var ambigDateOfMonthRegex = /^\s*\d{4}-\d\d$/;
var ambigTimeOrZoneRegex =
	/^\s*\d{4}-(?:(\d\d-\d\d)|(W\d\d$)|(W\d\d-\d)|(\d\d\d))((T| )(\d\d(:\d\d(:\d\d(\.\d+)?)?)?)?)?$/;
var newMomentProto = moment.fn; // where we will attach our new methods
var oldMomentProto = $.extend({}, newMomentProto); // copy of original moment methods
var allowValueOptimization;
var setUTCValues; // function defined below
var setLocalValues; // function defined below


// Creating
// -------------------------------------------------------------------------------------------------

// Creates a new moment, similar to the vanilla moment(...) constructor, but with
// extra features (ambiguous time, enhanced formatting). When given an existing moment,
// it will function as a clone (and retain the zone of the moment). Anything else will
// result in a moment in the local zone.
fc.moment = function() {
	return makeMoment(arguments);
};

// Sames as fc.moment, but forces the resulting moment to be in the UTC timezone.
fc.moment.utc = function() {
	var mom = makeMoment(arguments, true);

	// Force it into UTC because makeMoment doesn't guarantee it
	// (if given a pre-existing moment for example)
	if (mom.hasTime()) { // don't give ambiguously-timed moments a UTC zone
		mom.utc();
	}

	return mom;
};

// Same as fc.moment, but when given an ISO8601 string, the timezone offset is preserved.
// ISO8601 strings with no timezone offset will become ambiguously zoned.
fc.moment.parseZone = function() {
	return makeMoment(arguments, true, true);
};

// Builds an enhanced moment from args. When given an existing moment, it clones. When given a
// native Date, or called with no arguments (the current time), the resulting moment will be local.
// Anything else needs to be "parsed" (a string or an array), and will be affected by:
//    parseAsUTC - if there is no zone information, should we parse the input in UTC?
//    parseZone - if there is zone information, should we force the zone of the moment?
function makeMoment(args, parseAsUTC, parseZone) {
	var input = args[0];
	var isSingleString = args.length == 1 && typeof input === 'string';
	var isAmbigTime;
	var isAmbigZone;
	var ambigMatch;
	var mom;

	if (moment.isMoment(input)) {
		mom = moment.apply(null, args); // clone it
		transferAmbigs(input, mom); // the ambig flags weren't transfered with the clone
	}
	else if (isNativeDate(input) || input === undefined) {
		mom = moment.apply(null, args); // will be local
	}
	else { // "parsing" is required
		isAmbigTime = false;
		isAmbigZone = false;

		if (isSingleString) {
			if (ambigDateOfMonthRegex.test(input)) {
				// accept strings like '2014-05', but convert to the first of the month
				input += '-01';
				args = [ input ]; // for when we pass it on to moment's constructor
				isAmbigTime = true;
				isAmbigZone = true;
			}
			else if ((ambigMatch = ambigTimeOrZoneRegex.exec(input))) {
				isAmbigTime = !ambigMatch[5]; // no time part?
				isAmbigZone = true;
			}
		}
		else if ($.isArray(input)) {
			// arrays have no timezone information, so assume ambiguous zone
			isAmbigZone = true;
		}
		// otherwise, probably a string with a format

		if (parseAsUTC || isAmbigTime) {
			mom = moment.utc.apply(moment, args);
		}
		else {
			mom = moment.apply(null, args);
		}

		if (isAmbigTime) {
			mom._ambigTime = true;
			mom._ambigZone = true; // ambiguous time always means ambiguous zone
		}
		else if (parseZone) { // let's record the inputted zone somehow
			if (isAmbigZone) {
				mom._ambigZone = true;
			}
			else if (isSingleString) {
				if (mom.utcOffset) {
					mom.utcOffset(input); // if not a valid zone, will assign UTC
				}
				else {
					mom.zone(input); // for moment-pre-2.9
				}
			}
		}
	}

	mom._fullCalendar = true; // flag for extended functionality

	return mom;
}


// A clone method that works with the flags related to our enhanced functionality.
// In the future, use moment.momentProperties
newMomentProto.clone = function() {
	var mom = oldMomentProto.clone.apply(this, arguments);

