Модул:Citation/CS1/Date validation

Из Википедије, слободне енциклопедије
Иди на навигацију Иди на претрагу


Овај модул подржава испис датума у CS1 и CS2 шаблонима за референцирање. Тачније, модул садржи низ функција које валидирају формате датума и садржаје разних параметара у које се уноси датум у CS1 и CS2 шаблонима.


Ови модули раде заједно како би CS1 и CS2 шаблони за референцирање функционисали:

CS1 | CS2 модули
  Модули Песак за модуле Опис
sysop Модул:Citation/CS1 Модул:Citation/CS1/sandbox [уреди] Обрада и помоћне функције
Модул:Citation/CS1/Configuration Модул:Citation/CS1/Configuration/sandbox [уреди] Табеле превођења; грешке и идентификатори
Модул:Citation/CS1/Whitelist Модул:Citation/CS1/Whitelist/sandbox [уреди] Листа активних, застарелих и превазиђених CS1 и CS2 параметара
Модул:Citation/CS1/Date validation Модул:Citation/CS1/Date validation/sandbox [уреди] Функције за валидацију формата датума
Модул:Citation/CS1/Identifiers Модул:Citation/CS1/Identifiers/sandbox [уреди] Функције које подржавају именоване идентификаторе (isbn, doi, pmid итд.)
Модул:Citation/CS1/Utilities Модул:Citation/CS1/Utilities/sandbox [уреди] Уобичајене функције и табеле
Module:Citation/CS1/COinS Module:Citation/CS1/COinS/sandbox [уреди] Функције које обрађују метаподатке CS1 и CS2 шаблона
auto confirmed Модул:Citation/CS1/Suggestions Модул:Citation/CS1/Suggestions/sandbox [уреди] Листа која садржи заједничка погрешна имена параметара у успоредби са важећим имена параметара

local p = {}

--[[--------------------------< N O T E >----------------------------------------

It was neccessary to move these lists below out of their corresponding functions (e.g. "get_month_number()" etc.) in order to fix
error »Lua error in Module:Citation/CS1/Date_validation at line "xyz": attempt to index global '"name_of_the_list"' (a nil value).«.

]]

--------------------------< D E F I N E _ M O N T H _ N A M E S _ L I S T S >----------------------------------------
-- long month names of varying lengths; not shortened versions; divided by scripts into Cyrillic and Latin + English
local long_cyrillic_months = {['јануар']=1, ['фебруар']=2, ['март']=3, ['април']=4, ['мај']=5, ['јун']=6, ['јуни']=6, ['јул']=7, ['јули']=7, ['август']=8, ['септембар']=9, ['октобар']=10, ['новембар']=11, ['децембар']=12};
local long_latin_months = {['januar']=1, ['februar']=2, ['mart']=3, ['april']=4, ['maj']=5, ['jun']=6, ['juni']=6, ['jul']=7, ['juli']=7, ['avgust']=8, ['septembar']=9, ['oktobar']=10, ['novembar']=11, ['decembar']=12};
local long_english_months = {['January']=1, ['February']=2, ['March']=3, ['April']=4, ['May']=5, ['June']=6, ['July']=7, ['August']=8, ['September']=9, ['October']=10, ['November']=11, ['December']=12};

-- short month names all three characters; these do not use terminal period; divided by scripts into Cyrillic and Latin + English
local short_cyrillic_months = {['мај']=5, ['јун']=6, ['јул']=7};
local short_latin_months = {['maj']=5, ['jun']=6, ['jul']=7};
local short_english_months = {['Jan']=1, ['Feb']=2, ['Mar']=3, ['Apr']=4, ['May']=5, ['Jun']=6, ['Jul']=7, ['Aug']=8, ['Sep']=9, ['Oct']=10, ['Nov']=11, ['Dec']=12};

-- short month names all three characters; these require terminal period; divided by scripts into Cyrillic and Latin
local dot_cyrillic_months = {['јан']=1, ['феб']=2, ['мар']=3, ['апр']=4, ['авг']=8, ['сеп']=9, ['окт']=10, ['нов']=11, ['дец']=12};
local dot_latin_months = {['jan']=1, ['feb']=2, ['mar']=3, ['apr']=4, ['avg']=8, ['sep']=9, ['okt']=10, ['nov']=11, ['dec']=12};

--------------------------< D E F I N E _ S E A S O N _ N A M E S _ L I S T S >----------------------------------------
-- season ekavian names; make sure these numbers do not overlap month numbers; divided by scripts into Cyrillic and Latin + English
local season_cyrillic_ekavian_list = {['зима']=21, ['пролеће']=22, ['лето']=23, ['јесен']=24};
local season_latin_ekavian_list = {['zima']=21, ['proleće']=22, ['leto']=23, ['jesen']=24};
local season_english_list = {['Winter']=21, ['Spring']=22, ['Summer']=23, ['Fall']=24, ['Autumn']=24};

-- season ijekavian names; make sure these numbers do not overlap month numbers; divided by scripts into Cyrillic and Latin
local season_cyrillic_ijekavian_list = {['зима']=21, ['прољеће']=22, ['љето']=23, ['јесен']=24};
local season_latin_ijekavian_list = {['zima']=21, ['proljeće']=22, ['ljeto']=23, ['jesen']=24};

--------------------------< D E F I N E _ O T H E R _ A C C E P T A B L E _ N A M E S _ L I S T S >----------------------------------------
-- proper names; make sure these numbers do not overlap month or season numbers; divided by scripts into Cyrillic and Latin + English
local name_cyrillic_list = {['Божић']=31}
local name_latin_list = {['Božić']=31}
local name_english_list = {['Christmas']=31}



--[[--------------------------< F O R W A R D   D E C L A R A T I O N S >--------------------------------------
]]

local is_set, in_array;																	-- imported function from selected Module:Citation/CS1/Utilities


--[=[--------------------------< I S _ V A L I D _ A C C E S S D A T E >----------------------------------------

returns true if:
	Wikipedia start date <= accessdate < today + 2 days

Wikipedia start date is 2001-01-15T00:00:00 UTC which is 979516800 seconds after 1970-01-01T00:00:00 UTC (the start of Unix time)
accessdate is the date provided in |accessdate= at time 00:00:00 UTC
today is the current date at time 00:00:00 UTC plus 48 hours
	if today is 2015-01-01T00:00:00 then
		adding 24 hours gives 2015-01-02T00:00:00 – one second more than today
		adding 24 hours gives 2015-01-03T00:00:00 – one second more than tomorrow

This function does not work if it is fed month names for languages other than English.  Wikimedia #time: parser
apparently doesn't understand non-Engish date month names. This function will always return false when the date
contains a non-English month name because good1 is false after the call to lang.formatDate().  To get around that
call this function with YYYY-MM-DD format dates.

For the time being, to use this function, supply it with YYYY-MM-DD format dates.  See
[[bs:Modul:Citation/CS1/Date validation/igralište]] for one possible solution.

]=]

local function is_valid_accessdate (accessdate)
	local lang = mw.getContentLanguage();
	local good1, good2;
	local access_ts, tomorrow_ts;												-- to hold unix time stamps representing the dates
		
	good1, access_ts = pcall( lang.formatDate, lang, 'U', accessdate );			-- convert accessdate value to unix timestamp 
	good2, tomorrow_ts = pcall( lang.formatDate, lang, 'U', 'today + 2 days' );	-- today midnight + 2 days is one second more than all day tomorrow
	
	if good1 and good2 then
		access_ts = tonumber (access_ts);										-- convert to numbers for the comparison
		tomorrow_ts = tonumber (tomorrow_ts);
	else
		return false;															-- one or both failed to convert to unix time stamp
	end

	if 979516800 <= access_ts and access_ts < tomorrow_ts then					-- Wikipedia start date <= accessdate < tomorrow's date
		return true;
	else
		return false;															-- accessdate out of range
	end
end


--[[--------------------------< G E T _ M O N T H _ N U M B E R >----------------------------------------------

Returns a number according to the month in a date: 1 for јануар, 5 for мај or maj, etc.

Capitalization and spelling must be correct.

If not a valid month, returns 0.

]]

local function get_month_number (month)
	return long_cyrillic_months[month] or										-- if month is the long-Cyrillic-form name
		long_latin_months[month] or												-- if month is the long-Latin-form name
		short_cyrillic_months[month] or											-- if month is non-dotted short-Cyrillic-form name
		short_latin_months[month] or												-- if month is non-dotted short-Latin-form name
		0;																		-- misspelled, improper case, or not a month name
end

--[[--------------------------< G E T _ E N G L I S H _ M O N T H _ N U M B E R >----------------------------------------------

Returns a number according to the month in a date: 1 for January, 5 for May, etc.

Capitalization and spelling must be correct.

If not a valid month, returns 0.

]]

local function get_english_month_number (month)
	return long_english_months[month] or										-- if month is the long-English-form name
		short_english_months[month] or											-- if month is short-English-form name
		0;																		-- misspelled, improper case, or not a month name
end

--[[--------------------------< G E T _ D O T _ M O N T H _ N U M B E R >--------------------------------------

Returns a number according to the short dotted month in a date: 1 for јан., 4 for апр. or apr., etc.

This function is specially made for short months that must be followed with a dot.
The short months мај, јун, јул, maj, jun, and jul are omitted here because these
month names are not followed with a dot, and will not be allowed for use in any
short-dotted-months-ranges.

If not a valid month, returns 0.

]]

local function get_dot_month_number (month)
	return dot_cyrillic_months[month] or											-- if month is dotted short-Cyrillic-form name
		dot_latin_months[month] or												-- if month is dotted short-Latin-form name
		0;																		-- misspelled, improper case, or not a month name
end


--[[--------------------------< I S _ V A L I D _ E M B A R G O _ D A T E >------------------------------------

returns true and date value if that value has proper dmy, mdy, ymd format.

returns false and 9999 (embargoed forever) when date value is not proper format; assumes that when |embargo= is
set, the editor intended to embargo a pmc but |embargo= does not hold a single date.

]]
	
local function is_valid_embargo_date (v)
	if v:match ('^%d%d%d%d%-%d%d%-%d%d$') or												-- ymd
		mw.ustring.match (v, '^%d%d?%.?%s+%a+%s+%d%d%d%d$') or							-- dmy
		mw.ustring.match (v, '^%a+%s+%d%d?%s*,%s*%d%d%d%d$') then						-- mdy
			return true, v;
	end
	return false, '9999';														-- if here not good date so return false and set embargo date to long time in future
end


--[[--------------------------< G E T _ S E A S O N _ N U M B E R >--------------------------------------------

Returns a number according to the sequence of seasons in a year: 1 for зима or zima, etc. Capitalization and spelling must be correct. If not a valid season, returns 0.

Divided by scripts into Cyrillic and Latin, and by pronunciation into ekavian and ijekavian.

