local m = {}  local EasterData = {     defaultMethod = 3,        -- default method of Easter date calculation when Easter type is not given     defaultFormat = "Y-m-d",  -- default date output format     noFormat      = "none",   -- prevent from final date formatting     defaultOffset = 0,        -- the Easter date     minimumOffset = -69,      -- start of Niniveh lenten fast     maximumOffset = 69,       -- Feast of the Immaculate Heart of Mary       -- API     apiEaster            = "Berechnung", -- public function name     argEasterYear        = 1,            -- index or name of the argument with year     argEasterMethod      = "Methode",    -- index or name of the argument with calculation method     argEasterOffset      = "Tag",        -- index or name of the argument with offset in days relative to the calculated Easter Sunday     argEasterFormat      = "Format",     -- index or name of the argument with date output format (#time style)       -- errors     errorMissingYear     = "Der erforderliche Parameter 'Jahr' fehlt",     errorInvalidYear     = "Fehlerhafte Angabe 'Jahr': '%s'",     errorInvalidOffset   = "Fehlerhafte Angabe 'Tag': '%s'",     errorInvalidMethod   = "Fehlerhafte Angabe 'Methode': '%s'",     errorYearOutOfRange  = "Osterdaten können nur zwischen 326 und 4099 berechnet werden; Jahr: %d",     errorIncorrectMethod = "Das westliche oder orthodoxe Ostern besteht seit 1583; Jahr: %d",     errorUnknownMethod   = "Unbekannte Methode: %d",       methods = {         ["Julian"]             = 1,         ["Eastern"]            = 2,         ["Orthodox"]           = 2, -- alias for Eastern         ["Ostkirche"]          = 2, -- alias for Eastern         ["Coptic"]             = 2, -- alias for Eastern         ["Koptische Kirche"]   = 2, -- alias for Eastern         ["Ethiopian"]          = 2, -- alias for Eastern         ["Äthiopische Kirche"] = 2, -- alias for Eastern         ["Western"]            = 3,         ["Roman"]              = 3, -- alias for Western         ["Westkirche"]         = 3, -- alias for Western         ["Gregorian"]          = 3, -- alias for Western     },       -- the Meletian/Revised Julian Calendar from 1923 used by some Orthodox churches     -- and any proposed reformed algorithms are not supported (yet):     -- * astronomically observed Nicean rule at the meridian of Jerusalem (Aleppo 1997 proposal), differs from Gregorian in      -- * fifteenth Sunday of the year: Sunday in 099–105 day of the year     -- * Sunday after second Saturday in April (UK): Sunday in 9–15 April     -- * second Sunday in April: Sunday in 8–14 April     -- * Sunday after 6 April (Pepuzite sect): Sunday in 7–13 April     -- * World Calendar: day 099, any day of the week in Gregorian/Julian calendar     -- * Positivist Calendar: day 098, any day of the week in Gregorian/Julian calendar      -- * Sunday of ISO week 14: Sunday in 099–105 day of the year      -- * Sunday of ISO week 15: Sunday in 106–112 day of the year     -- * Nisan 14: any day of the week      -- * Nisan 15: any day of the week      relativeDates = {         Septuagesima                 = -63,         Fastensonntag                = -63,         Sexagesima                   = -56,         ["Fat Thursday"]             = -52,         Fettdonnerstag               = -52,         ["Schmotziger Donnerstag"]   = -52,         Weiberfastnacht              = -52,         ["Karneval"]                 = -51,         ["Carnival"]                 = -51,         ["Nelkensamstag"]            = -50,         ["Quinquagesima"]            = -49, -- Estomihi, Shrove Sunday         ["Tulpensonntag"]            = -49,         ["Shrove Monday"]            = -48, -- Rose Monday         ["Rosenmontag"]              = -48,         ["Shrove Tuesday"]           = -47, -- Mardi Gras, Carnival         ["Fastnachtsdienstag"]       = -47,         ["Veilchendienstag"]         = -47,         ["Ash Wednesday"]            = -46,         ["Aschermittwoch"]           = -46,         ["Invocabit"]                = -42,         ["Invocabit Sunday"]         = -42,         ["Reminiscere"]              = -35,         ["Reminiscere Sunday"]       = -35,         ["Oculi"]                    = -28,         ["Oculi Sunday"]             = -28,         ["Laetare"]                  = -21,         ["Laetare Sunday"]           = -21, -- Mothering Sunday         ["Rosensonntag"]             = -21,         ["Judica"]                   = -14,         ["Schwarzer Sonntag"]        = -14,         ["Passionssonntag"]          = -14,         ["Palm Sunday"]              =  -7,         ["Palmsonntag"]              =  -7,         ["Holy Week"]                =  -7,         ["Karwoche"]                 =  -7,         ["Holy Monday"]              =  -6,         ["Karmontag"]                =  -6,         ["Holy Tuesday"]             =  -5,         ["Kardienstag"]              =  -5,         ["Holy Wednesday"]           =  -4,         ["Karmittwoch"]              =  -4,         ["Maundy Thursday"]          =  -3,         ["Gründonnerstag"]           =  -3,         ["Good Friday"]              =  -2, -- Crucifixion         ["Karfreitag"]               =  -2,         ["Holy Saturday"]            =  -1,          ["Karsamstag"]               =  -1,         ["Easter"]                   =   0, -- Easter Sunday, Resurrection         ["Ostern"]                   =   0,         ["Easter Monday"]            =   1,         ["Ostermontag"]              =   1,         ["Quasimodogeniti"]          =   7,         ["Divine Mercy"]             =   7,         ["Weißer Sonntag"]           =   7,         ["Schamm an-Nasim"]          =   8,         ["Misericordias Domini"]     =  14,         ["Jubilate"]                 =  21,         ["Jubilate Sunday"]          =  21,         ["Kantate"]                  =  28,         ["Cantate Sunday"]           =  28,         ["Vocem jucunditatis"]       =  35,         ["Rogate"]                   =  35,         ["Ascension Thursday"]       =  39, -- Ascension         ["Christi Himmelfahrt"]      =  39,         ["Exaudi"]                   =  42,         ["Pentecost"]                =  49, -- Whitsun         ["Pfingstsonntag"]           =  49,         ["Pfingsten"]                =  50,         ["Pfingstmontag"]            =  50,         ["Whit Monday"]              =  50,         ["Trinity Sunday"]           =  56,         ["Dreifaltigkeitssonntag"]   =  56,         ["Trinitatis"]               =  56,         ["Goldener Sonntag"]         =  56,         ["Frommtag"]                 =  56,         ["Corpus Christi"]           =  60, -- Body and Blood of Christ         ["Fronleichnam"]             =  60,         ["Sacred Heart"]             =  68,         ["Heiligstes Herz Jesu"]     =  68,         ["Immaculate Heart"]         =  69,         ["Unbeflecktes Herz"]        =  69,     }, }   local function formatEasterError(message, ...)     if select('#', ... ) > 0 then         message = string.format(message, ...)     end     return "<span class=\"error\">" .. message .. "</span>" end   local function loadEasterYear(year)     if not year then         return false, formatEasterError(EasterData.errorMissingYear)     end     local result = tonumber(year)     if not result or math.floor(result) ~= result then         return false, formatEasterError(EasterData.errorInvalidYear, year)     end       return true, result end   local function loadEasterMethod(method, year)     local result = EasterData.defaultMethod     if method then         result = EasterData.methods[method]         if not result then             return false, formatEasterError(EasterData.errorInvalidMethod, method)         end     end       if year < 1583 then         result = 1     end       return true, result end   local function loadEasterOffset(day)     if not day then         return true, ""     end       local data = EasterData.relativeDates     local offset = tonumber(day)     if not offset then         offset = data[day]     end     if not offset or offset ~= math.floor(offset) or offset < EasterData.minimumOffset or offset > EasterData.maximumOffset then         return false, formatEasterError(EasterData.errorInvalidOffset, day)     end       if offset < -1 then         return true, string.format(" %d days", offset)     elseif offset == -1 then         return true, " -1 day"     elseif offset == 0 then         return true, ""     elseif offset == 1 then         return true, " +1 day"     else -- if offset > 1 then         return true, string.format(" +%d days", offset)     end end   local function loadEasterFormat(fmt)     if fmt == EasterData.noFormat then         return true, nil     elseif not fmt then         return true, EasterData.defaultFormat     else         return true, fmt     end end   --[[  PURPOSE:     This function returns Easter Sunday day and month               for a specified year and method.    INPUTS:      Year   - Any year between 326 and 4099.               Method - 1 = the original calculation based on the                            Julian calendar                        2 = the original calculation, with the                            Julian date converted to the                            equivalent Gregorian calendar                        3 = the revised calculation based on the                            Gregorian calendar    OUTPUTS:     None.    RETURNS:     0, error message - Error; invalid arguments               month, day       - month and day of the Sunday    NOTES:               The code is translated from DN OSP 6.4.0 sources.               