	// these flags weren't transfered with the clone
	transferAmbigs(this, mom);
	if (this._fullCalendar) {
		mom._fullCalendar = true;
	}

	return mom;
};


// Week Number
// -------------------------------------------------------------------------------------------------


// Returns the week number, considering the locale's custom week number calcuation
// `weeks` is an alias for `week`
newMomentProto.week = newMomentProto.weeks = function(input) {
	var weekCalc = (this._locale || this._lang) // works pre-moment-2.8
		._fullCalendar_weekCalc;

	if (input == null && typeof weekCalc === 'function') { // custom function only works for getter
		return weekCalc(this);
	}
	else if (weekCalc === 'ISO') {
		return oldMomentProto.isoWeek.apply(this, arguments); // ISO getter/setter
	}

	return oldMomentProto.week.apply(this, arguments); // local getter/setter
};


// Time-of-day
// -------------------------------------------------------------------------------------------------

// GETTER
// Returns a Duration with the hours/minutes/seconds/ms values of the moment.
// If the moment has an ambiguous time, a duration of 00:00 will be returned.
//
// SETTER
// You can supply a Duration, a Moment, or a Duration-like argument.
// When setting the time, and the moment has an ambiguous time, it then becomes unambiguous.
newMomentProto.time = function(time) {

	// Fallback to the original method (if there is one) if this moment wasn't created via FullCalendar.
	// `time` is a generic enough method name where this precaution is necessary to avoid collisions w/ other plugins.
	if (!this._fullCalendar) {
		return oldMomentProto.time.apply(this, arguments);
	}

	if (time == null) { // getter
		return moment.duration({
			hours: this.hours(),
			minutes: this.minutes(),
			seconds: this.seconds(),
			milliseconds: this.milliseconds()
		});
	}
	else { // setter

		this._ambigTime = false; // mark that the moment now has a time

		if (!moment.isDuration(time) && !moment.isMoment(time)) {
			time = moment.duration(time);
		}

		// The day value should cause overflow (so 24 hours becomes 00:00:00 of next day).
		// Only for Duration times, not Moment times.
		var dayHours = 0;
		if (moment.isDuration(time)) {
			dayHours = Math.floor(time.asDays()) * 24;
		}

		// We need to set the individual fields.
		// Can't use startOf('day') then add duration. In case of DST at start of day.
		return this.hours(dayHours + time.hours())
			.minutes(time.minutes())
			.seconds(time.seconds())
			.milliseconds(time.milliseconds());
	}
};

// Converts the moment to UTC, stripping out its time-of-day and timezone offset,
// but preserving its YMD. A moment with a stripped time will display no time
// nor timezone offset when .format() is called.
newMomentProto.stripTime = function() {
	var a;

	if (!this._ambigTime) {

		// get the values before any conversion happens
		a = this.toArray(); // array of y/m/d/h/m/s/ms

		// TODO: use keepLocalTime in the future
		this.utc(); // set the internal UTC flag (will clear the ambig flags)
		setUTCValues(this, a.slice(0, 3)); // set the year/month/date. time will be zero

		// Mark the time as ambiguous. This needs to happen after the .utc() call, which might call .utcOffset(),
		// which clears all ambig flags. Same with setUTCValues with moment-timezone.
		this._ambigTime = true;
		this._ambigZone = true; // if ambiguous time, also ambiguous timezone offset
	}

	return this; // for chaining
};

// Returns if the moment has a non-ambiguous time (boolean)
newMomentProto.hasTime = function() {
	return !this._ambigTime;
};


// Timezone
// -------------------------------------------------------------------------------------------------

// Converts the moment to UTC, stripping out its timezone offset, but preserving its
// YMD and time-of-day. A moment with a stripped timezone offset will display no
// timezone offset when .format() is called.
// TODO: look into Moment's keepLocalTime functionality
newMomentProto.stripZone = function() {
	var a, wasAmbigTime;

	if (!this._ambigZone) {

		// get the values before any conversion happens
		a = this.toArray(); // array of y/m/d/h/m/s/ms
		wasAmbigTime = this._ambigTime;

		this.utc(); // set the internal UTC flag (might clear the ambig flags, depending on Moment internals)
		setUTCValues(this, a); // will set the year/month/date/hours/minutes/seconds/ms

