---------------------------------------------------------------------------------------
-- Module for date and time calculations
--
-- Version 2.2
-- Copyright (C) 2005-2006, by Jas Latrix (jastejada@yahoo.com)
-- Copyright (C) 2013-2021, by Thijs Schreijer
-- Licensed under MIT, http://opensource.org/licenses/MIT

-- The MIT License (MIT) http://opensource.org/licenses/MIT
--
-- Copyright (c) 2013-2021 Thijs Schreijer
--
-- Permission is hereby granted, free of charge, to any person obtaining a copy
-- of this software and associated documentation files (the "Software"), to deal
-- in the Software without restriction, including without limitation the rights
-- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-- copies of the Software, and to permit persons to whom the Software is
-- furnished to do so, subject to the following conditions:
--
-- The above copyright notice and this permission notice shall be included in
-- all copies or substantial portions of the Software.
--
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-- THE SOFTWARE.

--[[ CONSTANTS ]]
--
local HOURPERDAY = 24
local MINPERHOUR = 60
local MINPERDAY = 1440 -- 24*60
local SECPERMIN = 60
local SECPERHOUR = 3600 -- 60*60
local SECPERDAY = 86400 -- 24*60*60
local TICKSPERSEC = 1000000
local TICKSPERDAY = 86400000000
local TICKSPERHOUR = 3600000000
local TICKSPERMIN = 60000000
local DAYNUM_MAX = 365242500 -- Sat Jan 01 1000000 00:00:00
local DAYNUM_MIN = -365242500 -- Mon Jan 01 1000000 BCE 00:00:00
local DAYNUM_DEF = 0 -- Mon Jan 01 0001 00:00:00
local _
--[[ GLOBAL SETTINGS ]]
--
local centuryflip = 0 -- year >= centuryflip == 1900, < centuryflip == 2000
--[[ LOCAL ARE FASTER ]]
--
local type = type
local pairs = pairs
local error = error
local assert = assert
local tonumber = tonumber
local tostring = tostring
local string = string
local math = math
local os = os
local unpack = unpack or table.unpack
local setmetatable = setmetatable
local getmetatable = getmetatable
--[[ EXTRA FUNCTIONS ]]
--
local fmt = string.format
local lwr = string.lower
local rep = string.rep
local len = string.len -- luacheck: ignore
local sub = string.sub
local gsub = string.gsub
local gmatch = string.gmatch or string.gfind
local find = string.find
local ostime = os.time
local osdate = os.date
local floor = math.floor
local ceil = math.ceil
local abs = math.abs
-- removes the decimal part of a number
local function fix(n)
    n = tonumber(n)
    return n and ((n > 0 and floor or ceil)(n))
end
-- returns the modulo n % d;
local function mod(n, d)
    return n - d * floor(n / d)
end
-- is `str` in string list `tbl`, `ml` is the minimun len
local function inlist(str, tbl, ml, tn)
    local sl = len(str)
    if sl < (ml or 0) then
        return nil
    end
    str = lwr(str)
    for k, v in pairs(tbl) do
        if str == lwr(sub(v, 1, sl)) then
            if tn then
                tn[0] = k
            end
            return k
        end
    end
end
local function fnil() end
--[[ DATE FUNCTIONS ]]
--
local DATE_EPOCH -- to be set later
local sl_weekdays = {
    [0] = "Sunday",
    [1] = "Monday",
    [2] = "Tuesday",
    [3] = "Wednesday",
    [4] = "Thursday",
    [5] = "Friday",
    [6] = "Saturday",
    [7] = "Sun",
    [8] = "Mon",
    [9] = "Tue",
    [10] = "Wed",
    [11] = "Thu",
    [12] = "Fri",
    [13] = "Sat",
}
local sl_meridian = { [-1] = "AM", [1] = "PM" }
local sl_months = {
    [00] = "January",
    [01] = "February",
    [02] = "March",
    [03] = "April",
    [04] = "May",
    [05] = "June",
    [06] = "July",
    [07] = "August",
    [08] = "September",
    [09] = "October",
    [10] = "November",
    [11] = "December",
    [12] = "Jan",
    [13] = "Feb",
    [14] = "Mar",
    [15] = "Apr",
    [16] = "May",
    [17] = "Jun",
    [18] = "Jul",
    [19] = "Aug",
    [20] = "Sep",
    [21] = "Oct",
    [22] = "Nov",
    [23] = "Dec",
}
-- added the '.2'  to avoid collision, use `fix` to remove
local sl_timezone = {
    [000] = "utc",
    [0.2] = "gmt",
    [300] = "est",
    [240] = "edt",
    [360] = "cst",
    [300.2] = "cdt",
    [420] = "mst",
    [360.2] = "mdt",
    [480] = "pst",
    [420.2] = "pdt",
}
-- set the day fraction resolution
