-- Option am = 'am' does not mean the hour is AM; it means 'am' or 'pm' is used, depending on the hour,
-- and am = 'pm' has the same meaning.
-- Similarly, era = 'BC' means 'BC' is used if year <= 0.
-- BCMINUS displays a MINUS if year < 0 and the display format does not include %{era}.
-- BCNEGATIVE is similar but displays a hyphen.
local result = { bydefault = {} }
if type(options1) == 'table' then
result.am = options1.am
result.era = options1.era
elseif type(options1) == 'string' then
-- Example: 'am:AM era:BC' or 'am=AM era=BC'.
for item in options1:gmatch('%S+') do
local lhs, rhs = item:match('^(%w+)[:=](.+)$')
if lhs then
result[lhs] = rhs
end
end
end
options2 = type(options2) == 'table' and options2 or {}
local defaults = { am = 'am', era = 'BC' }
for k, v in pairs(defaults) do
if not result[k] then
if options2[k] then
result[k] = options2[k]
else
result[k] = v
result.bydefault[k] = true
end
end
end
return result
end  
local ampm_options = {
-- lhs = input text accepted as an am/pm option
-- rhs = code used internally
['am'] = 'am',
['AM'] = 'AM',
['a.m.'] = 'a.m.',
['A.M.'] = 'A.M.',
['pm'] = 'am', -- same as am
['PM'] = 'AM',
['p.m.'] = 'a.m.',
['P.M.'] = 'A.M.',
}  
local era_text = {
-- Text for displaying an era with a positive year (after adjusting
-- by replacing year with 1 - year if date.year <= 0).
-- options.era = { year<=0 , year>0 }
['BCMINUS'] = { 'BC' , '' , isbc = true, sign = MINUS },
['BCNEGATIVE'] = { 'BC' , '' , isbc = true, sign = '-' },
['BC'] = { 'BC' , '' , isbc = true },
['B.C.'] = { 'B.C.' , '' , isbc = true },
['BCE'] = { 'BCE' , '' , isbc = true },
['B.C.E.'] = { 'B.C.E.', '' , isbc = true },
['AD'] = { 'BC' , 'AD' },
['A.D.'] = { 'B.C.' , 'A.D.' },
['CE'] = { 'BCE' , 'CE' },
['C.E.'] = { 'B.C.E.', 'C.E.' },
}  
local function get_era_for_year(era, year)
return (era_text[era] or era_text['BC'])[year > 0 and 2 or 1] or ''
end  
local function strftime(date, format, options)
-- Return date formatted as a string using codes similar to those
-- in the C strftime library function.
local sformat = string.format
local shortcuts = {
['%c'] = '%-I:%M %p %-d %B %-Y %{era}', -- date and time: 2:30 pm 1 April 2016
['%x'] = '%-d %B %-Y %{era}', -- date: 1 April 2016
['%X'] = '%-I:%M %p', -- time: 2:30 pm
}
if shortcuts[format] then
format = shortcuts[format]
end
local codes = {
a = { field = 'dayabbr' },
A = { field = 'dayname' },
b = { field = 'monthabbr' },
B = { field = 'monthname' },
u = { fmt = '%d' , field = 'dowiso' },
w = { fmt = '%d' , field = 'dow' },
d = { fmt = '%02d', fmt2 = '%d', field = 'day' },
m = { fmt = '%02d', fmt2 = '%d', field = 'month' },
Y = { fmt = '%04d', fmt2 = '%d', field = 'year' },
H = { fmt = '%02d', fmt2 = '%d', field = 'hour' },
M = { fmt = '%02d', fmt2 = '%d', field = 'minute' },
S = { fmt = '%02d', fmt2 = '%d', field = 'second' },
j = { fmt = '%03d', fmt2 = '%d', field = 'dayofyear' },
I = { fmt = '%02d', fmt2 = '%d', field = 'hour', special = 'hour12' },
p = { field = 'hour', special = 'am' },
}
options = make_option_table(options, date.options)
local amopt = options.am
local eraopt = options.era
local function replace_code(spaces, modifier, id)
local code = codes[id]
if code then
local fmt = code.fmt
if modifier == '-' and code.fmt2 then
fmt = code.fmt2
end
local value = date[code.field]
if not value then
return nil -- an undefined field in a partial date
end
local special = code.special
if special then
if special == 'hour12' then
value = value % 12
value = value == 0 and 12 or value
elseif special == 'am' then
local ap = ({
['a.m.'] = { 'a.m.', 'p.m.' },
['AM'] = { 'AM', 'PM' },
['A.M.'] = { 'A.M.', 'P.M.' },
})[ampm_options[amopt]] or { 'am', 'pm' }
return (spaces == * and * or '&nbsp;') .. (value < 12 and ap[1] or ap[2])
end
end
if code.field == 'year' then
local sign = (era_text[eraopt] or {}).sign
if not sign or format:find('%{era}', 1, true) then
sign = ''
if value <= 0 then
value = 1 - value
end
else
if value >= 0 then
sign = ''
else
value = -value
end
end
return spaces .. sign .. sformat(fmt, value)
end
return spaces .. (fmt and sformat(fmt, value) or value)
end
end
local function replace_property(spaces, id)
if id == 'era' then
-- Special case so can use local era option.
