// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package time_test

import (
	"bytes"
	"encoding/gob"
	"encoding/json"
	"math/rand"
	"strconv"
	"strings"
	"testing"
	"testing/quick"
	. "time"
)

// We should be in PST/PDT, but if the time zone files are missing we
// won't be. The purpose of this test is to at least explain why some of
// the subsequent tests fail.
func TestZoneData(t *testing.T) {
	lt := Now()
	// PST is 8 hours west, PDT is 7 hours west.  We could use the name but it's not unique.
	if name, off := lt.Zone(); off != -8*60*60 && off != -7*60*60 {
		t.Errorf("Unable to find US Pacific time zone data for testing; time zone is %q offset %d", name, off)
		t.Error("Likely problem: the time zone files have not been installed.")
	}
}

// parsedTime is the struct representing a parsed time value.
type parsedTime struct {
	Year                 int
	Month                Month
	Day                  int
	Hour, Minute, Second int // 15:04:05 is 15, 4, 5.
	Nanosecond           int // Fractional second.
	Weekday              Weekday
	ZoneOffset           int    // seconds east of UTC, e.g. -7*60*60 for -0700
	Zone                 string // e.g., "MST"
}

type TimeTest struct {
	seconds int64
	golden  parsedTime
}

var utctests = []TimeTest{
	{0, parsedTime{1970, January, 1, 0, 0, 0, 0, Thursday, 0, "UTC"}},
	{1221681866, parsedTime{2008, September, 17, 20, 4, 26, 0, Wednesday, 0, "UTC"}},
	{-1221681866, parsedTime{1931, April, 16, 3, 55, 34, 0, Thursday, 0, "UTC"}},
	{-11644473600, parsedTime{1601, January, 1, 0, 0, 0, 0, Monday, 0, "UTC"}},
	{599529660, parsedTime{1988, December, 31, 0, 1, 0, 0, Saturday, 0, "UTC"}},
	{978220860, parsedTime{2000, December, 31, 0, 1, 0, 0, Sunday, 0, "UTC"}},
}

var nanoutctests = []TimeTest{
	{0, parsedTime{1970, January, 1, 0, 0, 0, 1e8, Thursday, 0, "UTC"}},
	{1221681866, parsedTime{2008, September, 17, 20, 4, 26, 2e8, Wednesday, 0, "UTC"}},
}

var localtests = []TimeTest{
	{0, parsedTime{1969, December, 31, 16, 0, 0, 0, Wednesday, -8 * 60 * 60, "PST"}},
	{1221681866, parsedTime{2008, September, 17, 13, 4, 26, 0, Wednesday, -7 * 60 * 60, "PDT"}},
}

var nanolocaltests = []TimeTest{
	{0, parsedTime{1969, December, 31, 16, 0, 0, 1e8, Wednesday, -8 * 60 * 60, "PST"}},
	{1221681866, parsedTime{2008, September, 17, 13, 4, 26, 3e8, Wednesday, -7 * 60 * 60, "PDT"}},
}

func same(t Time, u *parsedTime) bool {
	// Check aggregates.
	year, month, day := t.Date()
	hour, min, sec := t.Clock()
	name, offset := t.Zone()
	if year != u.Year || month != u.Month || day != u.Day ||
		hour != u.Hour || min != u.Minute || sec != u.Second ||
		name != u.Zone || offset != u.ZoneOffset {
		return false
	}
	// Check individual entries.
	return t.Year() == u.Year &&
		t.Month() == u.Month &&
		t.Day() == u.Day &&
		t.Hour() == u.Hour &&
		t.Minute() == u.Minute &&
		t.Second() == u.Second &&
		t.Nanosecond() == u.Nanosecond &&
		t.Weekday() == u.Weekday
}

func TestSecondsToUTC(t *testing.T) {
	for _, test := range utctests {
		sec := test.seconds
		golden := &test.golden
		tm := Unix(sec, 0).UTC()
		newsec := tm.Unix()
		if newsec != sec {
			t.Errorf("SecondsToUTC(%d).Seconds() = %d", sec, newsec)
		}
		if !same(tm, golden) {
			t.Errorf("SecondsToUTC(%d):  // %#v", sec, tm)
			t.Errorf("  want=%+v", *golden)
			t.Errorf("  have=%v", tm.Format(RFC3339+" MST"))
		}
	}
}

func TestNanosecondsToUTC(t *testing.T) {
	for _, test := range nanoutctests {
		golden := &test.golden
		nsec := test.seconds*1e9 + int64(golden.Nanosecond)
		tm := Unix(0, nsec).UTC()
		newnsec := tm.Unix()*1e9 + int64(tm.Nanosecond())
		if newnsec != nsec {
			t.Errorf("NanosecondsToUTC(%d).Nanoseconds() = %d", nsec, newnsec)
		}
		if !same(tm, golden) {
			t.Errorf("NanosecondsToUTC(%d):", nsec)
			t.Errorf("  want=%+v", *golden)
			t.Errorf("  have=%+v", tm.Format(RFC3339+" MST"))
		}
	}
}

func TestSecondsToLocalTime(t *testing.T) {
	for _, test := range localtests {
		sec := test.seconds
		golden := &test.golden
		tm := Unix(sec, 0)
		newsec := tm.Unix()
		if newsec != sec {
			t.Errorf("SecondsToLocalTime(%d).Seconds() = %d", sec, newsec)
		}
		if !same(tm, golden) {
			t.Errorf("SecondsToLocalTime(%d):", sec)
			t.Errorf("  want=%+v", *golden)
			t.Errorf("  have=%+v", tm.Format(RFC3339+" MST"))
		}
	}
}