The roots of the code might be found in               http://www.gmarts.org/index.php?go=415    ORIGINAL NOTES:                 This algorithm is an arithmetic interpretation               of the 3 step Easter Dating Method developed               by Ron Mallen 1985, as a vast improvement on               the method described in the Common Prayer Book                 Published Australian Almanac 1988               Refer to this publication, or the Canberra Library               for a clear understanding of the method used                 Because this algorithm is a direct translation of               the official tables, it can be easily proved to be               100% correct                 It's free! Please do not modify code or comments! ]] local function calculateEasterDate(year, method)     if year < 326 or year > 4099 then         -- Easter dates are valid for years between 326 and 4099         -- Method 2 would have to support dates in June thereafter         return 0, formatEasterError(EasterData.errorYearOutOfRange, year)     end     if year < 1583 and method ~= 1 then         -- Western or Orthodox Easter is valid since 1583         return 0, formatEasterError(EasterData.errorIncorrectMethod, year)     end       -- intermediate result     local firstDig = math.floor(year / 100)     local remain19 = year % 19     local temp = 0     -- table A to E results     local tA = 0     local tB = 0     local tC = 0     local tD = 0     local tE = 0      -- Easter Sunday day     local d = 0       if method == 1 or method == 2 then         -- calculate PFM date         tA   = ((225 - 11 * remain19) % 30) + 21         -- find the next Sunday         tB   = (tA - 19) % 7         tC   = (40 - firstDig) % 7         temp = year % 100         tD   = (temp + math.floor(temp / 4)) % 7         tE   = ((20 - tB - tC - tD) % 7) + 1         d    = tA + tE         if method == 2 then             -- convert Julian to Gregorian date             -- 10 days were skipped in the Gregorian calendar from 5-14 Oct 1582             temp = 10             -- only 1 in every 4 century years are leap years in the Gregorian             -- calendar (every century is a leap year in the Julian calendar)             if year > 1600 then                 temp = temp + firstDig - 16 - math.floor((firstDig - 16) / 4)             end             d = d + temp         end     elseif method == 3 then         -- calculate PFM date         temp = math.floor((firstDig - 15) / 2)  + 202 - 11 * remain19         if firstDig > 26 then             temp = temp - 1         end         if firstDig > 38 then             temp = temp - 1         end         if firstDig == 21 or firstDig == 24 or firstDig == 25 or firstDig == 33 or firstDig == 36 or firstDig == 37 then             temp = temp - 1         end         temp = temp % 30         tA   = temp + 21         if temp == 29 then             tA = tA - 1         end         if temp == 28 and remain19 > 10 then             tA = tA - 1         end         -- find the next Sunday         tB   = (tA - 19) % 7         tC   = (40 - firstDig) % 4         if tC == 3 then             tC = tC + 1         end         if tC > 1 then             tC = tC + 1         end         temp = year % 100         tD   = (temp + math.floor(temp / 4)) % 7         tE   = ((20 - tB - tC - tD) % 7) + 1         d    = tA + tE     else         -- Unknown method         return 0, formatEasterError(EasterData.errorUnknownMethod, method)     end     if d > 61 then         -- when the original calculation is converted to the Gregorian         -- calendar, Easter Sunday can occur in May         return 5, d - 61     elseif d > 31 then         return 4, d - 31     else         return 3, d     end end   local function Easter(args)     local ok     local year     ok, year = loadEasterYear(args[EasterData.argEasterYear])     if not ok then         return year     end       local method     ok, method = loadEasterMethod(args[EasterData.argEasterMethod], year)     if not ok then         return method     end       local offset     ok, offset = loadEasterOffset(args[EasterData.argEasterOffset])     if not ok then         return offset     end       local format     ok, format = loadEasterFormat(args[EasterData.argEasterFormat])     if not ok then         return format     end       local month, day = calculateEasterDate(year, method)     if month == 0 then         return day     end       local result = string.format("%04d-%02d-%02d%s", year, month, day, offset)     if format then         result = mw.language.getContentLanguage():formatDate(format, result)     end       return result end   m[EasterData.apiEaster] = function (frame)     return Easter(frame.args) end   return m