Hijri.lua

--[[--------------- luaHijri---------------------
by hubaishan
v0.5
locate at https://github.com/hubaishan/luaHijri

]]
--[[ ------------ C O N F I G U R A T I O N S ----------------------]]
--[[ As
local adjust_data = { [1443] = 
	[5] = {2021,12,6},
	[7] = 1 }
	this means ad just start of month 5 of 1443 to 2021-12-06, and add one day to month 7 of 1443  

]]
local adjust_data = {}
-- Gregorian Calender epoch used only for wertern calendar default value are in Italy some countries may differ
local gregorian_epoch = { jd = 2299161, y = 1582 , m = 10, d = 15}
-- sunday index can be 0 or 1
local wday_sunday = 1
-- day of year (1-1) index
local yday_1_1 = 1
-- @var int 1 to use adjusted Um Al-Qura algorithm, 2 to use Um Al-Qura algorithm, 0 use Hijri Tabular Algorithm
local hijri_mode = 1
--[[ ------------ C O N S T A N T S ----------------]]
--  the Um Al-Qura Calendar start year
local umstartyear = 1318
--  the Um Al-Qura Calendar end year
local umendyear = 1500
--  the Um Al-Qura Calendar start Julian day
local umstartjd = 2415140
-- the Um Al-Qura Calendar end  Julian day
local umendjd = 2479960
local UMDATA_COUNT = 2196
--[[ ------------ V A R S ----------------]]
local adjusted_umdata
local raw_umdata
--[[------------------- U T I L T Y   U S E F U L   F U N C T I O N S------------------------]]
local floor = math.floor

local function round(number)
	return floor(number + 0.5)
end

local function in_array( needle, haystack )
	if needle == nil then
		return false;
	end
	for n,v in ipairs( haystack ) do
		if v == needle then
			return n;
		end
	end
	return false;
end

--[[------------------- C A L E N D A R   F U N C T I O N S------------------------]]

--[[--- Data ---]]
local function gregorian2jd(year, month, day)
	-- from postgresql source
	local jd, century
	
	if year < 1 then
		year = year + 1
	end

	if month > 2 then
		month = month + 1
		year = year + 4800
	else
		month = month + 13
		year = year + 4799
	end

	century = floor(year / 100)

	return (year * 365 - 32167 + floor(year / 4) - century + floor(century / 4) + floor(7834 * month / 256) + day)
end

-- load Umm al-Qura Calendar Data
local function get_umdata(mode)
	mode = mode or hijri_mode

	if raw_umdata and (mode==2 or #adjust_data == 0) then
		return raw_umdata
	elseif adjusted_umdata and mode==1 then
		return adjusted_umdata
	end