		// the above call to .utc()/.utcOffset() unfortunately might clear the ambig flags, so restore
		this._ambigTime = wasAmbigTime || false;

		// Mark the zone as ambiguous. This needs to happen after the .utc() call, which might call .utcOffset(),
		// which clears the ambig flags. Same with setUTCValues with moment-timezone.
		this._ambigZone = true;
	}

	return this; // for chaining
};

// Returns of the moment has a non-ambiguous timezone offset (boolean)
newMomentProto.hasZone = function() {
	return !this._ambigZone;
};


// this method implicitly marks a zone
newMomentProto.local = function() {
	var a = this.toArray(); // year,month,date,hours,minutes,seconds,ms as an array
	var wasAmbigZone = this._ambigZone;

	oldMomentProto.local.apply(this, arguments);

	// ensure non-ambiguous
	// this probably already happened via local() -> utcOffset(), but don't rely on Moment's internals
	this._ambigTime = false;
	this._ambigZone = false;

	if (wasAmbigZone) {
		// If the moment was ambiguously zoned, the date fields were stored as UTC.
		// We want to preserve these, but in local time.
		// TODO: look into Moment's keepLocalTime functionality
		setLocalValues(this, a);
	}

	return this; // for chaining
};


// implicitly marks a zone
newMomentProto.utc = function() {
	oldMomentProto.utc.apply(this, arguments);

	// ensure non-ambiguous
	// this probably already happened via utc() -> utcOffset(), but don't rely on Moment's internals
	this._ambigTime = false;
	this._ambigZone = false;

	return this;
};


// methods for arbitrarily manipulating timezone offset.
// should clear time/zone ambiguity when called.
$.each([
	'zone', // only in moment-pre-2.9. deprecated afterwards
	'utcOffset'
], function(i, name) {
	if (oldMomentProto[name]) { // original method exists?

		// this method implicitly marks a zone (will probably get called upon .utc() and .local())
		newMomentProto[name] = function(tzo) {

			if (tzo != null) { // setter
				// these assignments needs to happen before the original zone method is called.
				// I forget why, something to do with a browser crash.
				this._ambigTime = false;
				this._ambigZone = false;
			}

			return oldMomentProto[name].apply(this, arguments);
		};
	}
});


// Formatting
// -------------------------------------------------------------------------------------------------

newMomentProto.format = function() {
	if (this._fullCalendar && arguments[0]) { // an enhanced moment? and a format string provided?
		return formatDate(this, arguments[0]); // our extended formatting
	}
	if (this._ambigTime) {
		return oldMomentFormat(this, 'YYYY-MM-DD');
	}
	if (this._ambigZone) {
		return oldMomentFormat(this, 'YYYY-MM-DD[T]HH:mm:ss');
	}
	return oldMomentProto.format.apply(this, arguments);
};

newMomentProto.toISOString = function() {
	if (this._ambigTime) {
		return oldMomentFormat(this, 'YYYY-MM-DD');
	}
	if (this._ambigZone) {
		return oldMomentFormat(this, 'YYYY-MM-DD[T]HH:mm:ss');
	}
	return oldMomentProto.toISOString.apply(this, arguments);
};


// Querying
// -------------------------------------------------------------------------------------------------

// Is the moment within the specified range? `end` is exclusive.
// FYI, this method is not a standard Moment method, so always do our enhanced logic.
newMomentProto.isWithin = function(start, end) {
	var a = commonlyAmbiguate([ this, start, end ]);
	return a[0] >= a[1] && a[0] < a[2];
};

// When isSame is called with units, timezone ambiguity is normalized before the comparison happens.
// If no units specified, the two moments must be identically the same, with matching ambig flags.
newMomentProto.isSame = function(input, units) {
	var a;

