/**
 * A helper class responsible in assisting the formatting and unformatting of
 * date/time.
 */

define(
		[ 'dojo/_base/declare', 'dojo/date', 'dojox/date/timezone',
				'dojo/date/locale', "dojo/_base/kernel", 'dojo/i18n' ],
		function(declare, dojoDate, dojoxDate, dateLocale, kernel, i18n) {
			var DateTimeFormatterHelper = declare(
					null,
					{
						DSTIndicatorPosition : Object.freeze({
							AFTER : "AFTER",
							BEFORE : "BEFORE"
						}),

						hourPatterns : [ "hh", "h", "HH", "H", "kk", "k" ],

						constructor : function() {
							this.dstHourIndicator = {
								position : this.DSTIndicatorPosition.AFTER,
								A : '',
								B : '*'
							}

							this.dateTimeDelimiter = " ";

							// Override dojo's default localized short format
							// to consider our delimiter
							i18n.cache["dojo/cldr/nls/gregorian/"
									+ dojo.config.locale]["dateTimeFormat-short"] = "{1}"
									+ this.dateTimeDelimiter + "{0}";
						},

						getSelector : function(datePattern, timePattern) {
							if (!datePattern || datePattern === "") {
								return "time";
							}

							if (!this.selector
									&& (!timePattern || timePattern === "")) {
								return "date";
							}

							return null;
						},

						dateTimeToString : function(date, configuration) {
							var datePattern = configuration.datePattern;
							var timePattern = configuration.timePattern;
							var timezone = configuration.timezone;

							if (date == null
									|| (!(datePattern || datePattern === '') && (!timePattern || timePattern === ''))) {
								return "";
							}

							if (typeof date == 'number') {
								date = new Date(date);
							}

							if (!timezone) {
								timezone = dojo.config.timezone;
							}

							var selector = this.getSelector(datePattern,
									timePattern);

							// This adds the dst indicator to the pattern.
							timePattern = this.getDSTTimePattern(date,
									timezone, timePattern);

							// This indicates if the datestamp needs to be
							// rendered for the previous date. This is used as
							// we want to render
							// the midnight as 24:00.
							var switchDayBack = false;
							if (timePattern && timePattern !== '') {
								// If we are at midnight on a case with k
								// rendering, set the timestamp to 24 and the
								// day switchback to true.
								if (timePattern.indexOf("k") != -1
										&& date.getHours() == 0
										&& date.getMinutes() == 0
										&& date.getSeconds() == 0
										&& date.getMilliseconds() == 0) {
									// Replace cases of two k with one so the
									// next step can just replace the remaining
									// k.
									timePattern = timePattern
											.replace("kk", "k");
									// Replace the k with 24.
									timePattern = timePattern.replace("k",
											"'24'");
									// Set the day to be switched back a day
									// when rendering since we are midnight of
									// the previous day.
									switchDayBack = true;
								} else {
									timePattern = timePattern
											.replace(/k/g, "H");
								}
							}

							var tmpDate = new Date(date.getTime());

							if (switchDayBack) {
								tmpDate = dojoDate.add(tmpDate, "day", -1);
							}

							var result = dateLocale.format(tmpDate, {
								datePattern : datePattern,
								timePattern : timePattern,
								timezone : timezone,
								selector : selector
							});

							return result;
						},

						stringToDateTime : function(dateString, configuration) {
							var datePattern = configuration.datePattern;
							var timePattern = configuration.timePattern;
							var timezone = configuration.timezone;
							var selector = this.getSelector(datePattern,
									timePattern);

							if (!dateString || dateString === '') {
								return null;
							}

							if (!timezone) {
								timezone = dojo.config.timezone;
							}

							var dateTimePattern = "";
							var tmpTimePattern = timePattern;

							if (datePattern !== '') {
								dateTimePattern += datePattern;
							}

							if (datePattern !== '' && timePattern !== '') {
								dateTimePattern += this.dateTimeDelimiter;
							}

							if (timePattern !== '') {
								dateTimePattern += timePattern;
							}

							if (timePattern.indexOf("kk") != -1) {
								tmpTimePattern = timePattern
										.replace("kk", "HH");
								dateTimePattern = dateTimePattern.replace("kk",
										"HH");
							} else if (timePattern.indexOf("k") != -1) {
								tmpTimePattern = timePattern.replace("k", "H");
								dateTimePattern = dateTimePattern.replace("k",
										"H");
							}

							var isHourA = dateString
									.indexOf(this.dstHourIndicator.A) != -1;
							if (isHourA) {
								dateString = dateString.replace(
										this.dstHourIndicator.A, "");
								if (this.dstHourIndicator.A !== '') {
									dateString = dateString.replace("kk", "k");
									dateString = dateString.replace("HH", "H");
								}
							}

							var isHourB = dateString
									.indexOf(this.dstHourIndicator.B) != -1;
							if (isHourB) {
								dateString = dateString.replace(
										this.dstHourIndicator.B, "");
								if (this.dstHourIndicator.B !== '') {
									dateString = dateString.replace("kk", "k");
									dateString = dateString.replace("HH", "H");
								}
							}

