var preferredCharsets = require('./lib/charset');
var preferredEncodings = require('./lib/encoding');
var preferredLanguages = require('./lib/language');
var preferredMediaTypes = require('./lib/mediaType');

module.exports = Negotiator;
Negotiator.Negotiator = Negotiator;

function Negotiator(request) {
  if (!(this instanceof Negotiator)) {
    return new Negotiator(request);
  }

  this.request = request;
}

Negotiator.prototype.charset = function charset(available) {
  var set = this.charsets(available);
  return set && set[0];
};

Negotiator.prototype.charsets = function charsets(available) {
  return preferredCharsets(this.request.headers['accept-charset'], available);
};

Negotiator.prototype.encoding = function encoding(available) {
  var set = this.encodings(available);
  return set && set[0];
};

Negotiator.prototype.encodings = function encodings(available) {
  return preferredEncodings(this.request.headers['accept-encoding'], available);
};

Negotiator.prototype.language = function language(available) {
  var set = this.languages(available);
  return set && set[0];
};

Negotiator.prototype.languages = function languages(available) {
  return preferredLanguages(this.request.headers['accept-language'], available);
};

Negotiator.prototype.mediaType = function mediaType(available) {
  var set = this.mediaTypes(available);
  return set && set[0];
};

Negotiator.prototype.mediaTypes = function mediaTypes(available) {
  return preferredMediaTypes(this.request.headers.accept, available);
};

// Backwards compatibility
Negotiator.prototype.preferredCharset = Negotiator.prototype.charset;
Negotiator.prototype.preferredCharsets = Negotiator.prototype.charsets;
Negotiator.prototype.preferredEncoding = Negotiator.prototype.encoding;
Negotiator.prototype.preferredEncodings = Negotiator.prototype.encodings;
Negotiator.prototype.preferredLanguage = Negotiator.prototype.language;
Negotiator.prototype.preferredLanguages = Negotiator.prototype.languages;
Negotiator.prototype.preferredMediaType = Negotiator.prototype.mediaType;
Negotiator.prototype.preferredMediaTypes = Negotiator.prototype.mediaTypes;