	// only do custom logic if this is an enhanced moment
	if (!this._fullCalendar) {
		return oldMomentProto.isSame.apply(this, arguments);
	}

	if (units) {
		a = commonlyAmbiguate([ this, input ], true); // normalize timezones but don't erase times
		return oldMomentProto.isSame.call(a[0], a[1], units);
	}
	else {
		input = fc.moment.parseZone(input); // normalize input
		return oldMomentProto.isSame.call(this, input) &&
			Boolean(this._ambigTime) === Boolean(input._ambigTime) &&
			Boolean(this._ambigZone) === Boolean(input._ambigZone);
	}
};

// Make these query methods work with ambiguous moments
$.each([
	'isBefore',
	'isAfter'
], function(i, methodName) {
	newMomentProto[methodName] = function(input, units) {
		var a;

		// only do custom logic if this is an enhanced moment
		if (!this._fullCalendar) {
			return oldMomentProto[methodName].apply(this, arguments);
		}

		a = commonlyAmbiguate([ this, input ]);
		return oldMomentProto[methodName].call(a[0], a[1], units);
	};
});


// Misc Internals
// -------------------------------------------------------------------------------------------------

// given an array of moment-like inputs, return a parallel array w/ moments similarly ambiguated.
// for example, of one moment has ambig time, but not others, all moments will have their time stripped.
// set `preserveTime` to `true` to keep times, but only normalize zone ambiguity.
// returns the original moments if no modifications are necessary.
function commonlyAmbiguate(inputs, preserveTime) {
	var anyAmbigTime = false;
	var anyAmbigZone = false;
	var len = inputs.length;
	var moms = [];
	var i, mom;

	// parse inputs into real moments and query their ambig flags
	for (i = 0; i < len; i++) {
		mom = inputs[i];
		if (!moment.isMoment(mom)) {
			mom = fc.moment.parseZone(mom);
		}
		anyAmbigTime = anyAmbigTime || mom._ambigTime;
		anyAmbigZone = anyAmbigZone || mom._ambigZone;
		moms.push(mom);
	}

	// strip each moment down to lowest common ambiguity
	// use clones to avoid modifying the original moments
	for (i = 0; i < len; i++) {
		mom = moms[i];
		if (!preserveTime && anyAmbigTime && !mom._ambigTime) {
			moms[i] = mom.clone().stripTime();
		}
		else if (anyAmbigZone && !mom._ambigZone) {
			moms[i] = mom.clone().stripZone();
		}
	}

	return moms;
}

// Transfers all the flags related to ambiguous time/zone from the `src` moment to the `dest` moment
// TODO: look into moment.momentProperties for this.
function transferAmbigs(src, dest) {
	if (src._ambigTime) {
		dest._ambigTime = true;
	}
	else if (dest._ambigTime) {
		dest._ambigTime = false;
	}

	if (src._ambigZone) {
		dest._ambigZone = true;
	}
	else if (dest._ambigZone) {
		dest._ambigZone = false;
	}
}


// Sets the year/month/date/etc values of the moment from the given array.
// Inefficient because it calls each individual setter.
function setMomentValues(mom, a) {
	mom.year(a[0] || 0)
		.month(a[1] || 0)
		.date(a[2] || 0)
		.hours(a[3] || 0)
		.minutes(a[4] || 0)
		.seconds(a[5] || 0)
		.milliseconds(a[6] || 0);
}

// Can we set the moment's internal date directly?
allowValueOptimization = '_d' in moment() && 'updateOffset' in moment;

// Utility function. Accepts a moment and an array of the UTC year/month/date/etc values to set.
// Assumes the given moment is already in UTC mode.
setUTCValues = allowValueOptimization ? function(mom, a) {
	// simlate what moment's accessors do
	mom._d.setTime(Date.UTC.apply(Date, a));
	moment.updateOffset(mom, false); // keepTime=false
} : setMomentValues;

// Utility function. Accepts a moment and an array of the local year/month/date/etc values to set.
// Assumes the given moment is already in local mode.
setLocalValues = allowValueOptimization ? function(mom, a) {
	// simlate what moment's accessors do
	mom._d.setTime(+new Date( // FYI, there is now way to apply an array of args to a constructor
		a[0] || 0,
		a[1] || 0,
		a[2] || 0,
		a[3] || 0,
		a[4] || 0,
		a[5] || 0,
		a[6] || 0
	));
	moment.updateOffset(mom, false); // keepTime=false
} : setMomentValues;