Mô đun:Citation/CS1/Date validation/sandbox

------------------------------------------------------------------

local add_prop_cat, is_set, in_array, set_message, substitute, wrap_style; -- imported functions from selected Module:Citation/CS1/Utilities
local cfg; -- table of tables imported from selected Module:Citation/CS1/Configuration

------------------------------------------------------------

File-scope variables are declared here

local lang_object = mw.getContentLanguage(); -- used by is_valid_accessdate(), is_valid_year(), date_name_xlate(); TODO: move to ~/Configuration?
local year_limit; -- used by is_valid_year()

--[=[-----------------------------------------------------------------

returns true if:
Wikipedia start date ----------------------------------------------

returns a number according to the month in a date: 1 for January, etc. Capitalization and spelling must be correct.
If not a valid month, returns 0

]]

local function get_month_number (month)
return cfg.date_names['local'].long[month] or cfg.date_names['local'].short[month] or -- look for local names first
cfg.date_names['en'].long[month] or cfg.date_names['en'].short[month] or -- failing that, look for English names
0; -- not a recognized month name
end

--date=

Season numbering is defined by Extended Date/Time Format (EDTF) specification (https://www.loc.gov/standards/datetime/)
which became part of ISO 8601 in 2019. See '§Sub-year groupings'. The standard defines various divisions using
numbers 21-41. cs1|2 only supports generic seasons. EDTF does support the distinction between north and south
hemisphere seasons but cs1|2 has no way to make that distinction.

These additional divisions not currently supported:
25-28 = Spring - Northern Hemisphere, Summer- Northern Hemisphere, Autumn - Northern Hemisphere, Winter - Northern Hemisphere
29-32 = Spring – Southern Hemisphere, Summer– Southern Hemisphere, Autumn – Southern Hemisphere, Winter - Southern Hemisphere
33-36 = Quarter 1, Quarter 2, Quarter 3, Quarter 4 (3 months each)
37-39 = Quadrimester 1, Quadrimester 2, Quadrimester 3 (4 months each)
40-41 = Semestral 1, Semestral-2 (6 months each)

local function get_season_number (season, param)
if 'date' ~= param then
return 0; -- season dates only supported by |date=
end
return cfg.date_names['local'].season[season] or -- look for local names first
cfg.date_names['en'].season[season] or -- failing that, look for English names
0; -- not a recognized season name
end

--date=

Quarter numbering is defined by Extended Date/Time Format (EDTF) specification (https://www.loc.gov/standards/datetime/)
which became part of ISO 8601 in 2019. See '§Sub-year groupings'. The standard defines various divisions using
numbers 21-41. cs1|2 only supports generic seasons and quarters.

These additional divisions not currently supported:
37-39 = Quadrimester 1, Quadrimester 2, Quadrimester 3 (4 months each)
40-41 = Semestral 1, Semestral-2 (6 months each)

local function get_quarter_number (quarter, param)
if 'date' ~= param then
return 0; -- quarter dates only supported by |date=
end
quarter = mw.ustring.gsub (quarter, ' +', ' '); -- special case replace multiple space chars with a single space char
return cfg.date_names['local'].quarter[quarter] or -- look for local names first
cfg.date_names['en'].quarter[quarter] or -- failing that, look for English names
0; -- not a recognized quarter name
end

--date=

local function get_proper_name_number (name, param)
if 'date' ~= param then
return 0; -- proper-name dates only supported by |date=
end
return cfg.date_names['local'].named[name] or -- look for local names dates first
cfg.date_names['en'].named[name] or -- failing that, look for English names
0; -- not a recognized named date
end

--pmc-embargo-date=: years more than two years in the future are not acceptable

local function is_valid_year (year, param)
if not is_set (year_limit) then
year_limit = tonumber(os.date("%Y"))+1; -- global variable so we only have to fetch it once
end

year = tonumber (year) or lang_object:parseFormattedNumber (year); -- convert to number for the comparison
if year and (100 > year) then -- years less than 100 not supported
return false;
end

if 'pmc-embargo-date' == param then -- special case for |pmc-embargo-date=
return year and (year ----------------------------------------------------

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, param)
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, param) then -- no farther into the future than next year except |pmc-embargo-date= no more than two years in the future
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 -- is a leap year?
month_length = 29; -- if leap year then 29 days in February
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

------------------------------------------------------

Months in a range are expected to have the same style: Jan–Mar or October–December but not February–Mar or Jul–August.
This function looks in cfg.date_names{} to see if both month names are listed in the long subtable or both are
listed in the short subtable. When both have the same style (both are listed in the same table), returns true; false else

local function is_valid_month_range_style (month1, month2)
local len1 = month1:len();
local len2 = month2:len();
local viet1 = mw.ustring.match(month1, "[Tt]háng (.)")
local viet2 = mw.ustring.match(month2, "[Tt]háng (.)")
if tonumber(viet1) and tonumber(viet2) then
return true;
elseif viet1 and viet2 and not tonumber(viet1) and not tonumber(viet2) then
return true;
elseif viet1 or viet2 then
return false;
elseif len1 len2 then
return true; -- both months are short form so return true
elseif 'May' month1 or 'May' month2 then -- ToDo: I18N
return true; -- both months are long form so return true
elseif 3 len1 or 3 == len2 then
return false; -- months are mixed form so return false
else
return true; -- both months are long form so return true
end
end

----------------------------------------------------

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

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

All season ranges are accepted as valid because there are publishers out there who have published a Summer–Spring YYYY issue, hence treat as ok

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

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

if (0 ~= range_start_number) and (0 ~= range_end_number) and (range_start_number ~= range_end_number) then
return true; -- any season pairing is accepted except when both are the same
end
return false; -- range_start and/or range_end is not a season
end
-- here when range_start is a month
range_end_number = get_month_number (range_end); -- get end month number
if range_start_number ------------------------------------------------

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= 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; 99 Christmas
day, day2 – 0 if not provided, 1-31 for days

the output table receives:
rftdate: an ISO 8601 formatted date
rftchron: a free-form version of the date, usually without year which is in rftdate (season ranges and proper-name dates)
rftssn: one of four season keywords: winter, spring, summer, fall (lowercase)
rftquarter: one of four values: 1, 2, 3, 4