func TestNanosecondsToLocalTime(t *testing.T) {
	for _, test := range nanolocaltests {
		golden := &test.golden
		nsec := test.seconds*1e9 + int64(golden.Nanosecond)
		tm := Unix(0, nsec)
		newnsec := tm.Unix()*1e9 + int64(tm.Nanosecond())
		if newnsec != nsec {
			t.Errorf("NanosecondsToLocalTime(%d).Seconds() = %d", nsec, newnsec)
		}
		if !same(tm, golden) {
			t.Errorf("NanosecondsToLocalTime(%d):", nsec)
			t.Errorf("  want=%+v", *golden)
			t.Errorf("  have=%+v", tm.Format(RFC3339+" MST"))
		}
	}
}

func TestSecondsToUTCAndBack(t *testing.T) {
	f := func(sec int64) bool { return Unix(sec, 0).UTC().Unix() == sec }
	f32 := func(sec int32) bool { return f(int64(sec)) }
	cfg := &quick.Config{MaxCount: 10000}

	// Try a reasonable date first, then the huge ones.
	if err := quick.Check(f32, cfg); err != nil {
		t.Fatal(err)
	}
	if err := quick.Check(f, cfg); err != nil {
		t.Fatal(err)
	}
}

func TestNanosecondsToUTCAndBack(t *testing.T) {
	f := func(nsec int64) bool {
		t := Unix(0, nsec).UTC()
		ns := t.Unix()*1e9 + int64(t.Nanosecond())
		return ns == nsec
	}
	f32 := func(nsec int32) bool { return f(int64(nsec)) }
	cfg := &quick.Config{MaxCount: 10000}

	// Try a small date first, then the large ones. (The span is only a few hundred years
	// for nanoseconds in an int64.)
	if err := quick.Check(f32, cfg); err != nil {
		t.Fatal(err)
	}
	if err := quick.Check(f, cfg); err != nil {
		t.Fatal(err)
	}
}

type TimeFormatTest struct {
	time           Time
	formattedValue string
}

var rfc3339Formats = []TimeFormatTest{
	{Date(2008, 9, 17, 20, 4, 26, 0, UTC), "2008-09-17T20:04:26Z"},
	{Date(1994, 9, 17, 20, 4, 26, 0, FixedZone("EST", -18000)), "1994-09-17T20:04:26-05:00"},
	{Date(2000, 12, 26, 1, 15, 6, 0, FixedZone("OTO", 15600)), "2000-12-26T01:15:06+04:20"},
}

func TestRFC3339Conversion(t *testing.T) {
	for _, f := range rfc3339Formats {
		if f.time.Format(RFC3339) != f.formattedValue {
			t.Error("RFC3339:")
			t.Errorf("  want=%+v", f.formattedValue)
			t.Errorf("  have=%+v", f.time.Format(RFC3339))
		}
	}
}

type FormatTest struct {
	name   string
	format string
	result string
}

var formatTests = []FormatTest{
	{"ANSIC", ANSIC, "Wed Feb  4 21:00:57 2009"},
	{"UnixDate", UnixDate, "Wed Feb  4 21:00:57 PST 2009"},
	{"RubyDate", RubyDate, "Wed Feb 04 21:00:57 -0800 2009"},
	{"RFC822", RFC822, "04 Feb 09 2100 PST"},
	{"RFC850", RFC850, "Wednesday, 04-Feb-09 21:00:57 PST"},
	{"RFC1123", RFC1123, "Wed, 04 Feb 2009 21:00:57 PST"},
	{"RFC1123Z", RFC1123Z, "Wed, 04 Feb 2009 21:00:57 -0800"},
	{"RFC3339", RFC3339, "2009-02-04T21:00:57-08:00"},
	{"Kitchen", Kitchen, "9:00PM"},
	{"am/pm", "3pm", "9pm"},
	{"AM/PM", "3PM", "9PM"},
	{"two-digit year", "06 01 02", "09 02 04"},
	// Time stamps, Fractional seconds.
	{"Stamp", Stamp, "Feb  4 21:00:57"},
	{"StampMilli", StampMilli, "Feb  4 21:00:57.012"},
	{"StampMicro", StampMicro, "Feb  4 21:00:57.012345"},
	{"StampNano", StampNano, "Feb  4 21:00:57.012345678"},
}

func TestFormat(t *testing.T) {
	// The numeric time represents Thu Feb  4 21:00:57.012345678 PST 2010
	time := Unix(0, 1233810057012345678)
	for _, test := range formatTests {
		result := time.Format(test.format)
		if result != test.result {
			t.Errorf("%s expected %q got %q", test.name, test.result, result)
		}
	}
}

type ParseTest struct {
	name       string
	format     string
	value      string
	hasTZ      bool // contains a time zone
	hasWD      bool // contains a weekday
	yearSign   int  // sign of year
	fracDigits int  // number of digits of fractional second
}

