/**
 * Class that manages making request, called by all of the API methods.
 * @type {[type]}
 */
module.exports = Transport;

var _ = require('lodash');
var utils = require('./utils');
var errors = require('./errors');
var Host = require('./host');
var patchSniffOnConnectionFault = require('./transport/sniff_on_connection_fault');
var findCommonProtocol = require('./transport/find_common_protocol');

function Transport(config) {
  var self = this;
  config = self._config = config || {};

  var LogClass = (typeof config.log === 'function') ? config.log : require('./log');
  config.log = self.log = new LogClass(config);

  // setup the connection pool
  var ConnectionPool = utils.funcEnum(config, 'connectionPool', Transport.connectionPools, 'main');
  self.connectionPool = new ConnectionPool(config);

  // setup the serializer
  var Serializer = utils.funcEnum(config, 'serializer', Transport.serializers, 'json');
  self.serializer = new Serializer(config);

  // setup the nodesToHostCallback
  self.nodesToHostCallback = utils.funcEnum(config, 'nodesToHostCallback', Transport.nodesToHostCallbacks, 'main');

  // setup max retries
  self.maxRetries = config.hasOwnProperty('maxRetries') ? config.maxRetries : 3;

  // setup endpoint to use for sniffing
  self.sniffEndpoint = config.hasOwnProperty('sniffEndpoint') ? config.sniffEndpoint : '/_nodes/_all/http';

  // setup requestTimeout default
  self.requestTimeout = config.hasOwnProperty('requestTimeout') ? config.requestTimeout : 30000;

  if (config.hasOwnProperty('defer')) {
    self.defer = config.defer;
  }

  // randomizeHosts option
  var randomizeHosts = config.hasOwnProperty('randomizeHosts') ? !!config.randomizeHosts : true;

  if (config.host) {
    config.hosts = config.host;
  }

  if (config.hosts) {
    var hostsConfig = utils.createArray(config.hosts, function (val) {
      if (_.isPlainObject(val) || _.isString(val) || val instanceof Host) {
        return val;
      }
    });

    if (!hostsConfig) {
      throw new TypeError('Invalid hosts config. Expected a URL, an array of urls, a host config object, ' +
        'or an array of host config objects.');
    }

    if (randomizeHosts) {
      hostsConfig = _.shuffle(hostsConfig);
    }

    self.setHosts(hostsConfig);
  }

  if (config.hasOwnProperty('sniffedNodesProtocol')) {
    self.sniffedNodesProtocol = config.sniffedNodesProtocol || null;
  } else {
    self.sniffedNodesProtocol = findCommonProtocol(self.connectionPool.getAllHosts()) || null;
  }

  if (config.hasOwnProperty('sniffedNodesFilterPath')) {
    self.sniffedNodesFilterPath = config.sniffedNodesFilterPath;
  } else {
    self.sniffedNodesFilterPath = [
      'nodes.*.http.publish_address',
      'nodes.*.name',
      'nodes.*.hostname',
      'nodes.*.host',
      'nodes.*.version',
    ].join(',');
  }

  if (config.sniffOnStart) {
    self.sniff();
  }

  if (config.sniffInterval) {
    self._timeout(function doSniff() {
      self.sniff();
      self._timeout(doSniff, config.sniffInterval);
    }, config.sniffInterval);
  }

  if (config.sniffOnConnectionFault) {
    patchSniffOnConnectionFault(self);
  }
}

Transport.connectionPools = {
  main: require('./connection_pool')
};

Transport.serializers = require('./serializers');

Transport.nodesToHostCallbacks = {
  main: require('./nodes_to_host')
};

Transport.prototype.defer = function () {
  if (typeof Promise === 'undefined') {
    throw new Error(
      'No Promise implementation found. In order for elasticsearch-js to create promises ' +
      'either specify the `defer` configuration or include a global Promise shim'
    )
  }

  var defer = {};
  defer.promise = new Promise(function (resolve, reject) {
    defer.resolve = resolve;
    defer.reject = reject;
  });
  return defer;
};