	local umdata_raw = { [0]=15140, 15169, 15199, 15228, 15258, 15287, 15317, 15347, 15377, 15406, 15436, 15465, 15494, 15524, 15553, 15582, 15612, 15641, 15671, 15701, 15731, 15760, 15790, 15820, 15849, 15878, 15908, 15937, 15966, 15996, 16025, 16055, 16085, 16114, 16144, 16174, 16204, 16233, 16262, 16292, 16321, 16350, 16380, 16409, 16439, 16468, 16498, 16528, 16558, 16587, 16617, 16646, 16676, 16705, 16734, 16764, 16793, 16823, 16852, 16882, 16912, 16941, 16971, 17001, 17030, 17060, 17089, 17118, 17148, 17177, 17207, 17236, 17266, 17295, 17325, 17355, 17384, 17414, 17444, 17473, 17502, 17532, 17561, 17591, 17620, 17650, 17679, 17709, 17738, 17768, 17798, 17827, 17857, 17886, 17916, 17945, 17975, 18004, 18034, 18063, 18093, 18122, 18152, 18181, 18211, 18241, 18270, 18300, 18330, 18359, 18388, 18418, 18447, 18476, 18506, 18535, 18565, 18595, 18625, 18654,
					18684, 18714, 18743, 18772, 18802, 18831, 18860, 18890, 18919, 18949, 18979, 19008, 19038, 19068, 19098, 19127, 19156, 19186, 19215, 19244, 19274, 19303, 19333, 19362, 19392, 19422, 19452, 19481, 19511, 19540, 19570, 19599, 19628, 19658, 19687, 19717, 19746, 19776, 19806, 19836, 19865, 19895, 19924, 19954, 19983, 20012, 20042, 20071, 20101, 20130, 20160, 20190, 20219, 20249, 20279, 20308, 20338, 20367, 20396, 20426, 20455, 20485, 20514, 20544, 20573, 20603, 20633, 20662, 20692, 20721, 20751, 20780, 20810, 20839, 20869, 20898, 20928, 20957, 20987, 21016, 21046, 21076, 21105, 21135, 21164, 21194, 21223, 21253, 21282, 21312, 21341, 21371, 21400, 21430, 21459, 21489, 21519, 21548, 21578, 21607, 21637, 21666, 21696, 21725, 21754, 21784, 21813, 21843, 21873, 21902, 21932, 21962, 21991, 22021, 22050, 22080, 22109, 22138, 22168, 22197,
					22227, 22256, 22286, 22316, 22346, 22375, 22405, 22434, 22464, 22493, 22522, 22552, 22581, 22611, 22640, 22670, 22700, 22730, 22759, 22789, 22818, 22848, 22877, 22906, 22936, 22965, 22994, 23024, 23054, 23083, 23113, 23143, 23173, 23202, 23232, 23261, 23290, 23320, 23349, 23379, 23408, 23438, 23467, 23497, 23527, 23556, 23586, 23616, 23645, 23674, 23704, 23733, 23763, 23792, 23822, 23851, 23881, 23910, 23940, 23970, 23999, 24029, 24058, 24088, 24117, 24147, 24176, 24206, 24235, 24265, 24294, 24324, 24353, 24383, 24413, 24442, 24472, 24501, 24531, 24560, 24590, 24619, 24648, 24678, 24707, 24737, 24767, 24796, 24826, 24856, 24885, 24915, 24944, 24974, 25003, 25032, 25062, 25091, 25121, 25150, 25180, 25210, 25240, 25269, 25299, 25328, 25358, 25387, 25416, 25446, 25475, 25505, 25534, 25564, 25594, 25624, 25653, 25683, 25712, 25742,
					25771, 25800, 25830, 25859, 25888, 25918, 25948, 25977, 26007, 26037, 26067, 26096, 26126, 26155, 26184, 26214, 26243, 26272, 26302, 26332, 26361, 26391, 26421, 26451, 26480, 26510, 26539, 26568, 26598, 26627, 26656, 26686, 26715, 26745, 26775, 26805, 26834, 26864, 26893, 26923, 26952, 26982, 27011, 27041, 27070, 27099, 27129, 27159, 27188, 27218, 27248, 27277, 27307, 27336, 27366, 27395, 27425, 27454, 27484, 27513, 27542, 27572, 27602, 27631, 27661, 27691, 27720, 27750, 27779, 27809, 27838, 27868, 27897, 27926, 27956, 27985, 28015, 28045, 28074, 28104, 28134, 28163, 28193, 28222, 28252, 28281, 28310, 28340, 28369, 28399, 28428, 28458, 28488, 28517, 28547, 28577, 28606, 28636, 28665, 28694, 28724, 28753, 28782, 28812, 28842, 28871, 28901, 28931, 28961, 28990, 29020, 29049, 29078, 29108, 29137, 29166, 29196, 29226, 29255, 29285,
					29315, 29345, 29374, 29404, 29433, 29462, 29492, 29521, 29550, 29580, 29609, 29639, 29669, 29699, 29728, 29758, 29788, 29817, 29846, 29876, 29905, 29934, 29964, 29993, 30023, 30053, 30082, 30112, 30142, 30171, 30201, 30230, 30260, 30289, 30319, 30348, 30377, 30407, 30436, 30466, 30496, 30525, 30555, 30585, 30614, 30644, 30673, 30703, 30732, 30761, 30791, 30820, 30850, 30879, 30909, 30939, 30968, 30998, 31028, 31057, 31087, 31116, 31146, 31175, 31204, 31234, 31263, 31293, 31322, 31352, 31382, 31411, 31441, 31471, 31500, 31530, 31559, 31588, 31618, 31647, 31677, 31706, 31736, 31765, 31795, 31825, 31855, 31884, 31914, 31943, 31972, 32002, 32031, 32060, 32090, 32119, 32149, 32179, 32209, 32239, 32268, 32298, 32327, 32356, 32386, 32415, 32444, 32474, 32503, 32533, 32563, 32593, 32622, 32652, 32682, 32711, 32740, 32770, 32799, 32828,
					32858, 32887, 32917, 32947, 32976, 33006, 33036, 33065, 33095, 33124, 33154, 33183, 33212, 33242, 33271, 33301, 33330, 33360, 33390, 33420, 33449, 33479, 33508, 33538, 33567, 33596, 33626, 33655, 33685, 33714, 33744, 33774, 33803, 33833, 33862, 33892, 33922, 33951, 33981, 34010, 34039, 34069, 34098, 34128, 34157, 34187, 34216, 34246, 34276, 34305, 34335, 34365, 34394, 34424, 34453, 34482, 34512, 34541, 34571, 34600, 34630, 34660, 34689, 34719, 34749, 34778, 34808, 34837, 34866, 34896, 34925, 34954, 34984, 35014, 35043, 35073, 35103, 35133, 35162, 35192, 35221, 35250, 35280, 35309, 35338, 35368, 35397, 35427, 35457, 35487, 35516, 35546, 35576, 35605, 35634, 35664, 35693, 35722, 35752, 35781, 35811, 35841, 35870, 35900, 35930, 35959, 35989, 36018, 36048, 36077, 36106, 36136, 36165, 36195, 36224, 36254, 36284, 36314, 36343, 36373,
