define(["exports"], function (exports) {
  "use strict";

  /**
   * Date utilities
   */

  var DateHelper = {
    isValid: function (dateStr, format) {
      if (!format) {
        format = "DMY";
      }
      format = format.toUpperCase();
      if (format.length != 3) {
        if (format === "DDMMMYYYY") {
          var d = this.format(dateStr, format);
          dateStr = d.getDate() + "/" + (d.getMonth() + 1) + "/" + d.getFullYear();
          format = "DMY";
        }
      }
      if ((format.indexOf("M") === -1) || (format.indexOf("D") === -1) || (format.indexOf("Y") === -1)) {
        format = "DMY";
      }
      var reg1, reg2;
      // If the year is first
      if (format.substring(0, 1) == "Y") {
        reg1 = /^\d{2}(\-|\/|\.)\d{1,2}\1\d{1,2}$/;
        reg2 = /^\d{4}(\-|\/|\.)\d{1,2}\1\d{1,2}$/;
      } else if (format.substring(1, 2) == "Y") {
        // If the year is second
        reg1 = /^\d{1,2}(\-|\/|\.)\d{2}\1\d{1,2}$/;
        reg2 = /^\d{1,2}(\-|\/|\.)\d{4}\1\d{1,2}$/;
      } else {
        // The year must be third
        reg1 = /^\d{1,2}(\-|\/|\.)\d{1,2}\1\d{2}$/;
        reg2 = /^\d{1,2}(\-|\/|\.)\d{1,2}\1\d{4}$/;
      }
      // If it doesn't conform to the right format (with either a 2 digit year or
      // 4 digit year), fail
      if (reg1.test(dateStr) === false && reg2.test(dateStr) === false) {
        return false;
      }
      // Split into 3 parts based on what the divider was
      var parts = dateStr.split(RegExp.$1);
      var mm, dd, yy;
      // Check to see if the 3 parts end up making a valid date
      if (format.substring(0, 1) === "M") {
        mm = parts[0];
      } else if (format.substring(1, 2) === "M") {
        mm = parts[1];
      } else {
        mm = parts[2];
      }
      if (format.substring(0, 1) === "D") {
        dd = parts[0];
      } else if (format.substring(1, 2) === "D") {
        dd = parts[1];
      } else {
        dd = parts[2];
      }
      if (format.substring(0, 1) === "Y") {
        yy = parts[0];
      } else if (format.substring(1, 2) === "Y") {
        yy = parts[1];
      } else {
        yy = parts[2];
      }
      if (parseInt(yy, 10) <= 50) {
        yy = (parseInt(yy, 10) + 2000).toString();
      }
      if (parseInt(yy, 10) <= 99) {
        yy = (parseInt(yy, 10) + 1900).toString();
      }
      var dt = new Date(parseInt(yy, 10), parseInt(mm, 10) - 1, parseInt(dd, 10), 0, 0, 0, 0);
      if (parseInt(dd, 10) != dt.getDate()) {
        return false;
      }
      if (parseInt(mm, 10) - 1 != dt.getMonth()) {
        return false;
      }
      return true;
    },
    format: function (dateStr, format) {
      if (!format) {
        format = "DMY";
      }
      if (!dateStr || dateStr === "") {
        return new Date(1001, 0, 1);
      }
      var oDate, parts;

      function y2kDate(yr) {
        if (yr === undefined) {
          return 0;
        }
        if (yr.length > 2) {
          return yr;
        }
        var y;
        //>50 belong to 1900
        if (yr <= 99 && yr > 50) {
          y = "19" + yr;
        }
        //<50 belong to 2000
        if (yr < 50 || yr === "00") {
          y = "20" + yr;
        }
        return y;
      }

      function mmm2mm(mmm) {
        if (mmm === undefined) {
          return 0;
        }
        var mondigit;
        var MONTH_NAMES = ["january", "february", "march", "april", "may", "june", "july", "august", "september", "october", "november", "december", "jan", "feb", "mar", "apr", "may", "jun", "jul", "aug", "sep", "oct", "nov", "dec"];
        for (var m_i = 0; m_i < MONTH_NAMES.length; m_i++) {
          var month_name = MONTH_NAMES[m_i];
          if (mmm.toLowerCase() === month_name) {
            mondigit = m_i + 1;
            break;
          }
        }
        if (mondigit > 11 || mondigit < 23) {
          mondigit = mondigit - 12;
        }
        if (mondigit < 1 || mondigit > 12) {
          return 0;
        }
        return mondigit;
      }

      switch (format.toUpperCase()) {
        case "DDMMMYYYY":
          parts = dateStr.replace(/[- \/.]/g, " ").split(" ");
          oDate = new Date(y2kDate(parts[2]), mmm2mm(parts[1]) - 1, parts[0]);
          break;
        case "DMY":
          parts = dateStr.replace(/^(0?[1-9]|[12][0-9]|3[01])([- \/.])(0?[1-9]|1[012])([- \/.])((\d\d)?\d\d)$/, "$1 $3 $5").split(" ");
          oDate = new Date(y2kDate(parts[2]), parts[1] - 1, parts[0]);
          break;
        case "MDY":
          parts = dateStr.replace(/^(0?[1-9]|1[012])([- \/.])(0?[1-9]|[12][0-9]|3[01])([- \/.])((\d\d)?\d\d)$/, "$1 $3 $5").split(" ");
          oDate = new Date(y2kDate(parts[2]), parts[0] - 1, parts[1]);
          break;
        case "YMD":
          parts = dateStr.replace(/^((\d\d)?\d\d)([- \/.])(0?[1-9]|1[012])([- \/.])(0?[1-9]|[12][0-9]|3[01])$/, "$1 $4 $6").split(" ");
          oDate = new Date(y2kDate(parts[0]), parts[1] - 1, parts[2]);
          break;
        default: //in case format is not correct
          parts = dateStr.replace(/^(0?[1-9]|[12][0-9]|3[01])([- \/.])(0?[1-9]|1[012])([- \/.])((\d\d)?\d\d)$/, "$1 $3 $5").split(" ");
          oDate = new Date(y2kDate(parts[2]), parts[1] - 1, parts[0]);
          break;
      }
      return oDate;
    }
  };

  exports.DateHelper = DateHelper;
});