var parseTests = []ParseTest{
	{"ANSIC", ANSIC, "Thu Feb  4 21:00:57 2010", false, true, 1, 0},
	{"UnixDate", UnixDate, "Thu Feb  4 21:00:57 PST 2010", true, true, 1, 0},
	{"RubyDate", RubyDate, "Thu Feb 04 21:00:57 -0800 2010", true, true, 1, 0},
	{"RFC850", RFC850, "Thursday, 04-Feb-10 21:00:57 PST", true, true, 1, 0},
	{"RFC1123", RFC1123, "Thu, 04 Feb 2010 21:00:57 PST", true, true, 1, 0},
	{"RFC1123Z", RFC1123Z, "Thu, 04 Feb 2010 21:00:57 -0800", true, true, 1, 0},
	{"RFC3339", RFC3339, "2010-02-04T21:00:57-08:00", true, false, 1, 0},
	{"custom: \"2006-01-02 15:04:05-07\"", "2006-01-02 15:04:05-07", "2010-02-04 21:00:57-08", true, false, 1, 0},
	// Optional fractional seconds.
	{"ANSIC", ANSIC, "Thu Feb  4 21:00:57.0 2010", false, true, 1, 1},
	{"UnixDate", UnixDate, "Thu Feb  4 21:00:57.01 PST 2010", true, true, 1, 2},
	{"RubyDate", RubyDate, "Thu Feb 04 21:00:57.012 -0800 2010", true, true, 1, 3},
	{"RFC850", RFC850, "Thursday, 04-Feb-10 21:00:57.0123 PST", true, true, 1, 4},
	{"RFC1123", RFC1123, "Thu, 04 Feb 2010 21:00:57.01234 PST", true, true, 1, 5},
	{"RFC1123Z", RFC1123Z, "Thu, 04 Feb 2010 21:00:57.01234 -0800", true, true, 1, 5},
	{"RFC3339", RFC3339, "2010-02-04T21:00:57.012345678-08:00", true, false, 1, 9},
	// Amount of white space should not matter.
	{"ANSIC", ANSIC, "Thu Feb 4 21:00:57 2010", false, true, 1, 0},
	{"ANSIC", ANSIC, "Thu      Feb     4     21:00:57     2010", false, true, 1, 0},
	// Case should not matter
	{"ANSIC", ANSIC, "THU FEB 4 21:00:57 2010", false, true, 1, 0},
	{"ANSIC", ANSIC, "thu feb 4 21:00:57 2010", false, true, 1, 0},
	// Fractional seconds.
	{"millisecond", "Mon Jan _2 15:04:05.000 2006", "Thu Feb  4 21:00:57.012 2010", false, true, 1, 3},
	{"microsecond", "Mon Jan _2 15:04:05.000000 2006", "Thu Feb  4 21:00:57.012345 2010", false, true, 1, 6},
	{"nanosecond", "Mon Jan _2 15:04:05.000000000 2006", "Thu Feb  4 21:00:57.012345678 2010", false, true, 1, 9},
	// Leading zeros in other places should not be taken as fractional seconds.
	{"zero1", "2006.01.02.15.04.05.0", "2010.02.04.21.00.57.0", false, false, 1, 1},
	{"zero2", "2006.01.02.15.04.05.00", "2010.02.04.21.00.57.01", false, false, 1, 2},
}

func TestParse(t *testing.T) {
	for _, test := range parseTests {
		time, err := Parse(test.format, test.value)
		if err != nil {
			t.Errorf("%s error: %v", test.name, err)
		} else {
			checkTime(time, &test, t)
		}
	}
}

var rubyTests = []ParseTest{
	{"RubyDate", RubyDate, "Thu Feb 04 21:00:57 -0800 2010", true, true, 1, 0},
	// Ignore the time zone in the test. If it parses, it'll be OK.
	{"RubyDate", RubyDate, "Thu Feb 04 21:00:57 -0000 2010", false, true, 1, 0},
	{"RubyDate", RubyDate, "Thu Feb 04 21:00:57 +0000 2010", false, true, 1, 0},
	{"RubyDate", RubyDate, "Thu Feb 04 21:00:57 +1130 2010", false, true, 1, 0},
}

// Problematic time zone format needs special tests.
func TestRubyParse(t *testing.T) {
	for _, test := range rubyTests {
		time, err := Parse(test.format, test.value)
		if err != nil {
			t.Errorf("%s error: %v", test.name, err)
		} else {
			checkTime(time, &test, t)
		}
	}
}

func checkTime(time Time, test *ParseTest, t *testing.T) {
	// The time should be Thu Feb  4 21:00:57 PST 2010
	if test.yearSign*time.Year() != 2010 {
		t.Errorf("%s: bad year: %d not %d", test.name, time.Year(), 2010)
	}
	if time.Month() != February {
		t.Errorf("%s: bad month: %s not %s", test.name, time.Month(), February)
	}
	if time.Day() != 4 {
		t.Errorf("%s: bad day: %d not %d", test.name, time.Day(), 4)
	}
	if time.Hour() != 21 {
		t.Errorf("%s: bad hour: %d not %d", test.name, time.Hour(), 21)
	}
	if time.Minute() != 0 {
		t.Errorf("%s: bad minute: %d not %d", test.name, time.Minute(), 0)
	}
	if time.Second() != 57 {
		t.Errorf("%s: bad second: %d not %d", test.name, time.Second(), 57)
	}
	// Nanoseconds must be checked against the precision of the input.
	nanosec, err := strconv.ParseUint("012345678"[:test.fracDigits]+"000000000"[:9-test.fracDigits], 10, 0)
	if err != nil {
		panic(err)
	}
	if time.Nanosecond() != int(nanosec) {
		t.Errorf("%s: bad nanosecond: %d not %d", test.name, time.Nanosecond(), nanosec)
	}
	name, offset := time.Zone()
	if test.hasTZ && offset != -28800 {
		t.Errorf("%s: bad tz offset: %s %d not %d", test.name, name, offset, -28800)
	}
	if test.hasWD && time.Weekday() != Thursday {
		t.Errorf("%s: bad weekday: %s not %s", test.name, time.Weekday(), Thursday)
	}
}

