package moment

import (
	"fmt"
	"strings"
	"time"
)

// Time Formate format
var (
	// TimeAndDate2 eg.2006-01-02 15:04:05
	TimeAndDate2 = "2006-01-02 15:04:05"
	// TimeAndDate2 eg.2006-01-02 15:04:05 -0700 MST
	TimeAndDate2WithTimezone = "2006-01-02 15:04:05.999999999 -0700 MST"
	// PGTimestampStyle 2006-01-02 15:04:05.999999-07
	PGTimestamp = "2006-01-02 15:04:05.999999-07"

	YYYY           = "2006"
	YY             = "06"
	MM             = "01"
	DD             = "02"
	H12            = "3"
	Minute         = "04"
	SS             = "05"
	Timezone       = "MST"
	TimezoneOffset = "-0700"

	MMDDYY   = "01/02/06"
	YYYYMMDD = "2006-01-02"

	HHmm    = "15:04"
	HHmmss  = "15:04:05"
	HmmssPM = "3:04:05 PM"
	AmPm    = "PM"
)

var timeFormats = []string{
	"2006", "2006-1", "2006-1-2", "2006-1-2 15", "2006-1-2 15:4", "2006-1-2 15:4:5", "1-2",
	"15:4:5", "15:4", "15",
	"15:4:5 Jan 2, 2006 MST", "2006-01-02T15:04:05-07:00",
	"2006-01-02 15:04:05.999999999",
	"2006.1.2", "2006.1.2 15:04:05", "2006.01.02", "2006.01.02 15:04:05",
	"1/2/2006", "1/2/2006 15:4:5", "2006/01/02", "2006/01/02 15:04:05",
	time.ANSIC, time.UnixDate, time.RubyDate, time.RFC822, time.RFC822Z, time.RFC850,
	time.RFC1123, time.RFC1123Z, // time.RFC3339, time.RFC3339Nano,  RFC3339 取时间戳转换
	time.Kitchen, time.Stamp, time.StampMilli, time.StampMicro, time.StampNano,
	PGTimestamp, TimeAndDate2, TimeAndDate2WithTimezone,
}

// Now 返回 golang 内建的 time.Now()
func Now() time.Time {
	return time.Now()
}

// ToANSIC 格式化指定时间到 Mon Jan _2 15:04:05 2006 格式
func ToANSIC(t time.Time) string {
	return Format(t, time.ANSIC)
}

// ToRFC3339 格式化指定时间到 2006-01-02T15:04:05Z07:00 格式
func ToRFC3339(t time.Time) string {
	return Format(t, time.RFC3339)
}

// ToTimeAndDate2 格式化指定时间到 2006-01-02 15:04:05 格式
func ToTimeAndDate2(t time.Time) string {
	return Format(t, TimeAndDate2)
}

// ToTimeAndDate2WithTimezone 格式化指定时间到 2006-01-02 15:04:05 -0700 MST 格式
func ToTimeAndDate2WithTimezone(t time.Time) string {
	return Format(t, TimeAndDate2WithTimezone)
}

// ToPGTimestamp 格式化指定时间到 2006-01-02 15:04:05.999999-07 格式
func ToPGTimestamp(t time.Time) string {
	return Format(t, PGTimestamp)
}

// ToYYYYMMDD 格式化指定时间到 2006-01-02 格式
func ToYYYYMMDD(t time.Time) string {
	return Format(t, YYYYMMDD)
}

// ToHHmmss 格式化指定时间到 15:04:05 格式
func ToHHmmss(t time.Time) string {
	return Format(t, HHmmss)
}

// Format 返回日期时间的格式化结果
func Format(t time.Time, format ...string) string {
	bs := []byte{}
	bs = t.AppendFormat(bs, strings.Join(format, " "))

	return string(bs)
}

// From 将字符串转换为 `time.Time`
func From(str string, timeFormat ...string) (time.Time, error) {
	tfs := append(timeFormats, timeFormat...)

	for _, tf := range tfs {
		stamp, err := time.ParseInLocation(tf, str, time.Local)

		if err == nil {
			return time.Unix(0, stamp.UnixNano()), nil
		}
	}

	return time.Time{}, fmt.Errorf("can't parse string as time: %s", str)
}

// BeginningOfMinute 返回指定时间的第0秒 2013-11-18 17:51:00 Mon
func BeginningOfMinute(t time.Time) time.Time {
	return t.Truncate(time.Minute)
}

