//app/mixins/dates.js
import Ember from 'ember';

var Dates = Ember.Mixin.create({
  convert: function(d) {
    // Converts the date in d to a date-object. The input can be:
    //   a date object: returned without modification
    //  an array      : Interpreted as [year,month,day]. NOTE: month is 0-11.
    //   a number     : Interpreted as number of milliseconds
    //                  since 1 Jan 1970 (a timestamp)
    //   a string     : Any format supported by the javascript engine, like
    //                  "YYYY/MM/DD", "MM/DD/YYYY", "Jan 31 2009" etc.
    //  an object     : Interpreted as an object with year, month and date
    //                  attributes.  **NOTE** month is 0-11.
    return (
      d.constructor === Date ? d :
      d.constructor === Array ? new Date(d[0],d[1],d[2]) :
      d.constructor === Number ? new Date(d) :
      d.constructor === String ? new Date(d) :
      typeof d === "object" ? new Date(d.year,d.month,d.date) :
      NaN
    );
  },
  compare: function(a,b) {
    // Compare two dates (could be of any type supported by the convert
    // function above) and returns:
    //  -1 : if a < b
    //   0 : if a = b
    //   1 : if a > b
    // NaN : if a or b is an illegal date
    // NOTE: The code inside isFinite does an assignment (=).
    return (
      isFinite(a=this.convert(a).valueOf()) &&
      isFinite(b=this.convert(b).valueOf()) ?
      (a>b)-(a<b) :
      NaN
    );
  },
  inRange: function(d,start,end) {
    // Checks if date in d is between dates in start and end.
    // Returns a boolean or NaN:
    //    true  : if d is between start and end (inclusive)
    //    false : if d is before start or after end
    //    NaN   : if one or more of the dates is illegal.
    // NOTE: The code inside isFinite does an assignment (=).
    return (
      isFinite(d=this.convert(d).valueOf()) &&
      isFinite(start=this.convert(start).valueOf()) &&
      isFinite(end=this.convert(end).valueOf()) ?
      start <= d && d <= end :
      NaN
      );
  }
});

export default Dates;