func TestFormatAndParse(t *testing.T) {
	const fmt = "Mon MST " + RFC3339 // all fields
	f := func(sec int64) bool {
		t1 := Unix(sec, 0)
		if t1.Year() < 1000 || t1.Year() > 9999 {
			// not required to work
			return true
		}
		t2, err := Parse(fmt, t1.Format(fmt))
		if err != nil {
			t.Errorf("error: %s", err)
			return false
		}
		if t1.Unix() != t2.Unix() || t1.Nanosecond() != t2.Nanosecond() {
			t.Errorf("FormatAndParse %d: %q(%d) %q(%d)", sec, t1, t1.Unix(), t2, t2.Unix())
			return false
		}
		return true
	}
	f32 := func(sec int32) bool { return f(int64(sec)) }
	cfg := &quick.Config{MaxCount: 10000}

	// Try a reasonable date first, then the huge ones.
	if err := quick.Check(f32, cfg); err != nil {
		t.Fatal(err)
	}
	if err := quick.Check(f, cfg); err != nil {
		t.Fatal(err)
	}
}

type ParseErrorTest struct {
	format string
	value  string
	expect string // must appear within the error
}

var parseErrorTests = []ParseErrorTest{
	{ANSIC, "Feb  4 21:00:60 2010", "cannot parse"}, // cannot parse Feb as Mon
	{ANSIC, "Thu Feb  4 21:00:57 @2010", "cannot parse"},
	{ANSIC, "Thu Feb  4 21:00:60 2010", "second out of range"},
	{ANSIC, "Thu Feb  4 21:61:57 2010", "minute out of range"},
	{ANSIC, "Thu Feb  4 24:00:60 2010", "hour out of range"},
	{"Mon Jan _2 15:04:05.000 2006", "Thu Feb  4 23:00:59x01 2010", "cannot parse"},
	{"Mon Jan _2 15:04:05.000 2006", "Thu Feb  4 23:00:59.xxx 2010", "cannot parse"},
	{"Mon Jan _2 15:04:05.000 2006", "Thu Feb  4 23:00:59.-123 2010", "fractional second out of range"},
}

func TestParseErrors(t *testing.T) {
	for _, test := range parseErrorTests {
		_, err := Parse(test.format, test.value)
		if err == nil {
			t.Errorf("expected error for %q %q", test.format, test.value)
		} else if strings.Index(err.Error(), test.expect) < 0 {
			t.Errorf("expected error with %q for %q %q; got %s", test.expect, test.format, test.value, err)
		}
	}
}

func TestNoonIs12PM(t *testing.T) {
	noon := Date(0, January, 1, 12, 0, 0, 0, UTC)
	const expect = "12:00PM"
	got := noon.Format("3:04PM")
	if got != expect {
		t.Errorf("got %q; expect %q", got, expect)
	}
	got = noon.Format("03:04PM")
	if got != expect {
		t.Errorf("got %q; expect %q", got, expect)
	}
}

func TestMidnightIs12AM(t *testing.T) {
	midnight := Date(0, January, 1, 0, 0, 0, 0, UTC)
	expect := "12:00AM"
	got := midnight.Format("3:04PM")
	if got != expect {
		t.Errorf("got %q; expect %q", got, expect)
	}
	got = midnight.Format("03:04PM")
	if got != expect {
		t.Errorf("got %q; expect %q", got, expect)
	}
}

func Test12PMIsNoon(t *testing.T) {
	noon, err := Parse("3:04PM", "12:00PM")
	if err != nil {
		t.Fatal("error parsing date:", err)
	}
	if noon.Hour() != 12 {
		t.Errorf("got %d; expect 12", noon.Hour())
	}
	noon, err = Parse("03:04PM", "12:00PM")
	if err != nil {
		t.Fatal("error parsing date:", err)
	}
	if noon.Hour() != 12 {
		t.Errorf("got %d; expect 12", noon.Hour())
	}
}

func Test12AMIsMidnight(t *testing.T) {
	midnight, err := Parse("3:04PM", "12:00AM")
	if err != nil {
		t.Fatal("error parsing date:", err)
	}
	if midnight.Hour() != 0 {
		t.Errorf("got %d; expect 0", midnight.Hour())
	}
	midnight, err = Parse("03:04PM", "12:00AM")
	if err != nil {
		t.Fatal("error parsing date:", err)
	}
	if midnight.Hour() != 0 {
		t.Errorf("got %d; expect 0", midnight.Hour())
	}
}

