'use strict';

/**
 * Return the mime type for the given `str`.
 *
 * @param {String} str
 * @return {String}
 * @api private
 */

exports.type = function(str){
  return str.split(/ *; */).shift();
};

/**
 * Return header field parameters.
 *
 * @param {String} str
 * @return {Object}
 * @api private
 */

exports.params = function(str){
  return str.split(/ *; */).reduce(function(obj, str){
    var parts = str.split(/ *= */);
    var key = parts.shift();
    var val = parts.shift();

    if (key && val) obj[key] = val;
    return obj;
  }, {});
};

/**
 * Parse Link header fields.
 *
 * @param {String} str
 * @return {Object}
 * @api private
 */

exports.parseLinks = function(str){
  return str.split(/ *, */).reduce(function(obj, str){
    var parts = str.split(/ *; */);
    var url = parts[0].slice(1, -1);
    var rel = parts[1].split(/ *= */)[1].slice(1, -1);
    obj[rel] = url;
    return obj;
  }, {});
};

/**
 * Strip content related fields from `header`.
 *
 * @param {Object} header
 * @return {Object} header
 * @api private
 */

exports.cleanHeader = function(header, changesOrigin){
  delete header['content-type'];
  delete header['content-length'];
  delete header['transfer-encoding'];
  delete header['host'];
  // secuirty
  if (changesOrigin) {
    delete header['authorization'];
    delete header['cookie'];
  }
  return header;
};