From 286a0a1371b20b9b8c587c96c2e9c556c74df3fc Mon Sep 17 00:00:00 2001
From: lutherwenxu <lutherchanpublic+git@gmail.com>
Date: Wed, 1 Jan 2020 00:11:47 +0800
Subject: [PATCH] time: rewrite unix() function

---
 examples/random_ips.v                 |   2 +-
 examples/tetris/tetris.v              |   2 +-
 examples/vcasino/VCasino.v            |   2 +-
 vlib/bitfield/bitfield_test.v         |  24 +++---
 vlib/sdl/examples/tvintris/tvintris.v |   2 +-
 vlib/time/time.v                      | 112 +++++--------------------
 vlib/time/time_test.v                 |  38 ++++++++-
 vlib/time/time_unix.v                 | 113 ++++++++++++++++++++++++++
 8 files changed, 186 insertions(+), 109 deletions(-)
 create mode 100644 vlib/time/time_unix.v

diff --git a/examples/random_ips.v b/examples/random_ips.v
index 7fb694541a..fa6d003398 100644
--- a/examples/random_ips.v
+++ b/examples/random_ips.v
@@ -2,7 +2,7 @@ import rand
 import time
 
 fn main() {
-	rand.seed(time.now().uni)
+	rand.seed(time.now().unix)
 
 	for _ in 0..10 {
 		println('${rand.next(255)}.${rand.next(255)}.${rand.next(255)}.${rand.next(255)}')
diff --git a/examples/tetris/tetris.v b/examples/tetris/tetris.v
index 5f6aac33a5..61b3f8e580 100644
--- a/examples/tetris/tetris.v
+++ b/examples/tetris/tetris.v
@@ -173,7 +173,7 @@ fn main() {
 
 fn (g mut Game) init_game() {
 	g.parse_tetros()
-	rand.seed(time.now().uni)
+	rand.seed(time.now().unix)
 	g.generate_tetro()
 	g.field = [] // TODO: g.field = [][]int
 	// Generate the field, fill it with 0's, add -1's on each edge
diff --git a/examples/vcasino/VCasino.v b/examples/vcasino/VCasino.v
index 2dbd62f53a..c5f5c9fac7 100644
--- a/examples/vcasino/VCasino.v
+++ b/examples/vcasino/VCasino.v
@@ -89,7 +89,7 @@ fn get_bet(money int) int {
 
 fn run_wheel(bet_nbr int, _bet int) int {
 	mut bet := _bet
-    rand.seed(time.now().uni)
+    rand.seed(time.now().unix)
     winning_nbr := rand.next(50)
     print('Roulette Wheel spinning... and stops on the number $winning_nbr which is a ')
     if winning_nbr % 2 == 1 {
diff --git a/vlib/bitfield/bitfield_test.v b/vlib/bitfield/bitfield_test.v
index 8d86e6b64e..6977b1d38c 100644
--- a/vlib/bitfield/bitfield_test.v
+++ b/vlib/bitfield/bitfield_test.v
@@ -19,7 +19,7 @@ fn test_bf_set_clear_toggle_get() {
 }
 
 fn test_bf_and_not_or_xor() {
-	rand.seed(time.now().uni)
+	rand.seed(time.now().unix)
 	len := 80
 	mut input1 := bitfield.new(len)
 	mut input2 := bitfield.new(len)
@@ -46,7 +46,7 @@ fn test_bf_and_not_or_xor() {
 }
 
 fn test_clone_cmp() {
-	rand.seed(time.now().uni)
+	rand.seed(time.now().unix)
 	len := 80
 	mut input := bitfield.new(len)
 	for i := 0; i < len; i++ {
@@ -60,7 +60,7 @@ fn test_clone_cmp() {
 }
 
 fn test_slice_join() {
-	rand.seed(time.now().uni)
+	rand.seed(time.now().unix)
 	len := 80
 	mut input := bitfield.new(len)
 	for i := 0; i < len; i++ {
@@ -83,7 +83,7 @@ fn test_slice_join() {
 }
 
 fn test_popcount() {
-	rand.seed(time.now().uni)
+	rand.seed(time.now().unix)
 	len := 80
 	mut count0 := 0
 	mut input := bitfield.new(len)
@@ -98,7 +98,7 @@ fn test_popcount() {
 }
 
 fn test_hamming() {
-	rand.seed(time.now().uni)
+	rand.seed(time.now().unix)
 	len := 80
 	mut count := 0
 	mut input1 := bitfield.new(len)
@@ -138,7 +138,7 @@ fn test_bf_from_bytes() {
 }
 