					36402, 36432, 36461, 36490, 36520, 36549, 36579, 36608, 36638, 36668, 36697, 36727, 36757, 36786, 36816, 36845, 36874, 36904, 36933, 36963, 36992, 37022, 37051, 37081, 37111, 37140, 37170, 37199, 37229, 37258, 37288, 37317, 37347, 37376, 37406, 37435, 37465, 37494, 37524, 37554, 37583, 37613, 37642, 37672, 37702, 37731, 37760, 37790, 37819, 37848, 37878, 37908, 37937, 37967, 37997, 38026, 38056, 38086, 38115, 38144, 38174, 38203, 38232, 38262, 38291, 38321, 38351, 38381, 38410, 38440, 38470, 38499, 38528, 38558, 38587, 38616, 38646, 38675, 38705, 38735, 38764, 38794, 38824, 38854, 38883, 38912, 38942, 38971, 39000, 39030, 39059, 39089, 39118, 39148, 39178, 39208, 39237, 39267, 39296, 39326, 39355, 39384, 39414, 39443, 39473, 39502, 39532, 39562, 39591, 39621, 39651, 39680, 39710, 39739, 39768, 39798, 39827, 39857, 39886, 39916,
					39945, 39975, 40005, 40034, 40064, 40093, 40123, 40152, 40182, 40211, 40241, 40270, 40300, 40329, 40359, 40388, 40418, 40448, 40477, 40507, 40536, 40566, 40595, 40625, 40654, 40684, 40713, 40743, 40772, 40802, 40831, 40861, 40891, 40920, 40950, 40979, 41009, 41038, 41068, 41097, 41126, 41156, 41185, 41215, 41245, 41275, 41304, 41334, 41364, 41393, 41422, 41452, 41481, 41510, 41540, 41569, 41599, 41629, 41658, 41688, 41718, 41748, 41777, 41806, 41836, 41865, 41894, 41924, 41953, 41983, 42012, 42042, 42072, 42102, 42131, 42161, 42190, 42220, 42249, 42278, 42308, 42337, 42367, 42396, 42426, 42456, 42485, 42515, 42545, 42574, 42604, 42633, 42662, 42692, 42721, 42751, 42780, 42810, 42839, 42869, 42899, 42929, 42958, 42988, 43017, 43046, 43076, 43105, 43135, 43164, 43194, 43223, 43253, 43283, 43312, 43342, 43371, 43401, 43430, 43460,
					43489, 43519, 43548, 43578, 43607, 43637, 43666, 43696, 43726, 43755, 43785, 43814, 43844, 43873, 43903, 43932, 43962, 43991, 44021, 44050, 44080, 44109, 44139, 44169, 44198, 44228, 44257, 44287, 44316, 44346, 44375, 44404, 44434, 44463, 44493, 44523, 44552, 44582, 44612, 44641, 44671, 44700, 44730, 44759, 44788, 44818, 44847, 44877, 44906, 44936, 44966, 44996, 45025, 45055, 45084, 45114, 45143, 45172, 45202, 45231, 45261, 45290, 45320, 45350, 45380, 45409, 45439, 45468, 45498, 45527, 45556, 45586, 45615, 45644, 45674, 45704, 45733, 45763, 45793, 45823, 45852, 45882, 45911, 45940, 45970, 45999, 46028, 46058, 46088, 46117, 46147, 46177, 46206, 46236, 46265, 46295, 46324, 46354, 46383, 46413, 46442, 46472, 46501, 46531, 46560, 46590, 46620, 46649, 46679, 46708, 46738, 46767, 46797, 46826, 46856, 46885, 46915, 46944, 46974, 47003,
					47033, 47063, 47092, 47122, 47151, 47181, 47210, 47240, 47269, 47298, 47328, 47357, 47387, 47417, 47446, 47476, 47506, 47535, 47565, 47594, 47624, 47653, 47682, 47712, 47741, 47771, 47800, 47830, 47860, 47890, 47919, 47949, 47978, 48008, 48037, 48066, 48096, 48125, 48155, 48184, 48214, 48244, 48273, 48303, 48333, 48362, 48392, 48421, 48450, 48480, 48509, 48538, 48568, 48598, 48627, 48657, 48687, 48717, 48746, 48776, 48805, 48834, 48864, 48893, 48922, 48952, 48982, 49011, 49041, 49071, 49100, 49130, 49160, 49189, 49218, 49248, 49277, 49306, 49336, 49365, 49395, 49425, 49455, 49484, 49514, 49543, 49573, 49602, 49632, 49661, 49690, 49720, 49749, 49779, 49809, 49838, 49868, 49898, 49927, 49957, 49986, 50016, 50045, 50075, 50104, 50133, 50163, 50192, 50222, 50252, 50281, 50311, 50340, 50370, 50400, 50429, 50459, 50488, 50518, 50547,
					50576, 50606, 50635, 50665, 50694, 50724, 50754, 50784, 50813, 50843, 50872, 50902, 50931, 50960, 50990, 51019, 51049, 51078, 51108, 51138, 51167, 51197, 51227, 51256, 51286, 51315, 51345, 51374, 51403, 51433, 51462, 51492, 51522, 51552, 51582, 51611, 51641, 51670, 51699, 51729, 51758, 51787, 51816, 51846, 51876, 51906, 51936, 51965, 51995, 52025, 52054, 52083, 52113, 52142, 52171, 52200, 52230, 52260, 52290, 52319, 52349, 52379, 52408, 52438, 52467, 52497, 52526, 52555, 52585, 52614, 52644, 52673, 52703, 52733, 52762, 52792, 52822, 52851, 52881, 52910, 52939, 52969, 52998, 53028, 53057, 53087, 53116, 53146, 53176, 53205, 53235, 53264, 53294, 53324, 53353, 53383, 53412, 53441, 53471, 53500, 53530, 53559, 53589, 53619, 53648, 53678, 53708, 53737, 53767, 53796, 53825, 53855, 53884, 53914, 53943, 53973, 54003, 54032, 54062, 54092,
					54121, 54151, 54180, 54209, 54239, 54268, 54297, 54327, 54357, 54387, 54416, 54446, 54476, 54505, 54535, 54564, 54593, 54623, 54652, 54681, 54711, 54741, 54770, 54800, 54830, 54859, 54889, 54919, 54948, 54977, 55007, 55036, 55066, 55095, 55125, 55154, 55184, 55213, 55243, 55273, 55302, 55332, 55361, 55391, 55420, 55450, 55479, 55508, 55538, 55567, 55597, 55627, 55657, 55686, 55716, 55745, 55775, 55804, 55834, 55863, 55892, 55922, 55951, 55981, 56011, 56040, 56070, 56100, 56129, 56159, 56188, 56218, 56247, 56276, 56306, 56335, 56365, 56394, 56424, 56454, 56483, 56513, 56543, 56572, 56601, 56631, 56660, 56690, 56719, 56749, 56778, 56808, 56837, 56867, 56897, 56926, 56956, 56985, 57015, 57044, 57074, 57103, 57133, 57162, 57192, 57221, 57251, 57280, 57310, 57340, 57369, 57399, 57429, 57458, 57487, 57517, 57546, 57576, 57605, 57634,