]]

local function make_COinS_date (input, tCOinS_date)
local date; -- one date or first date in a range
local date2 = ; -- end of range date
input.year = tonumber (input.year) or lang_object:parseFormattedNumber (input.year); -- language-aware tonumber()
input.year2 = tonumber (input.year2) or lang_object:parseFormattedNumber (input.year2); -- COinS dates are pseudo-ISO 8601 so convert to Arabic numerals

if ((1582 == input.year) and (10 > tonumber(input.month))) or (1582 > input.year) then -- if a Julian calendar date
tCOinS_date.rftdate = tostring (input.year); -- &rft.date gets year only
return; -- done
end
-- here for all forms of Gregorian dates
if 20 ----------------------------------------------------------

this is the list of patterns for date formats that this module recognizes. Approximately the first half of these
patterns represent formats that might be reformatted into another format. Those that might be reformatted have
'indicator' letters that identify the content of the matching capture: 'd' (day), 'm' (month), 'a' (anchor year),
'y' (year); second day, month, year have a '2' suffix.

These patterns are used for both date validation and for reformatting. This table should not be moved to ~/Configuration
because changes to this table require changes to check_date() and to reformatter() and reformat_date()

]]

local patterns_t = {
-- year-initial numerical year-month-day
['ymd'] = {'^(%d%d%d%d)%-(%d%d)%-(%d%d)$', 'y', 'm', 'd'},
-- month-initial: month day, year
['Mdy'] = {'^(%D-) +([1-9]%d?), +((%d%d%d%d?)%a?)$', 'm', 'd', 'a', 'y'},
-- month-initial day range: month day–day, year; days are separated by endash
['Md-dy'] = {'^(%D-) +([1-9]%d?)[%-–]([1-9]%d?), +((%d%d%d%d)%a?)$', 'm', 'd', 'd2', 'a', 'y'},
-- day-initial: day month year
['dMy'] = {'^([1-9]%d?) +(%D-) +((%d%d%d%d?)%a?)$', 'd', 'm', 'a', 'y'},
['dMy_v1'] = {'^([1-9]%d?) +(%a+ +[%a%d]+) +năm +((%d%d%d%d?)%a?)$', 'd', 'm', 'a', 'y'},
['dMy_v2'] = {'^([1-9]%d?) +(%a+ +[%a%d]+), +((%d%d%d%d?)%a?)$', 'd', 'm', 'a', 'y'},
-- year-initial: year month day; day: 1 or 2 two digits, leading zero allowed; not supported at en.wiki
-- ['yMd'] = {'^((%d%d%d%d?)%a?) +(%D-) +(%d%d?)$', 'a', 'y', 'm', 'd'},
-- day-range-initial: day–day month year; days are separated by endash
['d-dMy'] = {'^([1-9]%d?)[%-–]([1-9]%d?) +(%D-) +((%d%d%d%d)%a?)$', 'd', 'd2', 'm', 'a', 'y'},
['d-dMy_v1'] = {'^([1-9]%d?)[%-–]([1-9]%d?) +(%a+ +[%a%d]+) +năm +((%d%d%d%d)%a?)$', 'd', 'd2', 'm', 'a', 'y'},
['d-dMy_v2'] = {'^([1-9]%d?)[%-–]([1-9]%d?) +(%a+ +[%a%d]+), +((%d%d%d%d)%a?)$', 'd', 'd2', 'm', 'a', 'y'},
-- day initial month-day-range: day month - day month year; uses spaced endash
['dM-dMy'] = {'^([1-9]%d?) +(%D-) +[%-–] +([1-9]%d?) +(%D-) +((%d%d%d%d)%a?)$', 'd', 'm', 'd2', 'm2', 'a', 'y'},
['dM-dMy_v1'] = {'^([1-9]%d?) +(%a+ +[1-9]%d?) +[%-–] +([1-9]%d?) +(%a+ +[%a%d]+) +năm +((%d%d%d%d)%a?)$', 'd', 'm', 'd2', 'm2', 'a', 'y'},
['dM-dMy_v2'] = {'^([1-9]%d?) +(%a+ +[1-9]%d?) +[%-–] +([1-9]%d?) +(%a+ +[%a%d]+), +((%d%d%d%d)%a?)$', 'd', 'm', 'd2', 'm2', 'a', 'y'},
-- month initial month-day-range: month day – month day, year; uses spaced endash
['Md-Mdy'] = {'^(%D-) +([1-9]%d?) +[%-–] +(%D-) +([1-9]%d?), +((%d%d%d%d)%a?)$','m', 'd', 'm2', 'd2', 'a', 'y'},
-- day initial month-day-year-range: day month year - day month year; uses spaced endash
['dMy-dMy'] = {'^([1-9]%d?) +(%D-) +(%d%d%d%d) +[%-–] +([1-9]%d?) +(%D-) +((%d%d%d%d)%a?)$', 'd', 'm', 'y', 'd2', 'm2', 'a', 'y2'},
['dMy-dMy_v1'] = {'^([1-9]%d?) +(%a+ +[%a%d]+) +năm +(%d%d%d%d) +[%-–] +([1-9]%d?) +(%a+ +[%a%d]+) +năm +((%d%d%d%d)%a?)$', 'd', 'm', 'y', 'd2', 'm2', 'a', 'y2'},
['dMy-dMy_v2'] = {'^([1-9]%d?) +(%a+ +[%a%d]+), +(%d%d%d%d) +[%-–] +([1-9]%d?) +(%a+ +[%a%d]+), +((%d%d%d%d)%a?)$', 'd', 'm', 'y', 'd2', 'm2', 'a', 'y2'},
-- month initial month-day-year-range: month day, year – month day, year; uses spaced endash
['Mdy-Mdy'] = {'^(%D-) +([1-9]%d?), +(%d%d%d%d) +[%-–] +(%D-) +([1-9]%d?), +((%d%d%d%d)%a?)$', 'm', 'd', 'y', 'm2', 'd2', 'a', 'y2'},

