From efa8dcf4d2e21ffee5738cbf7afabaa495e063b6 Mon Sep 17 00:00:00 2001
From: Delyan Angelov <delian66@gmail.com>
Date: Wed, 4 Aug 2021 13:12:02 +0300
Subject: [PATCH] time: turn Time.unix to i64, so it can represent times before
 1970-01-01, fix time operators, add more tests (#11050)

---
 vlib/net/websocket/websocket_client.v |  2 +-
 vlib/os/os_test.v                     |  2 +-
 vlib/rand/rand.v                      |  2 +-
 vlib/rand/random_identifiers_test.v   |  2 +-
 vlib/time/chrono.v                    | 31 +++++++++++++++++++++++++
 vlib/time/misc/misc.v                 |  2 +-
 vlib/time/operator.v                  |  6 ++---
 vlib/time/parse.v                     |  4 ++--
 vlib/time/time.v                      | 25 ++++++++++++--------
 vlib/time/time_addition_test.v        | 33 +++++++++++++++++++++++++++
 vlib/time/time_nix.c.v                |  4 ++--
 vlib/time/time_test.v                 | 10 ++++----
 vlib/time/time_windows.c.v            | 16 ++++++-------
 vlib/time/unix.v                      |  4 ++--
 vlib/vweb/assets/assets.v             |  4 ++--
 15 files changed, 107 insertions(+), 40 deletions(-)
 create mode 100644 vlib/time/chrono.v
 create mode 100644 vlib/time/time_addition_test.v

diff --git a/vlib/net/websocket/websocket_client.v b/vlib/net/websocket/websocket_client.v
index 4408c7e4d1..48f8c5c8b1 100644
--- a/vlib/net/websocket/websocket_client.v
+++ b/vlib/net/websocket/websocket_client.v
@@ -38,7 +38,7 @@ pub mut:
 	state             State    // current state of connection
 	logger            &log.Log // logger used to log messages
 	resource_name     string   // name of current resource
-	last_pong_ut      u64      // last time in unix time we got a pong message
+	last_pong_ut      i64      // last time in unix time we got a pong message
 }
 
 // Flag represents different types of headers in websocket handshake
diff --git a/vlib/os/os_test.v b/vlib/os/os_test.v
index 04c14e738a..7107a34f2b 100644
--- a/vlib/os/os_test.v
+++ b/vlib/os/os_test.v
@@ -747,6 +747,6 @@ fn test_utime() {
 	f.write_string(hello) or { panic(err) }
 	atime := time.now().add_days(2).unix_time()
 	mtime := time.now().add_days(4).unix_time()
-	os.utime(filename, atime, mtime) or { panic(err) }
+	os.utime(filename, int(atime), int(mtime)) or { panic(err) }
 	assert os.file_last_mod_unix(filename) == mtime
 }
diff --git a/vlib/rand/rand.v b/vlib/rand/rand.v
index 0136ec1a96..e43a7abef4 100644
--- a/vlib/rand/rand.v
+++ b/vlib/rand/rand.v
@@ -275,7 +275,7 @@ const (
 // users or business transactions.
 // (https://news.ycombinator.com/item?id=14526173)
 pub fn ulid() string {
-	return ulid_at_millisecond(time.utc().unix_time_milli())
+	return ulid_at_millisecond(u64(time.utc().unix_time_milli()))
 }
 
 // ulid_at_millisecond does the same as `ulid` but takes a custom Unix millisecond timestamp via `unix_time_milli`.
diff --git a/vlib/rand/random_identifiers_test.v b/vlib/rand/random_identifiers_test.v
index 3daee4d464..d54fa84acf 100644
--- a/vlib/rand/random_identifiers_test.v
+++ b/vlib/rand/random_identifiers_test.v
@@ -37,7 +37,7 @@ fn test_ulids_max_start_character_is_ok() {
 }
 