					57664, 57694, 57723, 57753, 57783, 57813, 57842, 57871, 57901, 57930, 57959, 57989, 58018, 58048, 58077, 58107, 58137, 58167, 58196, 58226, 58255, 58285, 58314, 58343, 58373, 58402, 58432, 58461, 58491, 58521, 58551, 58580, 58610, 58639, 58669, 58698, 58727, 58757, 58786, 58816, 58845, 58875, 58905, 58934, 58964, 58994, 59023, 59053, 59082, 59111, 59141, 59170, 59200, 59229, 59259, 59288, 59318, 59348, 59377, 59407, 59436, 59466, 59495, 59525, 59554, 59584, 59613, 59643, 59672, 59702, 59731, 59761, 59791, 59820, 59850, 59879, 59909, 59939, 59968, 59997, 60027, 60056, 60086, 60115, 60145, 60174, 60204, 60234, 60264, 60293, 60323, 60352, 60381, 60411, 60440, 60469, 60499, 60528, 60558, 60588, 60618, 60647, 60677, 60707, 60736, 60765, 60795, 60824, 60853, 60883, 60912, 60942, 60972, 61002, 61031, 61061, 61090, 61120, 61149, 61179,
					61208, 61237, 61267, 61296, 61326, 61356, 61385, 61415, 61445, 61474, 61504, 61533, 61563, 61592, 61621, 61651, 61680, 61710, 61739, 61769, 61799, 61828, 61858, 61888, 61917, 61947, 61976, 62006, 62035, 62064, 62094, 62123, 62153, 62182, 62212, 62242, 62271, 62301, 62331, 62360, 62390, 62419, 62448, 62478, 62507, 62537, 62566, 62596, 62625, 62655, 62685, 62715, 62744, 62774, 62803, 62832, 62862, 62891, 62921, 62950, 62980, 63009, 63039, 63069, 63099, 63128, 63157, 63187, 63216, 63246, 63275, 63305, 63334, 63363, 63393, 63423, 63453, 63482, 63512, 63541, 63571, 63600, 63630, 63659, 63689, 63718, 63747, 63777, 63807, 63836, 63866, 63895, 63925, 63955, 63984, 64014, 64043, 64073, 64102, 64131, 64161, 64190, 64220, 64249, 64279, 64309, 64339, 64368, 64398, 64427, 64457, 64486, 64515, 64545, 64574, 64603, 64633, 64663, 64692, 64722,
					64752, 64782, 64811, 64841, 64870, 64899, 64929, 64958, 64987, 65017, 65047, 65076, 65106, 65136, 65166, 65195, 65225, 65254, 65283, 65313, 65342, 65371, 65401, 65431, 65460, 65490, 65520, 65549, 65579, 65608, 65638, 65667, 65697, 65726, 65755, 65785, 65815, 65844, 65874, 65903, 65933, 65963, 65992, 66022, 66051, 66081, 66110, 66140, 66169, 66199, 66228, 66258, 66287, 66317, 66346, 66376, 66405, 66435, 66465, 66494, 66524, 66553, 66583, 66612, 66641, 66671, 66700, 66730, 66760, 66789, 66819, 66849, 66878, 66908, 66937, 66967, 66996, 67025, 67055, 67084, 67114, 67143, 67173, 67203, 67233, 67262, 67292, 67321, 67351, 67380, 67409, 67439, 67468, 67497, 67527, 67557, 67587, 67617, 67646, 67676, 67705, 67735, 67764, 67793, 67823, 67852, 67882, 67911, 67941, 67971, 68000, 68030, 68060, 68089, 68119, 68148, 68177, 68207, 68236, 68266,
					68295, 68325, 68354, 68384, 68414, 68443, 68473, 68502, 68532, 68561, 68591, 68620, 68650, 68679, 68708, 68738, 68768, 68797, 68827, 68857, 68886, 68916, 68946, 68975, 69004, 69034, 69063, 69092, 69122, 69152, 69181, 69211, 69240, 69270, 69300, 69330, 69359, 69388, 69418, 69447, 69476, 69506, 69535, 69565, 69595, 69624, 69654, 69684, 69713, 69743, 69772, 69802, 69831, 69861, 69890, 69919, 69949, 69978, 70008, 70038, 70067, 70097, 70126, 70156, 70186, 70215, 70245, 70274, 70303, 70333, 70362, 70392, 70421, 70451, 70481, 70510, 70540, 70570, 70599, 70629, 70658, 70687, 70717, 70746, 70776, 70805, 70835, 70864, 70894, 70924, 70954, 70983, 71013, 71042, 71071, 71101, 71130, 71159, 71189, 71218, 71248, 71278, 71308, 71337, 71367, 71397, 71426, 71455, 71485, 71514, 71543, 71573, 71602, 71632, 71662, 71691, 71721, 71751, 71781, 71810,
					71839, 71869, 71898, 71927, 71957, 71986, 72016, 72046, 72075, 72105, 72135, 72164, 72194, 72223, 72253, 72282, 72311, 72341, 72370, 72400, 72429, 72459, 72489, 72518, 72548, 72577, 72607, 72637, 72666, 72695, 72725, 72754, 72784, 72813, 72843, 72872, 72902, 72931, 72961, 72991, 73020, 73050, 73080, 73109, 73139, 73168, 73197, 73227, 73256, 73286, 73315, 73345, 73375, 73404, 73434, 73464, 73493, 73523, 73552, 73581, 73611, 73640, 73669, 73699, 73729, 73758, 73788, 73818, 73848, 73877, 73907, 73936, 73965, 73995, 74024, 74053, 74083, 74113, 74142, 74172, 74202, 74231, 74261, 74291, 74320, 74349, 74379, 74408, 74437, 74467, 74497, 74526, 74556, 74585, 74615, 74645, 74675, 74704, 74733, 74763, 74792, 74822, 74851, 74881, 74910, 74940, 74969, 74999, 75029, 75058, 75088, 75117, 75147, 75176, 75206, 75235, 75264, 75294, 75323, 75353,
					75383, 75412, 75442, 75472, 75501, 75531, 75560, 75590, 75619, 75648, 75678, 75707, 75737, 75766, 75796, 75826, 75856, 75885, 75915, 75944, 75974, 76003, 76032, 76062, 76091, 76121, 76150, 76180, 76210, 76239, 76269, 76299, 76328, 76358, 76387, 76416, 76446, 76475, 76505, 76534, 76564, 76593, 76623, 76653, 76682, 76712, 76741, 76771, 76801, 76830, 76859, 76889, 76918, 76948, 76977, 77007, 77036, 77066, 77096, 77125, 77155, 77185, 77214, 77243, 77273, 77302, 77332, 77361, 77390, 77420, 77450, 77479, 77509, 77539, 77569, 77598, 77627, 77657, 77686, 77715, 77745, 77774, 77804, 77833, 77863, 77893, 77923, 77952, 77982, 78011, 78041, 78070, 78099, 78129, 78158, 78188, 78217, 78247, 78277, 78307, 78336, 78366, 78395, 78425, 78454, 78483, 78513, 78542, 78572, 78601, 78631, 78661, 78690, 78720, 78750, 78779, 78808, 78838, 78867, 78897,
					78926, 78956, 78985, 79015, 79044, 79074, 79104, 79133, 79163, 79192, 79222, 79251, 79281, 79310, 79340, 79369, 79399, 79428, 79458, 79487, 79517, 79546, 79576, 79606, 79635, 79665, 79695, 79724, 79753, 79783, 79812, 79841, 79871, 79900, 79930, 79960,
	}