local function setticks(t)
    TICKSPERSEC = t
    TICKSPERDAY = SECPERDAY * TICKSPERSEC
    TICKSPERHOUR = SECPERHOUR * TICKSPERSEC
    TICKSPERMIN = SECPERMIN * TICKSPERSEC
end
-- is year y leap year?
local function isleapyear(y) -- y must be int!
    return (mod(y, 4) == 0 and (mod(y, 100) ~= 0 or mod(y, 400) == 0))
end
-- day since year 0
local function dayfromyear(y) -- y must be int!
    return 365 * y + floor(y / 4) - floor(y / 100) + floor(y / 400)
end
-- day number from date, month is zero base
local function makedaynum(y, m, d)
    local mm = mod(mod(m, 12) + 10, 12)
    return dayfromyear(y + floor(m / 12) - floor(mm / 10))
        + floor((mm * 306 + 5) / 10)
        + d
        - 307
    --local yy = y + floor(m/12) - floor(mm/10)
    --return dayfromyear(yy) + floor((mm*306 + 5)/10) + (d - 1)
end
-- date from day number, month is zero base
local function breakdaynum(g)
    local g = g + 306
    local y = floor((10000 * g + 14780) / 3652425)
    local d = g - dayfromyear(y)
    if d < 0 then
        y = y - 1
        d = g - dayfromyear(y)
    end
    local mi = floor((100 * d + 52) / 3060)
    return (floor((mi + 2) / 12) + y),
        mod(mi + 2, 12),
        (d - floor((mi * 306 + 5) / 10) + 1)
end
--[[ for floats or int32 Lua Number data type
  local function breakdaynum2(g)
    local g, n = g + 306;
    local n400 = floor(g/DI400Y);n = mod(g,DI400Y);
    local n100 = floor(n/DI100Y);n = mod(n,DI100Y);
    local n004 = floor(n/DI4Y);   n = mod(n,DI4Y);
    local n001 = floor(n/365);   n = mod(n,365);
    local y = (n400*400) + (n100*100) + (n004*4) + n001  - ((n001 == 4 or n100 == 4) and 1 or 0)
    local d = g - dayfromyear(y)
    local mi = floor((100*d + 52)/3060)
    return (floor((mi + 2)/12) + y), mod(mi + 2,12), (d - floor((mi*306 + 5)/10) + 1)
  end
  ]]
-- day fraction from time
local function makedayfrc(h, r, s, t)
    return ((h * 60 + r) * 60 + s) * TICKSPERSEC + t
end
-- time from day fraction
local function breakdayfrc(df)
    return mod(floor(df / TICKSPERHOUR), HOURPERDAY),
        mod(floor(df / TICKSPERMIN), MINPERHOUR),
        mod(floor(df / TICKSPERSEC), SECPERMIN),
        mod(df, TICKSPERSEC)
end
-- weekday sunday = 0, monday = 1 ...
local function weekday(dn)
    return mod(dn + 1, 7)
end
-- yearday 0 based ...
local function yearday(dn)
    return dn - dayfromyear((breakdaynum(dn)) - 1)
end
-- parse v as a month
local function getmontharg(v)
    local m = tonumber(v)
    return (m and fix(m - 1)) or inlist(tostring(v) or "", sl_months, 2)
end
-- get daynum of isoweek one of year y
local function isow1(y)
    local f = makedaynum(y, 0, 4) -- get the date for the 4-Jan of year `y`
    local d = weekday(f)
    d = d == 0 and 7 or d -- get the ISO day number, 1 == Monday, 7 == Sunday
    return f + (1 - d)
end
local function isowy(dn)
    local w1
    local y = (breakdaynum(dn))
    if dn >= makedaynum(y, 11, 29) then
        w1 = isow1(y + 1)
        if dn < w1 then
            w1 = isow1(y)
        else
            y = y + 1
        end
    else
        w1 = isow1(y)
        if dn < w1 then
            w1 = isow1(y - 1)
            y = y - 1
        end
    end
    return floor((dn - w1) / 7) + 1, y
end
local function isoy(dn)
    local y = (breakdaynum(dn))
    return y
        + (
            ((dn >= makedaynum(y, 11, 29)) and (dn >= isow1(y + 1))) and 1
            or (dn < isow1(y) and -1 or 0)
        )
end
local function makedaynum_isoywd(y, w, d)
    return isow1(y) + 7 * w + d - 8 -- simplified: isow1(y) + ((w-1)*7) + (d-1)
end
--[[ THE DATE MODULE ]]
--
local fmtstr = "%x %X"
--#if not DATE_OBJECT_AFX then
local date = {}
setmetatable(date, date)
-- Version:  VMMMRRRR; V-Major, M-Minor, R-Revision;  e.g. 5.45.321 == 50450321
do
    local major = 2
    local minor = 2
    local revision = 0
    date.version = major * 10000000 + minor * 10000 + revision
end
--#end -- not DATE_OBJECT_AFX
--[[ THE DATE OBJECT ]]
--
local dobj = {}
dobj.__index = dobj
dobj.__metatable = dobj
-- shout invalid arg
local function date_error_arg()
    return error("invalid argument(s)", 0)
end
-- create new date object
local function date_new(dn, df)
    return setmetatable({ daynum = dn, dayfrc = df }, dobj)
end