							var switchDate = false;
							if (timePattern != null
									&& timePattern.indexOf("k") != -1) {
								var index = dateTimePattern.indexOf("H");
								if (index != -1) {
									var str = dateString.substring(index);
									if (str.length > 1) {
										if ("24" === str.substring(0, 2)) {
											dateString = dateString.substring(
													0, index)
													+ "00"
													+ dateString.substring(
															index + 2,
															dateString.length);
											switchDate = true;
										}
									}
								}
							}

							var date = dateLocale.parse(dateString, {
								datePattern : datePattern,
								timePattern : tmpTimePattern,
								timezone : timezone,
								selector : selector
							});

							// Dojo's formatter always uses the current timezone
							// when parsing. Need to adjust the necessary amount
							// of minutes from the
							// timezone offset of the current timezone and the
							// provided timezone.

							var tzInfo = dojoxDate.getTzInfo(date, timezone);
							date = dojoDate.add(date, "minute", tzInfo.tzOffset
									- date.getTimezoneOffset());

							if (switchDate) {
								date = dojoDate.add(date, "day", 1);
							}

							if (timezoneInfo.enableDST) {
								var daylightTime = timezoneInfo.dstChangeDate[date
										.getFullYear()];
								if (daylightTime != null) {
									// if dst end hour, subtract hour from
									// date
									for ( var i in daylightTime.endDates) {
										var endDate = new Date(
												daylightTime.endDates[i]);
										var endHour = endDate.getHours() == 0 ? 24
												: endDate.getHours();

										if ((date.getDate() == endDate
												.getDate())
												&& (date.getMonth() == endDate
														.getMonth())
												&& (date.getHours() == endHour - 1)) {

											if (date.getTimezoneOffset() >= endDate
													.getTimezoneOffset()) {
												date = dojoDate.add(date,
														"hour", -1);
											} else if (isHourB) {
												date = dojoDate.add(date,
														"hour", 1);
											}

											break;
										}
									}
								}

							}

							return date;
						},

						getDSTTimePattern : function(date, timezone,
								timePattern) {
							if (timePattern !== '') {
								// if extra hour, add hourBIndicator
								if (this.isDstSwitchbackHour(date, timezone)) {
									timePattern = this.applyIndicator(
											timePattern,
											this.dstHourIndicator.position, "'"
													+ this.dstHourIndicator.B
													+ "'");
									timePattern = timePattern
											.replace("kk", "k");
									timePattern = timePattern
											.replace("HH", "H");
									timePattern = timePattern
											.replace("hh", "h");
								} else { // if one hour before the extra
									// hour, add hourAIndicator
									var tmpDate = new Date(date.getTime());
									tmpDate = dojoDate.add(tmpDate, "hour", 1);
									if (this.isDstSwitchbackHour(tmpDate,
											timezone)) {
										timePattern = this.applyIndicator(
												timePattern,
												this.dstHourIndicator.position,
												"'" + this.dstHourIndicator.A
														+ "'");
										timePattern = timePattern.replace("kk",
												"k");
										timePattern = timePattern.replace("HH",
												"H");
										timePattern = timePattern.replace("hh",
												"h");
									}
								}
							}

							return timePattern;
						},

						applyIndicator : function(timePattern,
								dstIndicatorPosition, dstIndicator) {

							for ( var i in this.hourPatterns) {
								var pattern = this.hourPatterns[i];
								if (timePattern.indexOf(pattern) != -1) {
									timePattern = timePattern
											.replace(
													pattern,
													dstIndicatorPosition == this.DSTIndicatorPosition.BEFORE ? dstIndicator
															+ pattern
															: pattern
																	+ dstIndicator);
									break;
								}
							}

							return timePattern;
						},

						isDstSwitchbackHour : function(date, timezone) {
							// check for DST end hour
							if (timezoneInfo.enableDST) {
								var daylightTime = timezoneInfo.dstChangeDate[date
										.getFullYear()];

								if (!daylightTime) {
									return false;
								}

								// check if DST end hour
								for ( var i in daylightTime.endDates) {
									var endDate = new Date(
											daylightTime.endDates[i]);
									var endHour = endDate.getHours() == 0 ? 24
											: endDate.getHours();

									if ((date.getDate() == endDate.getDate())
											&& (date.getMonth() == endDate
													.getMonth())
											&& (date.getHours() == endHour - 1)) {

										if (date.getTimezoneOffset() >= endDate
												.getTimezoneOffset()) {
											var tmpDate = dojoDate
													.add(new Date(endDate
															.getTime()),
															"hour", -2);

											if (date.getTimezoneOffset() != tmpDate
													.getTimezoneOffset()) {
												// this is the extra hour
												return true;
											}
										}
									}
								}
							}
							return false;
						}
					});

			return new DateTimeFormatterHelper();
		});