	if mode==2 or #adjust_data == 0 then
		raw_umdata = umdata_raw
		return umdata_raw
	elseif mode==1 then
		adjusted_umdata = umdata_raw
		for yk,yv in pairs(adjust_data) do
			for mk,mv in pairs(yv) do
				local uk = (yk-umstartyear)*12 + mk -1
				if type(mv) == 'table' then
					adjusted_umdata[uk] = gregorian2jd(mv[1],mv[2],mv[3]) - 2400000
				elseif mv >-2 and mv <2 then
					adjusted_umdata[uk] = adjusted_umdata[uk] - mv
				end
			end
		end
		return adjusted_umdata
	end
end

--[[--- Hijri ---]]

local function jd2hijri(julianday, mode)
    local mjd, ii, n, y, i
	local j, j1
	local hy, hm, hd, hz
	mode = mode or hijri_mode
	if (mode>0 and (julianday > umstartjd) and (julianday < umendjd)) then
		local umdata = get_umdata(mode)
		i = floor((julianday - 1948438) / 29.53056) - ((umstartyear - 1) * 12)
        mjd = julianday - 2400000
        if i<0 then i = 0 end
        for c = i, UMDATA_COUNT do
            if (umdata[c] > mjd) then
				i = c
                break
            end
		end
		ii = floor((i - 1) / 12) 
		hy = umstartyear + ii
		hm = i - 12 * ii 
		hd = mjd - umdata[i - 1] + 1
		hz = mjd - umdata[12 * ii]
	else
		j = julianday + 7666
		n = floor(j / 10631)
		j = j - (n * 10631)
		j1 = j
		y = floor(j / 354.36667)
		j = j - round(y * 354.36667)
		if j == 0 then
			y=y-1
			j = j1 - round(y * 354.36667)
			hz = j
			hd = j - 325
			hm = 12
		else
			hz = j - 1
			j = j + 29
			hm = floor((24 * j) / 709)
			hd = j -  floor(((709 * hm) / 24))
		end
		hy = (n * 30) + y + 1
		hy = hy - 5520
		if hy <= 0 then
			hy = hy - 1
		end
    end
	hz = hz + yday_1_1
    return hy, hm, hd, hz
end


local function hijri2jd(hy, hm, hd, mode)
	mode = mode or hijri_mode
	local ii, i, n
	local j
	if (mode > 0 and hy >= umstartyear and hy <= umendyear) then
		local umdata = get_umdata(mode)
		ii = hy - umstartyear
		i = hm + 12 * ii
		j = hd + umdata[i - 1] - 1
		j = j + 2400000
	elseif (hy < -5499 or (hy == -5499 and hm < 8) or (hy == -5499 and hm == 8 and hd < 18)) then
		j = 0
	else
		hy = hy < 0 and (hy + 5520) or (hy + 5519)
		n = floor(hy / 30)
		j = (n * 10631) + round((hy - (n * 30)) * 354.36667)
		hm = hm - 1
		j = j + (hm * 29) + floor((hm + 1) / 2) + hd
		j = j- 7666
	end
	return j
end

local function hijri_days_in_month(year, month, mode)
	mode = mode or hijri_mode
	local t = 29
	if mode>0 and year >= umstartyear and year <= umendyear then
		local i = (year-umstartyear)*12 + month -1
		local umdata = get_umdata(mode)
		t = umdata[i + 1] - umdata[i]
	else
		if month == 12 then
			if year < 0 then
				year = year + 5521
			end

			if round((year % 30) * 0.36667) > round(((year - 1) % 30) * 0.36667) then
				t = 30
			end
		else
			t = 29 + (month % 2);
		end
	end
	return t
end

local function hijri_isleap(year, mode)
	mode = mode or hijri_mode
	local l
	if mode>0 and year >= umstartyear and year <= umendyear then
		local umdata = get_umdata(mode)
		local ii = year - umstartyear
		l = ((umdata[12 * (ii + 1)] - umdata[12 * ii]) > 354) and true or false
	else
		if year < 0 then
			year = year + 5521;
		end
		l = (round((year % 30) * 0.36667) > round(((year - 1) % 30) * 0.36667)) and true or false
	end
	return l
end