local result = get_era_for_year(eraopt, date.year)
if result == '' then
return ''
end
return (spaces == * and * or '&nbsp;') .. result
end
local result = date[id]
if type(result) == 'string' then
return spaces .. result
end
if type(result) == 'number' then
return spaces .. tostring(result)
end
if type(result) == 'boolean' then
return spaces .. (result and '1' or '0')
end
-- This occurs if id is an undefined field in a partial date, or is the name of a function.
return nil
end
local PERCENT = '\127PERCENT\127'
return (format
:gsub('%%%%', PERCENT)
:gsub('(%s*)%%{(%w+)}', replace_property)
:gsub('(%s*)%%(%-?)(%a)', replace_code)
:gsub(PERCENT, '%%')
end  
local function _date_text(date, fmt, options)
-- Return a formatted string representing the given date.
if not is_date(date) then
error('date:text: need a date (use "date:text" with a colon)', 2)
end
if type(fmt) == 'string' and fmt:match('%S') then
if fmt:find('%', 1, true) then
return strftime(date, fmt, options)
end
elseif date.partial then
fmt = date.month and 'my' or 'y'
else
fmt = 'dmy'
if date.hastime then
fmt = (date.second > 0 and 'hms ' or 'hm ') .. fmt
end
end
local function bad_format
-- For consistency with other format processing, return given format
-- (or cleaned format if original was not a string) if invalid.
return mw.text.nowiki(fmt)
end
if date.partial then
-- Ignore days in standard formats like 'ymd'.
if fmt == 'ym' or fmt == 'ymd' then
fmt = date.month and '%Y-%m %{era}' or '%Y %{era}'
elseif fmt == 'my' or fmt == 'dmy' or fmt == 'mdy' then
fmt = date.month and '%B %-Y %{era}' or '%-Y %{era}'
elseif fmt == 'y' then
fmt = date.month and '%-Y %{era}' or '%-Y %{era}'
else
return bad_format
end
return strftime(date, fmt, options)
end
local function hm_fmt
local plain = make_option_table(options, date.options).bydefault.am
return plain and '%H:%M' or '%-I:%M %p'
end
local need_time = date.hastime
local t = collection
for item in fmt:gmatch('%S+') do
local f
if item == 'hm' then
f = hm_fmt
need_time = false
elseif item == 'hms' then
f = '%H:%M:%S'
need_time = false
elseif item == 'ymd' then
f = '%Y-%m-%d %{era}'
elseif item == 'mdy' then
f = '%B %-d, %-Y %{era}'
elseif item == 'dmy' then
f = '%-d %B %-Y %{era}'
else
return bad_format
end
t:add(f)
end
fmt = t:join(' ')
if need_time then
fmt = hm_fmt .. ' ' .. fmt
end
return strftime(date, fmt, options)
end  
local day_info = {
-- 0=Sun to 6=Sat
[0] = { 'Sun', 'Sunday' },
{ 'Mon', 'Monday' },
{ 'Tue', 'Tuesday' },
{ 'Wed', 'Wednesday' },
{ 'Thu', 'Thursday' },
{ 'Fri', 'Friday' },
{ 'Sat', 'Saturday' },
}  
local month_info = {
-- 1=Jan to 12=Dec
{ 'Jan', 'January' },
{ 'Feb', 'February' },
{ 'Mar', 'March' },
{ 'Apr', 'April' },
{ 'May', 'May' },
{ 'Jun', 'June' },
{ 'Jul', 'July' },
{ 'Aug', 'August' },
{ 'Sep', 'September' },
{ 'Oct', 'October' },
{ 'Nov', 'November' },
{ 'Dec', 'December' },
}  
local function name_to_number(text, translate)
if type(text) == 'string' then
return translate[text:lower]
end
end  
local function day_number(text)
return name_to_number(text, {
sun = 0, sunday = 0,
mon = 1, monday = 1,
tue = 2, tuesday = 2,
wed = 3, wednesday = 3,
thu = 4, thursday = 4,
fri = 5, friday = 5,
sat = 6, saturday = 6,
})
end  
local function month_number(text)
return name_to_number(text, {
jan = 1, january = 1,
feb = 2, february = 2,
mar = 3, march = 3,
apr = 4, april = 4,
may = 5,
jun = 6, june = 6,
jul = 7, july = 7,
aug = 8, august = 8,
sep = 9, september = 9, sept = 9,
oct = 10, october = 10,
nov = 11, november = 11,
dec = 12, december = 12,
})
end  
local function _list_text(list, fmt)
-- Return a list of formatted strings from a list of dates.
if not type(list) == 'table' then
error('date:list:text: need "list:text" with a colon', 2)
end
local result = { join = _list_join }