Module:ISOdate
--[[  
  
 This module is intended for processing of date strings.
 
 Please do not modify this code without applying the changes first at Module:ISOdate/sandbox and testing 
 at Module:ISOdate/sandbox/testcases and Module talk:ISOdate/sandbox/testcases.
 
 Authors and maintainers:
 * User:Parent5446 - original version of the function mimicking template:ISOdate
 * User:Jarekt - original version of the functions mimicking template:Date and template:ISOyear
 
 ]]
 
  
 local p = {}
 
 -- =======================================
 -- === Dependencies ======================
 -- =======================================
 local D = require('Module:DateI18n') -- the enwp version of c:Module:Date
 
 --[[
 ISOyear
  
 This function returns year part of date string.
  
 Usage:
 {{#invoke:ISOdate|ISOyear|target_string}}
  
 Parameters
     1: The date string 
  
 Error Handling:
    If the string does not look like it contain the year than the function will not return anything.
    That is the preferred treatment for the template:Creator which is the main (only?) template calling it.
 ]]
 function p.ISOyear( frame )
 	 return p._ISOyear( frame.args[1] )
 end
 
 function p._ISOyear( input )
 	if not input then
 		return ''
 	end
 	input = mw.text.trim( input )
     
 	-- if empty string then return it
 	if input == &quot;&quot; then
 		return input
 	end
     
 	-- if number then return it
 	if tonumber( input ) then
 		return mw.ustring.format( '%04i', input )
 	end
     
 	-- otherwise use regular expression match
 	input = mw.ustring.match( input, '^+?(-?%d%d?%d?%d?)-' )
 	if input and tonumber( input ) then
 		return mw.ustring.format( '%04i', input )
 	else
 		return ''
 	end
 end
 
 --[[
 ISOdate
  
 This function is the core part of the ISOdate template. 
  
 Usage:
 {{#invoke:ISOdate|ISOdate|target_string|lang=}}
  
 Parameters:
      1: The date string 
   lang: The language to display it in
   form: Language format (genitive, etc.) for some languages
  class: CSS class for the &lt;time&gt; node
 
  Error Handling:
    If the string does not look like it contain the proper ISO date than the function will return the original string.
    
    That is the preferred treatment for the template:Information (and similar templates) which calling it.
 ]]
 function p.ISOdate(frame)
 	local datestr, succeded
 	local args = frame.args
 	if not (args.lang and mw.language.isSupportedLanguage(args.lang)) then 
 		args.lang = frame:callParserFunction( &quot;int&quot;, &quot;lang&quot; ) -- get user's chosen language 
 	end
 	datestr, succeded = p._ISOdate(
 		mw.text.trim(args[1]),
 		args.lang,                  -- language
 		args.case  or '',           -- allows to specify grammatical case for the month for languages that use them
 		args.class or 'dtstart',    -- allows to set the html class of the time node where the date is included. 
 		args.trim_year or '100-999' -- by default pad one and 2 digit years to be 4 digit long, while keeping 3 digit years as is	
 	)
 	return datestr
 end
 
 function p._ISOdate(datestr, lang, case, class, trim_year)
 
 	-- pattern: regexp - regular expresion to test; dlen - number of date elements; tail = which element is a &quot;tail&quot; if any
 	-- regexp hints:
 	--  1) Strings starting with &quot;^&quot; and ending with &quot;$&quot; indicate whole string match
 	--  2) optional tail part copied as-is and following the main parsed part of the date have to be separated from the date by a whitespace, so &quot;(\s.+)?&quot;
 	local patterns = {
 		-- strings starting with YYYY-MM-DD HH:MM:SS. Year 4 digits (if we know seconds than it was within the last 100 years), the rest 1-2
 		-- date and time can be separated by space or &quot;T&quot; and there could be a &quot;Z&quot; on the end indicating &quot;Zulu&quot; time zone
 		{dlen=6, tail=7, regexp=&quot;^+?(%d%d%d%d)-(%d%d?)-(%d%d?)[ T](%d%d?):(%d%d?):(%d%d?)Z?(%s.*)&quot;}, 
 		{dlen=6, tail=0, regexp=&quot;^+?(%d%d%d%d)-(%d%d?)-(%d%d?)[ T](%d%d?):(%d%d?):(%d%d?)Z?$&quot;}, 
 		-- strings starting with YYYY-MM-DD HH:MM. Year 4 digits, the rest 1-2
 		-- (if one knows hour and minute than it was probably after a year 1000)
 		{dlen=5, tail=6, regexp=&quot;^+?(%d%d%d%d)-(%d%d?)-(%d%d?)[ T](%d%d?):(%d%d?)(%s.+)&quot;},
 		{dlen=5, tail=0, regexp=&quot;^+?(%d%d%d%d)-(%d%d?)-(%d%d?)[ T](%d%d?):(%d%d?)$&quot;},
 		-- strings starting with YYYY-MM-DD. Year 1-4 digits, the rest 1-2
 		{dlen=3, tail=4, regexp=&quot;^+?(%d%d?%d?%d?)-(%d%d?)-(%d%d?)(%s.+)&quot;},
 		{dlen=3, tail=0, regexp=&quot;^+?(%d%d?%d?%d?)-(%d%d?)-(%d%d?)$&quot;},
 		-- strings starting with YYYY-MM. Year 3-4 digits, month 2 digits
 		-- (want to avoit converting to dates strings like 10-5 = 5
 		{dlen=2, tail=3, regexp=&quot;^+?(%d%d%d%d?)-(%d%d)(%s.+)&quot;}, 
 		-- if whole string is in YYYY-MM form: If Year 1-4 digits, month 1-2 digits
 		{dlen=2, tail=0, regexp=&quot;^+?(%d%d?%d?%d?)-(%d%d?)$&quot;}, 
 		-- string starts with a number -&gt; it has to be 3 or 4 digit long to be a year
 		{dlen=1, tail=2, regexp=&quot;^+?(%d%d%d%d?)(%s.+)&quot;},	
 		 -- if whole string is a number (1-4 digit long) than it will be interpreted as a year
 		{dlen=1, tail=0, regexp=&quot;^+?(%d%d?%d?%d?)$&quot;},
 	}
 	
