password, function(err) {
      if (err) return handleCallback(callback, err, false);
      _callback(null, true);
    });
  } else if (authMechanism === 'SCRAM-SHA-256') {
    client.topology.auth('scram-sha-256', authdb, username, password, function(err) {
      if (err) return handleCallback(callback, err, false);
      _callback(null, true);
    });
  } else if (authMechanism === 'GSSAPI') {
    if (process.platform === 'win32') {
      client.topology.auth('sspi', authdb, username, password, options, function(err) {
        if (err) return handleCallback(callback, err, false);
        _callback(null, true);
      });
    } else {
      client.topology.auth('gssapi', authdb, username, password, options, function(err) {
        if (err) return handleCallback(callback, err, false);
        _callback(null, true);
      });
    }
  } else if (authMechanism === 'DEFAULT') {
    client.topology.auth('default', authdb, username, password, function(err) {
      if (err) return handleCallback(callback, err, false);
      _callback(null, true);
    });
  } else {
    handleCallback(
      callback,
      MongoError.create({
        message: f('authentication mechanism %s not supported', options.authMechanism),
        driver: true
      })
    );
  }
};

module.exports = function(self, username, password, options, callback) {
  if (typeof options === 'function') (callback = options), (options = {});
  options = options || {};

  // Shallow copy the options
  options = shallowClone(options);

  // Set default mechanism
  if (!options.authMechanism) {
    options.authMechanism = 'DEFAULT';
  } else if (
    options.authMechanism !== 'GSSAPI' &&
    options.authMechanism !== 'DEFAULT' &&
    options.authMechanism !== 'MONGODB-CR' &&
    options.authMechanism !== 'MONGODB-X509' &&
    options.authMechanism !== 'SCRAM-SHA-1' &&
    options.authMechanism !== 'SCRAM-SHA-256' &&
    options.authMechanism !== 'PLAIN'
  ) {
    return handleCallback(
      callback,
      MongoError.create({
        message:
          'only DEFAULT, GSSAPI, PLAIN, MONGODB-X509, or SCRAM-SHA-1 is supported by authMechanism',
        driver: true
      })
    );
  }

  // If we have a callback fallback
  if (typeof callback === 'function')
    return authenticate(self, username, password, options, function(err, r) {
      // Support failed auth method
      if (err && err.message && err.message.indexOf('saslStart') !== -1) err.code = 59;
      // Reject error
      if (err) return callback(err, r);
      callback(null, r);
    });

  // Return a promise
  return new self.s.promiseLibrary(function(resolve, reject) {
    authenticate(self, username, password, options, function(err, r) {
      // Support failed auth method
      if (err && err.message && err.message.indexOf('saslStart') !== -1) err.code = 59;
      // Reject error
      if (err) return reject(err);
      resolve(r);
    });
  });
};