-- these date formats cannot be converted, per se, but month name can be rendered short or long
-- month/season year - month/season year; separated by spaced endash
['My-My'] = {'^(%D-) +(%d%d%d%d) +[%-–] +(%D-) +((%d%d%d%d)%a?)$', 'm', 'y', 'm2', 'a', 'y2'},
['My-My_v1'] = {'^(%a+ +[%a%d]+) +năm +(%d%d%d%d) +[%-–] +(%a+ +[%a%d]+) +năm +((%d%d%d%d)%a?)$', 'm', 'y', 'm2', 'a', 'y2'},
-- month/season range year; months separated by endash
['M-My'] = {'^(%D-)[%-–](%D-) +((%d%d%d%d)%a?)$', 'm', 'm2', 'a', 'y'},
['M-My_v1'] = {'^([Tt]háng +[%a%d]+)[%-–]([%a%d]+) +năm +((%d%d%d%d)%a?)$', 'm', 'm2', 'a', 'y'},
['M-My_v2'] = {'^([Tt]háng +[%a%d]+)[%-–]([%a%d]+), +((%d%d%d%d)%a?)$', 'm', 'm2', 'a', 'y'},
-- month/season year or proper-name year; quarter year when First Quarter YYYY etc.
['My'] = {'^([^%d–]-) +((%d%d%d%d)%a?)$', 'm', 'a', 'y'}, -- this way because endash is a member of %D; %D- will match January–March 2019 when it shouldn't
['My_v1'] = {'^(%a+ +[%a%d]+) +năm +((%d%d%d%d)%a?)$', 'm', 'a', 'y'},
-- these date formats cannot be converted
['Sy4-y2'] = {'^(%D-) +((%d%d)%d%d)[%-–]((%d%d)%a?)$'}, -- special case Winter/Summer year-year (YYYY-YY); year separated with unspaced endash
['Sy4-y2_v1'] = {'^(%a+ +%a+) +năm +((%d%d)%d%d)[%-–]((%d%d)%a?)$'},
['Sy-y'] = {'^(%D-) +(%d%d%d%d)[%-–]((%d%d%d%d)%a?)$'}, -- special case Winter/Summer year-year; year separated with unspaced endash
['Sy-y_v1'] = {'^(%a+ +%a+) +năm +(%d%d%d%d)[%-–]((%d%d%d%d)%a?)$'},
['y-y'] = {'^(%d%d%d%d?)[%-–]((%d%d%d%d?)%a?)$'}, -- year range: YYY-YYY or YYY-YYYY or YYYY–YYYY; separated by unspaced endash; 100-9999
['y4-y2'] = {'^((%d%d)%d%d)[%-–]((%d%d)%a?)$'}, -- year range: YYYY–YY; separated by unspaced endash
['ymx'] = {'^(%d%d%d%d)%-(%d%d)%-XX$', 'y', 'm'}, -- edtf year-initial numerical year-month-XX
['y'] = {'^((%d%d%d%d?)%a?)$'}, -- year; here accept either YYY or YYYY
}

--pmc-embargo-date= is
set, the editor intended to embargo a PMC but |pmc-embargo-date= does not hold a single date.

local function is_valid_embargo_date (v)
if v:match (patterns_t['ymd'][1]) or -- ymd
v:match (patterns_t['Mdy'][1]) or -- dmy
v:match (patterns_t['dMy'][1]) 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

--------------------------------------------------------------------------------------

Check date format to see that it is one of the formats approved by WP:DATESNO or WP:DATERANGE. Exception: only
allowed range separator is endash. Additionally, check 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 three character 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 (DEBUG: not?) 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, publication-date, access-date, pmc-embargo-date, archive-date, lay-date)

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()

local function check_date (date_string, param, tCOinS_date)
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;
local iso_date;

date_string = mw.ustring.gsub(date_string, "Tháng", "tháng", 1)
date_string = mw.ustring.gsub(date_string, "^[Nn]gày ", "", 1)

if date_string:match (patterns_t['ymd'][1]) then -- year-initial numerical year month day format
year, month, day = date_string:match (patterns_t['ymd'][1]);
if 12 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 date_string:match (patterns_t['ymx'][1]) then -- year-initial numerical year month edtf format
year, month = date_string:match (patterns_t['ymx'][1]);
if 12 tonumber(month) or 1582 > tonumber(year) or not is_valid_year(year) then return false; end -- month number not valid or not Gregorian calendar or future year
anchor_year = year;

elseif mw.ustring.match(date_string, patterns_t['Mdy'][1]) then -- month-initial: month day, year
month, day, anchor_year, year = mw.ustring.match(date_string, patterns_t['Mdy'][1]);
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, patterns_t['Md-dy'][1]) then -- month-initial day range: month day–day, year; days are separated by endash
month, day, day2, anchor_year, year = mw.ustring.match(date_string, patterns_t['Md-dy'][1]);
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
year2 = year;

elseif (mw.ustring.match(date_string, patterns_t['dMy'][1]) or
mw.ustring.match(date_string, patterns_t['dMy_v1'][1]) or
mw.ustring.match(date_string, patterns_t['dMy_v2'][1])) then -- day-initial: day month year
day, month, anchor_year, year = mw.ustring.match(date_string, patterns_t['dMy'][1]);
if day == nil then day, month, anchor_year, year = mw.ustring.match(date_string, patterns_t['dMy_v1'][1]) end
if day == nil then day, month, anchor_year, year = mw.ustring.match(date_string, patterns_t['dMy_v2'][1]) end
month = get_month_number (month);
if 0 == month then return false; end -- return false if month text isn't one of the twelve months