]]
local year_limit;
local function get_season_number (season)
	return season_cyrillic_ekavian_list[season] or								-- if season is a valid Cyrillic ekavian name return its number
		season_latin_ekavian_list[season] or										-- if season is a valid Latin ekavian name return its number
		season_cyrillic_ijekavian_list[season] or								-- if season is a valid Cyrillic ijekavian name return its number
		season_latin_ijekavian_list[season] or									-- if season is a valid Latin ijekavian name return its number
		0;																		-- misspelled, improper case, or not a season name
end

--[[--------------------------< G E T _ E N G L I S H _ S E A S O N _ N U M B E R >--------------------------------------------

Returns a number according to the sequence of seasons in a year: 1 for Winter, etc. Capitalization and spelling must be correct. If not a valid season, returns 0.

]]
local year_limit;
local function get_english_season_number (season)
	return season_english_list[season] or								-- if season is a valid English name return its number
		0;																		-- misspelled, improper case, or not a season name
end

--[[--------------------------< I S _ P R O P E R _ N A M E >--------------------------------------------------

Returns a non-zero number if date contains a recognized proper name. Capitalization and spelling must be correct. Divided by scripts into Cyrillic and Latin.

]]

local function is_proper_name (name)
	return name_cyrillic_list[name] or											-- if name is a valid Cyrillic name return its number
		name_english_list[name] or											-- if name is a valid English name return its number
		name_latin_list[name] or													-- if name is a valid Latin name return its number
		0;																		-- misspelled, improper case, or not a proper name
end

--[[--------------------------< I S _ V A L I D _ M O N T H _ O R _ S E A S O N >------------------------------

Returns true if month or season is valid (properly spelled, capitalized, abbreviated, (non-)dotted, etc.).

]]

local function is_valid_month_or_season (month_season)
	if 0 == get_month_number (month_season) then						-- if month text isn't one of the long months or short non-dotted months, might be a short dotted month or season
		if 0 == get_english_month_number (month_season) then				-- not a long month or a short non-dotted month, is it a English month?
			if 0 == get_dot_month_number (month_season) then				-- not a long month or a short non-dotted month, is it a short dotted month?
				if 0 == get_season_number (month_season) then			-- not a short dotted month i.e. not a month, is it a season?
					if 0 == get_english_season_number (month_season) then			-- not a short dotted month i.e. not a month, is it an English season?
					return false;											-- return false; not a month or one of the seasons
					end											-- return false; not a month or one of the seasons
				end
			end
		end
	end
	return true;
end

--[[--------------------------< I S _ V A L I D _ Y E A R >----------------------------------------------------

Function gets current year from the server and compares it to year from a citation parameter.  Years more than one year in the future are not acceptable.

]]
local year_limit;
local function is_valid_year(year)
	if not is_set(year_limit) then
		year_limit = tonumber(os.date("%Y"))+1;			-- save a copy so we only have to fetch it once
	end
	return tonumber(year) <= year_limit;					-- false if year is in the future more than one year
end

--[[--------------------------< I S _ V A L I D _ D A T E >----------------------------------------------------		
Returns true if day is less than or equal to the number of days in month and year is no farther into the future
than next year; else returns false.

Assumes Julian calendar prior to year 1582 and Gregorian calendar thereafter. Accounts for Julian calendar leap
years before 1582 and Gregorian leap years after 1582. Where the two calendars overlap (1582 to approximately
1923) dates are assumed to be Gregorian.
]]

local function is_valid_date (year, month, day)
local days_in_month = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
local month_length;
	if not is_valid_year(year) then												-- no farther into the future than next year
		return false;
	end
	
	month = tonumber(month);														-- required for YYYY-MM-DD dates
	
	if (2==month) then															-- if February
		month_length = 28;														-- then 28 days unless
		if 1582 > tonumber(year) then											-- Julian calendar
			if 0==(year%4) then
				month_length = 29;
			end
		else																	-- Gregorian calendar
			if (0==(year%4) and (0~=(year%100) or 0==(year%400))) then			-- is a leap year?
				month_length = 29;												-- if leap year then 29 days in February
			end
		end
	else
		month_length=days_in_month[month];
	end

	if tonumber (day) > month_length then
		return false;
	end
	return true;
end

--[[--------------------------< I S _ V A L I D _ M O N T H _ R A N G E _ S T Y L E >--------------------------

Months in a range are expected to have the same style: "јануар—март" or "јан.—мар." but not "фебруар—мар." or "апр.—август" etc.

These are special tests for long Cyrillic months, long Latin months, short Cyrillic months, short Latin months, dot Cyrillic months, and dot Latin months.

Returns true when style (depending on whether Cyrillic or Latin, whether long or short, whether dotted or non-dotted) for both months is the same.

]]

local function is_valid_month_range_style (month1, month2)
	if long_cyrillic_months[month1] and long_cyrillic_months[month2] then
		return true;																							-- both are long Cyrillic month names
	elseif long_english_months[month1] and long_english_months[month2] then
		return true;																							-- both are long English month names
	elseif long_latin_months[month1] and long_latin_months[month2] then
		return true;																							-- both are long Latin month names
	elseif short_cyrillic_months[month1] and short_cyrillic_months[month2] then
		return true;																							-- both are non-dotted short Cyrillic month names
	elseif short_english_months[month1] and short_english_months[month2] then
		return true;																							-- both are [non-dotted] short English month names
	elseif short_latin_months[month1] and short_latin_months[month2] then
		return true;																							-- both are non-dotted short Latin month names
	elseif dot_cyrillic_months[month1] and dot_cyrillic_months[month2] then
		return true;																							-- both are dotted short Cyrillic month names
	elseif dot_latin_months[month1] and dot_latin_months[month2] then
		return true;																							-- both are dotted short Latin month names
	else
		return false;																						-- months are mixed form so return false
	end
end

--[[--------------------------< I S _ V A L I D _ S E A S O N _ R A N G E _ S T Y L E >--------------------------

Seasons in a range are expected to have the same style: "пролеће—лето" or "ljeto—jesen" but not "прољеће—лето" or "ljeto—јесен" etc.

These are special tests for Cyrillic ekavian seasons, Cyrillic ijekavian seasons, Latin ekavian seasons and Latin ijekavian seasons.

Returns true when style (depending on whether Cyrillic or Latin, whether ekavian or ijekavian) for both seasons is the same.

]]

local function is_valid_season_range_style (season1, season2)
	if season_cyrillic_ekavian_list[season1] and season_cyrillic_ekavian_list[season2] then
		return true;																							-- both are Cyrillic ekavian season names
	elseif season_english_list[season1] and season_english_list[season2] then
		return true;																							-- both are English season names
	elseif season_cyrillic_ijekavian_list[season1] and season_cyrillic_ijekavian_list[season2] then
		return true;																							-- both are Cyrillic ijekavian season names
	elseif season_latin_ekavian_list[season1] and season_latin_ekavian_list[season2] then
		return true;																							-- both are Latin ekavian season names
	elseif season_latin_ijekavian_list[season1] and season_latin_ijekavian_list[season2] then
		return true;																							-- both are Latin ijekavian season names
	else
		return false;																						-- seasons are mixed form so return false
	end
end


--[[--------------------------< I S _ V A L I D _ M O N T H _ S E A S O N _ R A N G E >------------------------

Check a pair of long months or short non-dotted months, or seasons to see if both are valid members of a long month or short non-dotted month, or season pair.

Month pairs are expected to be left to right, earliest to latest in time.

Similarly, seasons are also left to right, earliest to latest in time. There is an oddity with seasons: Winter is assigned a value of 21, Spring 22, Summer 23,
Fall/Autumn 24. Because Winter can follow Fall/Autumn at the end of a calender year, a special test is made to see if "|date=јесен-зима yyyy" (24-21) is the date.

]]

local function is_valid_month_season_range(range_start, range_end)
	local range_start_number = get_month_number (range_start);
	local range_end_number;

	if 0 == range_start_number then																-- is this a month range?
		local range_start_number = get_season_number (range_start);								-- not a month; is it a season? get start season number
		range_end_number = get_season_number (range_end);										-- get end season number

		if 0 ~= range_start_number then															-- is start of range a season?
			if range_start_number < range_end_number and 21 ~= range_start_number then			-- range_start is a season except Winter
				if is_valid_season_range_style (range_start, range_end) then						-- do seasons have the same style?
					return true;																	-- return true when range_end is also a season and follows start season, and both season names are of same style; else false
				end
			end
			if (24 == range_start_number and 21 == range_end_number) or (23 == range_start_number and 21 == range_end_number) or (22 == range_start_number and 21 == range_end_number) then		-- special cases when season range is Fall-Winter or Autumn-Winter, or Summer-Winter, or Spring-Winter
				if is_valid_season_range_style (range_start, range_end) then						-- do seasons have the same style?
				return true;
				end
			end
		end
		return false;		-- range_start is not a month or a season; or range_start is a season and range_end is not; or improper season sequence; or seasons are not of same style
	end

	range_end_number = get_month_number (range_end);						-- get end month number
	if range_start_number < range_end_number then						-- range_start is a month; does range_start precede range_end?
		if is_valid_month_range_style (range_start, range_end) then		-- do months have the same style?
			return true;													-- proper order and same style
		end
	end
	return false;			-- range_start month number is greater than or equal to range end number; or range end isn't a month
end

--[[--------------------------< I S _ V A L I D _ E N G L I S H _ M O N T H _ S E A S O N _ R A N G E >------------------------

Check a pair of long months or short English months, or seasons to see if both are valid members of a long month or short month, or season pair.

Month pairs are expected to be left to right, earliest to latest in time.

Similarly, seasons are also left to right, earliest to latest in time. There is an oddity with seasons: Winter is assigned a value of 21, Spring 22, Summer 23,
Fall/Autumn 24. Because Winter can follow Fall/Autumn at the end of a calender year, a special test is made to see if "|date=Fall–Winter yyyy" (24-21) is the date.

]]

local function is_valid_english_month_season_range(range_start, range_end)
	local range_start_number = get_english_month_number (range_start);
	local range_end_number;

	if 0 == range_start_number then																-- is this a month range?
		local range_start_number = get_english_season_number (range_start);								-- not a month; is it a season? get start season number
		range_end_number = get_english_season_number (range_end);										-- get end season number

		if 0 ~= range_start_number then															-- is start of range a season?
			if range_start_number < range_end_number and 21 ~= range_start_number then			-- range_start is a season except Winter
				if is_valid_season_range_style (range_start, range_end) then						-- do seasons have the same style?
					return true;																	-- return true when range_end is also a season and follows start season, and both season names are of same style; else false
				end
			end
			if (24 == range_start_number and 21 == range_end_number) or (23 == range_start_number and 21 == range_end_number) or (22 == range_start_number and 21 == range_end_number) then		-- special cases when season range is Fall-Winter or Autumn-Winter, or Summer-Winter, or Spring-Winter
				if is_valid_season_range_style (range_start, range_end) then						-- do seasons have the same style?
				return true;
				end
			end
		end
		return false;		-- range_start is not a month or a season; or range_start is a season and range_end is not; or improper season sequence; or seasons are not of same style
	end

	range_end_number = get_english_month_number (range_end);						-- get end month number
	if range_start_number < range_end_number then						-- range_start is a month; does range_start precede range_end?
		if is_valid_month_range_style (range_start, range_end) then		-- do months have the same style?
			return true;													-- proper order and same style
		end
	end
	return false;			-- range_start month number is greater than or equal to range end number; or range end isn't a month
end

--[[--------------------------< I S _ V A L I D _ D O T _ M O N T H _ R A N G E >------------------------

Check a pair of dot-months to see if both are valid members of a dot-month pair.