 fn test_ulids_generated_in_the_same_millisecond_have_the_same_prefix() {
-	t := time.utc().unix_time_milli()
+	t := u64(time.utc().unix_time_milli())
 	mut ulid1 := ''
 	mut ulid2 := ''
 	mut ulid3 := ''
diff --git a/vlib/time/chrono.v b/vlib/time/chrono.v
new file mode 100644
index 0000000000..209d3dfe6c
--- /dev/null
+++ b/vlib/time/chrono.v
@@ -0,0 +1,31 @@
+module time
+
+// days_from_civil - return the number of days since the
+// Unix epoch 1970-01-01. A detailed description of the algorithm here
+// is in: http://howardhinnant.github.io/date_algorithms.html
+// Note that it will return negative values for days before 1970-01-01.
+pub fn days_from_civil(oy int, m int, d int) int {
+	y := if m <= 2 { oy - 1 } else { oy }
+	era := y / 400
+	yoe := y - era * 400 // [0, 399]
+	doy := (153 * (m + (if m > 2 { -3 } else { 9 })) + 2) / 5 + d - 1 // [0, 365]
+	doe := yoe * 365 + yoe / 4 - yoe / 100 + doy // [0, 146096]
+	return era * 146097 + doe - 719468
+}
+
+// portable_timegm does the same as C._mkgmtime, but unlike it,
+// can work with dates before the Unix epoch of 1970-01-01 .
+pub fn portable_timegm(t &C.tm) i64 {
+	mut year := t.tm_year + 1900
+	mut month := t.tm_mon // 0-11
+	if month > 11 {
+		year += month / 12
+		month %= 12
+	} else if month < 0 {
+		years_diff := (11 - month) / 12
+		year -= years_diff
+		month += 12 * years_diff
+	}
+	days_since_1970 := i64(days_from_civil(year, month + 1, t.tm_mday))
+	return 60 * (60 * (24 * days_since_1970 + t.tm_hour) + t.tm_min) + t.tm_sec
+}
diff --git a/vlib/time/misc/misc.v b/vlib/time/misc/misc.v
index 0ae7b94d1d..b0be1269a7 100644
--- a/vlib/time/misc/misc.v
+++ b/vlib/time/misc/misc.v
@@ -9,5 +9,5 @@ const (
 
 // random returns a random time struct in *the past*.
 pub fn random() time.Time {
-	return time.unix(int(rand.u64n(misc.start_time_unix)))
+	return time.unix(int(rand.i64n(misc.start_time_unix)))
 }
diff --git a/vlib/time/operator.v b/vlib/time/operator.v
index 7c6e616035..f62854983d 100644
--- a/vlib/time/operator.v
+++ b/vlib/time/operator.v
@@ -15,7 +15,7 @@ pub fn (t1 Time) < (t2 Time) bool {
 // Time subtract using operator overloading.
 [inline]
 pub fn (lhs Time) - (rhs Time) Duration {
-	lhs_micro := lhs.unix * 1000 * 1000 + u64(lhs.microsecond)
-	rhs_micro := rhs.unix * 1000 * 1000 + u64(rhs.microsecond)
-	return (i64(lhs_micro) - i64(rhs_micro)) * microsecond
+	lhs_micro := lhs.unix * 1_000_000 + lhs.microsecond
+	rhs_micro := rhs.unix * 1_000_000 + rhs.microsecond
+	return (lhs_micro - rhs_micro) * microsecond
 }
diff --git a/vlib/time/parse.v b/vlib/time/parse.v
index 95c5352429..b74cd412c7 100644
--- a/vlib/time/parse.v
+++ b/vlib/time/parse.v
@@ -131,9 +131,9 @@ pub fn parse_iso8601(s string) ?Time {
 	}
 	mut unix_time := t.unix
 	if unix_offset < 0 {
-		unix_time -= u64(-unix_offset)
+		unix_time -= (-unix_offset)
 	} else if unix_offset > 0 {
-		unix_time += u64(unix_offset)
+		unix_time += unix_offset
 	}
 	t = unix2(i64(unix_time), t.microsecond)
 	return t
diff --git a/vlib/time/time.v b/vlib/time/time.v
index 14f0c7afd7..dbb012bf89 100644
--- a/vlib/time/time.v
+++ b/vlib/time/time.v
@@ -50,7 +50,7 @@ pub:
 	minute      int
 	second      int
 	microsecond int
-	unix        u64
+	unix        i64
 }
 
 // FormatDelimiter contains different time formats.
@@ -162,7 +162,7 @@ pub fn new_time(t Time) Time {
 		tm_mon: t.month - 1
 		tm_year: t.year - 1900
 	}
-	utime := u64(make_unix_time(tt))
+	utime := make_unix_time(tt)
 	return Time{
 		...t
 		unix: utime
@@ -171,21 +171,21 @@ pub fn new_time(t Time) Time {
 
 // unix_time returns Unix time.
 [inline]
-pub fn (t Time) unix_time() int {
-	return int(t.unix)
+pub fn (t Time) unix_time() i64 {
+	return t.unix
 }
 
 // unix_time_milli returns Unix time with millisecond resolution.
 [inline]
-pub fn (t Time) unix_time_milli() u64 {
-	return t.unix * 1000 + u64(t.microsecond / 1000)
+pub fn (t Time) unix_time_milli() i64 {
+	return t.unix * 1000 + (t.microsecond / 1000)
 }
 