local function hijri_yday(year,month,day,mode)
    local ii
	mode = mode or hijri_mode
	if (mode>0 and year >= umstartyear and year <= umendyear) then
		local umdata = get_umdata(mode)
		ii = year - umstartyear
		return umdata[(12 * ii) + month -1] - umdata[12 * ii] + day - 1 + yday_1_1
	else
		return select(month, 0,30,59,89,118,148,177,207,236,266,295,325) + day - 1 + yday_1_1 
	end
end

local function hijri_check(year,month,day,mode,may_adjusted)
	if month < 1 or month > 12 then
		return false
	end

	if day < 1 or day > 30 then
		return false
	end

	if not may_adjusted and day > hijri_days_in_month(year,month,mode) then
		return false
	end

	return true
end
--[[--- Unix and wday---]]

local function jd2unix(jd)
	-- 2440588 -- J.D. of 1.1.1970
	if jd == nil then
		return nil
	end
	return ((jd - 2440588) * 24 * 3600)
end

local function unix2jd(unix)
	if unix == nil then
		return nil
	end
	return floor(unix/(24 * 3600)) + 2440588
end

--returns wday number sunday=wday_sunday
local function jd2wday(jd)
	jd = jd + 1
	jd = jd % 7
	if (jd<0) then
		jd = jd + 7
	end
	return jd + wday_sunday
end

--[[--- Gregorian ---]]

local function jd2gregorian(jd)
	-- inspired by postgresql function
	local julian, quad, extra, y
	local year,month,day
	julian = jd + 32044
	
	quad = floor(julian / 146097)
	
	extra = (julian - quad * 146097) * 4 + 3
	julian = julian + 60 + quad * 3 + floor(extra / 146097)
	quad = floor(julian / 1461)
	julian = julian - quad * 1461
	y = floor(julian * 4 / 1461)
	
	if (y ~= 0) then
		julian = ((julian + 305) % 365) + 123
	else
		julian = ((julian + 306) % 366) + 123
	end
	y = y + quad * 4;
	year = y - 4800;
	
	quad = floor(julian * 2141 / 65536)
	day = julian - floor(7834 * quad / 256)
	month = (quad + 10) % 12 + 1

	if (year<1) then
		year = year-1
	end
	return year,month,day
end

local function gre_isleap(year)
	if year<1 then year=year+1 end
	return (year % 4) == 0 and ((year % 100) ~= 0 or (year % 400) == 0)
end

local function gre_yday(year,month,day)
	if gre_isleap(year) then
		return  select(month,0,31,60,91,121,152,182,213,244,274,305,335) + day - 1 + yday_1_1
	else
		return  select(month,0,31,59,90,120,151,181,212,243,273,304,334) + day - 1 + yday_1_1
	end
end

local function gre_days_in_month(year, month)
	if month == 2 and gre_isleap(year) then
		return 29
	else
		return select(month,31,28,31,30,31,30,31,31,30,31,30,31)
	end
end

local function gre_check(year,month,day)
	if month < 1 or month > 12 then
		return false
	end

	if day < 1 or day > gre_days_in_month(year,month) then
		return false
	end
	return true
end
--[[--- Julian ---]]

local function jd2julian(jd)
	local year, month, day
	local temp, dayofYear

	temp = jd * 4 + (32083 * 4 - 1)

	year = floor(temp / 1461)
	dayofYear = floor((temp % 1461) / 4) + 1

	temp = dayofYear * 5 - 3
	month = floor(temp / 153)
	day = floor((temp % 153) / 5) + 1

	if (month < 10) then
		month = month + 3
	else
		year = year + 1
		month = month - 9
	end

	year = year - 4800
	if (year < 1) then
		year = year -1
	end

	return year, month, day
end

local function julian2jd(year,month,day)
	if year<0 then
		year = year + 4801
	else
		year = year + 4800
	end

	if month > 2 then
		month = month -3
	else
		month = month + 9
		year = year - 1
	end

	return (floor((year * 1461) / 4) + floor((month * 153 + 2) / 5) + day - 32083)
end

local function julian_isleap(year)
	if year < 1 then year = year + 1 end
	return (year % 4) == 0
end

local function julian_yday(year,month,day)
	if julian_isleap(year) then
		return  select(month,0,31,60,91,121,152,182,213,244,274,305,335) + day - 1 + yday_1_1
	else
		return  select(month,0,31,59,90,120,151,181,212,243,273,304,334) + day - 1 + yday_1_1
	end
end

local function julian_days_in_month(year, month)
	if month == 2 and julian_isleap(year) then
		return 29
	else
		return select(month,31,28,31,30,31,30,31,31,30,31,30,31)
	end
end

local function julian_check(year,month,day)
	if month < 1 or month > 12 then
		return false
	end
	if day < 1 or day > julian_days_in_month(year,month) then
		return false
	end
	return true
end

--[[--- Convertion ---]]

-- Return Hijri Date from Gregorian date
local function gregorian2hijri(gyear, gmonth, gday)
	return jd2hijri(gregorian2jd(gyear, gmonth, gday))
end

local function hijri2gregorian(hyear, hmonth, hday)
	return jd2gregorian(hijri2jd(hyear, hmonth, hday))
end

