---  
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:  
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
return p._ISOyear( .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 == "" 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:  
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 <time> 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
local datestr, succeded
local args = .args
if not (args.lang and mw.language.isSupportedLanguage(args.lang)) then
args.lang = :callParserFunction( "int", "lang" ) -- 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 "tail" if any
-- regexp hints:
-- 1) Strings starting with "^" and ending with "$" indicate whole string match
-- 2) optional tail part copied as-is and following the main parsed part of the date have to be separated from the date by a whitespace, so "(\s.+)?"
local patterns = {
-- strings starting with YYYY-MM-DD HH:MM:SS. Year 4 digits (if we know seconds than it was within the last 100 years), the rest 1-2
-- date and time can be separated by space or "T" and there could be a "Z" on the end indicating "Zulu" time zone
{dlen=6, tail=7, regexp="^+?(%d%d%d%d)-(%d%d?)-(%d%d?)[ T](%d%d?):(%d%d?):(%d%d?)Z?(%s.*)"},
{dlen=6, tail=0, regexp="^+?(%d%d%d%d)-(%d%d?)-(%d%d?)[ T](%d%d?):(%d%d?):(%d%d?)Z?$"},
-- 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="^+?(%d%d%d%d)-(%d%d?)-(%d%d?)[ T](%d%d?):(%d%d?)(%s.+)"},
{dlen=5, tail=0, regexp="^+?(%d%d%d%d)-(%d%d?)-(%d%d?)[ T](%d%d?):(%d%d?)$"},
-- strings starting with YYYY-MM-DD. Year 1-4 digits, the rest 1-2
{dlen=3, tail=4, regexp="^+?(%d%d?%d?%d?)-(%d%d?)-(%d%d?)(%s.+)"},
{dlen=3, tail=0, regexp="^+?(%d%d?%d?%d?)-(%d%d?)-(%d%d?)$"},
-- 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="^+?(%d%d%d%d?)-(%d%d)(%s.+)"},
-- if whole string is in YYYY-MM form: If Year 1-4 digits, month 1-2 digits
{dlen=2, tail=0, regexp="^+?(%d%d?%d?%d?)-(%d%d?)$"},
-- string starts with a number -> it has to be 3 or 4 digit long to be a year
{dlen=1, tail=2, regexp="^+?(%d%d%d%d?)(%s.+)"},
-- if whole string is a number (1-4 digit long) than it will be interpreted as a year
{dlen=1, tail=0, regexp="^+?(%d%d?%d?%d?)$"},
}  
-- 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
-- pattern: regexp - regular expresion to test; dlen - number of date elements; tail = which element is a "tail" if any
-- regexp hints:
-- 1) Strings starting with "^" and ending with "$" indicate whole string match
-- 2) optional tail part copied as-is and following the main parsed part of the date have to be separated from the date by a whitespace, so "(\s.+)?"  
local datestr, succeded
local args = .args
if not (args.lang and mw.language.isSupportedLanguage(args.lang)) then
args.lang = :callParserFunction( "int", "lang" ) -- get user's chosen language
end
datestr, succeded = p._ISOdate(
mw.text.trim(args[1]),
args.lang, -- language
args.case or '', -- allows to specify grammatical case for the month for languages that use them
args.class or 'dtstart', -- allows to set the html class of the time node where the date is included.
args.trim_year or '100-999' -- by default pad one and 2 digit years to be 4 digit long, while keeping 3 digit years as is
if succeded then
return datestr
end  
local patterns = {
-- Exended set of recognized formats: like MM/DD/YYYY
{dlen=3, tail=4, regexp="^(%d%d?)[-./](%d%d?)[-./](%d%d%d%d)(%s.+)"},
{dlen=3, tail=0, regexp="^(%d%d?)[-./](%d%d?)[-./](%d%d%d%d)$"},
{dlen=3, tail=0, regexp="^(%d%d?)%s(%w+)%s(%d%d%d%d)$"},
{dlen=3, tail=0, regexp="^(%w+)%s(%d%d?),%s(%d%d%d%d)$"},
}  
local datevec, tail, formatNum, category = ''
datevec, tail, formatNum = p.test_date_formats(.args[1], patterns)
if formatNum==1 or formatNum==2 then
vec = datevec;
if tonumber(datevec[1])>12 then
.args[1] = string.format('%04i-%02i-%02i', datevec[3], datevec[2], datevec[1] )
category = ''
return mw.text.trim( p.ISOdate .. tail);
elseif tonumber(datevec[2])>12 then
.args[1] = string.format('%04i-%02i-%02i', datevec[3], datevec[1], datevec[2] )
category = ''
return mw.text.trim( p.ISOdate .. tail);
end
elseif (formatNum==3 or formatNum==4) and (datevec[3]=='' or datevec[3]~=nil) then
local str = mw.getCurrentFrame:callParserFunction( "#time", { 'Y-m-d', datestr} )
local vec = {str:match( "^(%d%d?%d?%d?)-(%d%d?)-(%d%d?)$" )}
if vec and vec[1]~=nil then
.args[1] = string.format('%04i-%02i-%02i', vec[1], vec[2], vec[3] )
category = ''
return p.ISOdate;
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 "tail" 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>0 and vec[pat.tail]~=nil then
tail = mw.ustring.gsub(' ' .. vec[pat.tail], ' +', ' ')
end
formatNum = i
break
end
end