var AWS = require('../core');
var Stream = AWS.util.stream.Stream;
var TransformStream = AWS.util.stream.Transform;
var ReadableStream = AWS.util.stream.Readable;
require('../http');
var CONNECTION_REUSE_ENV_NAME = 'AWS_NODEJS_CONNECTION_REUSE_ENABLED';

/**
 * @api private
 */
AWS.NodeHttpClient = AWS.util.inherit({
  handleRequest: function handleRequest(httpRequest, httpOptions, callback, errCallback) {
    var self = this;
    var endpoint = httpRequest.endpoint;
    var pathPrefix = '';
    if (!httpOptions) httpOptions = {};
    if (httpOptions.proxy) {
      pathPrefix = endpoint.protocol + '//' + endpoint.hostname;
      if (endpoint.port !== 80 && endpoint.port !== 443) {
        pathPrefix += ':' + endpoint.port;
      }
      endpoint = new AWS.Endpoint(httpOptions.proxy);
    }

    var useSSL = endpoint.protocol === 'https:';
    var http = useSSL ? require('https') : require('http');
    var options = {
      host: endpoint.hostname,
      port: endpoint.port,
      method: httpRequest.method,
      headers: httpRequest.headers,
      path: pathPrefix + httpRequest.path
    };

    if (!httpOptions.agent) {
      options.agent = this.getAgent(useSSL, {
        keepAlive: process.env[CONNECTION_REUSE_ENV_NAME] === '1' ? true : false
      });
    }

    AWS.util.update(options, httpOptions);
    delete options.proxy; // proxy isn't an HTTP option
    delete options.timeout; // timeout isn't an HTTP option

    var stream = http.request(options, function (httpResp) {
      if (stream.didCallback) return;

      callback(httpResp);
      httpResp.emit(
        'headers',
        httpResp.statusCode,
        httpResp.headers,
        httpResp.statusMessage
      );
    });
    httpRequest.stream = stream; // attach stream to httpRequest
    stream.didCallback = false;

    // connection timeout support
    if (httpOptions.connectTimeout) {
      var connectTimeoutId;
      stream.on('socket', function(socket) {
        if (socket.connecting) {
          connectTimeoutId = setTimeout(function connectTimeout() {
            if (stream.didCallback) return; stream.didCallback = true;

            stream.abort();
            errCallback(AWS.util.error(
              new Error('Socket timed out without establishing a connection'),
              {code: 'TimeoutError'}
            ));
          }, httpOptions.connectTimeout);
          socket.on('connect', function() {
            clearTimeout(connectTimeoutId);
            connectTimeoutId = null;
          });
        }
      });
    }

    // timeout support
    stream.setTimeout(httpOptions.timeout || 0, function() {
      if (stream.didCallback) return; stream.didCallback = true;

      var msg = 'Connection timed out after ' + httpOptions.timeout + 'ms';
      errCallback(AWS.util.error(new Error(msg), {code: 'TimeoutError'}));
      stream.abort();
    });

    stream.on('error', function(err) {
      if (connectTimeoutId) {
        clearTimeout(connectTimeoutId);
        connectTimeoutId = null;
      }
      if (stream.didCallback) return; stream.didCallback = true;
      if ('ECONNRESET' === err.code || 'EPIPE' === err.code || 'ETIMEDOUT' === err.code) {
        errCallback(AWS.util.error(err, {code: 'TimeoutError'}));
      } else {
        errCallback(err);
      }
    });

    var expect = httpRequest.headers.Expect || httpRequest.headers.expect;
    if (expect === '100-continue') {
      stream.once('continue', function() {
        self.writeBody(stream, httpRequest);
      });
    } else {
      this.writeBody(stream, httpRequest);
    }

    return stream;
  },

  writeBody: function writeBody(stream, httpRequest) {
    var body = httpRequest.body;
    var totalBytes = parseInt(httpRequest.headers['Content-Length'], 10);

    if (body instanceof Stream) {
      // For progress support of streaming content -
      // pipe the data through a transform stream to emit 'sendProgress' events
      var progressStream = this.progressStream(stream, totalBytes);
      if (progressStream) {
        body.pipe(progressStream).pipe(stream);
      } else {
        body.pipe(stream);
      }
    } else if (body) {
      // The provided body is a buffer/string and is already fully available in memory -
      // For performance it's best to send it as a whole by calling stream.end(body),
      // Callers expect a 'sendProgress' event which is best emitted once
      // the http request stream has been fully written and all data flushed.
      // The use of totalBytes is important over body.length for strings where
      // length is char length and not byte length.
      stream.once('finish', function() {
        stream.emit('sendProgress', {
          loaded: totalBytes,
          total: totalBytes
        });
      });
      stream.end(body);
    } else {
      // no request body
      stream.end();
    }
  },

  /**
   * Create the https.Agent or http.Agent according to the request schema.
   */
  getAgent: function getAgent(useSSL, agentOptions) {
    var http = useSSL ? require('https') : require('http');
    if (useSSL) {
      if (!AWS.NodeHttpClient.sslAgent) {
        AWS.NodeHttpClient.sslAgent = new http.Agent(AWS.util.merge({
          rejectUnauthorized: process.env.NODE_TLS_REJECT_UNAUTHORIZED === '0' ? false : true
        }, agentOptions || {}));
        AWS.NodeHttpClient.sslAgent.setMaxListeners(0);

        // delegate maxSockets to globalAgent, set a default limit of 50 if current value is Infinity.
        // Users can bypass this default by supplying their own Agent as part of SDK configuration.
        Object.defineProperty(AWS.NodeHttpClient.sslAgent, 'maxSockets', {
          enumerable: true,
          get: function() {
            var defaultMaxSockets = 50;
            var globalAgent = http.globalAgent;
            if (globalAgent && globalAgent.maxSockets !== Infinity && typeof globalAgent.maxSockets === 'number') {
              return globalAgent.maxSockets;
            }
            return defaultMaxSockets;
          }
        });
      }
      return AWS.NodeHttpClient.sslAgent;
    } else {
      if (!AWS.NodeHttpClient.agent) {
        AWS.NodeHttpClient.agent = new http.Agent(agentOptions);
      }
      return AWS.NodeHttpClient.agent;
    }
  },

  progressStream: function progressStream(stream, totalBytes) {
    if (typeof TransformStream === 'undefined') {
      // for node 0.8 there is no streaming progress
      return;
    }
    var loadedBytes = 0;
    var reporter = new TransformStream();
    reporter._transform = function(chunk, encoding, callback) {
      if (chunk) {
        loadedBytes += chunk.length;
        stream.emit('sendProgress', {
          loaded: loadedBytes,
          total: totalBytes
        });
      }
      callback(null, chunk);
    };
    return reporter;
  },

  emitter: null
});

/**
 * @!ignore
 */

/**
 * @api private
 */
AWS.HttpClient.prototype = AWS.NodeHttpClient.prototype;

/**
 * @api private
 */
AWS.HttpClient.streamsApiVersion = ReadableStream ? 2 : 1;