Dot-month pairs are expected to be left to right, earliest to latest in time.

]]

local function is_valid_dot_month_range(range_start, range_end)
	local range_start_number = get_dot_month_number (range_start);
	
	if 0 == range_start_number then												-- is this a dot-month range?
		return false;															-- range_start is not a dot-month
	end

	local range_end_number = get_dot_month_number (range_end);					-- get end dot-month number
	if range_start_number < range_end_number then								-- range_start is a dot-month; does range_start precede range_end?
		if is_valid_month_range_style (range_start, range_end) then				-- do dot-months have the same style (either Cyrillic or Latin)?
			return true;															-- proper order and same style
		end
	end
	return false;																-- range_start dot-month number is greater than or equal to range end number; or range end isn't a month
end


--[[--------------------------< M A K E _ C O I N S _ D A T E >------------------------------------------------

This function receives a table of date parts for one or two dates and an empty table reference declared in
Module:Citation/CS1. The function is called only for |date= parameters and only if the |date=<value> is 
determined to be a valid date format. The question of what to do with invalid date formats is not answered here.

The date parts in the input table are converted to an ISO 8601 conforming date string:
	single whole dates:	yyyy-mm-dd
	month and year dates:	yyyy-mm
	year dates:				yyyy
	ranges:					yyyy-mm-dd/yyyy-mm-dd
							yyyy-mm/yyyy-mm
							yyyy/yyyy

Dates in the Julian calendar are reduced to year or year/year so that we don't have to do calendar conversion from
Julian to Proleptic Gregorian.

The input table has:
	year, year2 – always present; if before 1582, ignore months and days if present
	month, month2 – 0 if not provided, 1-12 for months, 21-24 for seasons; 31– proper name dates
	day, day2 –  0 if not provided, 1-31 for days
	
the output table receives:
	rftdate:	an IS8601 formatted date
	rftchron:	a free-form version of the date, usually without year which is in rftdate (season ranges and propername dates)
	rftssn:		one of four season keywords: winter, spring, summer, fall (lowercase)

]]

local function make_COinS_date (input, tCOinS_date)
	local date;																	-- one date or first date in a range
	local date2 = '';															-- end of range date
	
	if 1582 > tonumber(input.year) or 20 < tonumber(input.month) then			-- Julian calendar or season so &rft.date gets year only
		date = input.year;
		if 0 ~= input.year2 and input.year ~= input.year2 then					-- if a range, only the second year portion when not the same as range start year
			date = string.format ('%.4d/%.4d', tonumber(input.year), tonumber(input.year2))		-- assemble the date range
		end
		if 20 < tonumber(input.month) then										-- if season or propername date
			local season = {[21]='winter', [22]='spring', [23]='summer', [24]='fall', [31]='Christmas'};	-- seasons lowercase, no autumn; proper names use title case
			if 0 == input.month2 then											-- single season date
				if 30 <tonumber(input.month) then
					tCOinS_date.rftchron = season[input.month];					-- proper name dates
				else
					tCOinS_date.rftssn = season[input.month];					-- seasons
				end
			else																-- season range with a second season specified
				if input.year ~= input.year2 then								-- season year – season year range or season year–year
					tCOinS_date.rftssn = season[input.month];					-- start of range season; keep this?
					if 0~= input.month2 then
						tCOinS_date.rftchron = string.format ('%s %s - %s %s', season[input.month], input.year, season[input.month2], input.year2);	--use hyphen in metadata
					end
				else															-- season–season year range
					tCOinS_date.rftssn = season[input.month];					-- start of range season; keep this?
					tCOinS_date.rftchron = season[input.month] .. '-' .. season[input.month2];	-- season–season year range (uses hyphen separator)
				end
			end
		end
		tCOinS_date.rftdate = date;
		return;																	-- done
	end
	
	if 0 ~= input.day then
		date = string.format ('%s-%.2d-%.2d', input.year, tonumber(input.month), tonumber(input.day));	-- whole date
	elseif 0 ~= input.month then
		date = string.format ('%s-%.2d', input.year, tonumber(input.month));		-- year and month
	else
		date = string.format ('%s', input.year);									-- just year
	end

	if 0 ~= input.year2 then
		if 0 ~= input.day2 then
			date2 = string.format ('/%s-%.2d-%.2d', input.year2, tonumber(input.month2), tonumber(input.day2));		-- whole date
		elseif 0 ~= input.month2 then
			date2 = string.format ('/%s-%.2d', input.year2, tonumber(input.month2));		-- year and month
		else
			date2 = string.format ('/%s', input.year2);									-- just year
		end
	end
	
	tCOinS_date.rftdate = date .. date2;										-- date2 has the '/' separator
	return;
end


--[[--------------------------< C H E C K _ D A T E >----------------------------------------------------------

!!! DON'T UPDATE MATCH STRINGS ONLY HERE BUT ALSO IN Модул:Citation/CS1, AND BOTH AT THE SAME TIME !!!

Check date format to see that it is one of the formats approved by WP:DATESNO or WP:DATERANGE.

!!! NOTE !!!
Allowed range separators are mdash (primar), ndash and hyphen. Any ndash or hyphen is automatically converted to mdash.

Additionally, checks the date to see that it is a real date: no 31 in 30-day months; no 29 February when not a leap year.
Months, both long-form and abbreviations, and seasons must be spelled correctly. Future years beyond next year are not allowed.

If the date fails the format tests, this function returns false and does not return values for anchor_year and
COinS_date.  When this happens, the date parameter is used in the COinS metadata and the CITEREF identifier gets
its year from the year parameter if present otherwise CITEREF does not get a date value.

Inputs:
	date_string - date string from date-holding parameters (date, year, accessdate, embargo, archivedate, etc.)

Returns:
	false if date string is not a real date; else
	true, anchor_year, COinS_date
		anchor_year can be used in CITEREF anchors
		COinS_date is ISO 8601 format date; see make_COInS_date()

!!! DON'T UPDATE MATCH STRINGS ONLY HERE BUT ALSO IN Модул:Citation/CS1, AND BOTH AT THE SAME TIME !!!

]]

local function check_date (date_string, tCOinS_date, test_accessdate)
	local year;			-- assume that year2, months, and days are not used;
	local year2=0;		-- second year in a year range
	local month=0;
	local month2=0;		-- second month in a month range
	local day=0;
	local day2=0;		-- second day in a day range
	local anchor_year;
	local coins_date;

	if mw.ustring.match(date_string, "^%d%d%d%d%-%d%d%-%d%d$") then																				-- 01. yyyy-mm-dd
		year, month, day=mw.ustring.match(date_string, "(%d%d%d%d)%-(%d%d)%-(%d%d)");
		if 12 < tonumber(month) or 1 > tonumber(month) or 1582 > tonumber(year) or 0 == tonumber(day) then return false; end	 	-- month or day number not valid or not Gregorian calendar
		anchor_year = year;

	elseif mw.ustring.match(date_string, "^%d?%d%. *%d?%d%. *%d%d%d%d?%.?%a?$") then																	-- 02. [d]d. [m]m. yyyy
		day, month, year=mw.ustring.match(date_string, "(%d?%d)%. *(%d?%d)%. *(%d%d%d%d?)%.?%a?");
		if 12 < tonumber(month) or 1 > tonumber(month) or 0 == day then return false; end								 		-- return false if month number not valid or day is zero
		anchor_year = year;

	elseif mw.ustring.match(date_string, "^[1-9]%d?%. +%a+ +[1-9]%d%d%d?%.?%a?$") then															-- 03. (d)d. month yyyy
		day, month, anchor_year, year=mw.ustring.match(date_string, "(%d%d*)%.%s*(%a+)%s*((%d%d%d%d?)%.?%a?)");
		month = get_month_number (month);
		if 0 == month then return false; end																				 		-- return false if month text isn't one of the twelve months

	elseif mw.ustring.match(date_string, "^[1-9]%d? +%a+ +[1-9]%d%d%d?%a?$") then															-- 03. (d)d month yyyy /English/
		day, month, anchor_year, year=mw.ustring.match(date_string, "(%d%d*)%s*(%a+)%s*((%d%d%d%d?)%a?)");
		month = get_english_month_number (month);
		if 0 == month then return false; end																				 		-- return false if month text isn't one of the twelve months

	elseif mw.ustring.match(date_string, "^%a+ +[1-9]%d?, +[1-9]%d%d%d?%a?$") then															-- 03. month (d)d, yyyy /English md/
		month, day, anchor_year, year=mw.ustring.match(date_string, "(%a+)%s*(%d%d?),%s*((%d%d%d%d?)%a?)");
		month = get_english_month_number (month);
		if 0 == month then return false; end																				 		-- return false if month text isn't one of the twelve months

	elseif mw.ustring.match(date_string, "^[1-9]%d?%. +%a%a%a%. +[1-9]%d%d%d?%.?%a?$") then														-- 04. (d)d. mon. yyyy
		day, month, anchor_year, year=mw.ustring.match(date_string, "(%d%d*)%.%s*(%a%a%a)%.%s*((%d%d%d%d?)%.?%a?)");
		month = get_dot_month_number (month);
		if 0 == month then return false; end																				 		-- return false if month text isn't one of the nine dot-months

	elseif mw.ustring.match(date_string, "^%d?%d[%-–—]%d%d?%. +%d?%d%. +[1-9]%d%d%d?%.?$") then													-- 05. [d]d—[d]d. [m]m. yyyy
		day, day2, month, year=mw.ustring.match(date_string, "(%d%d?)[%-–—](%d%d?)%. +(%d?%d)%. +(%d%d%d%d?)%.?");
		if tonumber(day) >= tonumber(day2) then return false; end														 		-- date range order is left to right: earlier to later; dates may not be the same;
		if 12 < tonumber(month) or 1 > tonumber(month) or 0 == day then return false; end								 		-- return false if month number not valid or day is zero
		anchor_year = year;

	elseif mw.ustring.match(date_string, "^%d?%d/%d%d?%. +%d?%d%. +[1-9]%d%d%d?%.?%a?$") then													-- 06. [d]d/[d]d. [m]m. yyyy
		day, day2, month, year=mw.ustring.match(date_string, "(%d%d?)/(%d%d?)%. +(%d?%d)%. +(%d%d%d%d?)%.?");
		if 1 ~= tonumber(day2) - tonumber(day) then return false; end													 		-- date range order is left to right: earlier to later and CONSECUTIVE; dates may not be the same;
		if 12 < tonumber(month) or 1 > tonumber(month) or 0 == day then return false; end								 		-- return false if month number not valid or day is zero
		anchor_year = year;

	elseif mw.ustring.match(date_string, "^[1-9]%d?[%-–—][1-9]%d?%. +%a+ +[1-9]%d%d%d%.?%a?$") then												-- 07. (d)d—(d)d. month yyyy
		day, day2, month, anchor_year, year=mw.ustring.match(date_string, "(%d%d?)[%-–—](%d%d?)%. +(%a+) +((%d%d%d%d)%.?%a?)");
		if tonumber(day) >= tonumber(day2) then return false; end														 		-- date range order is left to right: earlier to later; dates may not be the same;
		month = get_month_number (month);
		if 0 == month then return false; end																			 			-- return false if month text isn't one of the twelve months
		month2=month;																									 		-- for metadata

