X-Git-Url: https://git.madduck.net/etc/awesome.git/blobdiff_plain/3a7693d5c89981e1230d0d49163fc23d02224873..6db06b57e851ec08d5355f015d6df1ebe58b4982:/src/timetable.lua

diff --git a/src/timetable.lua b/src/timetable.lua
index 7e986a1..d1cd534 100644
--- a/src/timetable.lua
+++ b/src/timetable.lua
@@ -1,3 +1,4 @@
+local strformat = string.format
 local floor = math.floor
 local function idiv ( n , d )
 	return floor ( n / d )
@@ -20,6 +21,7 @@ local function year_length ( y )
 end
 
 local function month_length ( m , y )
+	m = ( m - 1 ) % 12 + 1
 	if m == 2 then
 		return is_leap ( y ) and 29 or 28
 	else
@@ -27,9 +29,13 @@ local function month_length ( m , y )
 	end
 end
 
+local function leap_years_since ( year )
+	return idiv ( year , 4 ) - idiv ( year , 100 ) + idiv ( year , 400 )
+end
+
 local function doomsday ( year )
 	return ( 3 -- Tuesday
-		- 1 + year + idiv ( year , 4 ) - idiv ( year , 100 ) + idiv ( year , 400 ) )
+		- 1 + year + leap_years_since ( year ) )
 		% 7 + 1
 end
 local doomsday_cache = setmetatable ( { } , {
@@ -69,7 +75,9 @@ local function unpack_tm ( tm )
 		assert ( tm.day   , "day required" ) ,
 		tm.hour or 12 ,
 		tm.min  or 0 ,
-		tm.sec  or 0
+		tm.sec  or 0 ,
+		tm.yday ,
+		tm.wday
 end
 
 -- Modify parameters so they all fit within the "normal" range
@@ -98,6 +106,21 @@ local function normalise ( year , month , day , hour , min , sec )
 	return year , month , day , hour , min , sec
 end
 
+local leap_years_since_1970 = leap_years_since ( 1970 )
+local function timestamp ( year , month , day , hour , min , sec )
+	year , month , day , hour , min , sec = normalise ( year , month , day , hour , min , sec )
+
+	local days_since_epoch = day_of_year ( day , month , year )
+		+ 365 * ( year - 1970 )
+		-- Each leap year adds one day
+		+ ( leap_years_since ( year - 1 ) - leap_years_since_1970 ) - 1
+
+	return days_since_epoch * (60*60*24)
+		+ hour  * (60*60)
+		+ min   * 60
+		+ sec
+end
+
 
 local timetable_methods = { }
 
@@ -119,15 +142,40 @@ function timetable_methods:normalise ( )
 end
 timetable_methods.normalize = timetable_methods.normalise -- American English
 
-local timetable_mt = {
+function timetable_methods:timestamp ( )
+	return timestamp ( unpack_tm ( self ) )
+end
+
+function timetable_methods:rfc_3339 ( )
+	-- %06.4g gives 3 (=6-4+1) digits after decimal
+	return strformat ( "%04u-%02u-%02uT%02u:%02u:%06.4g" , unpack_tm ( self ) )
+end
+
+local timetable_mt
+
+local function coerce_arg ( t )
+	if getmetatable ( t ) == timetable_mt then
+		return t:timestamp ( )
+	end
+	return t
+end
+
+timetable_mt = {
 	__index    = timetable_methods ;
+	__tostring = timetable_methods.rfc_3339 ;
+	__eq = function ( a , b )
+		return coerce_arg ( a ) == coerce_arg ( b )
+	end ;
+	__lt = function ( a , b )
+		return coerce_arg ( a ) < coerce_arg ( b )
+	end ;
 }
 
 local function cast_timetable ( tm )
 	return setmetatable ( tm , timetable_mt )
 end
 
-local function new_timetable ( year , month , day , hour , min , sec )
+local function new_timetable ( year , month , day , hour , min , sec , yday , wday )
 	return cast_timetable {
 		year  = year ;
 		month = month ;
@@ -135,14 +183,26 @@ local function new_timetable ( year , month , day , hour , min , sec )
 		hour  = hour ;
 		min   = min ;
 		sec   = sec ;
+		yday  = yday ;
+		wday  = wday ;
 	}
 end
 
+function timetable_methods:clone ( )
+	return new_timetable ( unpack_tm ( self ) )
+end
+
+local function new_from_timestamp ( ts )
+	return new_timetable ( 1970 , 1 , 1 , 0 , 0 , ts )
+end
+
 return {
 	doomsday  = doomsday ;
 	normalise = normalise ;
+	timestamp = timestamp ;
 
 	new = new_timetable ;
+	new_from_timestamp = new_from_timestamp ;
 	cast = cast_timetable ;
 	timetable_mt = timetable_mt ;
 }