'use strict';

var toString = Object.prototype.toString;

/**
 * Extract names from functions.
 *
 * @param {Function} fn The function who's name we need to extract.
 * @returns {String} The name of the function.
 * @public
 */
var fn_name = function name(fn) {
  if ('string' === typeof fn.displayName && fn.constructor.name) {
    return fn.displayName;
  } else if ('string' === typeof fn.name && fn.name) {
    return fn.name;
  }

  //
  // Check to see if the constructor has a name.
  //
  if (
       'object' === typeof fn
    && fn.constructor
    && 'string' === typeof fn.constructor.name
  ) return fn.constructor.name;

  //
  // toString the given function and attempt to parse it out of it, or determine
  // the class.
  //
  var named = fn.toString()
    , type = toString.call(fn).slice(8, -1);

  if ('Function' === type) {
    named = named.substring(named.indexOf('(') + 1, named.indexOf(')'));
  } else {
    named = type;
  }

  return named || 'anonymous';
};

exports.fn_name = fn_name;