/**
 * Perform a request with the client's transport
 *
 * @method request
 * @todo async body writing
 * @todo abort
 * @todo access to custom headers, modifying of request in general
 * @param {object} params
 * @param {Number} params.requestTimeout - timeout for the entire request (inculding all retries)
 * @param {Number} params.maxRetries - number of times to re-run request if the
 *   original node chosen can not be connected to.
 * @param {string} [params.path="/"] - URL pathname. Do not include query string.
 * @param {string|object} [params.query] - Query string.
 * @param {String} params.method - The HTTP method for the request
 * @param {String} params.body - The body of the HTTP request
 * @param {Function} cb - A function to call back with (error, responseBody, responseStatus)
 */
Transport.prototype.request = function (params, cb) {
  var self = this;
  var remainingRetries = this.maxRetries;
  var requestTimeout = this.requestTimeout;

  var connection; // set in sendReqWithConnection
  var aborted = false; // several connector will respond with an error when the request is aborted
  var requestAborter; // an abort function, returned by connection#request()
  var requestTimeoutId; // the id of the ^timeout
  var ret; // the object returned to the user, might be a promise
  var defer; // the defer object, will be set when we are using promises.

  var body = params.body;
  var headers = !params.headers ? {} : _.transform(params.headers, function (headers, val, name) {
    headers[String(name).toLowerCase()] = val;
  });

  self.log.debug('starting request', params);

  // determine the response based on the presense of a callback
  if (typeof cb === 'function') {
    // handle callbacks within a domain
    if (process.domain) {
      cb = process.domain.bind(cb);
    }
    ret = {
      abort: abortRequest
    };
  } else {
    defer = this.defer();
    ret = defer.promise;
    ret.abort = abortRequest;
  }

  if (body && params.method === 'GET') {
    utils.nextTick(respond, new TypeError('Body can not be sent with method "GET"'));
    return ret;
  }

  // serialize the body
  if (body) {
    var serializer = self.serializer;
    var serializeFn = serializer[params.bulkBody ? 'bulkBody' : 'serialize'];

    body = serializeFn.call(serializer, body);
    if (!headers['content-type']) {
      headers['content-type'] = serializeFn.contentType;
    }
  }

  if (params.hasOwnProperty('maxRetries')) {
    remainingRetries = params.maxRetries;
  }

  if (params.hasOwnProperty('requestTimeout')) {
    requestTimeout = params.requestTimeout;
  }

  params.req = {
    method: params.method,
    path: params.path || '/',
    query: params.query,
    body: body,
    headers: headers
  };

  function sendReqWithConnection(err, _connection) {
    if (aborted) {
      return;
    }

    if (err) {
      respond(err);
    } else if (_connection) {
      connection = _connection;
      requestAborter = connection.request(params.req, checkRespForFailure);
    } else {
      self.log.warning('No living connections');
      respond(new errors.NoConnections());
    }
  }

  function checkRespForFailure(err, body, status, headers) {
    if (aborted) {
      return;
    }

    requestAborter = void 0;

    if (err instanceof errors.RequestTypeError) {
      self.log.error('Connection refused to execute the request', err);
      respond(err, body, status, headers);
      return;
    }

    if (err) {
      connection.setStatus('dead');

      var errMsg = err.message || '';

      errMsg =
        '\n' +
        params.req.method +
        ' ' +
        connection.host.makeUrl(params.req) +
        (errMsg.length ? ' => ' : '') +
        errMsg
      ;

      if (remainingRetries) {
        remainingRetries--;
        self.log.error('Request error, retrying' + errMsg);
        self.connectionPool.select(sendReqWithConnection);
      } else {
        self.log.error('Request complete with error' + errMsg);
        respond(new errors.ConnectionFault(err));
      }
    } else {
      self.log.debug('Request complete');
      respond(void 0, body, status, headers);
    }
  }

  function respond(err, body, status, headers) {
    if (aborted) {
      return;
    }

    self._timeout(requestTimeoutId);
    var parsedBody;
    var isJson = !headers || (headers['content-type'] && ~headers['content-type'].indexOf('application/json'));

    if (!err && body) {
      if (isJson) {
        parsedBody = self.serializer.deserialize(body);
        if (parsedBody == null) {
          err = new errors.Serialization();
          parsedBody = body;
        }
      } else {
        parsedBody = body;
      }
    }