--[[------------------- D A T E   C L A S S ------------------------]]


local datePrototype = {}

	-- Set julianDay
function datePrototype:set_jd(arg_jd)
	if self.p.type == 'hijri' then
		self.p.year, self.p.month, self.p.day, self.p.yday = jd2hijri(arg_jd,self.p.mode)
		self.p.jd = arg_jd
	elseif self.p.type == 'gregorian' or (self.p.type == 'western' and arg_jd >= gregorian_epoch.jd ) then
		self.p.year, self.p.month, self.p.day = jd2gregorian(arg_jd)
		self.p.jd, self.p.yday = arg_jd, nil
	elseif self.p.type == 'julian' or (self.p.type == 'western' and arg_jd < gregorian_epoch.jd ) then
		self.p.year, self.p.month, self.p.day = jd2julian(arg_jd)
		self.p.jd, self.p.yday = arg_jd, nil
	end
	self.p.wday, self.p.month_days, self.p.leap_year  = nil, nil, nil
end

function datePrototype:get_jd()
	if self.p.jd ~= nil then
		return self.p.jd
	elseif self.p.year and self.p.month and self.p.day then
		self:set_date(self.p.year,self.p.month,self.p.day)
	else
		local t=os.date("*t")
		if self.p.type=='gregorian' then
			self.p.year, self.p.month, self.p.day, self.p.wday, self.p.yday = t.year, t.month, t.day, t.wday - 1 + wday_sunday, t.yday
			self.p.jd = gregorian2jd(self.p.year, self.p.month, self.p.day)
		else
			self:from_gregorian(t.year,t.month,t.day)
			self.p.wday = t.wday -1 + wday_sunday
		end
	end
	return self.p.jd
end

function datePrototype:set_timestamp(arg_tm)
	if self.p.timestamp == arg_tm then
		return
	end
	self.p.timestamp = arg_tm
	self:set_jd(unix2jd(arg_tm))
end

    -- adjust type of western calendar
local function adj_type(type,year,month,day)
	if type == 'western' then
		if year>gregorian_epoch.y or (year==gregorian_epoch.y and month>gregorian_epoch.m) or (year==gregorian_epoch.y and month == gregorian_epoch.m and day>=gregorian_epoch.d) then
			type='gregorian'
		else
			type = 'julian'
		end
	end
	return type
end

	-- Check the Date
local function check_date(ctype,cmode,year,month,day,may_adjusted)
	local type = adj_type(ctype,year,month,day)
	if month <1 or month >12 or day <1 or day >31 then
		return false
	elseif type == 'hijri' then
		if day > 30 or (not may_adjusted and day> hijri_days_in_month(year,month,cmode)) then
			return false
		end
	elseif day > select(month,31,29,31,30,31,30,31,31,30,31,30,31) then 
		return false
	elseif month == 2 and day == 29 then
		if (((year % 4) ~= 0) or (type == 'gregorian'  and (year % 100) == 0 and (year % 400) ~= 0)) then
			return false
		end
	end
	return true
end

	-- Set Date
	-- may_adjusted argument used in Hijri only to accept any 30 day of any month
function datePrototype:set_date(year,month,day,may_adjusted)
	if not check_date(self.p.type, self.p.mode, year, month, day, may_adjusted) then
		error("Invalid Date")
	end
	local type=adj_type(self.p.type,year,month,day)
	if type == 'hijri' then
		self.p.jd = hijri2jd(year,month,day,self.p.mode)
	elseif type == 'gregorian' then
		self.p.jd = gregorian2jd(year,month,day)
	elseif type == 'julian' then
		self.p.jd = julian2jd(year,month,day)
	end
	self.p.year, self.p.month, self.p.day = year,month,day
	self.p.wday, self.p.month_days, self.p.leap_year, self.p.yday  = nil, nil, nil, nil
end

-- Convert date from hijri
function datePrototype:from_hijri(year,month,day,wday,mode)
	mode = mode or self.p.mode
	local jd = hijri2jd(year,month,day,mode)
	if wday and wday <= 6 and wday >=0 then
		local jd_weekday = jd2wday(jd)
		local differ = wday - jd_weekday

		if differ < - 4 then
			jd = jd + (differ + 7)
		elseif differ > -3 and differ < 3 then
			jd = jd + differ
		elseif differ > 4 then
			jd = jd + (differ - 7)
		else
			error("Weekday is very far from Hijri date")
		end
	end
	if self.p.type == 'hijri' and check_date(self.p.type, self.p.mode, year,month,day,true) then
		self.p.year,self.p.month,self.p.day,self.p.jd=year,month,day,jd
		self.p.wday, self.p.month_days, self.p.leap_year, self.p.yday  = nil, nil, nil, nil
	else
		self:set_jd(jd)
	end
end

-- Convert date from Gregorian
function datePrototype:from_gregorian(year,month,day)
	self:set_jd(gregorian2jd(year,month,day))
end
-- Convert date from Julian
function datePrototype:from_julian(year,month,day)
	self:set_jd(julian2jd(year,month,day))
end

-- Convert date from Western
function datePrototype:from_western(year,month,day)
	if year>gregorian_epoch.y or (year==gregorian_epoch.y and month>gregorian_epoch.m) or (year==gregorian_epoch.y and month == gregorian_epoch.m and day>=gregorian_epoch.d) then
		self:set_jd(gregorian2jd(year,month,day))
	else
		self:set_jd(julian2jd(year,month,day))
	end
end



-- set type of calendar
function datePrototype:set_type(arg_type)
	local new_type,new_mode
	arg_type = string.lower(arg_type)
	if in_array(arg_type, {'hijri', 'hijri_adjusted_umalqura', 'hijri_umalqura', 'hijri_tabular', 'gregorian', 'julian', 'western'}) then
		if string.sub(arg_type,1,5) == 'hijri' then
			new_type = 'hijri'
			if arg_type == 'hijri_umalqura' then
				new_mode = 2
			elseif arg_type == 'hijri_tabular' then
				new_mode = 0
			else
				new_mode = 1
			end
		else
			new_type = arg_type
		end

		if new_type ~= self.p.type or new_mode ~= self.p.mode then
			self.p.type = new_type
			self.p.mode = new_mode
			if self.p.jd then
				self:set_jd(self.p.jd)
			end
		end
	else
		error('bad calendar type')
	end
end