--#if not NO_LOCAL_TIME_SUPPORT then
-- magic year table
local date_epoch, yt
local function getequivyear(y)
    assert(not yt)
    yt = {}
    local de = date_epoch:copy()
    local dw, dy
    for _ = 0, 3000 do
        de:setyear(de:getyear() + 1, 1, 1)
        dy = de:getyear()
        dw = de:getweekday() * (isleapyear(dy) and -1 or 1)
        if not yt[dw] then
            yt[dw] = dy
        end --print(de)
        if
            yt[1]
            and yt[2]
            and yt[3]
            and yt[4]
            and yt[5]
            and yt[6]
            and yt[7]
            and yt[-1]
            and yt[-2]
            and yt[-3]
            and yt[-4]
            and yt[-5]
            and yt[-6]
            and yt[-7]
        then
            getequivyear = function(y)
                return yt[(weekday(makedaynum(y, 0, 1)) + 1) * (isleapyear(y) and -1 or 1)]
            end
            return getequivyear(y)
        end
    end
end
-- TimeValue from date and time
local function totv(y, m, d, h, r, s)
    return (makedaynum(y, m, d) - DATE_EPOCH) * SECPERDAY
        + ((h * 60 + r) * 60 + s)
end
-- TimeValue from TimeTable
local function tmtotv(tm)
    return tm and totv(tm.year, tm.month - 1, tm.day, tm.hour, tm.min, tm.sec)
end
-- Returns the bias in seconds of utc time daynum and dayfrc
local function getbiasutc2(self)
    local y, m, d = breakdaynum(self.daynum)
    local h, r, s = breakdayfrc(self.dayfrc)
    local tvu = totv(y, m, d, h, r, s) -- get the utc TimeValue of date and time
    local tml = osdate("*t", tvu) -- get the local TimeTable of tvu
    if not tml or (tml.year > (y + 1) or tml.year < (y - 1)) then -- failed try the magic
        y = getequivyear(y)
        tvu = totv(y, m, d, h, r, s)
        tml = osdate("*t", tvu)
    end
    local tvl = tmtotv(tml)
    if tvu and tvl then
        return tvu - tvl, tvu, tvl
    else
        return error("failed to get bias from utc time")
    end
end
-- Returns the bias in seconds of local time daynum and dayfrc
local function getbiasloc2(daynum, dayfrc)
    local tvu
    -- extract date and time
    local y, m, d = breakdaynum(daynum)
    local h, r, s = breakdayfrc(dayfrc)
    -- get equivalent TimeTable
    local tml = { year = y, month = m + 1, day = d, hour = h, min = r, sec = s }
    -- get equivalent TimeValue
    local tvl = tmtotv(tml)

    local function chkutc()
        tml.isdst = nil
        local tvug = ostime(tml)
        if tvug and (tvl == tmtotv(osdate("*t", tvug))) then
            tvu = tvug
            return
        end
        tml.isdst = true
        local tvud = ostime(tml)
        if tvud and (tvl == tmtotv(osdate("*t", tvud))) then
            tvu = tvud
            return
        end
        tvu = tvud or tvug
    end
    chkutc()
    if not tvu then
        tml.year = getequivyear(y)
        tvl = tmtotv(tml)
        chkutc()
    end
    return ((tvu and tvl) and (tvu - tvl)) or error(
        "failed to get bias from local time"
    ),
        tvu,
        tvl
end
--#end -- not NO_LOCAL_TIME_SUPPORT

--#if not DATE_OBJECT_AFX then
-- the date parser
local strwalker = {} -- ^Lua regular expression is not as powerful as Perl$
strwalker.__index = strwalker
local function newstrwalker(s)
    return setmetatable({ s = s, i = 1, e = 1, c = len(s) }, strwalker)
end
function strwalker:aimchr()
    return "\n" .. self.s .. "\n" .. rep(".", self.e - 1) .. "^"
end
function strwalker:finish()
    return self.i > self.c
end
function strwalker:back()
    self.i = self.e
    return self
end
function strwalker:restart()
    self.i, self.e = 1, 1
    return self
end
function strwalker:match(s)
    return (find(self.s, s, self.i))
end
function strwalker:__call(s, f) -- print("strwalker:__call "..s..self:aimchr())
    local is, ie
    is, ie, self[1], self[2], self[3], self[4], self[5] = find(
        self.s,
        s,
        self.i
    )
    if is then
        self.e, self.i = self.i, 1 + ie
        if f then
            f(unpack(self))
        end
        return self
    end
end
local function date_parse(str)
    local y, m, d, h, r, s, z, w, u, j, e, x, c, dn, df
    local sw = newstrwalker(gsub(gsub(str, "(%b())", ""), "^(%s*)", "")) -- remove comment, trim leading space
    --local function error_out() print(y,m,d,h,r,s) end
    local function error_dup(q) --[[error_out()]]
        error("duplicate value: " .. (q or "") .. sw:aimchr())
    end
    local function error_syn(q) --[[error_out()]]
        error("syntax error: " .. (q or "") .. sw:aimchr())
    end
    local function error_inv(q) --[[error_out()]]
        error("invalid date: " .. (q or "") .. sw:aimchr())
    end
    local function sety(q)
        y = y and error_dup() or tonumber(q)
    end
    local function setm(q)
        m = (m or w or j) and error_dup(m or w or j) or tonumber(q)
    end
    local function setd(q)
        d = d and error_dup() or tonumber(q)
    end
    local function seth(q)
        h = h and error_dup() or tonumber(q)
    end
    local function setr(q)
        r = r and error_dup() or tonumber(q)
    end
    local function sets(q)
        s = s and error_dup() or tonumber(q)
    end
    local function adds(q)
        s = s + tonumber(q)
    end
    local function setj(q)
        j = (m or w or j) and error_dup() or tonumber(q)
    end
    local function setz(q)
        z = (z ~= 0 and z) and error_dup() or q
    end
    local function setzn(zs, zn)
        zn = tonumber(zn)
        setz(
            ((zn < 24) and (zn * 60) or (mod(zn, 100) + floor(zn / 100) * 60))
                * (zs == "+" and -1 or 1)
        )
    end
    local function setzc(zs, zh, zm)
        setz(((tonumber(zh) * 60) + tonumber(zm)) * (zs == "+" and -1 or 1))
    end