	elseif mw.ustring.match(date_string, "^[1-9]%d?[%-–][1-9]%d? +%a+ +[1-9]%d%d%d%a?$") then												-- 07. (d)d–(d)d month yyyy /English/
		day, day2, month, anchor_year, year=mw.ustring.match(date_string, "(%d%d?)[%-–](%d%d?) +(%a+) +((%d%d%d%d)%a?)");
		if tonumber(day) >= tonumber(day2) then return false; end														 		-- date range order is left to right: earlier to later; dates may not be the same;
		month = get_english_month_number (month);
		if 0 == month then return false; end																			 			-- return false if month text isn't one of the twelve months
		month2=month;																									 		-- for metadata

	elseif mw.ustring.match(date_string, "^%a+ +[1-9]%d?[%-–][1-9]%d?, +[1-9]%d%d%d%a?$") then												-- 07. month (d)d–(d)d, yyyy /English md/
		month, day, day2, anchor_year, year=mw.ustring.match(date_string, "(%a+) +(%d%d?)[%-–](%d%d?), +((%d%d%d%d)%a?)");
		if tonumber(day) >= tonumber(day2) then return false; end														 		-- date range order is left to right: earlier to later; dates may not be the same;
		month = get_english_month_number (month);
		if 0 == month then return false; end																			 			-- return false if month text isn't one of the twelve months
		month2=month;																									 		-- for metadata

	elseif mw.ustring.match(date_string, "^[1-9]%d?/[1-9]%d?%. +%a+ +[1-9]%d%d%d%.?%a?$") then													-- 08. (d)d/(d)d. month yyyy
		day, day2, month, anchor_year, year=mw.ustring.match(date_string, "(%d%d?)/(%d%d?)%. +(%a+) +((%d%d%d%d)%.?%a?)");
		if 1 ~= tonumber(day2) - tonumber(day) then return false; end													 		-- date range order is left to right: earlier to later and CONSECUTIVE; dates may not be the same;
		month = get_month_number (month);
		if 0 == month then return false; end																				 		-- return false if month text isn't one of the twelve months
		month2=month;																									 		-- for metadata

	elseif mw.ustring.match(date_string, "^[1-9]%d?[%-–—][1-9]%d?%. +%a%a%a%. +[1-9]%d%d%d%.?%a?$") then											-- 09. (d)d—(d)d. mon. yyyy
		day, day2, month, anchor_year, year=mw.ustring.match(date_string, "(%d%d?)[%-–—](%d%d?)%. +(%a%a%a)%. +((%d%d%d%d)%.?%a?)");
		if tonumber(day) >= tonumber(day2) then return false; end														 		-- date range order is left to right: earlier to later; dates may not be the same;
		month = get_dot_month_number (month);
		if 0 == month then return false; end																			 			-- return false if month text isn't one of the nine dot-months
		month2=month;																									 		-- for metadata

	elseif mw.ustring.match(date_string, "^[1-9]%d?/[1-9]%d?%. +%a%a%a%. +[1-9]%d%d%d%.?%a?$") then												-- 10. (d)d/(d)d. mon. yyyy
		day, day2, month, anchor_year, year=mw.ustring.match(date_string, "(%d%d?)/(%d%d?)%. +(%a%a%a)%. +((%d%d%d%d)%.?%a?)");
		if 1 ~= tonumber(day2) - tonumber(day) then return false; end												 			-- date range order is left to right: earlier to later and CONSECUTIVE; dates may not be the same;
		month = get_dot_month_number (month);
		if 0 == month then return false; end																			 			-- return false if month text isn't one of the nine dot-months
		month2=month;																									 		-- for metadata

	elseif mw.ustring.match(date_string, "^%d%d?%. +%d?%d%.? [%-–—] %d%d?%. +%d?%d%. +[1-9]%d%d%d%.?$") then										-- 11. [d]d. [m]m. — [d]d. [m]m. yyyy
		day, month, day2, month2, year=mw.ustring.match(date_string, "(%d%d?)%. +(%d?%d)%.? [%-–—] (%d%d?)%. +(%d?%d)%. +(%d%d%d%d)%.?");
		if (not is_valid_month_season_range(month, month2)) or not is_valid_year(year) then return false; end			 		-- date range order is left to right: earlier to later;
		month = get_month_number (month);																				 		-- for metadata
		month2 = get_month_number (month2);
		year2=year;

	elseif mw.ustring.match(date_string, "^[1-9]%d?%. +%a+ [%-–—] [1-9]%d?%. +%a+ +[1-9]%d%d%d%.?%a?$") then										-- 12. (d)d. month — (d)d. month yyyy
		day, month, day2, month2, anchor_year, year=mw.ustring.match(date_string, "(%d%d?)%. +(%a+) [%-–—] (%d%d?)%. +(%a+) +((%d%d%d%d)%.?%a?)");
		if (not is_valid_month_season_range(month, month2)) or not is_valid_year(year) then return false; end			 		-- date range order is left to right: earlier to later;
		month = get_month_number (month);																				 		-- for metadata
		month2 = get_month_number (month2);
		year2=year;

	elseif mw.ustring.match(date_string, "^[1-9]%d? +%a+ [%-–] [1-9]%d? +%a+ +[1-9]%d%d%d%a?$") then										-- 12. (d)d month – (d)d month yyyy /English/
		day, month, day2, month2, anchor_year, year=mw.ustring.match(date_string, "(%d%d?) +(%a+) [%-–] (%d%d?) +(%a+) +((%d%d%d%d)%a?)");
		if (not is_valid_english_month_season_range(month, month2)) or not is_valid_year(year) then return false; end			 		-- date range order is left to right: earlier to later;
		month = get_english_month_number (month);																				 		-- for metadata
		month2 = get_english_month_number (month2);
		year2=year;

	elseif mw.ustring.match(date_string, "^%a+ +[1-9]%d? [%-–] %a+ +[1-9]%d?, +[1-9]%d%d%d%a?$") then										-- 12. month (d)d – month (d)d, yyyy /English md/
		month, day, month2, day2, anchor_year, year=mw.ustring.match(date_string, "(%a+) +(%d%d?) [%-–] (%a+) +(%d%d?), +((%d%d%d%d)%a?)");
		if (not is_valid_english_month_season_range(month, month2)) or not is_valid_year(year) then return false; end			 		-- date range order is left to right: earlier to later;
		month = get_english_month_number (month);																				 		-- for metadata
		month2 = get_english_month_number (month2);
		year2=year;

	elseif mw.ustring.match(date_string, "^[1-9]%d?%. +%a%a%a%. [%-–—] [1-9]%d?%. +%a%a%a%. +[1-9]%d%d%d%.?%a?$") then							-- 13. (d)d. mon. — (d)d. mon. yyyy
		day, month, day2, month2, anchor_year, year=mw.ustring.match(date_string, "(%d%d?)%. +(%a%a%a)%. [%-–—] (%d%d?)%. +(%a%a%a)%. +((%d%d%d%d)%.?%a?)");
		if (not is_valid_dot_month_range(month, month2)) or not is_valid_year(year) then return false; end			 			-- date range order is left to right: earlier to later;
		month = get_dot_month_number (month);																			 		-- for metadata
		month2 = get_dot_month_number (month2);
		year2=year;

	elseif mw.ustring.match(date_string, "^%d%d?%. +%d?%d%. +[1-9]%d%d%d%.? [%-–—] %d%d?%. +%d?%d%. +[1-9]%d%d%d%.?%a?$") then					-- 14. [d]d. [m]m. yyyy. — [d]d. [m]m. yyyy
		day, month, year, day2, month2, year2=mw.ustring.match(date_string, "(%d%d?)%. +(%d?%d)%. +(%d%d%d%d?)%.? [%-–—] (%d%d?)%. +(%d?%d)%. +(%d%d%d%d?)%.?");
		if tonumber(year2) <= tonumber(year) then return false; end														 		-- must be sequential years, left to right, earlier to later
		if not is_valid_year(year2) or not is_valid_month_range_style(month, month2) then return false; end				 		-- year2 no more than one year in the future; months same style
		month = get_month_number (month);																				 		-- for metadata
		month2 = get_month_number (month2);

	elseif mw.ustring.match(date_string, "^[1-9]%d?%. +%a+ +[1-9]%d%d%d%.? [%-–—] [1-9]%d?%. +%a+ +[1-9]%d%d%d%.?%a?$") then						-- 15. (d)d. month yyyy — (d)d. month yyyy
		day, month, year, day2, month2, anchor_year, year2=mw.ustring.match(date_string, "(%d%d?)%. +(%a+) +(%d%d%d%d)%.? [%-–—] (%d%d?)%. +(%a+) +((%d%d%d%d)%.?%a?)");
		if tonumber(year2) <= tonumber(year) then return false; end														 		-- must be sequential years, left to right, earlier to later
		if not is_valid_year(year2) or not is_valid_month_range_style(month, month2) then return false; end				 		-- year2 no more than one year in the future; months same style
		month = get_month_number (month);																				 		-- for metadata
		month2 = get_month_number (month2);

	elseif mw.ustring.match(date_string, "^[1-9]%d? +%a+ +[1-9]%d%d%d [%-–] [1-9]%d? +%a+ +[1-9]%d%d%d%a?$") then						-- 15. (d)d month yyyy – (d)d month yyyy /English/
		day, month, year, day2, month2, anchor_year, year2=mw.ustring.match(date_string, "(%d%d?) +(%a+) +(%d%d%d%d) [%-–] (%d%d?) +(%a+) +((%d%d%d%d)%a?)");
		if tonumber(year2) <= tonumber(year) then return false; end														 		-- must be sequential years, left to right, earlier to later
		if not is_valid_year(year2) or not is_valid_month_range_style(month, month2) then return false; end				 		-- year2 no more than one year in the future; months same style
		month = get_english_month_number (month);																				 		-- for metadata
		month2 = get_english_month_number (month2);

	elseif mw.ustring.match(date_string, "^%a+ +[1-9]%d?, +[1-9]%d%d%d [%-–] %a+ +[1-9]%d?, +[1-9]%d%d%d%a?$") then						-- 15. month (d)d, yyyy – month (d)d, yyyy /English md/
		month, day, year, month2, day2, anchor_year, year2=mw.ustring.match(date_string, "(%a+) +(%d%d?), +(%d%d%d%d) [%-–] (%a+) +(%d%d?), +((%d%d%d%d)%a?)");
		if tonumber(year2) <= tonumber(year) then return false; end														 		-- must be sequential years, left to right, earlier to later
		if not is_valid_year(year2) or not is_valid_month_range_style(month, month2) then return false; end				 		-- year2 no more than one year in the future; months same style
		month = get_english_month_number (month);																				 		-- for metadata
		month2 = get_english_month_number (month2);