 fn test_bf_from_string() {
-	rand.seed(time.now().uni)
+	rand.seed(time.now().unix)
 	len := 80
 	mut input := ''
 	for i := 0; i < len; i++ {
@@ -160,7 +160,7 @@ fn test_bf_from_string() {
 }
 
 fn test_bf_bf2str() {
-	rand.seed(time.now().uni)
+	rand.seed(time.now().unix)
 	len := 80
 	mut input := bitfield.new(len)
 	for i := 0; i < len; i++ {
@@ -188,7 +188,7 @@ fn test_bf_bf2str() {
 }
 
 fn test_bf_setall() {
-		rand.seed(time.now().uni)
+		rand.seed(time.now().unix)
 	len := 80
 	mut input := bitfield.new(len)
 	input.setall()
@@ -202,7 +202,7 @@ fn test_bf_setall() {
 }
 
 fn test_bf_clearall() {
-		rand.seed(time.now().uni)
+		rand.seed(time.now().unix)
 	len := 80
 	mut input := bitfield.new(len)
 	for i := 0; i < len; i++ {
@@ -221,7 +221,7 @@ fn test_bf_clearall() {
 }
 
 fn test_bf_reverse() {
-	rand.seed(time.now().uni)
+	rand.seed(time.now().unix)
 	len := 80
 	mut input := bitfield.new(len)
 	for i := 0; i < len; i++ {
@@ -241,7 +241,7 @@ fn test_bf_reverse() {
 }
 
 fn test_bf_resize() {
-	rand.seed(time.now().uni)
+	rand.seed(time.now().unix)
 	len := 80
 	mut input := bitfield.new(rand.next(len) + 1)
 	for i := 0; i < 100; i++ {
@@ -259,7 +259,7 @@ fn test_bf_pos() {
 	 * all haystacks here contain exactly one instanse of needle,
 	 * so search should return non-negative-values
 	**/
-	rand.seed(time.now().uni)
+	rand.seed(time.now().unix)
 	len := 80
 	mut result := 1
 	for i := 1; i < len; i++ {	// needle size
diff --git a/vlib/sdl/examples/tvintris/tvintris.v b/vlib/sdl/examples/tvintris/tvintris.v
index cca201a6c4..595d218a42 100644
--- a/vlib/sdl/examples/tvintris/tvintris.v
+++ b/vlib/sdl/examples/tvintris/tvintris.v
@@ -292,7 +292,7 @@ fn main() {
 	game.sdl.jids[1] = -1
 	game.sdl.set_sdl_context(WinWidth, WinHeight, Title)
 	game.font = C.TTF_OpenFont(FontName.str, TextSize)
-	seed := time.now().uni
+	seed := time.now().unix
 	mut game2 := &Game{ font: 0 }
 	game2.sdl = game.sdl
 	game2.font = game.font
diff --git a/vlib/time/time.v b/vlib/time/time.v
index f8dbdf88bd..1f4bd71a54 100644
--- a/vlib/time/time.v
+++ b/vlib/time/time.v
@@ -32,7 +32,7 @@ pub:
 	hour   int
 	minute int
 	second int
-	uni    int // TODO it's safe to use "unix" now
+	unix   int
 }
 
 pub enum FormatTime {
@@ -92,92 +92,11 @@ pub fn now() Time {
 }
 
 pub fn random() Time {
-	now_unix := now().uni
+	now_unix := now().unix
 	rand_unix := rand.next(now_unix)
 	return time.unix(rand_unix)
 }
 
