/*!

* Chai - addMethod utility
* Copyright(c) 2012-2014 Jake Luer <jake@alogicalparadox.com>
* MIT Licensed
*/

var addLengthGuard = require('./addLengthGuard'); var chai = require('../../chai'); var flag = require('./flag'); var proxify = require('./proxify'); var transferFlags = require('./transferFlags');

/**

* ### .addMethod(ctx, name, method)
*
* Adds a method to the prototype of an object.
*
*     utils.addMethod(chai.Assertion.prototype, 'foo', function (str) {
*       var obj = utils.flag(this, 'object');
*       new chai.Assertion(obj).to.be.equal(str);
*     });
*
* Can also be accessed directly from `chai.Assertion`.
*
*     chai.Assertion.addMethod('foo', fn);
*
* Then can be used as any other assertion.
*
*     expect(fooStr).to.be.foo('bar');
*
* @param {Object} ctx object to which the method is added
* @param {String} name of method to add
* @param {Function} method function to be used for name
* @namespace Utils
* @name addMethod
* @api public
*/

module.exports = function addMethod(ctx, name, method) {

var methodWrapper = function () {
  // Setting the `ssfi` flag to `methodWrapper` causes this function to be the
  // starting point for removing implementation frames from the stack trace of
  // a failed assertion.
  //
  // However, we only want to use this function as the starting point if the
  // `lockSsfi` flag isn't set.
  //
  // If the `lockSsfi` flag is set, then either this assertion has been
  // overwritten by another assertion, or this assertion is being invoked from
  // inside of another assertion. In the first case, the `ssfi` flag has
  // already been set by the overwriting assertion. In the second case, the
  // `ssfi` flag has already been set by the outer assertion.
  if (!flag(this, 'lockSsfi')) {
    flag(this, 'ssfi', methodWrapper);
  }

  var result = method.apply(this, arguments);
  if (result !== undefined)
    return result;

  var newAssertion = new chai.Assertion();
  transferFlags(this, newAssertion);
  return newAssertion;
};

addLengthGuard(methodWrapper, name, false);
ctx[name] = proxify(methodWrapper, name);

};