// Copyright 2015 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Copyright 2018 PingCAP, Inc. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSES/QL-LICENSE file.

package timeutil

import (
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"github.com/stretchr/testify/require"
)

func TestGetTZNameFromFileName(t *testing.T) {
	tz, err := inferTZNameFromFileName("/usr/share/zoneinfo/Asia/Shanghai")

	require.NoError(t, err)
	require.Equal(t, "Asia/Shanghai", tz)

	tz, err = inferTZNameFromFileName("/usr/share/zoneinfo.default/Asia/Shanghai")

	require.NoError(t, err)
	require.Equal(t, "Asia/Shanghai", tz)
}

func TestLocal(t *testing.T) {
	os.Setenv("TZ", "Asia/Shanghai")
	systemTZ.Store(InferSystemTZ())
	loc := SystemLocation()
	require.Equal(t, "Asia/Shanghai", systemTZ.Load())
	require.Equal(t, "Asia/Shanghai", loc.String())

	os.Setenv("TZ", "UTC")
	// reset systemTZ
	systemTZ.Store(InferSystemTZ())
	loc = SystemLocation()
	require.Equal(t, "UTC", loc.String())

	os.Setenv("TZ", "")
	// reset systemTZ
	systemTZ.Store(InferSystemTZ())
	loc = SystemLocation()
	require.Equal(t, "UTC", loc.String())
	os.Unsetenv("TZ")
}

func TestInferOneStepLinkForPath(t *testing.T) {
	os.Remove(filepath.Join(os.TempDir(), "testlink1"))
	os.Remove(filepath.Join(os.TempDir(), "testlink2"))
	os.Remove(filepath.Join(os.TempDir(), "testlink3"))
	var link2, link3 string
	var err error
	var link1 *os.File
	link1, err = os.Create(filepath.Join(os.TempDir(), "testlink1"))
	require.NoError(t, err)
	err = os.Symlink(link1.Name(), filepath.Join(os.TempDir(), "testlink2"))
	require.NoError(t, err)
	err = os.Symlink(filepath.Join(os.TempDir(), "testlink2"), filepath.Join(os.TempDir(), "testlink3"))
	require.NoError(t, err)
	link2, err = inferOneStepLinkForPath(filepath.Join(os.TempDir(), "testlink3"))
	require.NoError(t, err)
	require.Equal(t, filepath.Join(os.TempDir(), "testlink2"), link2)
	link3, err = filepath.EvalSymlinks(filepath.Join(os.TempDir(), "testlink3"))
	require.NoError(t, err)
	require.NotEqual(t, -1, strings.Index(link3, link1.Name()))
}

func TestParseTimeZone(t *testing.T) {
	SetSystemTZ("Asia/Tokyo")
	cases := []struct {
		name    string
		offset  int64
		invalid bool
	}{
		{
			name:   "SYSTEM",
			offset: int64(9 * 3600),
		},
		{
			name:   "system",
			offset: int64(9 * 3600),
		},
		{
			name:   "Asia/Shanghai",
			offset: int64(8 * 3600),
		},
		{
			name:   "Pacific/Honolulu",
			offset: int64(-10 * 3600),
		},
		{
			name:   "-07:00",
			offset: int64(-7 * 3600),
		},
		{
			name:   "+02:00",
			offset: int64(2 * 3600),
		},
		{
			name:    "aa",
			invalid: true,
		},
	}

	for _, c := range cases {
		loc, err := ParseTimeZone(c.name)
		if c.invalid {
			require.True(t, ErrUnknownTimeZone.Equal(err))
			require.Nil(t, loc, c.name)
			continue
		}
		require.NoError(t, err)
		require.NotNil(t, loc, c.name)
		_, offset := Zone(loc)
		require.Equal(t, c.offset, offset, c.name)
	}
}

func TestZoneName(t *testing.T) {
	cases := []struct {
		name     string
		loc      *time.Location
		expected string
	}{
		{
			name:     "iana timezone",
			loc:      time.UTC,
			expected: "UTC",
		},
		{
			name:     "unnamed positive fixed zone",
			loc:      time.FixedZone("", int((8*time.Hour + 30*time.Minute).Seconds())),
			expected: "+08:30",
		},
		{
			name:     "unnamed negative fixed zone",
			loc:      time.FixedZone("", -int((6*time.Hour + 15*time.Minute).Seconds())),
			expected: "-06:15",
		},
		{
			name:     "unnamed zero fixed zone",
			loc:      time.FixedZone("", 0),
			expected: "+00:00",
		},
		{
			name:     "named fixed zone",
			loc:      time.FixedZone("UTC+8", int((8 * time.Hour).Seconds())),
			expected: "UTC+8",
		},
	}