-// Based on Go's time package.
-// Copyright 2009 The Go Authors.
-pub fn unix(abs int) Time {
-	// Split into time and day.
-	mut d := abs / seconds_per_day
-	// Account for 400 year cycles.
-	mut n := d / days_per_400_years
-	mut y := 400 * n
-	d -= days_per_400_years * n
-	// Cut off 100-year cycles.
-	// The last cycle has one extra leap year, so on the last day
-	// of that year, day / days_per_100_years will be 4 instead of 3.
-	// Cut it back down to 3 by subtracting n>>2.
-	n = d / days_per_100_years
-	n -= n>>2
-	y += 100 * n
-	d -= days_per_100_years * n
-	// Cut off 4-year cycles.
-	// The last cycle has a missing leap year, which does not
-	// affect the computation.
-	n = d / days_per_4_years
-	y += 4 * n
-	d -= days_per_4_years * n
-	// Cut off years within a 4-year cycle.
-	// The last year is a leap year, so on the last day of that year,
-	// day / 365 will be 4 instead of 3. Cut it back down to 3
-	// by subtracting n>>2.
-	n = d / 365
-	n -= n>>2
-	y += n
-	d -= 365 * n
-	yday := d
-	mut day := yday
-	year := abs / int(3.154e+7) + 1970 // int(i64(y) + absolute_zero_year)
-	hour := (abs % seconds_per_day) / seconds_per_hour
-	minute := (abs % seconds_per_hour) / seconds_per_minute
-	second := (abs % seconds_per_minute)
-	if is_leap_year(year) {
-		// Leap year
-		if day > 31 + 29 - 1 {
-			// After leap day; pretend it wasn't there.
-			day--
-		}
-		else if day == 31 + 29 - 1 {
-			// Leap day.
-			day = 29
-			return Time{
-				year: year
-				month: 2
-				day: day
-				hour: hour
-				minute: minute
-				second: second
-			}
-		}
-	}
-	// Estimate month on assumption that every month has 31 days.
-	// The estimate may be too low by at most one month, so adjust.
-	mut month := day / 31
-	mut begin := 0
-	end := (days_before[month + 1])
-	if day >= end {
-		month++
-		begin = end
-	}
-	else {
-		begin = (days_before[month])
-	}
-	month++ // because January is 1
-	day = day - begin + 1
-	return Time{
-		year: year
-		month: month
-		day: day
-		hour: hour
-		minute: minute
-		second: second
-		uni: abs
-	}
-}
-
 pub fn convert_ctime(t tm) Time {
 	return Time{
 		year: t.tm_year + 1900
@@ -186,7 +105,7 @@ pub fn convert_ctime(t tm) Time {
 		hour: t.tm_hour
 		minute: t.tm_min
 		second: t.tm_sec
-		uni: C.mktime(&t)
+		unix: C.mktime(&t)
 	}
 }
 
@@ -337,15 +256,28 @@ pub fn parse_iso(s string) Time {
 }
 
 pub fn new_time(t Time) Time {
+	return Time{
+		year: t.year,
+		month: t.month,
+		day: t.day,
+		hour: t.hour,
+		minute: t.minute,
+		second: t.second,
+		unix: t.calc_unix()
+	}
+
+	//TODO: Use the syntax below when it works with reserved keywords like `unix`
+	/*
 	return {
 		t |
-		uni:t.calc_unix()
+		unix:t.calc_unix()
 	}
+	*/
 }
 
 pub fn (t &Time) calc_unix() int {
-	if t.uni != 0 {
-		return t.uni
+	if t.unix != 0 {
+		return t.unix
 	}
 	tt := C.tm{
 		tm_sec: t.second
@@ -360,11 +292,11 @@ pub fn (t &Time) calc_unix() int {
 
 // TODO add(d time.Duration)
 pub fn (t Time) add_seconds(seconds int) Time {
-	return unix(t.uni + seconds)
+	return unix(t.unix + seconds)
 }
 
 pub fn (t Time) add_days(days int) Time {
-	return unix(t.uni + days * 3600 * 24)
+	return unix(t.unix + days * 3600 * 24)
 }
 
 // TODO use time.Duration instead of seconds
@@ -374,7 +306,7 @@ fn since(t Time) int {
 
 pub fn (t Time) relative() string {
 	now := time.now()
-	secs := now.uni - t.uni
+	secs := now.unix - t.unix
 	if secs <= 30 {
 		// right now or in the future
 		// TODO handle time in the future
diff --git a/vlib/time/time_test.v b/vlib/time/time_test.v
index 3f2b44a89e..46d639d5f6 100644
--- a/vlib/time/time_test.v
+++ b/vlib/time/time_test.v
@@ -46,6 +46,38 @@ fn test_unix() {
 	assert t.hour == 2
 	assert t.minute == 14
 	assert t.second == 59
+
+	t2 := time.unix(1078058096)
+	assert t2.year == 2004
+	assert t2.month == 2
+	assert t2.day == 29
+	assert t2.hour == 12
+	assert t2.minute == 34
+	assert t2.second == 56
+
+	t3 := time.unix(1070236799)
+	assert t3.year == 2003
+	assert t3.month == 11
+	assert t3.day == 30
+	assert t3.hour == 23
+	assert t3.minute == 59
+	assert t3.second == 59
+
+	t4 := time.unix(1577783439)
+	assert t4.year == 2019
+	assert t4.month == 12
+	assert t4.day == 31
+	assert t4.hour == 9
+	assert t4.minute == 10
+	assert t4.second == 39
+
+	t5 := time.unix(-1824922433)
+	assert t5.year == 1912
+	assert t5.month == 3
+	assert t5.day == 4
+	assert t5.hour == 5
+	assert t5.minute == 6
+	assert t5.second == 7
 }
 