// Check that a time without a Zone still produces a (numeric) time zone
// when formatted with MST as a requested zone.
func TestMissingZone(t *testing.T) {
	time, err := Parse(RubyDate, "Thu Feb 02 16:10:03 -0500 2006")
	if err != nil {
		t.Fatal("error parsing date:", err)
	}
	expect := "Thu Feb  2 16:10:03 -0500 2006" // -0500 not EST
	str := time.Format(UnixDate)               // uses MST as its time zone
	if str != expect {
		t.Errorf("got %s; expect %s", str, expect)
	}
}

func TestMinutesInTimeZone(t *testing.T) {
	time, err := Parse(RubyDate, "Mon Jan 02 15:04:05 +0123 2006")
	if err != nil {
		t.Fatal("error parsing date:", err)
	}
	expected := (1*60 + 23) * 60
	_, offset := time.Zone()
	if offset != expected {
		t.Errorf("ZoneOffset = %d, want %d", offset, expected)
	}
}

type ISOWeekTest struct {
	year       int // year
	month, day int // month and day
	yex        int // expected year
	wex        int // expected week
}

var isoWeekTests = []ISOWeekTest{
	{1981, 1, 1, 1981, 1}, {1982, 1, 1, 1981, 53}, {1983, 1, 1, 1982, 52},
	{1984, 1, 1, 1983, 52}, {1985, 1, 1, 1985, 1}, {1986, 1, 1, 1986, 1},
	{1987, 1, 1, 1987, 1}, {1988, 1, 1, 1987, 53}, {1989, 1, 1, 1988, 52},
	{1990, 1, 1, 1990, 1}, {1991, 1, 1, 1991, 1}, {1992, 1, 1, 1992, 1},
	{1993, 1, 1, 1992, 53}, {1994, 1, 1, 1993, 52}, {1995, 1, 2, 1995, 1},
	{1996, 1, 1, 1996, 1}, {1996, 1, 7, 1996, 1}, {1996, 1, 8, 1996, 2},
	{1997, 1, 1, 1997, 1}, {1998, 1, 1, 1998, 1}, {1999, 1, 1, 1998, 53},
	{2000, 1, 1, 1999, 52}, {2001, 1, 1, 2001, 1}, {2002, 1, 1, 2002, 1},
	{2003, 1, 1, 2003, 1}, {2004, 1, 1, 2004, 1}, {2005, 1, 1, 2004, 53},
	{2006, 1, 1, 2005, 52}, {2007, 1, 1, 2007, 1}, {2008, 1, 1, 2008, 1},
	{2009, 1, 1, 2009, 1}, {2010, 1, 1, 2009, 53}, {2010, 1, 1, 2009, 53},
	{2011, 1, 1, 2010, 52}, {2011, 1, 2, 2010, 52}, {2011, 1, 3, 2011, 1},
	{2011, 1, 4, 2011, 1}, {2011, 1, 5, 2011, 1}, {2011, 1, 6, 2011, 1},
	{2011, 1, 7, 2011, 1}, {2011, 1, 8, 2011, 1}, {2011, 1, 9, 2011, 1},
	{2011, 1, 10, 2011, 2}, {2011, 1, 11, 2011, 2}, {2011, 6, 12, 2011, 23},
	{2011, 6, 13, 2011, 24}, {2011, 12, 25, 2011, 51}, {2011, 12, 26, 2011, 52},
	{2011, 12, 27, 2011, 52}, {2011, 12, 28, 2011, 52}, {2011, 12, 29, 2011, 52},
	{2011, 12, 30, 2011, 52}, {2011, 12, 31, 2011, 52}, {1995, 1, 1, 1994, 52},
	{2012, 1, 1, 2011, 52}, {2012, 1, 2, 2012, 1}, {2012, 1, 8, 2012, 1},
	{2012, 1, 9, 2012, 2}, {2012, 12, 23, 2012, 51}, {2012, 12, 24, 2012, 52},
	{2012, 12, 30, 2012, 52}, {2012, 12, 31, 2013, 1}, {2013, 1, 1, 2013, 1},
	{2013, 1, 6, 2013, 1}, {2013, 1, 7, 2013, 2}, {2013, 12, 22, 2013, 51},
	{2013, 12, 23, 2013, 52}, {2013, 12, 29, 2013, 52}, {2013, 12, 30, 2014, 1},
	{2014, 1, 1, 2014, 1}, {2014, 1, 5, 2014, 1}, {2014, 1, 6, 2014, 2},
	{2015, 1, 1, 2015, 1}, {2016, 1, 1, 2015, 53}, {2017, 1, 1, 2016, 52},
	{2018, 1, 1, 2018, 1}, {2019, 1, 1, 2019, 1}, {2020, 1, 1, 2020, 1},
	{2021, 1, 1, 2020, 53}, {2022, 1, 1, 2021, 52}, {2023, 1, 1, 2022, 52},
	{2024, 1, 1, 2024, 1}, {2025, 1, 1, 2025, 1}, {2026, 1, 1, 2026, 1},
	{2027, 1, 1, 2026, 53}, {2028, 1, 1, 2027, 52}, {2029, 1, 1, 2029, 1},
	{2030, 1, 1, 2030, 1}, {2031, 1, 1, 2031, 1}, {2032, 1, 1, 2032, 1},
	{2033, 1, 1, 2032, 53}, {2034, 1, 1, 2033, 52}, {2035, 1, 1, 2035, 1},
	{2036, 1, 1, 2036, 1}, {2037, 1, 1, 2037, 1}, {2038, 1, 1, 2037, 53},
	{2039, 1, 1, 2038, 52}, {2040, 1, 1, 2039, 52},
}

func TestISOWeek(t *testing.T) {
	// Selected dates and corner cases
	for _, wt := range isoWeekTests {
		dt := Date(wt.year, Month(wt.month), wt.day, 0, 0, 0, 0, UTC)
		y, w := dt.ISOWeek()
		if w != wt.wex || y != wt.yex {
			t.Errorf("got %d/%d; expected %d/%d for %d-%02d-%02d",
				y, w, wt.yex, wt.wex, wt.year, wt.month, wt.day)
		}
	}

