calendar = {}
local S
if minetest.get_translator then
	S = minetest.get_translator("calendar")
else
	S = function(s) return s end
end
local F = minetest.formspec_escape

calendar.MONTH_DAYS = 30

-- Long month names
calendar.month_names = { S('January'), S('February'), S('March'), S('April'), S('May'), S('June'), S('July'), S('August'), S('September'), S('October'), S('November'), S('December') }
--calendar.month_names = { S('Spring'), S('Summer'), S('Harvest'), S('Winter') }
-- Short month names
calendar.month_names_short = { S('Jan'), S('Feb'), S('Mar'), S('Apr'), S('May'), S('Jun'), S('Jul'), S('Aug'), S('Sep'), S('Oct'), S('Nov'), S('Dec') }
--calendar.month_names_short = { S('Spr'), S('Sum'), S('Har'), S('Win') }
calendar.MONTHS = #calendar.month_names

calendar.YEAR_DAYS = calendar.MONTHS * calendar.MONTH_DAYS

-- Week day names
calendar.weekday_names = { S("Monday"), S("Tuesday"), S("Wednesday"), S("Thursday"), S("Friday"), S("Saturday"), S("Sunday") }
calendar.weekday_names_short = { S("Mo"), S("Tu"), S("We"), S("Th"), S("Fr"), S("Sa"), S("Su") }
calendar.WEEK_DAYS = #calendar.weekday_names
calendar.FIRST_WEEK_DAY = 0

local holidays = {}

-- Register a holiday.
-- def: Table with these fields:
-- * name: Human-readable name
-- * days: Cardinal month day on which the holiday occurs
-- * months: Cardinal month on which the holiday occurs
calendar.register_holiday = function(def)
	table.insert(holidays, def)
end

calendar.register_holiday({
	name = S("New Year's Eve"),
	days = 0,
	months = 0
})

calendar.get_holidays = function(total_days)
	local days, months, years = calendar.get_date(total_days)
	local found_holidays = {}
	for h=1, #holidays do
		local holiday = holidays[h]
		if holiday.days == days and holiday.months == months then
			table.insert(found_holidays, holiday)
		end
	end
	return found_holidays
end

-- Returny weekday number
-- * total_days: elapsed days since start of world
calendar.get_weekday = function(total_days)
	return (total_days + calendar.FIRST_WEEK_DAY) % calendar.WEEK_DAYS
end

-- Returns day, month, year, days in year
-- * days: elapsed days since start of world
-- * ordinal: if true, use ordinal numbers (day, month, year start counting at 1).
--            if false, use cardinal numbers (day, month, year start counting at 0).
--            default: false
calendar.get_date = function(days, ordinal)
	if not days then
		days = minetest.get_day_count()
	end

	local y = math.floor( days / calendar.YEAR_DAYS ) -- elapsed years in epoch
	local m = math.floor( days % calendar.YEAR_DAYS / calendar.MONTH_DAYS ) -- elapsed months in year
	local d = math.floor( days % calendar.YEAR_DAYS % calendar.MONTH_DAYS ) -- elapsed days in month
	local j = math.floor( days % calendar.YEAR_DAYS ) -- elapsed days in year

	if ordinal == nil then
		ordinal = false
	end
	if ordinal then
		y = y + 1
		m = m + 1
		d = d + 1
		j = j + 1
	end
	return d, m, y, j
end

calendar.get_date_string = function( str, env_date )
	if not env_date then
		env_date = minetest.get_day_count( )
	end

	if str == nil then
		str = S("%D days, %M months, %Y years")
	end

	local y, m, d, j = calendar.get_date()

	-- cardinal values
	str = string.gsub( str, "%%Y", y )	      -- elapsed years in epoch
	str = string.gsub( str, "%%M", m )	      -- elapsed months in year
	str = string.gsub( str, "%%D", d )	      -- elapsed days in month
	str = string.gsub( str, "%%J", j )	      -- elapsed days in year

	-- ordinal values
	str = string.gsub( str, "%%y", y + 1 )	  -- current year of epoch
	str = string.gsub( str, "%%m", m + 1 )	  -- current month of year
	str = string.gsub( str, "%%d", d + 1 )	  -- current day of month
	str = string.gsub( str, "%%j", j + 1 )	  -- current day of year

	str = string.gsub( str, "%%b", calendar.month_names[ m + 1 ] )       -- current month long name
	str = string.gsub( str, "%%h", calendar.month_names_short[ m + 1 ] )       -- current month short name

	str = string.gsub( str, "%%z", "%%" )

	return str
end

dofile(minetest.get_modpath("calendar").."/gui.lua")
dofile(minetest.get_modpath("calendar").."/command.lua")
dofile(minetest.get_modpath("calendar").."/node.lua")