    if
        not (
            sw("^(%d%d%d%d)", sety)
            and (sw("^(%-?)(%d%d)%1(%d%d)", function(_, a, b)
                setm(tonumber(a))
                setd(tonumber(b))
            end) or sw("^(%-?)[Ww](%d%d)%1(%d?)", function(_, a, b)
                w, u = tonumber(a), tonumber(b or 1)
            end) or sw("^%-?(%d%d%d)", setj) or sw(
                "^%-?(%d%d)",
                function(a)
                    setm(a)
                    setd(1)
                end
            ))
            and (
                (
                    sw("^%s*[Tt]?(%d%d):?", seth)
                    and sw("^(%d%d):?", setr)
                    and sw("^(%d%d)", sets)
                    and sw("^(%.%d+)", adds)
                )
                or sw:finish()
                or (
                    sw("^%s*$")
                    or sw("^%s*[Zz]%s*$")
                    or sw("^%s-([%+%-])(%d%d):?(%d%d)%s*$", setzc)
                    or sw("^%s*([%+%-])(%d%d)%s*$", setzn)
                )
            )
        )
    then --print(y,m,d,h,r,s,z,w,u,j)
        sw:restart()
        y, m, d, h, r, s, z, w, u, j =
            nil, nil, nil, nil, nil, nil, nil, nil, nil, nil
        repeat -- print(sw:aimchr())
            if sw("^[tT:]?%s*(%d%d?):", seth) then --print("$Time")
                _ = sw("^%s*(%d%d?)", setr)
                    and sw("^%s*:%s*(%d%d?)", sets)
                    and sw("^(%.%d+)", adds)
            elseif sw("^(%d+)[/\\%s,-]?%s*") then --print("$Digits")
                x, c = tonumber(sw[1]), len(sw[1])
                if (x >= 70) or (m and d and not y) or (c > 3) then
                    sety(
                        x
                            + (
                                (x >= 100 or c > 3) and 0
                                or x < centuryflip and 2000
                                or 1900
                            )
                    )
                else
                    if m then
                        setd(x)
                    else
                        m = x
                    end
                end
            elseif sw("^(%a+)[/\\%s,-]?%s*") then --print("$Words")
                x = sw[1]
                if inlist(x, sl_months, 2, sw) then
                    if m and not d and not y then
                        d, m = m, false
                    end
                    setm(mod(sw[0], 12) + 1)
                elseif inlist(x, sl_timezone, 2, sw) then
                    c = fix(sw[0]) -- ignore gmt and utc
                    if c ~= 0 then
                        setz(c, x)
                    end
                elseif not inlist(x, sl_weekdays, 2, sw) then
                    sw:back()
                    -- am pm bce ad ce bc
                    if
                        sw("^([bB])%s*(%.?)%s*[Cc]%s*(%2)%s*[Ee]%s*(%2)%s*")
                        or sw("^([bB])%s*(%.?)%s*[Cc]%s*(%2)%s*")
                    then
                        e = e and error_dup() or -1
                    elseif
                        sw("^([aA])%s*(%.?)%s*[Dd]%s*(%2)%s*")
                        or sw("^([cC])%s*(%.?)%s*[Ee]%s*(%2)%s*")
                    then
                        e = e and error_dup() or 1
                    elseif sw("^([PApa])%s*(%.?)%s*[Mm]?%s*(%2)%s*") then
                        x = lwr(sw[1]) -- there should be hour and it must be correct
                        if not h or (h > 12) or (h < 0) then
                            return error_inv()
                        end
                        if x == "a" and h == 12 then
                            h = 0
                        end -- am
                        if x == "p" and h ~= 12 then
                            h = h + 12
                        end -- pm
                    else
                        error_syn()
                    end
                end
            elseif
                not (
                    sw("^([+-])(%d%d?):(%d%d)", setzc)
                    or sw("^([+-])(%d+)", setzn)
                    or sw("^[Zz]%s*$")
                )
            then -- sw{"([+-])",{"(%d%d?):(%d%d)","(%d+)"}}
                error_syn("?")
            end
            sw("^%s*")
        until sw:finish()
        --else print("$Iso(Date|Time|Zone)")
    end
    -- if date is given, it must be complete year, month & day
    if
        (not y and not h)
        or ((m and not d) or (d and not m))
        or ((m and w) or (m and j) or (j and w))
    then
        return error_inv("!")
    end
    -- fix month
    if m then
        m = m - 1
    end
    -- fix year if we are on BCE
    if e and e < 0 and y > 0 then
        y = 1 - y
    end
    --  create date object
    dn = (
            y
            and (
                (w and makedaynum_isoywd(y, w, u))
                or (j and makedaynum(y, 0, j))
                or makedaynum(y, m, d)
            )
        ) or DAYNUM_DEF
    df = makedayfrc(h or 0, r or 0, s or 0, 0) + ((z or 0) * TICKSPERMIN)
    --print("Zone",h,r,s,z,m,d,y,df)
    return date_new(dn, df) -- no need to :normalize();
end
local function date_fromtable(v)
    local y, m, d = fix(v.year), getmontharg(v.month), fix(v.day)
    local h, r, s, t =
        tonumber(v.hour), tonumber(v.min), tonumber(v.sec), tonumber(v.ticks)
    -- atleast there is time or complete date
    if (y or m or d) and not (y and m and d) then
        return error("incomplete table")
    end
    return (y or h or r or s or t)
        and date_new(
            y and makedaynum(y, m, d) or DAYNUM_DEF,
            makedayfrc(h or 0, r or 0, s or 0, t or 0)
        )
end
local tmap = {
    ["number"] = function(v)
        return date_epoch:copy():addseconds(v)
    end,
    ["string"] = function(v)
        return date_parse(v)
    end,
    ["boolean"] = function(v)
        return date_fromtable(osdate(v and "!*t" or "*t"))
    end,
    ["table"] = function(v)
        local ref = getmetatable(v) == dobj
        return ref and v or date_fromtable(v), ref
    end,
}
local function date_getdobj(v)
    local o, r = (tmap[type(v)] or fnil)(v)
    return (o and o:normalize() or error("invalid date time value")), r -- if r is true then o is a reference to a date obj
end
--#end -- not DATE_OBJECT_AFX
local function date_from(arg1, arg2, arg3, arg4, arg5, arg6, arg7)
    local y, m, d = fix(arg1), getmontharg(arg2), fix(arg3)
    local h, r, s, t =
        tonumber(arg4 or 0),
        tonumber(arg5 or 0),
        tonumber(arg6 or 0),
        tonumber(arg7 or 0)
    if y and m and d and h and r and s and t then
        return date_new(makedaynum(y, m, d), makedayfrc(h, r, s, t)):normalize()
    else
        return date_error_arg()
    end
end

