X-Git-Url: https://git.madduck.net/etc/awesome.git/blobdiff_plain/e0dbd486c7005f901811529ef5b82f5bd95211ea..86e57ee7249734545974d4b8ba2de3bcea6575a3:/src/timetable.lua

diff --git a/src/timetable.lua b/src/timetable.lua
index 9b78576..e7f2816 100644
--- a/src/timetable.lua
+++ b/src/timetable.lua
@@ -27,9 +27,13 @@ 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 ( { } , {
@@ -98,12 +102,16 @@ 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 )
-	return 60*60*24*(
-			year * year_length ( year )
-			+ month * month_length ( month , year )
-			+ day
-		)
+	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
@@ -134,8 +142,14 @@ 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 = {
 	__index    = timetable_methods ;
+	__tostring = timetable_methods.rfc_3339 ;
 	__eq = function ( a , b )
 		return a:timestamp() < b:timestamp()
 	end ;