var langOptionHash = fc.langs = {}; // initialize and expose


// TODO: document the structure and ordering of a FullCalendar lang file
// TODO: rename everything "lang" to "locale", like what the moment project did


// Initialize jQuery UI datepicker translations while using some of the translations
// Will set this as the default language for datepicker.
fc.datepickerLang = function(langCode, dpLangCode, dpOptions) {

	// get the FullCalendar internal option hash for this language. create if necessary
	var fcOptions = langOptionHash[langCode] || (langOptionHash[langCode] = {});

	// transfer some simple options from datepicker to fc
	fcOptions.isRTL = dpOptions.isRTL;
	fcOptions.weekNumberTitle = dpOptions.weekHeader;

	// compute some more complex options from datepicker
	$.each(dpComputableOptions, function(name, func) {
		fcOptions[name] = func(dpOptions);
	});

	// is jQuery UI Datepicker is on the page?
	if ($.datepicker) {

		// Register the language data.
		// FullCalendar and MomentJS use language codes like "pt-br" but Datepicker
		// does it like "pt-BR" or if it doesn't have the language, maybe just "pt".
		// Make an alias so the language can be referenced either way.
		$.datepicker.regional[dpLangCode] =
			$.datepicker.regional[langCode] = // alias
				dpOptions;

		// Alias 'en' to the default language data. Do this every time.
		$.datepicker.regional.en = $.datepicker.regional[''];

		// Set as Datepicker's global defaults.
		$.datepicker.setDefaults(dpOptions);
	}
};


// Sets FullCalendar-specific translations. Will set the language as the global default.
fc.lang = function(langCode, newFcOptions) {
	var fcOptions;
	var momOptions;

	// get the FullCalendar internal option hash for this language. create if necessary
	fcOptions = langOptionHash[langCode] || (langOptionHash[langCode] = {});

	// provided new options for this language? merge them in
	if (newFcOptions) {
		fcOptions = langOptionHash[langCode] = mergeOptions(fcOptions, newFcOptions);
	}

	// compute language options that weren't defined.
	// always do this. newFcOptions can be undefined when initializing from i18n file,
	// so no way to tell if this is an initialization or a default-setting.
	momOptions = getMomentLocaleData(langCode); // will fall back to en
	$.each(momComputableOptions, function(name, func) {
		if (fcOptions[name] == null) {
			fcOptions[name] = func(momOptions, fcOptions);
		}
	});

	// set it as the default language for FullCalendar
	Calendar.defaults.lang = langCode;
};


// NOTE: can't guarantee any of these computations will run because not every language has datepicker
// configs, so make sure there are English fallbacks for these in the defaults file.
var dpComputableOptions = {

	buttonText: function(dpOptions) {
		return {
			// the translations sometimes wrongly contain HTML entities
			prev: stripHtmlEntities(dpOptions.prevText),
			next: stripHtmlEntities(dpOptions.nextText),
			today: stripHtmlEntities(dpOptions.currentText)
		};
	},

	// Produces format strings like "MMMM YYYY" -> "September 2014"
	monthYearFormat: function(dpOptions) {
		return dpOptions.showMonthAfterYear ?
			'YYYY[' + dpOptions.yearSuffix + '] MMMM' :
			'MMMM YYYY[' + dpOptions.yearSuffix + ']';
	}

};

var momComputableOptions = {

	// Produces format strings like "ddd M/D" -> "Fri 9/15"
	dayOfMonthFormat: function(momOptions, fcOptions) {
		var format = momOptions.longDateFormat('l'); // for the format like "M/D/YYYY"

		// strip the year off the edge, as well as other misc non-whitespace chars
		format = format.replace(/^Y+[^\w\s]*|[^\w\s]*Y+$/g, '');

		if (fcOptions.isRTL) {
			format += ' ddd'; // for RTL, add day-of-week to end
		}
		else {
			format = 'ddd ' + format; // for LTR, add day-of-week to beginning
		}
		return format;
	},

	// Produces format strings like "h:mma" -> "6:00pm"
	mediumTimeFormat: function(momOptions) { // can't be called `timeFormat` because collides with option
		return momOptions.longDateFormat('LT')
			.replace(/\s*a$/i, 'a'); // convert AM/PM/am/pm to lowercase. remove any spaces beforehand
	},

	// Produces format strings like "h(:mm)a" -> "6pm" / "6:30pm"
	smallTimeFormat: function(momOptions) {
		return momOptions.longDateFormat('LT')
			.replace(':mm', '(:mm)')
			.replace(/(\Wmm)$/, '($1)') // like above, but for foreign langs
			.replace(/\s*a$/i, 'a'); // convert AM/PM/am/pm to lowercase. remove any spaces beforehand
	},

	// Produces format strings like "h(:mm)t" -> "6p" / "6:30p"
	extraSmallTimeFormat: function(momOptions) {
		return momOptions.longDateFormat('LT')
			.replace(':mm', '(:mm)')
			.replace(/(\Wmm)$/, '($1)') // like above, but for foreign langs
			.replace(/\s*a$/i, 't'); // convert to AM/PM/am/pm to lowercase one-letter. remove any spaces beforehand
	},

	// Produces format strings like "ha" / "H" -> "6pm" / "18"
	hourFormat: function(momOptions) {
		return momOptions.longDateFormat('LT')
			.replace(':mm', '')
			.replace(/(\Wmm)$/, '') // like above, but for foreign langs
			.replace(/\s*a$/i, 'a'); // convert AM/PM/am/pm to lowercase. remove any spaces beforehand
	},

	// Produces format strings like "h:mm" -> "6:30" (with no AM/PM)
	noMeridiemTimeFormat: function(momOptions) {
		return momOptions.longDateFormat('LT')
			.replace(/\s*a$/i, ''); // remove trailing AM/PM
	}

};


// options that should be computed off live calendar options (considers override options)
var instanceComputableOptions = { // TODO: best place for this? related to lang?

	// Produces format strings for results like "Mo 16"
	smallDayDateFormat: function(options) {
		return options.isRTL ?
			'D dd' :
			'dd D';
	},

	// Produces format strings for results like "Wk 5"
	weekFormat: function(options) {
		return options.isRTL ?
			'w[ ' + options.weekNumberTitle + ']' :
			'[' + options.weekNumberTitle + ' ]w';
	},

	// Produces format strings for results like "Wk5"
	smallWeekFormat: function(options) {
		return options.isRTL ?
			'w[' + options.weekNumberTitle + ']' :
			'[' + options.weekNumberTitle + ']w';
	}

};

function populateInstanceComputableOptions(options) {
	$.each(instanceComputableOptions, function(name, func) {
		if (options[name] == null) {
			options[name] = func(options);
		}
	});
}


// Returns moment's internal locale data. If doesn't exist, returns English.
// Works with moment-pre-2.8
function getMomentLocaleData(langCode) {
	var func = moment.localeData || moment.langData;
	return func.call(moment, langCode) ||
		func.call(moment, 'en'); // the newer localData could return null, so fall back to en
}


// Initialize English by forcing computation of moment-derived options.
// Also, sets it as the default.
fc.lang('en', Calendar.englishDefaults);