--[[ NOT supported at en.wiki
elseif mw.ustring.match(date_string, patterns_t['yMd'][1]) then -- year-initial: year month day; day: 1 or 2 two digits, leading zero allowed
anchor_year, year, month, day = mw.ustring.match(date_string, patterns_t['yMd'][1]);
month = get_month_number (month);
if 0 == month then return false; end -- return false if month text isn't one of the twelve months
-- end NOT supported at en.wiki ]]

elseif (mw.ustring.match(date_string, patterns_t['d-dMy'][1]) or
mw.ustring.match(date_string, patterns_t['d-dMy_v1'][1]) or
mw.ustring.match(date_string, patterns_t['d-dMy_v2'][1])) then -- day-range-initial: day–day month year; days are separated by endash
day, day2, month, anchor_year, year = mw.ustring.match(date_string, patterns_t['d-dMy'][1]);
if day == nil then day, day2, month, anchor_year, year = mw.ustring.match(date_string, patterns_t['d-dMy_v1'][1]) end
if day == nil then day, day2, month, anchor_year, year = mw.ustring.match(date_string, patterns_t['d-dMy_v2'][1]) end
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
year2 = year;

elseif (mw.ustring.match(date_string, patterns_t['dM-dMy'][1]) or
mw.ustring.match(date_string, patterns_t['dM-dMy_v1'][1]) or
mw.ustring.match(date_string, patterns_t['dM-dMy_v2'][1])) then -- day initial month-day-range: day month - day month year; uses spaced endash
day, month, day2, month2, anchor_year, year = mw.ustring.match(date_string, patterns_t['dM-dMy'][1]);
if day == nil then day, month, day2, month2, anchor_year, year = mw.ustring.match(date_string, patterns_t['dM-dMy_v1'][1]) end
if day == nil then day, month, day2, month2, anchor_year, year = mw.ustring.match(date_string, patterns_t['dM-dMy_v2'][1]) end
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, patterns_t['Md-Mdy'][1]) then -- month initial month-day-range: month day – month day, year; uses spaced endash
month, day, month2, day2, anchor_year, year = mw.ustring.match(date_string, patterns_t['Md-Mdy'][1]);
if (not is_valid_month_season_range(month, month2, param)) or not is_valid_year(year) then return false; end
month = get_month_number (month); -- for metadata
month2 = get_month_number (month2);
year2 = year;

elseif (mw.ustring.match(date_string, patterns_t['dMy-dMy'][1]) or
mw.ustring.match(date_string, patterns_t['dMy-dMy_v1'][1]) or
mw.ustring.match(date_string, patterns_t['dMy-dMy_v2'][1])) then -- day initial month-day-year-range: day month year - day month year; uses spaced endash
day, month, year, day2, month2, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['dMy-dMy'][1]);
if day == nil then day, month, year, day2, month2, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['dMy-dMy_v1'][1]) end
if day == nil then day, month, year, day2, month2, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['dMy-dMy_v2'][1]) end
if tonumber(year2) = 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, param) and 0 ~= get_season_number(month2, param) then -- both must be season year, not mixed
month = get_season_number(month, param);
month2 = get_season_number(month2, param);
else
return false;
end

elseif (mw.ustring.match(date_string, patterns_t['M-My'][1]) or
mw.ustring.match(date_string, patterns_t['M-My_v1'][1]) or
mw.ustring.match(date_string, patterns_t['M-My_v2'][1])) then -- month/season range year; months separated by endash
month, month2, anchor_year, year = mw.ustring.match(date_string, patterns_t['M-My'][1]);
local monthNumber2
if month == nil then month, monthNumber2, anchor_year, year = mw.ustring.match(date_string, patterns_t['M-My_v1'][1]) end
if month == nil then month, monthNumber2, anchor_year, year = mw.ustring.match(date_string, patterns_t['M-My_v2'][1]) end
if monthNumber2 ~= nil then month2 = 'tháng ' .. monthNumber2 end -- the second “tháng” is implicit
if (not is_valid_month_season_range(month, month2, param)) 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);
if 0 month or 0 month2 then return false; end
else
month = get_season_number(month, param);
month2 = get_season_number(month2, param);
end
year2 = year;

elseif (mw.ustring.match(date_string, patterns_t['My'][1]) or
mw.ustring.match(date_string, patterns_t['My_v1'][1])) then -- month/season/quarter/proper-name year
month, anchor_year, year = mw.ustring.match(date_string, patterns_t['My'][1]);
if month == nil then month, anchor_year, year = mw.ustring.match(date_string, patterns_t['My_v1'][1]) end
if not is_valid_year(year) then return false; end
month = get_element_number(month, param); -- get month season quarter proper-name number or nil
if not month then return false; end -- not valid whatever it is

elseif mw.ustring.match(date_string, patterns_t['y-y'][1]) then -- Year range: YYY-YYY or YYY-YYYY or YYYY–YYYY; separated by unspaced endash; 100-9999
year, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['y-y'][1]);
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, patterns_t['y4-y2'][1]) then -- Year range: YYYY–YY; separated by unspaced endash
local century;
year, century, anchor_year, year2 = mw.ustring.match(date_string, patterns_t['y4-y2'][1]);
anchor_year = year .. '–' .. anchor_year; -- assemble anchor year from both years

if in_array (param, {'date', 'publication-date', 'year'}) then
add_prop_cat ('year_range_abbreviated');
end

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) 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, patterns_t['y'][1]) then -- year; here accept either YYY or YYYY
anchor_year, year = mw.ustring.match(date_string, patterns_t['y'][1]);
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 'access-date' param 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

--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 metadata) are derived. The |date= parameter is the only date-holding parameter that is allowed to contain the no-date keywords "n.d." or "nd" (without quotes).

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,
parameters with errors are added to the sequence table as the dates are tested.

local function dates(date_parameters_list, tCOinS_date, error_list)
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 good_date = false;