	// The only real invariant: Jan 04 is in week 1
	for year := 1950; year < 2100; year++ {
		if y, w := Date(year, January, 4, 0, 0, 0, 0, UTC).ISOWeek(); y != year || w != 1 {
			t.Errorf("got %d/%d; expected %d/1 for Jan 04", y, w, year)
		}
	}
}

var durationTests = []struct {
	str string
	d   Duration
}{
	{"0", 0},
	{"1ns", 1 * Nanosecond},
	{"1.1us", 1100 * Nanosecond},
	{"2.2ms", 2200 * Microsecond},
	{"3.3s", 3300 * Millisecond},
	{"4m5s", 4*Minute + 5*Second},
	{"4m5.001s", 4*Minute + 5001*Millisecond},
	{"5h6m7.001s", 5*Hour + 6*Minute + 7001*Millisecond},
	{"8m0.000000001s", 8*Minute + 1*Nanosecond},
	{"2562047h47m16.854775807s", 1<<63 - 1},
	{"-2562047h47m16.854775808s", -1 << 63},
}

func TestDurationString(t *testing.T) {
	for _, tt := range durationTests {
		if str := tt.d.String(); str != tt.str {
			t.Errorf("Duration(%d).String() = %s, want %s", int64(tt.d), str, tt.str)
		}
		if tt.d > 0 {
			if str := (-tt.d).String(); str != "-"+tt.str {
				t.Errorf("Duration(%d).String() = %s, want %s", int64(-tt.d), str, "-"+tt.str)
			}
		}
	}
}

var dateTests = []struct {
	year, month, day, hour, min, sec, nsec int
	z                                      *Location
	unix                                   int64
}{
	{2011, 11, 6, 1, 0, 0, 0, Local, 1320566400},   // 1:00:00 PDT
	{2011, 11, 6, 1, 59, 59, 0, Local, 1320569999}, // 1:59:59 PDT
	{2011, 11, 6, 2, 0, 0, 0, Local, 1320573600},   // 2:00:00 PST

	{2011, 3, 13, 1, 0, 0, 0, Local, 1300006800},   // 1:00:00 PST
	{2011, 3, 13, 1, 59, 59, 0, Local, 1300010399}, // 1:59:59 PST
	{2011, 3, 13, 3, 0, 0, 0, Local, 1300010400},   // 3:00:00 PDT
	{2011, 3, 13, 2, 30, 0, 0, Local, 1300008600},  // 2:30:00 PDT ≡ 1:30 PST

	// Many names for Fri Nov 18 7:56:35 PST 2011
	{2011, 11, 18, 7, 56, 35, 0, Local, 1321631795},                 // Nov 18 7:56:35
	{2011, 11, 19, -17, 56, 35, 0, Local, 1321631795},               // Nov 19 -17:56:35
	{2011, 11, 17, 31, 56, 35, 0, Local, 1321631795},                // Nov 17 31:56:35
	{2011, 11, 18, 6, 116, 35, 0, Local, 1321631795},                // Nov 18 6:116:35
	{2011, 10, 49, 7, 56, 35, 0, Local, 1321631795},                 // Oct 49 7:56:35
	{2011, 11, 18, 7, 55, 95, 0, Local, 1321631795},                 // Nov 18 7:55:95
	{2011, 11, 18, 7, 56, 34, 1e9, Local, 1321631795},               // Nov 18 7:56:34 + 10⁹ns
	{2011, 12, -12, 7, 56, 35, 0, Local, 1321631795},                // Dec -21 7:56:35
	{2012, 1, -43, 7, 56, 35, 0, Local, 1321631795},                 // Jan -52 7:56:35 2012
	{2012, int(January - 2), 18, 7, 56, 35, 0, Local, 1321631795},   // (Jan-2) 18 7:56:35 2012
	{2010, int(December + 11), 18, 7, 56, 35, 0, Local, 1321631795}, // (Dec+11) 18 7:56:35 2010
}

func TestDate(t *testing.T) {
	for _, tt := range dateTests {
		time := Date(tt.year, Month(tt.month), tt.day, tt.hour, tt.min, tt.sec, tt.nsec, tt.z)
		want := Unix(tt.unix, 0)
		if !time.Equal(want) {
			t.Errorf("Date(%d, %d, %d, %d, %d, %d, %d, %s) = %v, want %v",
				tt.year, tt.month, tt.day, tt.hour, tt.min, tt.sec, tt.nsec, tt.z,
				time, want)
		}
	}
}