--[[ THE DATE OBJECT METHODS ]]
--
function dobj:normalize()
    local dn, df = fix(self.daynum), self.dayfrc
    self.daynum, self.dayfrc =
        dn + floor(df / TICKSPERDAY), mod(df, TICKSPERDAY)
    return (dn >= DAYNUM_MIN and dn <= DAYNUM_MAX) and self
        or error("date beyond imposed limits:" .. self)
end

function dobj:getdate()
    local y, m, d = breakdaynum(self.daynum)
    return y, m + 1, d
end
function dobj:gettime()
    return breakdayfrc(self.dayfrc)
end

function dobj:getclockhour()
    local h = self:gethours()
    return h > 12 and mod(h, 12) or (h == 0 and 12 or h)
end

function dobj:getyearday()
    return yearday(self.daynum) + 1
end
function dobj:getweekday()
    return weekday(self.daynum) + 1
end -- in lua weekday is sunday = 1, monday = 2 ...

function dobj:getyear()
    local r, _, _ = breakdaynum(self.daynum)
    return r
end
function dobj:getmonth()
    local _, r, _ = breakdaynum(self.daynum)
    return r + 1
end -- in lua month is 1 base
function dobj:getday()
    local _, _, r = breakdaynum(self.daynum)
    return r
end
function dobj:gethours()
    return mod(floor(self.dayfrc / TICKSPERHOUR), HOURPERDAY)
end
function dobj:getminutes()
    return mod(floor(self.dayfrc / TICKSPERMIN), MINPERHOUR)
end
function dobj:getseconds()
    return mod(floor(self.dayfrc / TICKSPERSEC), SECPERMIN)
end
function dobj:getfracsec()
    return mod(floor(self.dayfrc / TICKSPERSEC), SECPERMIN)
        + (mod(self.dayfrc, TICKSPERSEC) / TICKSPERSEC)
end
function dobj:getticks(u)
    local x = mod(self.dayfrc, TICKSPERSEC)
    return u and ((x * u) / TICKSPERSEC) or x
end

function dobj:getweeknumber(wdb)
    local wd, yd = weekday(self.daynum), yearday(self.daynum)
    if wdb then
        wdb = tonumber(wdb)
        if wdb then
            wd = mod(wd - (wdb - 1), 7) -- shift the week day base
        else
            return date_error_arg()
        end
    end
    return (yd < wd and 0) or (floor(yd / 7) + ((mod(yd, 7) >= wd) and 1 or 0))
end

function dobj:getisoweekday()
    return mod(weekday(self.daynum) - 1, 7) + 1
end -- sunday = 7, monday = 1 ...
function dobj:getisoweeknumber()
    return (isowy(self.daynum))
end
function dobj:getisoyear()
    return isoy(self.daynum)
end
function dobj:getisodate()
    local w, y = isowy(self.daynum)
    return y, w, self:getisoweekday()
end
function dobj:setisoyear(y, w, d)
    local cy, cw, cd = self:getisodate()
    if y then
        cy = fix(tonumber(y))
    end
    if w then
        cw = fix(tonumber(w))
    end
    if d then
        cd = fix(tonumber(d))
    end
    if cy and cw and cd then
        self.daynum = makedaynum_isoywd(cy, cw, cd)
        return self:normalize()
    else
        return date_error_arg()
    end
end