    // does the response represent an error?
    if (
      (!err || err instanceof errors.Serialization)
      && (status < 200 || status >= 300)
      && (!params.ignore || !_.includes(params.ignore, status))
    ) {

      var errorMetadata = _.pick(params.req, ['path', 'query', 'body']);
      errorMetadata.statusCode = status;
      errorMetadata.response = body;

      if (status === 401 && headers && headers['www-authenticate']) {
        errorMetadata.wwwAuthenticateDirective = headers['www-authenticate'];
      }

      if (errors[status]) {
        err = new errors[status](parsedBody && parsedBody.error, errorMetadata);
      } else {
        err = new errors.Generic('unknown error', errorMetadata);
      }
    }

    // can we cast notfound to false?
    if (params.castExists) {
      if (err && err instanceof errors.NotFound) {
        parsedBody = false;
        err = void 0;
      } else {
        parsedBody = !err;
      }
    }

    // how do we send the response?
    if (typeof cb === 'function') {
      if (err) {
        cb(err, parsedBody, status);
      } else {
        cb(void 0, parsedBody, status);
      }
    } else if (err) {
      err.body = parsedBody;
      err.status = status;
      defer.reject(err);
    } else {
      defer.resolve(parsedBody);
    }
  }

  function abortRequest() {
    if (aborted) {
      return;
    }

    aborted = true;
    remainingRetries = 0;
    self._timeout(requestTimeoutId);
    if (typeof requestAborter === 'function') {
      requestAborter();
    }
  }

  if (requestTimeout && requestTimeout !== Infinity) {
    requestTimeoutId = this._timeout(function () {
      respond(new errors.RequestTimeout('Request Timeout after ' + requestTimeout + 'ms'));
      abortRequest();
    }, requestTimeout);
  }

  if (connection) {
    sendReqWithConnection(void 0, connection);
  } else {
    self.connectionPool.select(sendReqWithConnection);
  }

  return ret;
};

Transport.prototype._timeout = function (cb, delay) {
  if (this.closed) return;

  var id;
  var timers = this._timers || (this._timers = []);

  if ('function' !== typeof cb) {
    id = cb;
    cb = void 0;
  }

  if (cb) {
    // set the timer
    id = setTimeout(function () {
      _.pull(timers, id);
      cb();
    }, delay);

    timers.push(id);
    return id;
  }

  if (id) {
    clearTimeout(id);

    var i = this._timers.indexOf(id);
    if (i !== -1) {
      this._timers.splice(i, 1);
    }
  }
};

/**
 * Ask an ES node for a list of all the nodes, add/remove nodes from the connection
 * pool as appropriate
 *
 * @param  {Function} cb - Function to call back once complete
 */
Transport.prototype.sniff = function (cb) {
  var self = this;
  var nodesToHostCallback = this.nodesToHostCallback;
  var log = this.log;
  var sniffedNodesProtocol = this.sniffedNodesProtocol;
  var sniffedNodesFilterPath = this.sniffedNodesFilterPath;

  // make cb a function if it isn't
  cb = typeof cb === 'function' ? cb : _.noop;

  this.request({
    path: this.sniffEndpoint,
    query: { filter_path: sniffedNodesFilterPath },
    method: 'GET'
  }, function (err, resp, status) {
    if (!err && resp && resp.nodes) {
      var hostsConfigs;

      try {
        hostsConfigs = nodesToHostCallback(resp.nodes);
      } catch (e) {
        log.error(new Error('Unable to convert node list from ' + self.sniffEndpoint +
          ' to hosts durring sniff. Encountered error:\n' + (e.stack || e.message)));
        return;
      }

      _.forEach(hostsConfigs, function (hostConfig) {
        if (sniffedNodesProtocol) hostConfig.protocol = sniffedNodesProtocol;
      });

      self.setHosts(hostsConfigs);
    }
    cb(err, resp, status);
  });
};

/**
 * Set the host list that the transport should use.
 *
 * @param {Array<HostConfig>} hostsConfigs - an array of Hosts, or configuration objects
 *                                         that will be used to create Host objects.
 */
Transport.prototype.setHosts = function (hostsConfigs) {
  var globalConfig = this._config;
  this.connectionPool.setHosts(_.map(hostsConfigs, function (conf) {
    return (conf instanceof Host) ? conf : new Host(conf, globalConfig);
  }));
};

/**
 * Close the Transport, which closes the logs and connection pool
 * @return {[type]} [description]
 */
Transport.prototype.close = function () {
  this.log.close();
  this.closed = true;
  _.each(this._timers, clearTimeout);
  this._timers = null;
  this.connectionPool.close();
};