 	-- create datevec based on which variables are provided
 	local datevec, tail, formatNum
 	datevec, tail, formatNum = p.test_date_formats(datestr or '', patterns)
 	if datevec[1]=='' or datevec[1]==nil then
 		-- quickly return if datestr does not look like date (it could be a template)
 		return datestr, false
 	end
 
 	-- call p._Date function to format date string
 	local succeded, datestr2
 	succeded, datestr2 = pcall( D._Date, datevec, lang, case, class, trim_year)
 	if succeded and datestr2~='' then
 		return mw.text.trim( datestr2 .. tail), true
 	else -- in case of errors return the original string
 		return datestr, false
 	end	
 end
 
 function p.ISOdate_extended(frame)
 	-- pattern: regexp - regular expresion to test; dlen - number of date elements; tail = which element is a &quot;tail&quot; if any
 	-- regexp hints:
 	--  1) Strings starting with &quot;^&quot; and ending with &quot;$&quot; indicate whole string match
 	--  2) optional tail part copied as-is and following the main parsed part of the date have to be separated from the date by a whitespace, so &quot;(\s.+)?&quot;
 
 	local datestr, succeded
 	local args = frame.args
 	if not (args.lang and mw.language.isSupportedLanguage(args.lang)) then 
 		args.lang = frame:callParserFunction( &quot;int&quot;, &quot;lang&quot; ) -- get user's chosen language 
 	end
 	datestr, succeded = p._ISOdate(
 		mw.text.trim(args[1]),
 		args.lang,                  -- language
 		args.case  or '',           -- allows to specify grammatical case for the month for languages that use them
 		args.class or 'dtstart',    -- allows to set the html class of the time node where the date is included. 
 		args.trim_year or '100-999' -- by default pad one and 2 digit years to be 4 digit long, while keeping 3 digit years as is	
 	)
 	if succeded then
 		return datestr
 	end
 
 	local patterns = {
 		-- Exended set of recognized formats: like MM/DD/YYYY
 		{dlen=3, tail=4, regexp=&quot;^(%d%d?)[-./](%d%d?)[-./](%d%d%d%d)(%s.+)&quot;},
 		{dlen=3, tail=0, regexp=&quot;^(%d%d?)[-./](%d%d?)[-./](%d%d%d%d)$&quot;},
 		{dlen=3, tail=0, regexp=&quot;^(%d%d?)%s(%w+)%s(%d%d%d%d)$&quot;},
 		{dlen=3, tail=0, regexp=&quot;^(%w+)%s(%d%d?),%s(%d%d%d%d)$&quot;},
 	}
 	
 	local datevec, tail, formatNum, category = ''
 	datevec, tail, formatNum = p.test_date_formats(frame.args[1], patterns)
 	if formatNum==1 or formatNum==2 then
 		vec = datevec;
 		if tonumber(datevec[1])&gt;12 then
 			frame.args[1] = string.format('%04i-%02i-%02i', datevec[3], datevec[2], datevec[1] )
 			category = '[[Category:Date in DD/MM/YYYY format]]'
 			return mw.text.trim( p.ISOdate(frame) .. tail);
 		elseif tonumber(datevec[2])&gt;12 then
 			frame.args[1] = string.format('%04i-%02i-%02i', datevec[3], datevec[1], datevec[2] )
 			category = '[[Category:Date in MM/DD/YYYY format]]'
 			return mw.text.trim( p.ISOdate(frame) .. tail);
 		end
 	elseif (formatNum==3 or formatNum==4) and (datevec[3]=='' or datevec[3]~=nil) then
 		local str = mw.getCurrentFrame():callParserFunction( &quot;#time&quot;, { 'Y-m-d', datestr} )
 		local vec = {str:match( &quot;^(%d%d?%d?%d?)-(%d%d?)-(%d%d?)$&quot; )}
 		if vec and vec[1]~=nil then
 			frame.args[1] = string.format('%04i-%02i-%02i', vec[1], vec[2], vec[3] )
 			category = '[[Category:Date in word format]]'
 			return p.ISOdate(frame);
 		end
 	end	
 	return datestr
 end
 
 function p.test_date_formats(datestr, patterns)
 	-- pattern: regexp - regular expresion to test; dlen - number of date elements; tail = which element is a &quot;tail&quot; if any
 
 	local datevec = {'','','','','',''}
 	local tail = ''
 	local vec, pat
 	local formatNum = 0
 	for i, pat in ipairs( patterns ) do
 		vec = {datestr:match( pat.regexp )}
 		if vec and vec[1]~=nil then
 			for j=1,pat.dlen do
 				datevec[j] = vec[j]
 			end
 			if pat.tail&gt;0 and vec[pat.tail]~=nil then
 				tail = mw.ustring.gsub(' ' .. vec[pat.tail], ' +', ' ')
 			end
 			formatNum = i
 			break
 		end
 	end
 	return datevec, tail, formatNum
 end