for k, v in pairs(date_parameters_list) do -- for each date-holding parameter in the list
if is_set(v.val) then -- if the parameter has a value
v.val = mw.ustring.gsub(v.val, '%d', cfg.date_names.local_digits); -- translate 'local' digits to Western 0-9
if v.val:match("^[ck]%. [1-9]%d%d%d?%a?$") then -- special case for c. year or with or without CITEREF disambiguator - only |date= and |year=
local year = v.val:match("[ck]%. ([1-9]%d%d%d?)%a?"); -- get the year portion so it can be tested
if 'date' == k then
anchor_year, COinS_date = v.val:match("(([ck]%. [1-9]%d%d%d?)%a?)"); -- anchor year and COinS_date only from |date= parameter
good_date = is_valid_year(year);
elseif 'year' == k then
good_date = is_valid_year(year);
end
elseif 'date' == k then -- if the parameter is |date=
if v.val:match("^n%.d%.%a?$") then -- ToDo: I18N -- if |date=n.d. with or without a CITEREF disambiguator
good_date, anchor_year, COinS_date = true, v.val:match("((n%.d%.)%a?)"); -- ToDo: I18N -- "n.d."; no error when date parameter is set to no date
elseif v.val:match("^nd%a?$") then -- ToDo: I18N -- if |date=nd with or without a CITEREF disambiguator
good_date, anchor_year, COinS_date = true, v.val:match("((nd)%a?)"); -- ToDo: I18N -- "nd"; no error when date parameter is set to no date
else
good_date, anchor_year, COinS_date = check_date (v.val, k, tCOinS_date); -- go test the date
end
elseif 'year' == k then -- if the parameter is |year= it should hold only a year value
if v.val:match("^[1-9]%d%d%d?%a?$") then -- if |year = 3 or 4 digits only with or without a CITEREF disambiguator
good_date, anchor_year, COinS_date = true, v.val:match("((%d+)%a?)");
end
elseif 'pmc-embargo-date' == k then -- if the parameter is |pmc-embargo-date=
good_date = check_date (v.val, k); -- 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.val); -- is |pmc-embargo-date= date a single dmy, mdy, or ymd formatted date? yes: returns embargo date; no: returns 9999
end
else -- any other date-holding parameter
good_date = check_date (v.val, k); -- go test the date
end
if false == good_date then -- assemble one error message so we don't add the tracking category multiple times
table.insert (error_list, wrap_style ('parameter', v.name)); -- make parameter name suitable for error message list
end
end
end
return anchor_year, embargo_date; -- and done
end

--year= for acceptable values:
YYY, YYYY, year-only ranges, their circa forms, with or without CITEREF disambiguators.

When |year= holds some form of date that is not one of these year-only dates, emit a maintenance message.

This function necessary because many non-cs1|2 templates have a |year= parameter so cirrus searches are more-or-
less useless

local function year_check (year)
year = year:gsub ('[ck]%. ', ); -- remove circa annotation (if present) before testing

for _, index in ipairs ({'y-y', 'y4-y2', 'y'}) do -- spin through these indexes into patterns_t
if mw.ustring.match (year, patterns_t[index][1]) then
return; -- if a match then |year= holds a valid 'year'
end
end

set_message ('maint_year'); -- if here, |year= value is not an accepted value; add a maint cat
end

--year= with the year value(s) provided in |date=. This function sets a local 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)

the numeric value in determines the 'output' if any from this function:
0 – adds error message to error_list sequence table
1 – adds maint cat
2 – does nothing

local function year_date_check (year_string, year_origin, date_string, date_origin, error_list)
local year;
local date1;
local date2;
local result = 1; -- result of the test; assume that the test passes

year = year_string:match ('(%d%d%d%d?)');

if date_string:match ('%d%d%d%d%-%d%d%-%d%d') and year_string:match ('%d%d%d%d%a') then --special case where both date and year are required YYYY-MM-DD and YYYYx
date1 = date_string:match ('(%d%d%d%d)');
year = year_string:match ('(%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 date_string:match ("%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 = date_string:match ("(%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 date_string:match ("%d%d%d%d?") then -- any of the standard formats of date with one year
date1 = date_string:match ("(%d%d%d%d?)");
if year ~= date1 then
result = 0;
end
else -- should never get here; this function called only when no other date errors
result = 0; -- no recognizable year in date
end

if 0 result then -- year / date mismatch
table.insert (error_list, substitute (cfg.messages['mismatch'], {year_origin, date_origin})); -- add error message to error_list sequence table
elseif 1 result then -- redundant year / date
set_message ('maint_date_year'); -- add a maint cat
end
end

--[[----------------------------------------------------------------------------------

reformat 'date' into new format specified by format_param if pattern_idx (the current format of 'date') can be
reformatted. Does the grunt work for reformat_dates().

The table re_formats maps pattern_idx (current format) and format_param (desired format) to a table that holds:
format string used by string.format()
identifier letters ('d', 'm', 'y', 'd2', 'm2', 'y2') that serve as indexes into a table t{} that holds captures
from mw.ustring.match() for the various date parts specified by patterns_t[pattern_idx][1]

Items in patterns_t{} have the general form:
['ymd'] = {'^(%d%d%d%d)%-(%d%d)%-(%d%d)$', 'y', 'm', 'd'}, where:
['ymd'] is pattern_idx
patterns_t['ymd'][1] is the match pattern with captures for mw.ustring.match()
patterns_t['ymd'][2] is an indicator letter identifying the content of the first capture
patterns_t['ymd'][3] ... the second capture etc.

when a pattern matches a date, the captures are loaded into table t{} in capture order using the idemtifier
characters as indexes into t{} For the above, a ymd date is in t{} as:
t.y = first capture (year), t.m = second capture (month), t.d = third capture (day)

To reformat, this function is called with the pattern_idx that matches the current format of the date and with
format_param set to the desired format. This function loads table t{} as described and then calls string.format()
with the format string specified by re_format[pattern_idx][format_param][1] using values taken from t{} according
to the capture identifier letters specified by patterns_t[pattern_idx][format_param][n] where n is 2..

]]