 fn test_format_ss() {
@@ -63,7 +95,7 @@ fn test_smonth() {
 
 		t := time.Time {
 			year: 1980, month: month_num, day: 1,
-			hour: 0, minute: 0, second: 0, uni: 0
+			hour: 0, minute: 0, second: 0, unix: 0
 		}
 
 		assert t.smonth() == name
@@ -105,7 +137,7 @@ fn test_day_of_week() {
 		// 2 Dec 2019 is Monday
 		t := time.Time {
 			year: 2019, month: 12, day: 2 + i,
-			hour: 0, minute: 0, second: 0, uni: 0
+			hour: 0, minute: 0, second: 0, unix: 0
 		}
 
 		assert day_of_week == t.day_of_week()
@@ -119,7 +151,7 @@ fn test_weekday_str() {
 		// 2 Dec 2019 is Monday
 		t := time.Time {
 			year: 2019, month: 12, day: 2 + i,
-			hour: 0, minute: 0, second: 0, uni: 0
+			hour: 0, minute: 0, second: 0, unix: 0
 		}
 
 		assert t.weekday_str() == name
diff --git a/vlib/time/time_unix.v b/vlib/time/time_unix.v
new file mode 100644
index 0000000000..40e9213174
--- /dev/null
+++ b/vlib/time/time_unix.v
@@ -0,0 +1,113 @@
+// Copyright (c) 2019 Alexander Medvednikov. All rights reserved.
+// Use of this source code is governed by an MIT license
+// that can be found in the LICENSE file.
+module time
+
+pub fn unix(abs int) Time {
+	// Split into day and time
+	mut day_offset := abs / seconds_per_day
+	if abs % seconds_per_day < 0 {
+		// Compensate for round towards zero on integers as we want floored instead
+		day_offset -= 1
+	}
+	year, month, day := calculate_date_from_offset(day_offset)
+	hr, min, sec := calculate_time_from_offset(abs % seconds_per_day)
+	return Time{
+		year: year
+		month: month
+		day: day
+		hour: hr
+		minute: min
+		second: sec
+		unix: abs
+	}
+}
+
+[inline]
+fn calculate_date_from_offset(day_offset_ int) (int, int, int) {
+	mut day_offset := day_offset_
+
+	// Move offset to year 2001 as it's the start of a new 400-year cycle
+	// Code below this rely on the fact that the day_offset is lined up with the 400-year cycle
+	// 1970-2000 (inclusive) has 31 years (8 of which are leap years)
+	mut year := 2001
+	day_offset -= 31*365 + 8
+
+	// Account for 400 year cycle
+	year += (day_offset / days_per_400_years) * 400
+	day_offset %= days_per_400_years
+
+	// Account for 100 year cycle
+	if day_offset == days_per_100_years * 4 {
+		year += 300
+		day_offset -= days_per_100_years * 3
+	} else {
+		year += (day_offset / days_per_100_years) * 100
+		day_offset %= days_per_100_years
+	}
+
+	// Account for 4 year cycle
+	if day_offset == days_per_4_years * 25 {
+		year += 96
+		day_offset -= days_per_4_years * 24
+	} else {
+		year += (day_offset / days_per_4_years) * 4
+		day_offset %= days_per_4_years
+	}
+
+	// Account for every year
+	if day_offset == 365 * 4 {
+		year += 3
+		day_offset -= 365 * 3
+	} else {
+		year += (day_offset / 365)
+		day_offset %= 365
+	}
+
+	if day_offset < 0 {
+		year -= 1
+		if is_leap_year(year) {
+			day_offset += 366
+		} else {
+			day_offset += 365
+		}
+	}
+
+	if is_leap_year(year) {
+		if day_offset > 31 + 29 - 1 {
+			// After leap day; pretend it wasn't there.
+			day_offset--
+		} else if day_offset == 31 + 29 - 1 {
+			// Leap day.
+			return year, 2, 29
+		}
+	}
+
+	mut estimated_month := day_offset / 31
+	for day_offset > days_before[estimated_month+1] {
+		estimated_month++
+	}
+	for day_offset <= days_before[estimated_month] {
+		estimated_month--
+	}
+
+	day_offset -= days_before[estimated_month]
+
+	return year, estimated_month+1, day_offset+1
+}
+
+[inline]
+fn calculate_time_from_offset(second_offset_ int) (int, int, int) {
+	mut second_offset := second_offset_
+	if second_offset < 0 {
+		second_offset += seconds_per_day
+	}
+
+	hour := second_offset / seconds_per_hour
+	second_offset %= seconds_per_hour
+
+	min := second_offset / seconds_per_minute
+	second_offset %= seconds_per_minute
+
+	return hour, min, second_offset
+}