	for _, c := range cases {
		t.Run(c.name, func(t *testing.T) {
			require.Equal(t, c.expected, ZoneName(c.loc))
		})
	}
}

func TestConstructTimeZone(t *testing.T) {
	secondsEastOfUTC := int((8 * time.Hour).Seconds())
	loc, err := ConstructTimeZone("", secondsEastOfUTC)
	require.NoError(t, err)
	timeInLoc := time.Date(2018, 8, 15, 20, 0, 0, 0, loc)
	timeInUTC := time.Date(2018, 8, 15, 12, 0, 0, 0, time.UTC)
	require.True(t, timeInLoc.Equal(timeInUTC))

	secondsEastOfUTC = int((-8 * time.Hour).Seconds())
	loc, err = ConstructTimeZone("", secondsEastOfUTC)
	require.NoError(t, err)
	timeInLoc = time.Date(2018, 8, 15, 12, 0, 0, 0, loc)
	timeInUTC = time.Date(2018, 8, 15, 20, 0, 0, 0, time.UTC)
	require.True(t, timeInLoc.Equal(timeInUTC))

	secondsEastOfUTC = 0
	loc, err = ConstructTimeZone("", secondsEastOfUTC)
	require.NoError(t, err)
	timeInLoc = time.Date(2018, 8, 15, 20, 0, 0, 0, loc)
	timeInUTC = time.Date(2018, 8, 15, 20, 0, 0, 0, time.UTC)
	require.True(t, timeInLoc.Equal(timeInUTC))

	// test the seconds east of UTC is ignored by the function
	// ConstructTimeZone().
	secondsEastOfUTC = int((23 * time.Hour).Seconds())
	loc, err = ConstructTimeZone("UTC", secondsEastOfUTC)
	require.NoError(t, err)
	timeInLoc = time.Date(2018, 8, 15, 12, 0, 0, 0, loc)
	timeInUTC = time.Date(2018, 8, 15, 12, 0, 0, 0, time.UTC)
	require.True(t, timeInLoc.Equal(timeInUTC))

	// test the seconds east of UTC is ignored by the function
	// ConstructTimeZone().
	secondsEastOfUTC = int((-23 * time.Hour).Seconds())
	loc, err = ConstructTimeZone("UTC", secondsEastOfUTC)
	require.NoError(t, err)
	timeInLoc = time.Date(2018, 8, 15, 12, 0, 0, 0, loc)
	timeInUTC = time.Date(2018, 8, 15, 12, 0, 0, 0, time.UTC)
	require.True(t, timeInLoc.Equal(timeInUTC))

	// test the seconds east of UTC is ignored by the function
	// ConstructTimeZone().
	loc, err = ConstructTimeZone("UTC", 0)
	require.NoError(t, err)
	timeInLoc = time.Date(2018, 8, 15, 12, 0, 0, 0, loc)
	timeInUTC = time.Date(2018, 8, 15, 12, 0, 0, 0, time.UTC)
	require.True(t, timeInLoc.Equal(timeInUTC))

	// test the seconds east of UTC is ignored by the function
	// ConstructTimeZone().
	secondsEastOfUTC = int((-23 * time.Hour).Seconds())
	loc, err = ConstructTimeZone("Asia/Shanghai", secondsEastOfUTC)
	require.NoError(t, err)
	timeInLoc = time.Date(2018, 8, 15, 20, 0, 0, 0, loc)
	timeInUTC = time.Date(2018, 8, 15, 12, 0, 0, 0, time.UTC)
	require.True(t, timeInLoc.Equal(timeInUTC))

	// test the seconds east of UTC is ignored by the function
	// ConstructTimeZone().
	secondsEastOfUTC = int((23 * time.Hour).Seconds())
	loc, err = ConstructTimeZone("Asia/Shanghai", secondsEastOfUTC)
	require.NoError(t, err)
	timeInLoc = time.Date(2018, 8, 15, 20, 0, 0, 0, loc)
	timeInUTC = time.Date(2018, 8, 15, 12, 0, 0, 0, time.UTC)
	require.True(t, timeInLoc.Equal(timeInUTC))

	// test the seconds east of UTC is ignored by the function
	// ConstructTimeZone().
	loc, err = ConstructTimeZone("Asia/Shanghai", 0)
	require.NoError(t, err)
	timeInLoc = time.Date(2018, 8, 15, 20, 0, 0, 0, loc)
	timeInUTC = time.Date(2018, 8, 15, 12, 0, 0, 0, time.UTC)
	require.True(t, timeInLoc.Equal(timeInUTC))

	// test the timezone name is not existed.
	_, err = ConstructTimeZone("asia/not-exist", 0)
	require.EqualError(t, err, "invalid name for timezone asia/not-exist")
}