local re_formats = {
['ymd'] = { -- date format is ymd; reformat to:
['mdy'] = {'%s %s, %s', 'm', 'd', 'y'}, -- |df=mdy
['dmy'] = {'%s %s %s', 'd', 'm', 'y'}, -- |df=dmy
-- ['yMd'] = {'%s %s %s', 'y', 'm', 'd'}, -- |df=yMd; not supported at en.wiki
},
['Mdy'] = { -- date format is Mdy; reformat to:
['mdy'] = {'%s %s, %s', 'm', 'd', 'y'}, -- for long/short reformatting
['dmy'] = {'%s %s %s', 'd', 'm', 'y'}, -- |df=dmy
['ymd'] = {'%s-%s-%s', 'y', 'm', 'd'}, -- |df=ymd
-- ['yMd'] = {'%s %s %s', 'y', 'm', 'd'}, -- |df=yMd; not supported at en.wiki
},
['dMy'] = { -- date format is dMy; reformat to:
['dmy'] = {'%s %s %s', 'd', 'm', 'y'}, -- for long/short reformatting
['mdy'] = {'%s %s, %s', 'm', 'd', 'y'}, -- |df=mdy
['ymd'] = {'%s-%s-%s', 'y', 'm', 'd'}, -- |df=ymd
-- ['yMd'] = {'%s %s %s', 'y', 'm', 'd'}, -- |df=yMd; not supported at en.wiki
},
['Md-dy'] = { -- date format is Md-dy; reformat to:
['mdy'] = {'%s %s–%s, %s', 'm', 'd', 'd2', 'y'}, -- for long/short reformatting
['dmy'] = {'%s–%s %s %s', 'd', 'd2', 'm', 'y'}, -- |df=dmy -> d-dMy
},
['d-dMy'] = { -- date format is d-d>y; reformat to:
['dmy'] = {'%s–%s %s %s', 'd', 'd2', 'm', 'y'}, -- for long/short reformatting
['mdy'] = {'%s %s–%s, %s', 'm', 'd', 'd2', 'y'}, -- |df=mdy -> Md-dy
},
['dM-dMy'] = { -- date format is dM-dMy; reformat to:
['dmy'] = {'%s %s – %s %s %s', 'd', 'm', 'd2', 'm2', 'y'}, -- for long/short reformatting
['mdy'] = {'%s %s – %s %s, %s', 'm', 'd', 'm2', 'd2', 'y'}, -- |df=mdy -> Md-Mdy
},
['Md-Mdy'] = { -- date format is Md-Mdy; reformat to:
['mdy'] = {'%s %s – %s %s, %s', 'm', 'd', 'm2', 'd2', 'y'}, -- for long/short reformatting
['dmy'] = {'%s %s – %s %s %s', 'd', 'm', 'd2', 'm2', 'y'}, -- |df=dmy -> dM-dMy
},
['dMy-dMy'] = { -- date format is dMy-dMy; reformat to:
['dmy'] = {'%s %s %s – %s %s %s', 'd', 'm', 'y', 'd2', 'm2', 'y2'}, -- for long/short reformatting
['mdy'] = {'%s %s, %s – %s %s, %s', 'm', 'd', 'y', 'm2', 'd2', 'y2'}, -- |df=mdy -> Mdy-Mdy
},
['Mdy-Mdy'] = { -- date format is Mdy-Mdy; reformat to:
['mdy'] = {'%s %s, %s – %s %s, %s', 'm', 'd', 'y', 'm2', 'd2', 'y2'}, -- for long/short reformatting
['dmy'] = {'%s %s %s – %s %s %s', 'd', 'm', 'y', 'd2', 'm2', 'y2'}, -- |df=dmy -> dMy-dMy
},
['My-My'] = { -- these for long/short reformatting
['any'] = {'%s %s – %s %s', 'm', 'y', 'm2', 'y2'}, -- dmy/mdy agnostic
},
['M-My'] = { -- these for long/short reformatting
['any'] = {'%s–%s %s', 'm', 'm2', 'y'}, -- dmy/mdy agnostic
},
['My'] = { -- these for long/short reformatting
['any'] = {'%s %s', 'm', 'y'}, -- dmy/mdy agnostic
},
-- ['yMd'] = { -- not supported at en.wiki
-- ['mdy'] = {'%s %s, %s', 'm', 'd', 'y'}, -- |df=mdy
-- ['dmy'] = {'%s %s %s', 'd', 'm', 'y'}, -- |df=dmy
-- ['ymd'] = {'%s-%s-%s', 'y', 'm', 'd'}, -- |df=ymd
-- },
}

local function reformatter (date, pattern_idx, format_param, mon_len)
if not in_array (pattern_idx, {'ymd', 'Mdy', 'Md-dy', 'dMy', 'yMd', 'd-dMy', 'dM-dMy', 'Md-Mdy', 'dMy-dMy', 'Mdy-Mdy', 'My-My', 'M-My', 'My'}) then
return; -- not in this set of date format patterns_t then not a reformattable date
end

if 'ymd' == format_param and in_array (pattern_idx, {'ymd', 'Md-dy', 'd-dMy', 'dM-dMy', 'Md-Mdy', 'dMy-dMy', 'Mdy-Mdy', 'My-My', 'M-My', 'My'}) then
return; -- ymd date ranges not supported at en.wiki; no point in reformatting ymd to ymd
end

if in_array (pattern_idx, {'My', 'M-My', 'My-My'}) then -- these are not dmy/mdy so can't be 'reformatted' into either
format_param = 'any'; -- so format-agnostic
end

-- yMd is not supported at en.wiki; when yMd is supported at your wiki, uncomment the next line
-- if 'yMd' format_param and in_array (pattern_idx, {'yMd', 'Md-dy', 'd-dMy', 'dM-dMy', 'Md-Mdy', 'dMy-dMy', 'Mdy-Mdy'}) then -- these formats not convertable; yMd not supported at en.wiki
if 'yMd' format_param then -- yMd not supported at en.wiki; when yMd is supported at your wiki, remove or comment-out this line
return; -- not a reformattable date
end

local c1, c2, c3, c4, c5, c6, c7; -- these hold the captures specified in patterns_t[pattern_idx][1]
c1, c2, c3, c4, c5, c6, c7 = mw.ustring.match (date, patterns_t[pattern_idx][1]); -- get the captures

local t = { -- table that holds k/v pairs of date parts from the captures and patterns_t[pattern_idx][2..]
[patterns_t[pattern_idx][2]] = c1; -- at minimum there is always one capture with a matching indicator letter
[patterns_t[pattern_idx][3] or 'x'] = c2; -- patterns_t can have a variable number of captures; each capture requires an indicator letter;
[patterns_t[pattern_idx][4] or 'x'] = c3; -- where there is no capture, there is no indicator letter so n in patterns_t[pattern_idx][n] will be nil;
[patterns_t[pattern_idx][5] or 'x'] = c4; -- the 'x' here spoofs an indicator letter to prevent 'table index is nil' error
[patterns_t[pattern_idx][6] or 'x'] = c5;
[patterns_t[pattern_idx][7] or 'x'] = c6;
[patterns_t[pattern_idx][8] or 'x'] = c7;
};