function dobj:setisoweekday(d)
    return self:setisoyear(nil, nil, d)
end
function dobj:setisoweeknumber(w, d)
    return self:setisoyear(nil, w, d)
end

function dobj:setyear(y, m, d)
    local cy, cm, cd = breakdaynum(self.daynum)
    if y then
        cy = fix(tonumber(y))
    end
    if m then
        cm = getmontharg(m)
    end
    if d then
        cd = fix(tonumber(d))
    end
    if cy and cm and cd then
        self.daynum = makedaynum(cy, cm, cd)
        return self:normalize()
    else
        return date_error_arg()
    end
end

function dobj:setmonth(m, d)
    return self:setyear(nil, m, d)
end
function dobj:setday(d)
    return self:setyear(nil, nil, d)
end

function dobj:sethours(h, m, s, t)
    local ch, cm, cs, ck = breakdayfrc(self.dayfrc)
    ch, cm, cs, ck =
        tonumber(h or ch),
        tonumber(m or cm),
        tonumber(s or cs),
        tonumber(t or ck)
    if ch and cm and cs and ck then
        self.dayfrc = makedayfrc(ch, cm, cs, ck)
        return self:normalize()
    else
        return date_error_arg()
    end
end

function dobj:setminutes(m, s, t)
    return self:sethours(nil, m, s, t)
end
function dobj:setseconds(s, t)
    return self:sethours(nil, nil, s, t)
end
function dobj:setticks(t)
    return self:sethours(nil, nil, nil, t)
end

function dobj:spanticks()
    return (self.daynum * TICKSPERDAY + self.dayfrc)
end
function dobj:spanseconds()
    return (self.daynum * TICKSPERDAY + self.dayfrc) / TICKSPERSEC
end
function dobj:spanminutes()
    return (self.daynum * TICKSPERDAY + self.dayfrc) / TICKSPERMIN
end
function dobj:spanhours()
    return (self.daynum * TICKSPERDAY + self.dayfrc) / TICKSPERHOUR
end
function dobj:spandays()
    return (self.daynum * TICKSPERDAY + self.dayfrc) / TICKSPERDAY
end

function dobj:addyears(y, m, d)
    local cy, cm, cd = breakdaynum(self.daynum)
    if y then
        y = fix(tonumber(y))
    else
        y = 0
    end
    if m then
        m = fix(tonumber(m))
    else
        m = 0
    end
    if d then
        d = fix(tonumber(d))
    else
        d = 0
    end
    if y and m and d then
        self.daynum = makedaynum(cy + y, cm + m, cd + d)
        return self:normalize()
    else
        return date_error_arg()
    end
end