// BeginningOfHour 返回指定时间的第0分钟 2013-11-18 17:00:00 Mon
func BeginningOfHour(t time.Time) time.Time {
	y, m, d := t.Date()
	return time.Date(y, m, d, t.Hour(), 0, 0, 0, t.Location())
}

// BeginningOfDay 返回指定时间的当天内的第0小时 2013-11-18 00:00:00 Mon
func BeginningOfDay(t time.Time) time.Time {
	y, m, d := t.Date()
	return time.Date(y, m, d, 0, 0, 0, 0, t.Location())
}

// BeginningOfWeek 返回指定时间所在周的第0天 2013-11-17 00:00:00 Sun
func BeginningOfWeek(t time.Time, weekStartDay time.Weekday) time.Time {
	t2 := BeginningOfDay(t)
	weekday := int(t.Weekday())

	if weekStartDay != time.Sunday {
		weekStartDayInt := int(weekStartDay)

		if weekday < weekStartDayInt {
			weekday = weekday + 7 - weekStartDayInt
		} else {
			weekday -= weekStartDayInt
		}
	}

	return t2.AddDate(0, 0, -weekday)
}

// BeginningOfMonth 返回指定时间所在月的第0天 2013-11-01 00:00:00 Fri
func BeginningOfMonth(t time.Time) time.Time {
	y, m, _ := t.Date()
	return time.Date(y, m, 1, 0, 0, 0, 0, t.Location())
}

// BeginningOfQuarter 返回指定时间所在季度的第0天 2013-10-01 00:00:00 Tue
func BeginningOfQuarter(t time.Time) time.Time {
	month := BeginningOfMonth(t)
	offset := (int(month.Month()) - 1) % 3

	return month.AddDate(0, -offset, 0)
}

// BeginningOfHalf 返回指定时间所在半年的第0天 2013-07-01 00:00:00 Tue
func BeginningOfHalf(t time.Time) time.Time {
	month := BeginningOfMonth(t)
	offset := (int(month.Month()) - 1) % 6

	return month.AddDate(0, -offset, 0)
}

// BeginningOfYear 返回指定时间所在年的第0天 2013-01-01 00:00:00 Tue
func BeginningOfYear(t time.Time) time.Time {
	y, _, _ := t.Date()

	return time.Date(y, time.January, 1, 0, 0, 0, 0, t.Location())
}

// EndOfMinute 返回指定时间的当前分钟的最后 2013-11-18 17:51:59.999999999 Mon
func EndOfMinute(t time.Time) time.Time {
	return BeginningOfMinute(t).Add(time.Minute - time.Nanosecond)
}

// EndOfHour 返回指定时间的当前小时的最后 2013-11-18 17:59:59.999999999 Mon
func EndOfHour(t time.Time) time.Time {
	return BeginningOfHour(t).Add(time.Hour - time.Nanosecond)
}

// EndOfDay 返回指定时间的当天的最后 2013-11-18 23:59:59.999999999 Mon
func EndOfDay(t time.Time) time.Time {
	y, m, d := t.Date()
	return time.Date(y, m, d, 23, 59, 59, int(time.Second-time.Nanosecond), t.Location())
}

// EndOfWeek 返回指定时间的当周的最后 2013-11-23 23:59:59.999999999 Sat
func EndOfWeek(t time.Time, weekStartDay time.Weekday) time.Time {
	return BeginningOfWeek(t, weekStartDay).AddDate(0, 0, 7).Add(-time.Nanosecond)
}

// EndOfMonth 返回指定时间的当月的最后 2013-11-30 23:59:59.999999999 Sat
func EndOfMonth(t time.Time) time.Time {
	return BeginningOfMonth(t).AddDate(0, 1, 0).Add(-time.Nanosecond)
}

// EndOfQuarter 返回指定时间的当季度的最后 2013-12-31 23:59:59.999999999 Tue
func EndOfQuarter(t time.Time) time.Time {
	return BeginningOfQuarter(t).AddDate(0, 3, 0).Add(-time.Nanosecond)
}

// EndOfHalf 返回指定时间的所在半年的最后 2013-12-31 23:59:59.999999999 Tue
func EndOfHalf(t time.Time) time.Time {
	return BeginningOfHalf(t).AddDate(0, 6, 0).Add(-time.Nanosecond)
}

// EndOfYear 返回指定时间的所在年的最后 2013-12-31 23:59:59.999999999 Tue
func EndOfYear(t time.Time) time.Time {
	return BeginningOfYear(t).AddDate(1, 0, 0).Add(-time.Nanosecond)
}