// Several ways of getting from
// Fri Nov 18 7:56:35 PST 2011
// to
// Thu Mar 19 7:56:35 PST 2016
var addDateTests = []struct {
	years, months, days int
}{
	{4, 4, 1},
	{3, 16, 1},
	{3, 15, 30},
	{5, -6, -18 - 30 - 12},
}

func TestAddDate(t *testing.T) {
	t0 := Date(2011, 11, 18, 7, 56, 35, 0, UTC)
	t1 := Date(2016, 3, 19, 7, 56, 35, 0, UTC)
	for _, at := range addDateTests {
		time := t0.AddDate(at.years, at.months, at.days)
		if !time.Equal(t1) {
			t.Errorf("AddDate(%d, %d, %d) = %v, want %v",
				at.years, at.months, at.days,
				time, t1)
		}
	}
}

var daysInTests = []struct {
	year, month, di int
}{
	{2011, 1, 31},  // January, first month, 31 days
	{2011, 2, 28},  // February, non-leap year, 28 days
	{2012, 2, 29},  // February, leap year, 29 days
	{2011, 6, 30},  // June, 30 days
	{2011, 12, 31}, // December, last month, 31 days
}

func TestDaysIn(t *testing.T) {
	// The daysIn function is not exported.
	// Test the daysIn function via the `var DaysIn = daysIn`
	// statement in the internal_test.go file.
	for _, tt := range daysInTests {
		di := DaysIn(Month(tt.month), tt.year)
		if di != tt.di {
			t.Errorf("got %d; expected %d for %d-%02d",
				di, tt.di, tt.year, tt.month)
		}
	}
}

func TestAddToExactSecond(t *testing.T) {
	// Add an amount to the current time to round it up to the next exact second.
	// This test checks that the nsec field still lies within the range [0, 999999999].
	t1 := Now()
	t2 := t1.Add(Second - Duration(t1.Nanosecond()))
	sec := (t1.Second() + 1) % 60
	if t2.Second() != sec || t2.Nanosecond() != 0 {
		t.Errorf("sec = %d, nsec = %d, want sec = %d, nsec = 0", t2.Second(), t2.Nanosecond(), sec)
	}
}

func equalTimeAndZone(a, b Time) bool {
	aname, aoffset := a.Zone()
	bname, boffset := b.Zone()
	return a.Equal(b) && aoffset == boffset && aname == bname
}

var gobTests = []Time{
	Date(0, 1, 2, 3, 4, 5, 6, UTC),
	Date(7, 8, 9, 10, 11, 12, 13, FixedZone("", 0)),
	Unix(81985467080890095, 0x76543210), // Time.sec: 0x0123456789ABCDEF
	Time{},                              // nil location
	Date(1, 2, 3, 4, 5, 6, 7, FixedZone("", 32767*60)),
	Date(1, 2, 3, 4, 5, 6, 7, FixedZone("", -32768*60)),
}

func TestTimeGob(t *testing.T) {
	var b bytes.Buffer
	enc := gob.NewEncoder(&b)
	dec := gob.NewDecoder(&b)
	for _, tt := range gobTests {
		var gobtt Time
		if err := enc.Encode(&tt); err != nil {
			t.Errorf("%v gob Encode error = %q, want nil", tt, err)
		} else if err := dec.Decode(&gobtt); err != nil {
			t.Errorf("%v gob Decode error = %q, want nil", tt, err)
		} else if !equalTimeAndZone(gobtt, tt) {
			t.Errorf("Decoded time = %v, want %v", gobtt, tt)
		}
		b.Reset()
	}
}

var invalidEncodingTests = []struct {
	bytes []byte
	want  string
}{
	{[]byte{}, "Time.GobDecode: no data"},
	{[]byte{0, 2, 3}, "Time.GobDecode: unsupported version"},
	{[]byte{1, 2, 3}, "Time.GobDecode: invalid length"},
}

func TestInvalidTimeGob(t *testing.T) {
	for _, tt := range invalidEncodingTests {
		var ignored Time
		err := ignored.GobDecode(tt.bytes)
		if err == nil || err.Error() != tt.want {
			t.Errorf("time.GobDecode(%#v) error = %v, want %v", tt.bytes, err, tt.want)
		}
	}
}

var notEncodableTimes = []struct {
	time Time
	want string
}{
	{Date(0, 1, 2, 3, 4, 5, 6, FixedZone("", 1)), "Time.GobEncode: zone offset has fractional minute"},
	{Date(0, 1, 2, 3, 4, 5, 6, FixedZone("", -1*60)), "Time.GobEncode: unexpected zone offset"},
	{Date(0, 1, 2, 3, 4, 5, 6, FixedZone("", -32769*60)), "Time.GobEncode: unexpected zone offset"},
	{Date(0, 1, 2, 3, 4, 5, 6, FixedZone("", 32768*60)), "Time.GobEncode: unexpected zone offset"},
}

func TestNotGobEncodableTime(t *testing.T) {
	for _, tt := range notEncodableTimes {
		_, err := tt.time.GobEncode()
		if err == nil || err.Error() != tt.want {
			t.Errorf("%v GobEncode error = %v, want %v", tt.time, err, tt.want)
		}
	}
}

var jsonTests = []struct {
	time Time
	json string
}{
	{Date(9999, 4, 12, 23, 20, 50, .52*1e9, UTC), `"9999-04-12T23:20:50.52Z"`},
	{Date(1996, 12, 19, 16, 39, 57, 0, Local), `"1996-12-19T16:39:57-08:00"`},
	{Date(0, 1, 1, 0, 0, 0, 1, FixedZone("", 1*60)), `"0000-01-01T00:00:00.000000001+00:01"`},
}

func TestTimeJSON(t *testing.T) {
	for _, tt := range jsonTests {
		var jsonTime Time

		if jsonBytes, err := json.Marshal(tt.time); err != nil {
			t.Errorf("%v json.Marshal error = %v, want nil", tt.time, err)
		} else if string(jsonBytes) != tt.json {
			t.Errorf("%v JSON = %q, want %q", tt.time, string(jsonBytes), tt.json)
		} else if err = json.Unmarshal(jsonBytes, &jsonTime); err != nil {
			t.Errorf("%v json.Unmarshal error = %v, want nil", tt.time, err)
		} else if !equalTimeAndZone(jsonTime, tt.time) {
			t.Errorf("Unmarshaled time = %v, want %v", jsonTime, tt.time)
		}
	}
}