function dobj:addmonths(m, d)
    return self:addyears(nil, m, d)
end

local function dobj_adddayfrc(self, n, pt, pd)
    n = tonumber(n)
    if n then
        local x = floor(n / pd)
        self.daynum = self.daynum + x
        self.dayfrc = self.dayfrc + (n - x * pd) * pt
        return self:normalize()
    else
        return date_error_arg()
    end
end
function dobj:adddays(n)
    return dobj_adddayfrc(self, n, TICKSPERDAY, 1)
end
function dobj:addhours(n)
    return dobj_adddayfrc(self, n, TICKSPERHOUR, HOURPERDAY)
end
function dobj:addminutes(n)
    return dobj_adddayfrc(self, n, TICKSPERMIN, MINPERDAY)
end
function dobj:addseconds(n)
    return dobj_adddayfrc(self, n, TICKSPERSEC, SECPERDAY)
end
function dobj:addticks(n)
    return dobj_adddayfrc(self, n, 1, TICKSPERDAY)
end
local tvspec = {
    -- Abbreviated weekday name (Sun)
    ["%a"] = function(self)
        return sl_weekdays[weekday(self.daynum) + 7]
    end,
    -- Full weekday name (Sunday)
    ["%A"] = function(self)
        return sl_weekdays[weekday(self.daynum)]
    end,
    -- Abbreviated month name (Dec)
    ["%b"] = function(self)
        return sl_months[self:getmonth() - 1 + 12]
    end,
    -- Full month name (December)
    ["%B"] = function(self)
        return sl_months[self:getmonth() - 1]
    end,
    -- Year/100 (19, 20, 30)
    ["%C"] = function(self)
        return fmt("%.2d", fix(self:getyear() / 100))
    end,
    -- The day of the month as a number (range 1 - 31)
    ["%d"] = function(self)
        return fmt("%.2d", self:getday())
    end,
    -- year for ISO 8601 week, from 00 (79)
    ["%g"] = function(self)
        return fmt("%.2d", mod(self:getisoyear(), 100))
    end,
    -- year for ISO 8601 week, from 0000 (1979)
    ["%G"] = function(self)
        return fmt("%.4d", self:getisoyear())
    end,
    -- same as %b
    ["%h"] = function(self)
        return self:fmt0("%b")
    end,
    -- hour of the 24-hour day, from 00 (06)
    ["%H"] = function(self)
        return fmt("%.2d", self:gethours())
    end,
    -- The  hour as a number using a 12-hour clock (01 - 12)
    ["%I"] = function(self)
        return fmt("%.2d", self:getclockhour())
    end,
    -- The day of the year as a number (001 - 366)
    ["%j"] = function(self)
        return fmt("%.3d", self:getyearday())
    end,
    -- Month of the year, from 01 to 12
    ["%m"] = function(self)
        return fmt("%.2d", self:getmonth())
    end,
    -- Minutes after the hour 55
    ["%M"] = function(self)
        return fmt("%.2d", self:getminutes())
    end,
    -- AM/PM indicator (AM)
    ["%p"] = function(self)
        return sl_meridian[self:gethours() > 11 and 1 or -1]
    end, --AM/PM indicator (AM)
    -- The second as a number (59, 20 , 01)
    ["%S"] = function(self)
        return fmt("%.2d", self:getseconds())
    end,
    -- ISO 8601 day of the week, to 7 for Sunday (7, 1)
    ["%u"] = function(self)
        return self:getisoweekday()
    end,
    -- Sunday week of the year, from 00 (48)
    ["%U"] = function(self)
        return fmt("%.2d", self:getweeknumber())
    end,
    -- ISO 8601 week of the year, from 01 (48)
    ["%V"] = function(self)
        return fmt("%.2d", self:getisoweeknumber())
    end,
    -- The day of the week as a decimal, Sunday being 0
    ["%w"] = function(self)
        return self:getweekday() - 1
    end,
    -- Monday week of the year, from 00 (48)
    ["%W"] = function(self)
        return fmt("%.2d", self:getweeknumber(2))
    end,
    -- The year as a number without a century (range 00 to 99)
    ["%y"] = function(self)
        return fmt("%.2d", mod(self:getyear(), 100))
    end,
    -- Year with century (2000, 1914, 0325, 0001)
    ["%Y"] = function(self)
        return fmt("%.4d", self:getyear())
    end,
    -- Time zone offset, the date object is assumed local time (+1000, -0230)
    ["%z"] = function(self)
        local b = -self:getbias()
        local x = abs(b)
        return fmt(
            "%s%.4d",
            b < 0 and "-" or "+",
            fix(x / 60) * 100 + floor(mod(x, 60))
        )
    end,
    -- Time zone name, the date object is assumed local time
    ["%Z"] = function(self)
        return self:gettzname()
    end,
    -- Misc --
    -- Year, if year is in BCE, prints the BCE Year representation, otherwise result is similar to "%Y" (1 BCE, 40 BCE)
    ["%\b"] = function(self)
        local x = self:getyear()
        return fmt("%.4d%s", x > 0 and x or (-x + 1), x > 0 and "" or " BCE")
    end,
    -- Seconds including fraction (59.998, 01.123)
    ["%\f"] = function(self)
        local x = self:getfracsec()
        return fmt("%s%.9f", x >= 10 and "" or "0", x)
    end,
    -- percent character %
    ["%%"] = function(self)
        return "%"
    end,
    -- Group Spec --
    -- 12-hour time, from 01:00:00 AM (06:55:15 AM); same as "%I:%M:%S %p"
    ["%r"] = function(self)
        return self:fmt0("%I:%M:%S %p")
    end,
    -- hour:minute, from 01:00 (06:55); same as "%I:%M"
    ["%R"] = function(self)
        return self:fmt0("%I:%M")
    end,
    -- 24-hour time, from 00:00:00 (06:55:15); same as "%H:%M:%S"
    ["%T"] = function(self)
        return self:fmt0("%H:%M:%S")
    end,
    -- month/day/year from 01/01/00 (12/02/79); same as "%m/%d/%y"
    ["%D"] = function(self)
        return self:fmt0("%m/%d/%y")
    end,
    -- year-month-day (1979-12-02); same as "%Y-%m-%d"
    ["%F"] = function(self)
        return self:fmt0("%Y-%m-%d")
    end,
    -- The preferred date and time representation;  same as "%x %X"
    ["%c"] = function(self)
        return self:fmt0("%x %X")
    end,
    -- The preferred date representation, same as "%a %b %d %\b"
    ["%x"] = function(self)
        return self:fmt0("%a %b %d %\b")
    end,
    -- The preferred time representation, same as "%H:%M:%\f"
    ["%X"] = function(self)
        return self:fmt0("%H:%M:%\f")
    end,
    -- GroupSpec --
    -- Iso format, same as "%Y-%m-%dT%T"
    ["${iso}"] = function(self)
        return self:fmt0("%Y-%m-%dT%T")
    end,
    -- http format, same as "%a, %d %b %Y %T GMT"
    ["${http}"] = function(self)
        return self:fmt0("%a, %d %b %Y %T GMT")
    end,
    -- ctime format, same as "%a %b %d %T GMT %Y"
    ["${ctime}"] = function(self)
        return self:fmt0("%a %b %d %T GMT %Y")
    end,
    -- RFC850 format, same as "%A, %d-%b-%y %T GMT"
    ["${rfc850}"] = function(self)
        return self:fmt0("%A, %d-%b-%y %T GMT")
    end,
    -- RFC1123 format, same as "%a, %d %b %Y %T GMT"
    ["${rfc1123}"] = function(self)
        return self:fmt0("%a, %d %b %Y %T GMT")
    end,
    -- asctime format, same as "%a %b %d %T %Y"
    ["${asctime}"] = function(self)
        return self:fmt0("%a %b %d %T %Y")
    end,
}
function dobj:fmt0(str)
    return (
            gsub(str, "%%[%a%%\b\f]", function(x)
                local f = tvspec[x]
                return (f and f(self)) or x
            end)
        )
end
function dobj:fmt(str)
    str = str or self.fmtstr or fmtstr
    return self:fmt0(
        (gmatch(str, "${%w+}"))
                and (gsub(str, "${%w+}", function(x)
                    local f = tvspec[x]
                    return (f and f(self)) or x
                end))
            or str
    )
end