 // add returns a new time that duration is added
 pub fn (t Time) add(d Duration) Time {
-	microseconds := i64(t.unix) * 1000 * 1000 + t.microsecond + d.microseconds()
-	unix := microseconds / (1000 * 1000)
-	micro := microseconds % (1000 * 1000)
+	microseconds := i64(t.unix) * 1_000_000 + t.microsecond + d.microseconds()
+	unix := microseconds / 1_000_000
+	micro := microseconds % 1_000_000
 	return unix2(unix, int(micro))
 }
 
@@ -358,6 +358,11 @@ pub fn (t Time) str() string {
 	return t.format_ss()
 }
 
+// str returns time in the same format as `parse` expects ("YYYY-MM-DD HH:MM:SS").
+pub fn (t Time) debug() string {
+	return 'Time{ year: ${t.year:04} month: ${t.month:02} day: ${t.day:02} hour: ${t.hour:02} minute: ${t.minute:02} second: ${t.second:02} microsecond: ${t.microsecond:06} unix: ${t.unix:07} }'
+}
+
 // convert_ctime converts a C time to V time.
 fn convert_ctime(t C.tm, microsecond int) Time {
 	return Time{
@@ -368,7 +373,7 @@ fn convert_ctime(t C.tm, microsecond int) Time {
 		minute: t.tm_min
 		second: t.tm_sec
 		microsecond: time.microsecond
-		unix: u64(make_unix_time(t))
+		unix: make_unix_time(t)
 	}
 }
 
diff --git a/vlib/time/time_addition_test.v b/vlib/time/time_addition_test.v
new file mode 100644
index 0000000000..8fde8744c1
--- /dev/null
+++ b/vlib/time/time_addition_test.v
@@ -0,0 +1,33 @@
+import time
+
+fn test_add_to_day_in_the_previous_century() ? {
+	a := time.parse_iso8601('1900-01-01') ?
+	aa := a.add_days(180)
+	dump(a.debug())
+	dump(aa.debug())
+	assert aa.ymmdd() == '1900-06-29'
+}
+
+fn test_add_to_day_in_the_past() ? {
+	a := time.parse_iso8601('1990-03-01') ?
+	aa := a.add_days(180)
+	assert aa.ymmdd() == '1990-08-27'
+}
+
+fn test_add_to_day_in_the_recent_past() ? {
+	a := time.parse_iso8601('2021-03-01') ?
+	aa := a.add_days(180)
+	assert aa.ymmdd() == '2021-08-28'
+}
+
+fn test_add_to_day_in_the_future_1() ? {
+	a := time.parse_iso8601('3000-11-01') ?
+	aa := a.add_days(180)
+	assert aa.ymmdd() == '3001-04-30'
+}
+
+fn test_add_to_day_in_the_future_2() ? {
+	a := time.parse_iso8601('3000-12-30') ?
+	aa := a.add_days(180)
+	assert aa.ymmdd() == '3001-06-28'
+}
diff --git a/vlib/time/time_nix.c.v b/vlib/time/time_nix.c.v
index 82ff5485af..29e0299809 100644
--- a/vlib/time/time_nix.c.v
+++ b/vlib/time/time_nix.c.v
@@ -23,8 +23,8 @@ fn C.timegm(&C.tm) C.time_t
 // fn C.gmtime_r(&tm, &gbuf)
 fn C.localtime_r(t &time_t, tm &C.tm)
 
-fn make_unix_time(t C.tm) int {
-	return int(C.timegm(&t))
+fn make_unix_time(t C.tm) i64 {
+	return i64(C.timegm(&t))
 }
 
 // local returns t with the location set to local time.
diff --git a/vlib/time/time_test.v b/vlib/time/time_test.v
index 0511916436..dbd3c48d65 100644
--- a/vlib/time/time_test.v
+++ b/vlib/time/time_test.v
@@ -160,18 +160,18 @@ fn test_add() {
 	t2 := time_to_test.add(duration)
 	assert t2.second == t1.second + d_seconds
 	assert t2.microsecond == t1.microsecond + d_microseconds
-	assert t2.unix == t1.unix + u64(d_seconds)
+	assert t2.unix == t1.unix + d_seconds
 	t3 := time_to_test.add(-duration)
 	assert t3.second == t1.second - d_seconds
 	assert t3.microsecond == t1.microsecond - d_microseconds
-	assert t3.unix == t1.unix - u64(d_seconds)
+	assert t3.unix == t1.unix - d_seconds
 }
 
 fn test_add_days() {
 	num_of_days := 3
 	t := time_to_test.add_days(num_of_days)
 	assert t.day == time_to_test.day + num_of_days
-	assert t.unix == time_to_test.unix + 86400 * u64(num_of_days)
+	assert t.unix == time_to_test.unix + 86400 * num_of_days
 }
 