	elseif mw.ustring.match(date_string, "^[1-9]%d?%. +%a%a%a%. +[1-9]%d%d%d%.? [%-–—] [1-9]%d?%. +%a%a%a%. +[1-9]%d%d%d%.?%a?$") then			-- 16. (d)d. mon. yyyy — (d)d. mon. yyyy
		day, month, year, day2, month2, anchor_year, year2=mw.ustring.match(date_string, "(%d%d?)%. +(%a%a%a)%. +(%d%d%d%d)%.? [%-–—] (%d%d?)%. +(%a%a%a)%. +((%d%d%d%d)%.?%a?)");
		if tonumber(year2) <= tonumber(year) then return false; end														 		-- must be sequential years, left to right, earlier to later
		if not is_valid_year(year2) or not is_valid_month_range_style(month, month2) then return false; end				 		-- year2 no more than one year in the future; months same style
		month = get_dot_month_number (month);																			 		-- for metadata
		month2 = get_dot_month_number (month2);

	elseif mw.ustring.match(date_string, "^%a+ +[1-9]%d%d%d[%-–—]%d%d%.?%a?$") then																-- 17. special case "Summer/Winter year—year" (YYYY-YY) {лето\зима\leto\zima\љето\ljeto yyyy—yy}
		local century;
		month, year, century, anchor_year, year2=mw.ustring.match(date_string, "(%a+) +((%d%d)%d%d)[%-–—]((%d%d)%.?%a?)");
		if ('лето' ~= month and 'зима' ~= month) and ('leto' ~= month and 'zima' ~= month) and ('љето' ~= month and 'зима' ~= month) and ('ljeto' ~= month and 'zima' ~= month) then return false end; -- 'month' can only be Summer or Winter
		anchor_year=year..'—'..anchor_year;																				 		-- assemble anchor_year from both years
		year2 = century..year2;																							 		-- add the century to year2 for comparisons
		if 1 ~= tonumber(year2) - tonumber(year) then return false; end													 		-- must be consecutive years, left to right, earlier to later
		if not is_valid_year(year2) then return false; end																 		-- no year farther in the future than next year
		month = get_season_number (month);

	elseif mw.ustring.match(date_string, "^%a+ +[1-9]%d%d%d[%-–]%d%d%a?$") then																-- 17. special case "Summer/Winter year—year" (YYYY-YY) {Summer\Winter yyyy–yy} /English/
		local century;
		month, year, century, anchor_year, year2=mw.ustring.match(date_string, "(%a+) +((%d%d)%d%d)[%-–]((%d%d)%a?)");
		if 'Winter' ~= month and 'Summer' ~= month then return false end; -- 'month' can only be Summer or Winter
		anchor_year=year..'—'..anchor_year;																				 		-- assemble anchor_year from both years
		year2 = century..year2;																							 		-- add the century to year2 for comparisons
		if 1 ~= tonumber(year2) - tonumber(year) then return false; end													 		-- must be consecutive years, left to right, earlier to later
		if not is_valid_year(year2) then return false; end																 		-- no year farther in the future than next year
		month = get_english_season_number (month);

	elseif mw.ustring.match(date_string, "^%a+ +[1-9]%d%d%d/%d%d%.?%a?$") then																	-- 18. special case "Summer/Winter year/year" (YYYY-YY); years separated by '/' {лето\зима\leto\zima\љето\ljeto yyyy/yy}
		local century;
		month, year, century, anchor_year, year2=mw.ustring.match(date_string, "(%a+) +((%d%d)%d%d)/((%d%d)%.?%a?)");
		if ('лето' ~= month and 'зима' ~= month) and ('leto' ~= month and 'zima' ~= month) and ('љето' ~= month and 'зима' ~= month) and ('ljeto' ~= month and 'zima' ~= month) then return false end; -- 'month' can only be Summer or Winter
		anchor_year=year..'/'..anchor_year;																				 		-- assemble anchor_year from both years
		year2 = century..year2;																							 		-- add the century to year2 for comparisons
		if 1 ~= tonumber(year2) - tonumber(year) then return false; end													 		-- must be consecutive years, left to right, earlier to later
		if not is_valid_year(year2) then return false; end																 		-- no year farther in the future than next year
		month = get_season_number (month);

	elseif mw.ustring.match(date_string, "^%a+ +[1-9]%d%d%d[%-–—][1-9]%d%d%d%.?%a?$") then														-- 19. special case "Summer/Winter year—year" (YYYY-YYYY) {лето\зима\leto\zima\љето\ljeto yyyy—yyyy}
		month, year, anchor_year, year2=mw.ustring.match(date_string, "(%a+) +(%d%d%d%d)[%-–—]((%d%d%d%d)%.?%a?)");
		if ('лето' ~= month and 'зима' ~= month) and ('leto' ~= month and 'zima' ~= month) and ('љето' ~= month and 'зима' ~= month) and ('ljeto' ~= month and 'zima' ~= month) then return false end; -- 'month' can only be Summer or Winter
		anchor_year=year..'—'..anchor_year;																				 		-- assemble anchor_year from both years
		if 1 ~= tonumber(year2) - tonumber(year) then return false; end													 		-- must be consecutive years, left to right, earlier to later
		if not is_valid_year(year2) then return false; end																 		-- no year farther in the future than next year
		month = get_season_number (month);																				 		-- for metadata

	elseif mw.ustring.match(date_string, "^%a+ +[1-9]%d%d%d[%-–][1-9]%d%d%d%a?$") then														-- 19. special case "Summer/Winter year–year" (YYYY-YYYY) {Summer\Winter yyyy–yyyy} /English/
		month, year, anchor_year, year2=mw.ustring.match(date_string, "(%a+) +(%d%d%d%d)[%-–]((%d%d%d%d)%a?)");
		if 'Winter' ~= month and 'Summer' ~= month then return false end; -- 'month' can only be Summer or Winter
		anchor_year=year..'—'..anchor_year;																				 		-- assemble anchor_year from both years
		if 1 ~= tonumber(year2) - tonumber(year) then return false; end													 		-- must be consecutive years, left to right, earlier to later
		if not is_valid_year(year2) then return false; end																 		-- no year farther in the future than next year
		month = get_english_season_number (month);																				 		-- for metadata

	elseif mw.ustring.match(date_string, "^%a+ +[1-9]%d%d%d/[1-9]%d%d%d%.?%a?$") then															-- 20. special case "Summer/Winter year/year" (YYYY-YYYY); years separated by '/' {лето\зима\leto\zima\љето\ljeto yyyy/yyyy}
		month, year, anchor_year, year2=mw.ustring.match(date_string, "(%a+) +(%d%d%d%d)/((%d%d%d%d)%.?%a?)");
		if ('лето' ~= month and 'зима' ~= month) and ('leto' ~= month and 'zima' ~= month) and ('љето' ~= month and 'зима' ~= month) and ('ljeto' ~= month and 'zima' ~= month) then return false end; -- 'month' can only be Summer or Winter
		anchor_year=year..'/'..anchor_year;																			 			-- assemble anchor_year from both years
		if 1 ~= tonumber(year2) - tonumber(year) then return false; end												 			-- must be consecutive years, left to right, earlier to later
		if not is_valid_year(year2) then return false; end															 			-- no year farther in the future than next year
		month = get_season_number (month);																				 		-- for metadata

	elseif mw.ustring.match(date_string, "^%a+ +[1-9]%d%d%d%.? +[%-–—] +%a+ +[1-9]%d%d%d%.?%a?$") then											-- 21. month\season yyyy — month\season yyyy
		month, year, month2, anchor_year, year2=mw.ustring.match(date_string, "(%a+) +(%d%d%d%d)%.? +[%-–—] +(%a+) +((%d%d%d%d)%.?%a?)");
		anchor_year=year..'—'..anchor_year;																			 			-- assemble anchor_year from both years
		if tonumber(year) >= tonumber(year2) then return false; end														 		-- left to right, earlier to later, not the same
		if not is_valid_year(year2) then return false; end																 		-- no year farther in the future than next year
		if 0 ~= get_month_number(month) and 0 ~= get_month_number(month2) and is_valid_month_range_style(month, month2) then 	-- both must be month year, same month style
			month = get_month_number(month);
			month2 = get_month_number(month2);
		elseif 0 ~= get_season_number(month) and 0 ~= get_season_number(month2) then									 			-- both must be or season year, not mixed
			month = get_season_number(month);
			month2 = get_season_number(month2);
		else
			 return false;
		end

	elseif mw.ustring.match(date_string, "^%a+ +[1-9]%d%d%d +[%-–] +%a+ +[1-9]%d%d%d%a?$") then											-- 21. month\season yyyy – month\season yyyy [English]
		month, year, month2, anchor_year, year2=mw.ustring.match(date_string, "(%a+) +(%d%d%d%d) +[%-–] +(%a+) +((%d%d%d%d)%a?)");
		anchor_year=year..'—'..anchor_year;																			 			-- assemble anchor_year from both years
		if tonumber(year) >= tonumber(year2) then return false; end														 		-- left to right, earlier to later, not the same
		if not is_valid_year(year2) then return false; end																 		-- no year farther in the future than next year
		if 0 ~= get_english_month_number(month) and 0 ~= get_english_month_number(month2) and is_valid_month_range_style(month, month2) then 	-- both must be month year, same month style
			month = get_english_month_number(month);
			month2 = get_english_month_number(month2);
		elseif 0 ~= get_english_season_number(month) and 0 ~= get_english_season_number(month2) then									 			-- both must be or season year, not mixed
			month = get_english_season_number(month);
			month2 = get_english_season_number(month2);
		else
			 return false;
		end

	elseif mw.ustring.match(date_string, "^%a%a%a%. +[1-9]%d%d%d%.? +[%-–—] +%a%a%a%. +[1-9]%d%d%d%.?%a?$") then									-- 22. mon. yyyy — mon. yyyy
		month, year, month2, anchor_year, year2=mw.ustring.match(date_string, "(%a%a%a)%. +(%d%d%d%d)%.? +[%-–—] +(%a%a%a)%. +((%d%d%d%d)%.?%a?)");
		anchor_year=year..'—'..anchor_year;																				 		-- assemble anchor_year from both years
		if tonumber(year) >= tonumber(year2) then return false; end														 		-- left to right, earlier to later, not the same
		if not is_valid_year(year2) then return false; end																 		-- no year farther in the future than next year
		if 0 ~= get_dot_month_number (month) and 0 ~= get_dot_month_number (month2) and is_valid_month_range_style(month, month2) then 	-- both must be month year, same month style
			month = get_dot_month_number (month);
			month2 = get_dot_month_number (month2);																		 		-- both must be months, not mixed; 'dot-seasons' don't exist
		else
			 return false;
		end

	elseif mw.ustring.match(date_string, "^%a+[%-–—]%a+ +[1-9]%d%d%d%.?%a?$") then																-- 23. month\season—month\season yyyy
		month, month2, anchor_year, year=mw.ustring.match(date_string, "(%a+)[%-–—](%a+)%s*((%d%d%d%d)%.?%a?)");
		if (not is_valid_month_season_range(month, month2)) or (not is_valid_year(year)) then return false; end
		if 0 ~= get_month_number(month) then																				 		-- determined to be a valid range so just check this one to know if month or season
			month = get_month_number(month);
			month2 = get_month_number(month2);
		else
			month = get_season_number(month);
			month2 = get_season_number(month2);
		end
		year2=year;