func TestInvalidTimeJSON(t *testing.T) {
	var tt Time
	err := json.Unmarshal([]byte(`{"now is the time":"buddy"}`), &tt)
	_, isParseErr := err.(*ParseError)
	if !isParseErr {
		t.Errorf("expected *time.ParseError unmarshaling JSON, got %v", err)
	}
}

var notJSONEncodableTimes = []struct {
	time Time
	want string
}{
	{Date(10000, 1, 1, 0, 0, 0, 0, UTC), "Time.MarshalJSON: year outside of range [0,9999]"},
	{Date(-1, 1, 1, 0, 0, 0, 0, UTC), "Time.MarshalJSON: year outside of range [0,9999]"},
}

func TestNotJSONEncodableTime(t *testing.T) {
	for _, tt := range notJSONEncodableTimes {
		_, err := tt.time.MarshalJSON()
		if err == nil || err.Error() != tt.want {
			t.Errorf("%v MarshalJSON error = %v, want %v", tt.time, err, tt.want)
		}
	}
}

var parseDurationTests = []struct {
	in   string
	ok   bool
	want Duration
}{
	// simple
	{"0", true, 0},
	{"5s", true, 5 * Second},
	{"30s", true, 30 * Second},
	{"1478s", true, 1478 * Second},
	// sign
	{"-5s", true, -5 * Second},
	{"+5s", true, 5 * Second},
	{"-0", true, 0},
	{"+0", true, 0},
	// decimal
	{"5.0s", true, 5 * Second},
	{"5.6s", true, 5*Second + 600*Millisecond},
	{"5.s", true, 5 * Second},
	{".5s", true, 500 * Millisecond},
	{"1.0s", true, 1 * Second},
	{"1.00s", true, 1 * Second},
	{"1.004s", true, 1*Second + 4*Millisecond},
	{"1.0040s", true, 1*Second + 4*Millisecond},
	{"100.00100s", true, 100*Second + 1*Millisecond},
	// different units
	{"10ns", true, 10 * Nanosecond},
	{"11us", true, 11 * Microsecond},
	{"12µs", true, 12 * Microsecond}, // U+00B5
	{"12μs", true, 12 * Microsecond}, // U+03BC
	{"13ms", true, 13 * Millisecond},
	{"14s", true, 14 * Second},
	{"15m", true, 15 * Minute},
	{"16h", true, 16 * Hour},
	// composite durations
	{"3h30m", true, 3*Hour + 30*Minute},
	{"10.5s4m", true, 4*Minute + 10*Second + 500*Millisecond},
	{"-2m3.4s", true, -(2*Minute + 3*Second + 400*Millisecond)},
	{"1h2m3s4ms5us6ns", true, 1*Hour + 2*Minute + 3*Second + 4*Millisecond + 5*Microsecond + 6*Nanosecond},
	{"39h9m14.425s", true, 39*Hour + 9*Minute + 14*Second + 425*Millisecond},

	// errors
	{"", false, 0},
	{"3", false, 0},
	{"-", false, 0},
	{"s", false, 0},
	{".", false, 0},
	{"-.", false, 0},
	{".s", false, 0},
	{"+.s", false, 0},
}

func TestParseDuration(t *testing.T) {
	for _, tc := range parseDurationTests {
		d, err := ParseDuration(tc.in)
		if tc.ok && (err != nil || d != tc.want) {
			t.Errorf("ParseDuration(%q) = %v, %v, want %v, nil", tc.in, d, err, tc.want)
		} else if !tc.ok && err == nil {
			t.Errorf("ParseDuration(%q) = _, nil, want _, non-nil", tc.in)
		}
	}
}

func TestParseDurationRoundTrip(t *testing.T) {
	for i := 0; i < 100; i++ {
		// Resolutions finer than milliseconds will result in
		// imprecise round-trips.
		d0 := Duration(rand.Int31()) * Millisecond
		s := d0.String()
		d1, err := ParseDuration(s)
		if err != nil || d0 != d1 {
			t.Errorf("round-trip failed: %d => %q => %d, %v", d0, s, d1, err)
		}
	}
}

func BenchmarkNow(b *testing.B) {
	for i := 0; i < b.N; i++ {
		Now()
	}
}

func BenchmarkFormat(b *testing.B) {
	time := Unix(1265346057, 0)
	for i := 0; i < b.N; i++ {
		time.Format("Mon Jan  2 15:04:05 2006")
	}
}

func BenchmarkParse(b *testing.B) {
	for i := 0; i < b.N; i++ {
		Parse(ANSIC, "Mon Jan  2 15:04:05 2006")
	}
}

func BenchmarkHour(b *testing.B) {
	t := Now()
	for i := 0; i < b.N; i++ {
		_ = t.Hour()
	}
}

func BenchmarkSecond(b *testing.B) {
	t := Now()
	for i := 0; i < b.N; i++ {
		_ = t.Second()
	}
}

func BenchmarkYear(b *testing.B) {
	t := Now()
	for i := 0; i < b.N; i++ {
		_ = t.Year()
	}
}

func BenchmarkDay(b *testing.B) {
	t := Now()
	for i := 0; i < b.N; i++ {
		_ = t.Day()
	}
}