/*!
 * Should
 * Copyright(c) 2010-2014 TJ Holowaychuk <tj@vision-media.ca>
 * MIT Licensed
 */

module.exports = function(should, Assertion) {

  /**
   * Assert given object is NaN
   * @name NaN
   * @memberOf Assertion
   * @category assertion numbers
   * @example
   *
   * (10).should.not.be.NaN();
   * NaN.should.be.NaN();
   */
  Assertion.add('NaN', function() {
    this.params = { operator: 'to be NaN' };

    this.assert(this.obj !== this.obj);
  });

  /**
   * Assert given object is not finite (positive or negative)
   *
   * @name Infinity
   * @memberOf Assertion
   * @category assertion numbers
   * @example
   *
   * (10).should.not.be.Infinity();
   * NaN.should.not.be.Infinity();
   */
  Assertion.add('Infinity', function() {
    this.params = { operator: 'to be Infinity' };

    this.is.a.Number()
      .and.not.a.NaN()
      .and.assert(!isFinite(this.obj));
  });

  /**
   * Assert given number between `start` and `finish` or equal one of them.
   *
   * @name within
   * @memberOf Assertion
   * @category assertion numbers
   * @param {number} start Start number
   * @param {number} finish Finish number
   * @param {string} [description] Optional message
   * @example
   *
   * (10).should.be.within(0, 20);
   */
  Assertion.add('within', function(start, finish, description) {
    this.params = { operator: 'to be within ' + start + '..' + finish, message: description };

    this.assert(this.obj >= start && this.obj <= finish);
  });

  /**
   * Assert given number near some other `value` within `delta`
   *
   * @name approximately
   * @memberOf Assertion
   * @category assertion numbers
   * @param {number} value Center number
   * @param {number} delta Radius
   * @param {string} [description] Optional message
   * @example
   *
   * (9.99).should.be.approximately(10, 0.1);
   */
  Assertion.add('approximately', function(value, delta, description) {
    this.params = { operator: 'to be approximately ' + value + " ±" + delta, message: description };

    this.assert(Math.abs(this.obj - value) <= delta);
  });

  /**
   * Assert given number above `n`.
   *
   * @name above
   * @alias Assertion#greaterThan
   * @memberOf Assertion
   * @category assertion numbers
   * @param {number} n Margin number
   * @param {string} [description] Optional message
   * @example
   *
   * (10).should.be.above(0);
   */
  Assertion.add('above', function(n, description) {
    this.params = { operator: 'to be above ' + n, message: description };

    this.assert(this.obj > n);
  });

  /**
   * Assert given number below `n`.
   *
   * @name below
   * @alias Assertion#lessThan
   * @memberOf Assertion
   * @category assertion numbers
   * @param {number} n Margin number
   * @param {string} [description] Optional message
   * @example
   *
   * (0).should.be.above(10);
   */
  Assertion.add('below', function(n, description) {
    this.params = { operator: 'to be below ' + n, message: description };

    this.assert(this.obj < n);
  });

  Assertion.alias('above', 'greaterThan');
  Assertion.alias('below', 'lessThan');

};