	elseif mw.ustring.match(date_string, "^%a+[%-–]%a+ +[1-9]%d%d%d%a?$") then																-- 23. month\season—month\season yyyy /English/
		month, month2, anchor_year, year=mw.ustring.match(date_string, "(%a+)[%-–](%a+)%s*((%d%d%d%d)%a?)");
		if (not is_valid_english_month_season_range(month, month2)) or (not is_valid_year(year)) then return false; end
		if 0 ~= get_english_month_number(month) then																				 		-- determined to be a valid range so just check this one to know if month or season
			month = get_english_month_number(month);
			month2 = get_english_month_number(month2);
		else
			month = get_english_season_number(month);
			month2 = get_english_season_number(month2);
		end
		year2=year;

	elseif mw.ustring.match(date_string, "^%a+/%a+ +[1-9]%d%d%d%.?%a?$") then																	-- 24. month\season/month\season yyyy
		month, month2, anchor_year, year=mw.ustring.match(date_string, "(%a+)/(%a+)%s*((%d%d%d%d)%.?%a?)");
		if (not is_valid_month_season_range(month, month2)) or (not is_valid_year(year)) then return false; end
		if 0 ~= get_month_number(month) then																				 		-- determined to be a valid range so just check this one to know if month or season
			if 1 ~= get_month_number(month2) - get_month_number(month) then return false; end							 		-- must be consecutive months
			month = get_month_number(month);
			month2 = get_month_number(month2);
		else
			if 1 ~= get_season_number(month2) - get_season_number(month) then return false; end							 		-- must be consecutive seasons
			month = get_season_number(month);
			month2 = get_season_number(month2);
		end
		year2=year;

	elseif mw.ustring.match(date_string, "^%a%a%a%.[%-–—]%a%a%a%. +[1-9]%d%d%d%.?%a?$") then														-- 25. mon.—mon. yyyy
		month, month2, anchor_year, year=mw.ustring.match(date_string, "(%a%a%a)%.[%-–—](%a%a%a)%.%s*((%d%d%d%d)%.?%a?)");
		if (not is_valid_dot_month_range(month, month2)) or (not is_valid_year(year)) then return false; end
		if 0 ~= get_dot_month_number (month) then																		 		-- determined to be a valid range so just check this one to know if month or season
			month = get_dot_month_number (month);
			month2 = get_dot_month_number (month2);
		end
		year2=year;

	elseif mw.ustring.match(date_string, "^%a%a%a%./%a%a%a%. +[1-9]%d%d%d%.?%a?$") then															-- 26. mon./mon. yyyy
		month, month2, anchor_year, year=mw.ustring.match(date_string, "(%a%a%a)%./(%a%a%a)%.%s*((%d%d%d%d)%.?%a?)");
		if (not is_valid_dot_month_range(month, month2)) or (not is_valid_year(year)) then return false; end
		if 0 ~= get_dot_month_number (month) then																		 		-- determined to be a valid range so just check this one to know if month or season
			if 1 ~= get_dot_month_number (month2) - get_dot_month_number (month) then return false; end					 		-- must be consecutive dot-months
			month = get_dot_month_number (month);
			month2 = get_dot_month_number (month2);
		end
		year2=year;
		
	elseif mw.ustring.match(date_string, "^%a+%. +%d%d%d%d%.?%a?$") then		--disabling long months of length three to be followed by dot
		return false

	elseif mw.ustring.match(date_string, "^%a+ +%d%d%d%d%.?%a?$") then																			-- 27. month\season yyyy
		month, anchor_year, year=mw.ustring.match(date_string, "(%a+)%s*((%d%d%d%d)%.?%a?)");
		if not is_valid_year(year) then return false; end
		if not is_valid_month_or_season (month) and 0 == is_proper_name (month) then return false; end
		if 0 ~= get_month_number(month) then																				 		-- determined to be a valid range so just check this one to know if month or season
			month = get_month_number(month);
		elseif 0 ~= get_season_number(month) then
			month = get_season_number(month);
		else
			month = is_proper_name (month);																				 		-- must be proper name; not supported in COinS
		end

	elseif mw.ustring.match(date_string, "^%d?%d%. +%d%d%d%d%.?%a?$") then																			-- 27. (m)m. yyyy
		month, anchor_year, year=mw.ustring.match(date_string, "(%d?%d)%.%s*((%d%d%d%d)%.?%a?)");
		if not is_valid_year(year) or 12 < tonumber(month) or 1 > tonumber(month) then return false; end

	elseif mw.ustring.match(date_string, "^%a+ +%d%d%d%d%a?$") then																			-- 27. month\season yyyy /English/
		month, anchor_year, year=mw.ustring.match(date_string, "(%a+)%s*((%d%d%d%d)%a?)");
		if not is_valid_year(year) then return false; end
		if not is_valid_month_or_season (month) and 0 == is_proper_name (month) then return false; end
		if 0 ~= get_english_month_number(month) then																				 		-- determined to be a valid range so just check this one to know if month or season
			month = get_english_month_number(month);
		elseif 0 ~= get_english_season_number(month) then
			month = get_english_season_number(month);
		else
			month = is_proper_name (month);																				 		-- must be proper name; not supported in COinS
		end
		
	elseif mw.ustring.match(date_string, "^%a%a%a%. +%d%d%d%d%.?%a?$") then																		-- 28. mon. yyyy
		month, anchor_year, year=mw.ustring.match(date_string, "(%a%a%a)%.%s*((%d%d%d%d)%.?%a?)");
		if not is_valid_year(year) then return false; end
		if not is_valid_month_or_season (month) and 0 == is_proper_name (month) then return false; end
		if 0 ~= get_dot_month_number (month) then																	 			-- check this one to know if month or season (it is dot-month, we know, but it's not important because it can stay here as same as it is above, just deleted checking for seasons; don't delete "else" for "month = is_proper_name (month);" part)
			month = get_dot_month_number (month);
		else
			month = is_proper_name (month);																				 		-- must be proper name; not supported in COinS
		end

	elseif mw.ustring.match(date_string, "^[1-9]%d%d%d?[%-–—][1-9]%d%d%d?%.?%a?$") then															-- 29. (y)yyy—(y)yyy
		year, anchor_year, year2=mw.ustring.match(date_string, "(%d%d%d%d?)[%-–—]((%d%d%d%d?)%.?%a?)");
		anchor_year=year..'—'..anchor_year;																				 		-- assemble anchor year from both years
		if tonumber(year) >= tonumber(year2) then return false; end														 		-- left to right, earlier to later, not the same
		if not is_valid_year(year2) then return false; end																 		-- no year farther in the future than next year

	elseif mw.ustring.match(date_string, "^[1-9]%d%d%d?/[1-9]%d%d%d?%.?%a?$") then																-- 30. (y)yyy/(y)yyy
		year, anchor_year, year2=mw.ustring.match(date_string, "(%d%d%d%d?)/((%d%d%d%d?)%.?%a?)");
		anchor_year=year..'/'..anchor_year;																				 		-- assemble anchor year from both years
		if 1 ~= tonumber(year2) - tonumber(year) then return false; end													 		-- left to right, earlier to later, not the same, CONSECUTIVE
		if not is_valid_year(year2) then return false; end																 		-- no year farther in the future than next year

	elseif mw.ustring.match(date_string, "^[1-9]%d%d%d[%-–—]%d%d%.?%a?$") then																	-- 31. yyyy—yy
		local century;
		year, century, anchor_year, year2=mw.ustring.match(date_string, "((%d%d)%d%d)[%-–—]((%d%d)%.?%a?)");
		anchor_year=year..'—'..anchor_year;																				 		-- assemble anchor year from both years
		if 13 > tonumber(year2) then return false; end																	 		-- don't allow 2003-05 which might be May 2003
		year2 = century..year2;																							 		-- add the century to year2 for comparisons
		if tonumber(year) >= tonumber(year2) or 1 ~= tonumber(year2) - tonumber(year) then return false; end			 			-- left to right, earlier to later, not the same
		if not is_valid_year(year2) then return false; end																 		-- no year farther in the future than next year

	elseif mw.ustring.match(date_string, "^[1-9]%d%d%d/%d%d%.?%a?$") then																		-- 32. yyyy/yy
		local century;
		year, century, anchor_year, year2=mw.ustring.match(date_string, "((%d%d)%d%d)/((%d%d)%.?%a?)");
		anchor_year=year..'/'..anchor_year;																			 			-- assemble anchor year from both years
		if 13 > tonumber(year2) then return false; end																	 		-- don't allow 2003-05 which might be May 2003
		year2 = century..year2;																							 		-- add the century to year2 for comparisons
		if 1 ~= tonumber(year2) - tonumber(year) then return false; end													 		-- left to right, earlier to later, not the same
		if not is_valid_year(year2) then return false; end																 		-- no year farther in the future than next year

	elseif mw.ustring.match(date_string, "^[1-9]%d%d%d?%.?%a?$") then																			-- 33. (y)yyy
		anchor_year, year=mw.ustring.match(date_string, "((%d%d%d%d?)%.?%a?)");
		if false == is_valid_year(year) then
			return false;
		end

	else
		return false;										-- date format not one of the MOS:DATE approved formats
	end

	if test_accessdate then									-- test accessdate here because we have numerical date parts
		if 0 ~= year and 0 ~= month and 0 ~= day and 				-- all parts of a single date required
			0 == year2 and 0 == month2 and 0 == day2 then					-- none of these; accessdate must not be a range
				if not is_valid_accessdate (year..'-'..month..'-'..day) then	
					return false;				-- return false when accessdate out of bounds
				end
		else
			return false;						-- return false when accessdate is a range of two dates
		end
	end

	local result=true;										-- check whole dates for validity; assume true because not all dates will go through this test
	if 0 ~= year and 0 ~= month and 0 ~= day and 0 == year2 and 0 == month2 and 0 == day2 then			-- YMD (simple whole date)
		result=is_valid_date(year,month,day);

	elseif 0 ~= year and 0 ~= month and 0 ~= day and 0 == year2 and 0 == month2 and 0 ~= day2 then		-- YMD-d (day range)
		result=is_valid_date(year,month,day);
		result=result and is_valid_date(year,month,day2);

	elseif 0 ~= year and 0 ~= month and 0 ~= day and 0 == year2 and 0 ~= month2 and 0 ~= day2 then		-- YMD-md (day month range)
		result=is_valid_date(year,month,day);
		result=result and is_valid_date(year,month2,day2);

	elseif 0 ~= year and 0 ~= month and 0 ~= day and 0 ~= year2 and 0 ~= month2 and 0 ~= day2 then		-- YMD-ymd (day month year range)
		result=is_valid_date(year,month,day);
		result=result and is_valid_date(year2,month2,day2);
	end
	
	if false == result then return false; end

	if nil ~= tCOinS_date then												-- this table only passed into this function when testing |date= parameter values
		make_COinS_date ({year=year, month=month, day=day, year2=year2, month2=month2, day2=day2}, tCOinS_date);			-- make an ISO 8601 date string for COinS
	end
	
	return true, anchor_year;												-- format is good and date string represents a real date
end	


--[[--------------------------< D A T E S >--------------------------------------------------------------------

Cycle the date-holding parameters in passed table date_parameters_list through check_date() to check compliance with MOS:DATE. For all valid dates, check_date() returns true. The |date= parameter
test is unique; it is the only date holding parameter from which values for anchor_year (used in CITEREF identifiers) and COinS_date (used in the COinS) are derived. The |date= parameter is the
only date-holding parameter that is allowed to contain the no-date keywords "н. д.", "б. д.", "Н. Д.", "Б. Д.", "НД", "БД" (without quotes; abbr. no date, нема датума, без датума; both scripts).