if t.a then -- if this date has an anchor year capture (all convertable date formats except ymd)
if t.y2 then -- for year range date formats
t.y2 = t.a; -- use the anchor year capture when reassembling the date
else -- here for single date formats (except ymd)
t.y = t.a; -- use the anchor year capture when reassembling the date
end
end

if tonumber(t.m) then -- if raw month is a number (converting from ymd)
if 's' == mon_len then -- if we are to use abbreviated month names
t.m = cfg.date_names['inv_local_short'][tonumber(t.m)]; -- convert it to a month name
else
t.m = cfg.date_names['inv_local_long'][tonumber(t.m)]; -- convert it to a month name
end
t.d = t.d:gsub ('0(%d)', '%1'); -- strip leading '0' from day if present
elseif 'ymd' == format_param then -- when converting to ymd
t.y = t.y:gsub ('%a', ); -- strip CITREF disambiguator if present; anchor year already known so process can proceed; TODO: maint message?
if 1582 > tonumber (t.y) then -- ymd format dates not allowed before 1582
return;
end
t.m = string.format ('%02d', get_month_number (t.m)); -- make sure that month and day are two digits
t.d = string.format ('%02d', t.d);
elseif mon_len then -- if mon_len is set to either 'short' or 'long'
for _, mon in ipairs ({'m', 'm2'}) do -- because there can be two month names, check both
if t[mon] then
t[mon] = get_month_number (t[mon]); -- get the month number for this month (is length agnostic)
if 0 == t[mon] then return; end -- seasons and named dates can't be converted
t[mon] = (('s' == mon_len) and cfg.date_names['inv_local_short'][t[mon]]) or cfg.date_names['inv_local_long'][t[mon]]; -- fetch month name according to length
end
end
end

local new_date = string.format (re_formats[pattern_idx][format_param][1], -- format string
t[re_formats[pattern_idx][format_param][2]], -- named captures from t{}
t[re_formats[pattern_idx][format_param][3]],
t[re_formats[pattern_idx][format_param][4]],
t[re_formats[pattern_idx][format_param][5]],
t[re_formats[pattern_idx][format_param][6]],
t[re_formats[pattern_idx][format_param][7]],
t[re_formats[pattern_idx][format_param][8]]
);

return new_date;
end

--cs1-dates= in
has legitimate value then that value determines how cs1|2 dates will be rendered. Legitimate
values for |cs1-dates= are:
l - all dates are rendered with long month names
ls - publication dates use long month names; access-/archive-dates use abbreviated month names
ly - publication dates use long month names; access-/archive-dates rendered in ymd format
s - all dates are rendered with abbreviated (short) month names
sy - publication dates use abbreviated month names; access-/archive-dates rendered in ymd format
y - all dates are rendered in ymd format

the format argument for automatic date formatting will be the format specified by with the
value supplied by |cs1-dates so one of: xxx-l, xxx-ls, xxx-ly, xxx-s, xxx-sy, xxx-y, or simply xxx (|cs1-dates=
empty, omitted, or invalid) where xxx shall be either of dmy or mdy.

dates are extracted from date_parameters_list, reformatted (if appropriate), and then written back into the
list in the new format. Dates in date_parameters_list are presumed here to be valid (no errors). This function
returns true when a date has been reformatted, false else. Actual reformatting is done by reformatter().

local function reformat_dates (date_parameters_list, format)
local all = false; -- set to false to skip access- and archive-dates
local len_p = 'l'; -- default publication date length shall be long
local len_a = 'l'; -- default access-/archive-date length shall be long
local result = false;
local new_date;

if format:match('%a+%-all') then -- manual df keyword; auto df keyword when length not specified in ;
format = format:match('(%a+)%-all'); -- extract the format
all = true; -- all dates are long format dates because this keyword doesn't specify length
elseif format:match('%a+%-[lsy][sy]?') then -- auto df keywords; internal only
all = true; -- auto df applies to all dates; use length specified by capture len_p for all dates
format, len_p, len_a = format:match('(%a+)%-([lsy])([sy]?)'); -- extract the format and length keywords
if 'y' == len_p then -- because allowed by MOS:DATEUNIFY (sort of) range dates and My dates not reformatted
format = 'ymd'; -- override
elseif (not is_set(len_a)) or (len_p == len_a) then -- no access-/archive-date length specified or same length as publication dates then
len_a = len_p; -- in case len_a not set
end
end -- else only publication dates and they are long

for param_name, param_val in pairs (date_parameters_list) do -- for each date-holding parameter in the list
if is_set (param_val.val) then -- if the parameter has a value
if not (not all and in_array (param_name, {'access-date', 'archive-date'})) then -- skip access- or archive-date unless format is xxx-all; yeah, ugly; TODO: find a better way
for pattern_idx, pattern in pairs (patterns_t) do
if mw.ustring.match (param_val.val, pattern[1]) then
if all and in_array (param_name, {'access-date', 'archive-date'}) then -- if this date is an access- or archive-date
new_date = reformatter (param_val.val, pattern_idx, (('y' == len_a) and 'ymd') or format, len_a); -- choose ymd or dmy/mdy according to len_a setting
else -- all other dates
new_date = reformatter (param_val.val, pattern_idx, format, len_p);
end

if new_date then -- set when date was reformatted
date_parameters_list[param_name].val = new_date; -- update date in date list
result = true; -- and announce that changes have been made
break;
end
end -- if
end -- for
end -- if
end -- if
end -- for
return result; -- declare boolean result and done
end

--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 is_set (param_val.val) and
not mw.ustring.match (param_val.val, patterns_t.ymd[1]) then -- for those that are not ymd dates (ustring because here digits may not be Western)
param_val.val, n = param_val.val:gsub ('%-', '–'); -- replace any hyphen with ndash
if 0 ~= n then
date_parameters_list[param_name].val = param_val.val; -- update the list
result = true;
end
end
end
return result; -- so we know if any hyphens were replaced
end

---------------------------------------------------------------------------

Attempts to translate English date names to local-language date names using names supplied by MediaWiki's
date parser function. This is simple name-for-name replacement and may not work for all languages.

if xlat_dig is true, this function will also translate Western (English) digits to the local language's digits.
This will also translate ymd dates.