function dobj.__lt(a, b)
    if a.daynum == b.daynum then
        return (a.dayfrc < b.dayfrc)
    else
        return (a.daynum < b.daynum)
    end
end
function dobj.__le(a, b)
    if a.daynum == b.daynum then
        return (a.dayfrc <= b.dayfrc)
    else
        return (a.daynum <= b.daynum)
    end
end
function dobj.__eq(a, b)
    return (a.daynum == b.daynum) and (a.dayfrc == b.dayfrc)
end
function dobj.__sub(a, b)
    local d1, d2 = date_getdobj(a), date_getdobj(b)
    local d0 = d1
        and d2
        and date_new(d1.daynum - d2.daynum, d1.dayfrc - d2.dayfrc)
    return d0 and d0:normalize()
end
function dobj.__add(a, b)
    local d1, d2 = date_getdobj(a), date_getdobj(b)
    local d0 = d1
        and d2
        and date_new(d1.daynum + d2.daynum, d1.dayfrc + d2.dayfrc)
    return d0 and d0:normalize()
end
function dobj.__concat(a, b)
    return tostring(a) .. tostring(b)
end
function dobj:__tostring()
    return self:fmt()
end

function dobj:copy()
    return date_new(self.daynum, self.dayfrc)
end

--[[ THE LOCAL DATE OBJECT METHODS ]]
--
function dobj:tolocal()
    local dn, df = self.daynum, self.dayfrc
    local bias = getbiasutc2(self)
    if bias then
        -- utc = local + bias; local = utc - bias
        self.daynum = dn
        self.dayfrc = df - bias * TICKSPERSEC
        return self:normalize()
    else
        return nil
    end
end

function dobj:toutc()
    local dn, df = self.daynum, self.dayfrc
    local bias = getbiasloc2(dn, df)
    if bias then
        -- utc = local + bias;
        self.daynum = dn
        self.dayfrc = df + bias * TICKSPERSEC
        return self:normalize()
    else
        return nil
    end
end

function dobj:getbias()
    return (getbiasloc2(self.daynum, self.dayfrc)) / SECPERMIN
end

function dobj:gettzname()
    local _, tvu, _ = getbiasloc2(self.daynum, self.dayfrc)
    return tvu and osdate("%Z", tvu) or ""
end

--#if not DATE_OBJECT_AFX then
function date.time(h, r, s, t)
    h, r, s, t =
        tonumber(h or 0), tonumber(r or 0), tonumber(s or 0), tonumber(t or 0)
    if h and r and s and t then
        return date_new(DAYNUM_DEF, makedayfrc(h, r, s, t))
    else
        return date_error_arg()
    end
end

function date:__call(arg1, ...)
    local arg_count = select("#", ...) + (arg1 == nil and 0 or 1)
    if arg_count > 1 then
        return (date_from(arg1, ...))
    elseif arg_count == 0 then
        return (date_getdobj(false))
    else
        local o, r = date_getdobj(arg1)
        return r and o:copy() or o
    end
end

date.diff = dobj.__sub

function date.isleapyear(v)
    local y = fix(v)
    if not y then
        y = date_getdobj(v)
        y = y and y:getyear()
    end
    return isleapyear(y + 0)
end

function date.epoch()
    return date_epoch:copy()
end

function date.isodate(y, w, d)
    return date_new(
        makedaynum_isoywd(y + 0, w and (w + 0) or 1, d and (d + 0) or 1),
        0
    )
end
function date.setcenturyflip(y)
    if y ~= floor(y) or y < 0 or y > 100 then
        date_error_arg()
    end
    centuryflip = y
end
function date.getcenturyflip()
    return centuryflip
end

-- Internal functions
function date.fmt(str)
    if str then
        fmtstr = str
    end
    return fmtstr
end
function date.daynummin(n)
    DAYNUM_MIN = (n and n < DAYNUM_MAX) and n or DAYNUM_MIN
    return n and DAYNUM_MIN or date_new(DAYNUM_MIN, 0):normalize()
end
function date.daynummax(n)
    DAYNUM_MAX = (n and n > DAYNUM_MIN) and n or DAYNUM_MAX
    return n and DAYNUM_MAX or date_new(DAYNUM_MAX, 0):normalize()
end
function date.ticks(t)
    if t then
        setticks(t)
    end
    return TICKSPERSEC
end
--#end -- not DATE_OBJECT_AFX

local tm = osdate("!*t", 0)
if tm then
    date_epoch = date_new(
        makedaynum(tm.year, tm.month - 1, tm.day),
        makedayfrc(tm.hour, tm.min, tm.sec, 0)
    )
    -- the distance from our epoch to os epoch in daynum
    DATE_EPOCH = date_epoch and date_epoch:spandays()
else -- error will be raise only if called!
    date_epoch = setmetatable({}, {
        __index = function()
            error("failed to get the epoch date")
        end,
    })
end

--#if not DATE_OBJECT_AFX then
return date
--#else
--$return date_from
--#end