Unlike most error messages created in this module, only one error message is created by this function. Because all of the date holding parameters are processed serially, a single error message is
created as the dates are tested.

In this part, we are also checking for "c. year", "cca. year" or "cca year" (without quotes; abbr. circa), so it can be enabled for use. "cca year" is the most optimal Serbian abbreviation form.

]]

local function dates(date_parameters_list, tCOinS_date)
	local anchor_year;		-- will return as nil if the date being tested is not |date=
	local COinS_date;		-- will return as nil if the date being tested is not |date=
	local embargo_date;															-- if embargo date is a good dmy, mdy, ymd date then holds original value else reset to 9999
	local error_message = "";
	local good_date = false;
	
	for k, v in pairs(date_parameters_list) do									-- for each date-holding parameter in the list
		if is_set(v) then														-- if the parameter has a value
			if mw.ustring.match(v, "^c%. [1-9]%d%d%d?%.?%a?$") then				-- special case for "c. year" or with or without CITEREF disambiguator - only |date= and |year=
				local year = mw.ustring.match(v, "c%. ([1-9]%d%d%d?)%.?%a?");					-- get the year portion so it can be tested
				if 'date'==k then
					anchor_year, COinS_date = mw.ustring.match(v, "((c%. [1-9]%d%d%d?)%.?%a?)");		-- anchor year and COinS_date only from |date= parameter
					good_date = is_valid_year(year);
				elseif 'year'==k then
					good_date = is_valid_year(year);
				end
			elseif mw.ustring.match(v, "^cca%.? [1-9]%d%d%d?%.?%a?$") then				-- special case for "cca(.) year" or with or without CITEREF disambiguator - only |date= and |year=
				local year = mw.ustring.match(v, "cca%.? ([1-9]%d%d%d?)%.?%a?");					-- get the year portion so it can be tested
				if 'date'==k then
					anchor_year, COinS_date = mw.ustring.match(v, "((cca%.? [1-9]%d%d%d?)%.?%a?)");		-- anchor year and COinS_date only from |date= parameter
					good_date = is_valid_year(year);
				elseif 'year'==k then
					good_date = is_valid_year(year);
				end
			elseif 'date'==k then												-- if the parameter is |date=
				if mw.ustring.match(v, "^н%. ?д%.%a?$") then												--if |date=н. д. with or without a CITEREF disambiguator
					good_date, anchor_year, COinS_date = true, mw.ustring.match(v, "((н%. ?д%.)%a?)");						--no error when date parameter is set to no date
				elseif mw.ustring.match(v, "^б%. ?д%.%a?$") then											--if |date=б. д. with or without a CITEREF disambiguator
					good_date, anchor_year, COinS_date = true, mw.ustring.match(v, "((б%. ?д%.)%a?)");						--no error when date parameter is set to no date
				elseif mw.ustring.match(v, "^Н%. ?Д%.%a?$") then											--if |date=Н. Д. with or without a CITEREF disambiguator
					good_date, anchor_year, COinS_date = true, mw.ustring.match(v, "((Н%. ?Д%.)%a?)");						--no error when date parameter is set to no date
				elseif mw.ustring.match(v, "^Б%. ?Д%.%a?$") then											--if |date=Б. Д. with or without a CITEREF disambiguator
					good_date, anchor_year, COinS_date = true, mw.ustring.match(v, "((Б%. ?Д%.)%a?)");						--no error when date parameter is set to no date
				elseif mw.ustring.match(v, "^НД%a?$") then												--if |date=НД with or without a CITEREF disambiguator
					good_date, anchor_year, COinS_date = true, mw.ustring.match(v, "((НД)%a?)");								--no error when date parameter is set to no date
				elseif mw.ustring.match(v, "^БД%a?$") then												--if |date=БД with or without a CITEREF disambiguator
					good_date, anchor_year, COinS_date = true, mw.ustring.match(v, "((БД)%a?)");								--no error when date parameter is set to no date
				elseif mw.ustring.match(v, "^n%.d%.%a?$") then												--if |date=n.d. with or without a CITEREF disambiguator
					good_date, anchor_year, COinS_date = true, mw.ustring.match(v, "((n%.d%.)%a?)");								--no error when date parameter is set to no date
				elseif mw.ustring.match(v, "^nd%a?$") then												--if |date=nd with or without a CITEREF disambiguator
					good_date, anchor_year, COinS_date = true, mw.ustring.match(v, "((nd)%a?)");								--no error when date parameter is set to no date
				else
					good_date, anchor_year, COinS_date = check_date (v, tCOinS_date);	-- go test the date
				end
			elseif 'year'==k then												-- if the parameter is |year= it should hold only a year value
				if mw.ustring.match(v, "^[1-9]%d%d%d?%.?%a?$") then							-- if |year= 3 or 4 digits only with or without a CITEREF disambiguator
					good_date, anchor_year, COinS_date = true, mw.ustring.match(v, "((%d+)%.?%a?)");
				end
			elseif 'access-date'==k then										-- if the parameter is |date=
				good_date = check_date (v, nil, true);							-- go test the date; nil is a placeholder; true is the test_accessdate flag
			elseif 'embargo'==k then											-- if the parameter is |embargo=
				good_date = check_date (v);										-- go test the date
				if true == good_date then										-- if the date is a valid date
					good_date, embargo_date = is_valid_embargo_date (v);		-- is |embargo= date a single dmy, mdy, or ymd formatted date? yes:returns embargo; no: returns 9999
				end
			else																-- any other date-holding parameter
				good_date = check_date (v);										-- go test the date
			end
			if false==good_date then											-- assemble one error message so we don't add the tracking category multiple times
				if is_set(error_message) then									-- once we've added the first portion of the error message ...
					error_message=error_message .. ", ";						-- ... add a comma space separator
				end
				error_message=error_message .. "&#124;" .. k .. "=";			-- add the failed parameter
			end
		end
	end
	return anchor_year, embargo_date, error_message;											-- and done
end


--[[--------------------------< Y E A R _ D A T E _ C H E C K >------------------------------------------------

Compare the value provided in |year= with the year value(s) provided in |date=. This function returns a numeric value:
	0 - year value does not match the year value in date
	1 - (default) year value matches the year value in date or one of the year values when date contains two years
	2 - year value matches the year value in date when date is in the form YYYY-MM-DD and year is disambiguated (|year=YYYYx)

]]

local function year_date_check (year_string, date_string)
	local year;
	local date1;
	local date2;
	local result = 1;															-- result of the test; assume that the test passes
	
	year = mw.ustring.match(year_string, '(%d%d%d%d?)%.?');

	if mw.ustring.match(date_string, '%d%d%d%d%-%d%d%-%d%d') and mw.ustring.match(year_string, '%d%d%d%d%.?%a') then		--special case where both date and year are required YYYY-MM-DD and YYYYx
		date1 = mw.ustring.match(date_string, '(%d%d%d%d)%.?');
		year = mw.ustring.match(year_string, '(%d%d%d%d)%.?');
		if year ~= date1 then
			result = 0;															-- years don't match
		else
			result = 2;															-- years match; but because disambiguated, don't add to maint cat
		end
		
	elseif mw.ustring.match(date_string, "%d%d%d%d?.-%d%d%d%d?%.?") then							-- any of the standard range formats of date with two three- or four-digit years
		date1, date2 = mw.ustring.match(date_string, "(%d%d%d%d?).-(%d%d%d%d?)%.?");
		if year ~= date1 and year ~= date2 then
			result = 0;
		end

	elseif mw.ustring.match(date_string, "%d%d%d%d[%-–—]%d%d%.?") then							-- YYYY-YY date ranges
		local century;
		date1, century, date2 = mw.ustring.match(date_string, "((%d%d)%d%d)[%-–—]+(%d%d)%.?");
		date2 = century..date2;													-- convert YY to YYYY
		if year ~= date1 and year ~= date2 then
			result = 0;
		end

	elseif mw.ustring.match(date_string, "%d%d%d%d?%.?") then									-- any of the standard formats of date with one year
		date1 = mw.ustring.match(date_string, "(%d%d%d%d?)%.?");
		if year ~= date1 then
			result = 0;
		end
	else
		result = 0;																-- no recognizable year in date
	end
	return result;
end


--[[-------------------------< R E F O R M A T   T A B L E S >------------------------------------------------

These table are used exclusively for reformatting dates

]]

local source_patterns = {							-- this table holds patterns that match allowed date formats used to extract date components
	['dmy'] = '(%d%d?)%.?%s+(%a+)%s+(%d%d%d%d)%.?',
	['mdy'] = '(%a+)%s+(%d%d?),%s+(%d%d%d%d)',
	['ymd'] = '(%d%d%d%d)%-(%d%d)-(%d%d)',
	}

local short_formats = {								-- this table holds format strings used by os.date() for short month names
	['dmy'] = '%e %b %Y',
	['mdy'] = '%b %e, %Y',
	['ymd'] = '%F',
	}

local long_formats = {								-- this table holds format strings used by os.date() for long month names
	['dmy'] = '%e %B %Y',
	['mdy'] = '%B %e, %Y',
	['ymd'] = '%F',
	}


--[[-------------------------< G E T _ D M Y _ D A T E _ P A R T S >------------------------------------------

extracts year, month and day from DMY formatted date, places them in the source_date table, and returns.

]]

local function get_dmy_date_parts (date, source_date)
	source_date.day, source_date.month, source_date.year = mw.ustring.match (date, source_patterns['dmy']);	-- get date components as strings
	source_date.month = get_month_number (source_date.month) or get_english_month_number (source_date.month);					-- get month number
end


--[[-------------------------< G E T _ M D Y _ D A T E _ P A R T S >------------------------------------------

extracts year, month and day from MDY formatted date, places them in the source_date table, and returns.

]]

local function get_mdy_date_parts (date, source_date)
	source_date.month, source_date.day, source_date.year = mw.ustring.match (date, source_patterns['mdy']);	-- get date components as strings
	source_date.month = get_english_month_number (source_date.month);					-- get month number
end


--[[-------------------------< G E T _ Y M D _ D A T E _ P A R T S >------------------------------------------

extracts year, month and day from YMD formatted date, places them in the source_date table, and returns.

]]

local function get_ymd_date_parts (date, source_date)
	source_date.year, source_date.month, source_date.day = mw.ustring.match (date, source_patterns['ymd']);	-- get date components as strings
end


--[[-------------------------< R E F O R M A T _ D A T E S >--------------------------------------------------

Reformats existing dates into the format specified by format and short.