function datePrototype:get_value(key)
	if not self.p[key] then
		local jd = self:get_jd() -- to init calendar if not
		if key=='wday' then
			self.p.wday = jd2wday(jd)
		elseif key == 'timestamp' then
			self.p.timestamp = jd2unix(jd)
		else
			if self.p.type=='hijri' and key=='leap_year' then
				self.p.leap_year = hijri_isleap(self.p.year,self.p.mode)
			elseif self.p.type == 'gregorian' or (self.p.type == 'western' and self.p.year > gregorian_epoch.y ) then
				self.p.leap_year = gre_isleap(self.p.year)
			elseif self.p.type == 'julian' or (self.p.type == 'western' and self.p.year <= gregorian_epoch.y ) then
				self.p.leap_year = julian_isleap(self.p.year)
			end
	
			if key == 'yday' then
				if  self.p.type ~= 'hijri' then
					if self.p.leap_year then
						self.p.yday =  select(self.p.month,0,31,60,91,121,152,182,213,244,274,305,335) + self.p.day - 1 + yday_1_1
					else
						self.p.yday =  select(self.p.month,0,31,59,90,120,151,181,212,243,273,304,334) + self.p.day - 1 + yday_1_1
					end
						
				elseif self.p.type == 'hijri' then
					self.p.yday = hijri_yday(self.p.year,self.p.month,self.p.day,self.p.mode)
				end
			elseif key == 'month_days' then
				if self.p.type=='hijri' then
					self.p.month_days = hijri_days_in_month(self.p.year,self.p.month,self.p.mode)
				else
					if self.p.month == 2 and self.p.leap_year then
						self.p.month_days = 29
					else
						self.p.month_days = select(self.p.month,31,28,31,30,31,30,31,31,30,31,30,31)
					end
				end
			end
		end
	end
	return self.p[key]
end

-- add interval to date
function datePrototype:add(y, m, d)
	y,m,d = tonumber(y) or 0,tonumber(m) or 0,tonumber(d) or 0
	local jd = self:get_jd()
	if y==0 and m == 0 then
		jd = jd + d
	else
		local year,month,day=self.p.year + y, self.p.month + m, self.p.day + d
		if self.p.type == 'hijri' then
			jd = hijri2jd(year,month,day,self.p.mode)
		elseif self.p.type == 'gregorian' then
			jd = gregorian2jd(year,month,day)
		elseif self.p.type == 'julian' then
			jd = julian2jd(year,month,day)
		elseif self.p.type == 'western' then
			if self.p.jd >= gregorian_epoch.jd then
				jd = gregorian2jd(year,month,day)
				if jd< gregorian_epoch.jd then
					jd = julian2jd(year,month,day)
				end
			else
				jd = julian2jd(year,month,day)
				if jd>= gregorian_epoch.jd then
					jd = gregorian2jd(year,month,day)
				end
			end
		end
	end

	if jd ~= self.p.jd then
		self:set_jd(jd)
	end
end


function datePrototype:iso()
	local ret, str, jd = '', '', self:get_jd()
	local year, month, day

	if self.p.type=='gregorian' then
		year, month, day = self.p.year, self.p.month, self.p.day
	else
		year, month, day = jd2gregorian(jd)
	end

	if year < 0 then
		year = year - 1
		ret = '-'
	end
	str = tostring(math.abs(year))
	return ret .. string.rep('0', 4 - #str) .. str .. '-' .. ((month<10) and '0' or '') .. month .. '-' .. ((day<10) and '0' or '') .. day
end

local function DateWrapper(dt)
	local t = {}
	t.p = {}
	local rop = {
		type = false,
		mode = true,
		jd  = false,
		timestamp = false,
		year = true,
		month = true,
		day = true,
		wday = true,
		yday = true,
		month_days = true,
		leap_year  = true
		}

	local mt = {
		__index = function ( tt, k )
			assert( t == tt )
			local v = tt.p[k] or  datePrototype[k]

			if v == nil and rop[k] ~=nil then
				v = tt:get_value(k)
			end
			return v
		end,
		__newindex = function ( t, k, v )
			if rop[k] then
				error("Attempt to modify read-only property")
			elseif k == 'jd' then
				t:set_jd(v)
			elseif k == 'type' then
				t:set_type(v)
			elseif k == 'timestamp' then
				t:set_timestamp(v)
			else
				rawset(t, k, v)
			end
		end
	}
	-- This is just to make setmetatable() fail
	mt.__metatable = mt

	return setmetatable( t, mt )
end

local function Date(arg_type, arg_jd, arg_month, arg_day)
	local d = DateWrapper({})
	-- process argument
	d:set_type(arg_type)

	if arg_jd and arg_month and arg_day  then
		d:set_date(arg_jd, arg_month, arg_day)
	elseif arg_jd then
		d:set_jd(arg_jd)
	end
	return d
end


return {
	gregorian2jd = gregorian2jd,
	jd2hijri = jd2hijri,
	hijri2jd = hijri2jd,
	hijri_days_in_month = hijri_days_in_month,
	hijri_isleap = hijri_isleap,
	hijri_yday = hijri_yday,
	jd2unix = jd2unix,
	unix2jd = unix2jd,
	jd2wday = jd2wday,
	jd2gregorian = jd2gregorian,
	gre_isleap = gre_isleap,
	gre_yday = gre_yday,
	gre_days_in_month = gre_days_in_month,
	jd2julian = jd2julian,
	julian2jd = julian2jd,
	julian_isleap = julian_isleap,
	julian_yday = julian_yday,
	julian_days_in_month = julian_days_in_month,
	gregorian2hijri = gregorian2hijri,
	hijri2gregorian = hijri2gregorian,
	Date = Date,
	hijri_check = hijri_check,
	gre_check = gre_check,
	julian_check = julian_check
}