 fn test_str() {
@@ -217,8 +217,8 @@ fn test_unix_time() {
 	//
 	utm1 := t1.unix_time_milli()
 	utm2 := t2.unix_time_milli()
-	assert (utm1 - u64(ut1) * 1000) < 1000
-	assert (utm2 - u64(ut2) * 1000) < 1000
+	assert (utm1 - ut1 * 1000) < 1000
+	assert (utm2 - ut2 * 1000) < 1000
 	//
 	// println('utm1: $utm1 | utm2: $utm2')
 	assert utm2 - utm1 > 2
diff --git a/vlib/time/time_windows.c.v b/vlib/time/time_windows.c.v
index d44e6c9413..a810cb97d7 100644
--- a/vlib/time/time_windows.c.v
+++ b/vlib/time/time_windows.c.v
@@ -52,14 +52,12 @@ struct C.timespec {
 	tv_nsec i64
 }
 
-fn C._mkgmtime(&C.tm) C.time_t
-
 fn C.QueryPerformanceCounter(&u64) C.BOOL
 
 fn C.QueryPerformanceFrequency(&u64) C.BOOL
 
-fn make_unix_time(t C.tm) int {
-	return int(C._mkgmtime(&t))
+fn make_unix_time(t C.tm) i64 {
+	return portable_timegm(&t)
 }
 
 fn init_win_time_freq() u64 {
@@ -91,7 +89,7 @@ fn vpc_now() u64 {
 }
 
 // local_as_unix_time returns the current local time as unix time
-fn local_as_unix_time() int {
+fn local_as_unix_time() i64 {
 	t := C.time(0)
 	tm := C.localtime(&t)
 	return make_unix_time(tm)
@@ -117,7 +115,7 @@ pub fn (t Time) local() Time {
 		minute: st_local.minute
 		second: st_local.second // These are the same
 		microsecond: st_local.millisecond * 1000
-		unix: u64(st_local.unix_time())
+		unix: st_local.unix_time()
 	}
 	return t_local
 }
@@ -140,7 +138,7 @@ fn win_now() Time {
 		minute: st_local.minute
 		second: st_local.second
 		microsecond: st_local.millisecond * 1000
-		unix: u64(st_local.unix_time())
+		unix: st_local.unix_time()
 	}
 	return t
 }
@@ -161,13 +159,13 @@ fn win_utc() Time {
 		minute: st_utc.minute
 		second: st_utc.second
 		microsecond: st_utc.millisecond * 1000
-		unix: u64(st_utc.unix_time())
+		unix: st_utc.unix_time()
 	}
 	return t
 }
 
 // unix_time returns Unix time.
-pub fn (st SystemTime) unix_time() int {
+pub fn (st SystemTime) unix_time() i64 {
 	tt := C.tm{
 		tm_sec: st.second
 		tm_min: st.minute
diff --git a/vlib/time/unix.v b/vlib/time/unix.v
index ac9d0100b6..7b6ec873b5 100644
--- a/vlib/time/unix.v
+++ b/vlib/time/unix.v
@@ -20,7 +20,7 @@ pub fn unix(abs int) Time {
 		hour: hr
 		minute: min
 		second: sec
-		unix: u64(abs)
+		unix: abs
 	}
 }
 
@@ -42,7 +42,7 @@ pub fn unix2(abs i64, microsecond int) Time {
 		minute: min
 		second: sec
 		microsecond: microsecond
-		unix: u64(abs)
+		unix: abs
 	}
 }
 
diff --git a/vlib/vweb/assets/assets.v b/vlib/vweb/assets/assets.v
index 1240e4123c..09a4ab97b7 100644
--- a/vlib/vweb/assets/assets.v
+++ b/vlib/vweb/assets/assets.v
@@ -106,7 +106,7 @@ fn (am AssetManager) combine(asset_type string, to_file bool) string {
 
 fn (am AssetManager) get_cache_key(asset_type string) string {
 	mut files_salt := ''
-	mut latest_modified := u64(0)
+	mut latest_modified := i64(0)
 	for asset in am.get_assets(asset_type) {
 		files_salt += asset.file_path
 		if asset.last_modified.unix > latest_modified {
@@ -151,7 +151,7 @@ fn (mut am AssetManager) add(asset_type string, file string) bool {
 	asset := Asset{
 		file_path: file
 		last_modified: time.Time{
-			unix: u64(os.file_last_mod_unix(file))
+			unix: os.file_last_mod_unix(file)
 		}
 	}
 	if asset_type == 'css' {