Format is one of several keywords: dmy, dmy-all, mdy, mdy-all, ymd, ymd-all. The all version includes access- and
archive-dates; otherwise these dates are not reformatted. On sr.wiki will not use any mdy format (mdy, mdy-all).

Date ranges, season dates, proper name dates are not currently supported.

]]

local function reformat_dates (date_parameters_list, format, short)
	local all = false;															-- set to false to skip access- and archive-dates
	local format_str;
	local source_date = {};
	
	if mw.ustring.match(format,'%a+%-all') then
		format = mw.ustring.match(format,'(%a+)%-all');									-- extract the format
		all = true;																-- set to true to format access- and archive-dates
	end
	
	for param_name, param_val in pairs(date_parameters_list) do					-- for each date-holding parameter in the list
		if is_set(param_val) then												-- if the parameter has a value
			if not all and in_array (param_name, {'access-date', 'archive-date'}) then	-- if access- or archive-date and format not xxx-all
				param_val = '';													-- set to empty string so we don't process this date
			end
			for source, pattern in pairs(source_patterns) do
				if mw.ustring.match(param_val,pattern) then
					if 'ymd' == source then
						get_ymd_date_parts (param_val, source_date);			-- get the date parts into the source_date table
					elseif 'dmy' == source then
						get_dmy_date_parts (param_val, source_date);			-- get the date parts into the source_date table
					elseif 'mdy' == source then
						get_mdy_date_parts (param_val, source_date);			-- get the date parts into the source_date table
					end

					if 'ymd' == format and 1582 > tonumber(source_date.year) then	-- ymd format dates not allowed before 1582
						return false;											-- abandon reformatting
					end
					
					if short then
						format_str = short_formats[format];
					else
						format_str = long_formats[format];
					end
																				-- convert date and save;
					date_parameters_list[param_name] = mw.text.trim (os.date (format_str, os.time(source_date)));	-- strip leading space when single digit day and %e is first format
				end
			end
		end
	end
	return true;																-- declare success and done
end


--[[--------------------------< D A T E _ H Y P H E N _ T O _ D A S H >----------------------------------------

Loops through the list of date-holding parameters and converts any hyphen to mdash.

Not called if the cs1|2 template has any date errors.

Modifies the date_parameters_list and returns true if hyphens are replaced, else returns false.

]]

local function date_hyphen_to_dash (date_parameters_list)
	local result = false;
	local n;
	for param_name, param_val in pairs(date_parameters_list) do					-- for each date-holding parameter in the list
		if not param_val:match ('%d%d%d%d%-%d%d%-%d%d') then					-- for those that are not ymd dates
			param_val, n = mw.ustring.gsub (param_val, '[%-]', '—');					-- replace any hyphen with mdash
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
		end
	end
	return result;																-- so we know if
end

--[[--------------------------< D A T E _ N D A S H _ T O _ D A S H >----------------------------------------

Loops through the list of date-holding parameters and converts any ndash to mdash.

Called even if the cs1|2 template has date error(s) because user might use English month ranges etc. or might not.
Not called only if ISO date format, as ISO date format does not have a ndash.

Modifies the date_parameters_list and returns true if hyphens are replaced, else returns false.

]]

local function date_ndash_to_dash (date_parameters_list)
	local result = false;
	local n;
	for param_name, param_val in pairs(date_parameters_list) do					-- for each date-holding parameter in the list
		if not param_val:match ('%d%d%d%d%-%d%d%-%d%d') then					-- for those that are not ymd dates
			param_val, n = mw.ustring.gsub (param_val, '[–]', '—');					-- replace any hyphen with mdash
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
		end
	end
	return result;																-- so we know if
end


--[[--------------------------< R E M O V E _ T R A I L I N G _ D O T >----------------------------------------

Loops through the list of date-holding parameters and removes any trailing dot that may or may not be entered after year number.
Generally speaking, date (alone) is incorrect without a traling dot but two dots or dot and right bracket are incorrect too.
While references used to display with templates, it was not possible to allow correct "1. 1. 2016." but only "1. 1. 2016" (example)
in order not to have date displayed as "(1. 1. 2016.)" but as correct "(1. 1. 2016)", or not as "1. 1. 2016.." but as "1. 1. 2016."

Called even if the cs1|2 template has date error(s) because user might specify dot (to comply alone-date writing norm) or might not
(because he knows it should/will not get displayed because ".)" or ".." is incorrect).
Not called only if ISO date format, as ISO date format does not have a trailing dot.

Modifies the date_parameters_list and returns true if trailing dots are replaced, else returns false.

]]

local function remove_trailing_dot (date_parameters_list)
	local result = false;
	local n;
	for param_name, param_val in pairs(date_parameters_list) do					-- for each date-holding parameter in the list
		if not param_val:match ('%d%d%d%d%-%d%d%-%d%d') then					-- for those that are not ymd dates as ISO "2005-05-05." does not exist
			param_val, n = mw.ustring.gsub (param_val, '%.$', '');						-- replace any trailing dot with empty string
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
		end
	end
	return result;																-- so we know if
end


--[[--------------------------< R E P L A C E _ E N G L I S H _ M O N T H S _ W I T H _ S E R B I A N >----------------------------------------

Loops through the list of date-holding parameters and translates any English month that may or may not be entered by user into Serbian format.

Not called if the cs1|2 template has any date errors.

Modifies the date_parameters_list and returns true if months are translated, else returns false.

]]

local function translate_english_months (date_parameters_list)
	local result = false;
	local n;
	for param_name, param_val in pairs(date_parameters_list) do					-- for each date-holding parameter in the list
		if not param_val:match ('%d%d%d%d%-%d%d%-%d%d') then					-- for those that are not ymd dates as ISO dates do not contain text
			param_val, n = mw.ustring.gsub (param_val, 'January', '1.');						-- replace for long month 1
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'February', '2.');						-- replace for long month 2
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'March', '3.');						-- replace for long month 3
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'April', '4.');						-- replace for long month 4
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'May', '5.');						-- replace for long month 5
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'June', '6.');						-- replace for long month 6
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'July', '7.');						-- replace for long month 7
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'August', '8.');						-- replace for long month 8
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'September', '9.');						-- replace for long month 9
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'October', '10.');						-- replace for long month 10
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'November', '11.');						-- replace for long month 11
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'December', '12.');						-- replace for long month 12
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Jan', '1.');						-- replace for short month 1
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Feb', '2.');						-- replace for short month 2
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Mar', '3.');						-- replace for short month 3
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Apr', '4.');						-- replace for short month 4
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'May', '5.');						-- replace for short month 5
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Jun', '6.');						-- replace for short month 6
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Jul', '7.');						-- replace for short month 7
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Aug', '8.');						-- replace for short month 8
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Sep', '9.');						-- replace for short month 9
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Oct', '10.');						-- replace for short month 10
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Nov', '11.');						-- replace for short month 11
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Dec', '12.');						-- replace for short month 12
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Winter', 'зима');						-- replace for season 4
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Spring', 'пролеће');						-- replace for season 1
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Summer', 'лето');						-- replace for season 2
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Fall', 'јесен');						-- replace for season 3
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Autumn', 'јесен');						-- replace for season 3
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, 'Christmas', 'Божић');						-- replace for only proper name
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '(%d%d?%.) (%d%d?) — (%d%d?%.) (%d%d?), (%d%d%d%d?)', '%2. %1 — %4. %3 %5');						-- reformat 1a
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '(%d%d?%.) (%d%d?), (%d%d%d%d?)', '%2. %1 %3');						-- reformat 1b
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '(%d%d?) (%d%d?%.) — (%d%d?) (%d%d?%.) (%d%d%d%d?)', '%1. %2 — %3. %4 %5');						-- reformat 2a
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '(%d%d?) (%d%d?%.) (%d%d%d%d?)', '%1. %2 %3');						-- reformat 2b
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '(%d%d?%.) (%d%d?—%d%d?), (%d%d%d%d?)', '%2. %1 %3');						-- reformat 3
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
		end
		if mw.ustring.match (param_val, '^%d%d?%. %d%d%d%d$') then					-- for those that are number-month and year
			param_val, n = mw.ustring.gsub (param_val, '^1%. (%d%d%d%d)', 'јануар %1');						-- replace for month 1
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '^2%. (%d%d%d%d)', 'фебруар %1');						-- replace for month 2
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '^3%. (%d%d%d%d)', 'март %1');						-- replace for month 3
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '^4%. (%d%d%d%d)', 'април %1');						-- replace for month 4
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '^5%. (%d%d%d%d)', 'мај %1');						-- replace for month 5
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '^6%. (%d%d%d%d)', 'јун %1');						-- replace for month 6
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '^7%. (%d%d%d%d)', 'јул %1');						-- replace for month 7
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '^8%. (%d%d%d%d)', 'август %1');						-- replace for month 8
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '^9%. (%d%d%d%d)', 'септембар %1');						-- replace for month 9
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '^10%. (%d%d%d%d)', 'октобар %1');						-- replace for month 10
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '^11%. (%d%d%d%d)', 'новембар %1');						-- replace for month 11
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
			param_val, n = mw.ustring.gsub (param_val, '^12%. (%d%d%d%d)', 'децембар %1');						-- replace for month 12
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
		end
		if mw.ustring.match (param_val, '%d%d?%.%d%d?%. %d%d%d%d') then					-- for those that are number-day, number-month without space before and year
			param_val, n = mw.ustring.gsub (param_val, '(%d%d?%.)(%d%d?%. %d%d%d%d)', '%1 %2');						-- replace
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
		end
		if mw.ustring.match (param_val, '%d%d?%. %d%d?%.%d%d%d%d') then					-- for those that are number-day, number-month and year without space before
			param_val, n = mw.ustring.gsub (param_val, '(%d%d?%. %d%d?%.)(%d%d%d%d)', '%1 %2');						-- replace
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
		end
		if mw.ustring.match (param_val, '%d%d?%.%d%d?%.%d%d%d%d') then					-- for those that are number-day, number-month without space before and year without space before
			param_val, n = mw.ustring.gsub (param_val, '(%d%d?%.)(%d%d?%.)(%d%d%d%d)', '%1 %2 %3');						-- replace
			if 0 ~= n then
				date_parameters_list[param_name] = param_val;					-- update the list
				result = true;
			end
		end
	end
	return result;																-- so we know if
end


--[[--------------------------< S E T _ S E L E C T E D _ M O D U L E S >--------------------------------------

Sets local imported functions table to same (live or sandbox) as that used by the other modules.

]]

local function set_selected_modules (utilities_page_ptr)
	is_set = utilities_page_ptr.is_set;											-- import functions from select Module:Citation/CS1/Utilities module
	in_array = utilities_page_ptr.in_array;											-- import functions from select Module:Citation/CS1/Utilities module
end



return {																		-- return exported functions
	dates = dates,
	year_date_check = year_date_check,
	reformat_dates = reformat_dates,
	date_hyphen_to_dash = date_hyphen_to_dash,
	date_ndash_to_dash = date_ndash_to_dash,
	remove_trailing_dot = remove_trailing_dot,
	translate_english_months = translate_english_months,
	set_selected_modules = set_selected_modules
	}