local function date_name_xlate (date_parameters_list, xlt_dig)
local xlate;
local mode; -- long or short month names
local modified = false;
local date;

local sources_t = {
{cfg.date_names.en.long, cfg.date_names.inv_local_long}, -- for translating long English month names to long local month names
{cfg.date_names.en.short, cfg.date_names.inv_local_short}, -- short month names
{cfg.date_names.en.quarter, cfg.date_names.inv_local_quarter}, -- quarter date names
{cfg.date_names.en.season, cfg.date_names.inv_local_season}, -- season date nam
{cfg.date_names.en.named, cfg.date_names.inv_local_named}, -- named dates
}

local function is_xlateable (month) -- local function to get local date name that replaces existing English-language date name
for _, date_names_t in ipairs (sources_t) do -- for each sequence table in date_names_t
if date_names_t[1][month] then -- if date name is English month (long or short), quarter, season or named and
if date_names_t[2][date_names_t[1][month]] then -- if there is a matching local date name
return date_names_t[2][date_names_t[1][month]]; -- return the local date name
end
end
end
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.val) then -- if the parameter has a value
date = param_val.val;
for month in mw.ustring.gmatch (date, '[%a ]+') do -- iterate through all date names in the date (single date or date range)
month = mw.text.trim (month); -- this because quarterly dates contain whitespace
xlate = is_xlateable (month); -- get translate ; returns translation or nil

if xlate then
date = mw.ustring.gsub (date, month, xlate); -- replace the English with the translation
date_parameters_list[param_name].val = date; -- save the translated date
modified = true;
end
end

if xlt_dig then -- shall we also translate digits?
date = date:gsub ('%d', cfg.date_names.xlate_digits); -- translate digits from Western to 'local digits'
date_parameters_list[param_name].val = date; -- save the translated date
modified = true;
end
end
end

return modified;
end

------------------------------------------------------------------

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

local function set_selected_modules (cfg_table_ptr, utilities_page_ptr)
add_prop_cat = utilities_page_ptr.add_prop_cat ; -- import functions from selected Module:Citation/CS1/Utilities module
is_set = utilities_page_ptr.is_set;
in_array = utilities_page_ptr.in_array;
set_message = utilities_page_ptr.set_message;
substitute = utilities_page_ptr.substitute;
wrap_style = utilities_page_ptr.wrap_style;

cfg = cfg_table_ptr; -- import tables from selected Module:Citation/CS1/Configuration
end

--archive-date= with the timestamp in Wayback machine urls. Emits an error message with suggested
date from the |archive-url= timestamp in an appropriate format when the value in |archive-date= does not match
the timestamp.

this function never called when any date in a cs1|2 template has errors

error message suggests new |archive-date= value in an appropriate format specified by . is either
|df= or cfg.global_df in that order. If is nil, suggested date has format from |archive-date=. There is
a caveat: when |df=dmy or |df=mdy, the reformatter leaves |access-date= and |archive-date= formats as they are.
The error message suggested date is passed to the formatter as YYYY-MM-DD so when |df=dmy or |df=mdy, the format
is not changed.

local contentLanguage = mw.getContentLanguage()

local function replace_vietnamese_date(date_str)
local replacements = {
["[Nn]gày "] = "",
["[Tt]háng 1"] = "January",
["[Tt]háng 2"] = "February",
["[Tt]háng 3"] = "March",
["[Tt]háng 4"] = "April",
["[Tt]háng 5"] = "May",
["[Tt]háng 6"] = "June",
["[Tt]háng 7"] = "July",
["[Tt]háng 8"] = "August",
["[Tt]háng 9"] = "September",
["[Tt]háng 10"] = "October",
["[Tt]háng 11"] = "November",
["[Tt]háng 12"] = "December",
["[Nn]ăm "] = "",
}

for k, v in pairs(replacements) do
date_str = mw.ustring.gsub(date_str, k, v)
end

return date_str
end

local vi_formatdate = require('Module:Ngày chuẩn').vi_formatdate

local function archive_date_check (archive_date, archive_url_timestamp, df)
archive_date = replace_vietnamese_date(archive_date) -- convert the input Vietnamese date from date_str before decoding, if it exists

local archive_date_format = 'dmy-y'; -- holds the date format of date in |archive-date; default to ymd; 'dmy' used here to spoof reformat_dates()

for _, v_t in ipairs ({{'dMy', 'dmy-all'}, {'Mdy', 'mdy-all'}}) do -- is |archive-date= format dmy or mdy?
if archive_date:match (patterns_t[v_t[1]][1]) then -- does the pattern match?
archive_date_format = cfg.keywords_xlate[v_t[2]]; -- get appropriate |df= supported keyword from the i18n translator table
break;
end
end

local dates_t = {};
dates_t['archive-date'] = {val=archive_date, name=}; -- setup to call reformat_dates(); never called when errors so unset as not needed
reformat_dates (dates_t, 'dmy-y'); -- reformat |archive-date= to ymd; 'dmy' used here to spoof reformat_dates()
local archive_url_date = archive_url_timestamp:gsub ('(%d%d%d%d)(%d%d)(%d%d)%d', '%1-%2-%3'); -- make ymd format date from timestamp

if dates_t['archive-date'].val == archive_url_date then -- are the two dates the same
return; -- yes, done
else
dates_t['archive-date'] = {val=archive_url_date, name=}; -- setup to call reformat_dates() with the timestamp date
reformat_dates (dates_t, df or archive_date_format); -- reformat timestamp to format specified by or format used in |archive-date=
archive_url_date = vi_formatdate(archive_url_date, true);
set_message ('err_archive_date_url_ts_mismatch', archive_url_date); -- emit an error message
end
end

----------------------------------------------------------------------

return { -- return exported functions
archive_date_check = archive_date_check,
date_hyphen_to_dash = date_hyphen_to_dash,
date_name_xlate = date_name_xlate,
dates = dates,
reformat_dates = reformat_dates,
replace_vietnamese_date = replace_vietnamese_date,
set_selected_modules = set_selected_modules,
vi_formatdate = vi_formatdate,
year_check = year_check,
year_date_check = year_date_check,
}