'use strict';

const util = require('util');
const Stream = require('stream');

function readStart(socket) {
  if (socket && !socket._paused && socket.readable)
    socket.resume();
}
exports.readStart = readStart;

function readStop(socket) {
  if (socket)
    socket.pause();
}
exports.readStop = readStop;


/* Abstract base class for ServerRequest and ClientResponse. */
function IncomingMessage(socket) {
  Stream.Readable.call(this);

  // XXX This implementation is kind of all over the place
  // When the parser emits body chunks, they go in this list.
  // _read() pulls them out, and when it finds EOF, it ends.

  this.socket = socket;
  this.connection = socket;

  this.httpVersionMajor = null;
  this.httpVersionMinor = null;
  this.httpVersion = null;
  this.complete = false;
  this.headers = {};
  this.rawHeaders = [];
  this.trailers = {};
  this.rawTrailers = [];

  this.readable = true;

  this.upgrade = null;

  // request (server) only
  this.url = '';
  this.method = null;

  // response (client) only
  this.statusCode = null;
  this.statusMessage = null;
  this.client = socket;

  // flag for backwards compatibility grossness.
  this._consuming = false;

  // flag for when we decide that this message cannot possibly be
  // read by the user, so there's no point continuing to handle it.
  this._dumped = false;
}
util.inherits(IncomingMessage, Stream.Readable);


exports.IncomingMessage = IncomingMessage;


IncomingMessage.prototype.setTimeout = function(msecs, callback) {
  if (callback)
    this.on('timeout', callback);
  this.socket.setTimeout(msecs);
  return this;
};


IncomingMessage.prototype.read = function(n) {
  this._consuming = true;
  this.read = Stream.Readable.prototype.read;
  return this.read(n);
};


IncomingMessage.prototype._read = function(n) {
  // We actually do almost nothing here, because the parserOnBody
  // function fills up our internal buffer directly.  However, we
  // do need to unpause the underlying socket so that it flows.
  if (this.socket.readable)
    readStart(this.socket);
};


// It's possible that the socket will be destroyed, and removed from
// any messages, before ever calling this.  In that case, just skip
// it, since something else is destroying this connection anyway.
IncomingMessage.prototype.destroy = function(error) {
  if (this.socket)
    this.socket.destroy(error);
};


IncomingMessage.prototype._addHeaderLines = function(headers, n) {
  if (headers && headers.length) {
    var raw, dest;
    if (this.complete) {
      raw = this.rawTrailers;
      dest = this.trailers;
    } else {
      raw = this.rawHeaders;
      dest = this.headers;
    }

    for (var i = 0; i < n; i += 2) {
      var k = headers[i];
      var v = headers[i + 1];
      raw.push(k);
      raw.push(v);
      this._addHeaderLine(k, v, dest);
    }
  }
};


// Add the given (field, value) pair to the message
//
// Per RFC2616, section 4.2 it is acceptable to join multiple instances of the
// same header with a ', ' if the header in question supports specification of
// multiple values this way. If not, we declare the first instance the winner
// and drop the second. Extended header fields (those beginning with 'x-') are
// always joined.
IncomingMessage.prototype._addHeaderLine = function(field, value, dest) {
  field = field.toLowerCase();
  switch (field) {
    // Array headers:
    case 'set-cookie':
      if (dest[field] !== undefined) {
        dest[field].push(value);
      } else {
        dest[field] = [value];
      }
      break;

    /* eslint-disable max-len */
    // list is taken from:
    // https://mxr.mozilla.org/mozilla/source/netwerk/protocol/http/src/nsHttpHeaderArray.cpp
    /* eslint-enable max-len */
    case 'content-type':
    case 'content-length':
    case 'user-agent':
    case 'referer':
    case 'host':
    case 'authorization':
    case 'proxy-authorization':
    case 'if-modified-since':
    case 'if-unmodified-since':
    case 'from':
    case 'location':
    case 'max-forwards':
    case 'retry-after':
    case 'etag':
    case 'last-modified':
    case 'server':
    case 'age':
    case 'expires':
      // drop duplicates
      if (dest[field] === undefined)
        dest[field] = value;
      break;

    default:
      // make comma-separated list
      if (dest[field] !== undefined) {
        dest[field] += ', ' + value;
      } else {
        dest[field] = value;
      }
  }
};


// Call this instead of resume() if we want to just
// dump all the data to /dev/null
IncomingMessage.prototype._dump = function() {
  if (!this._dumped) {
    this._dumped = true;
    this.resume();
  }
};