package timeutil

import (
	"math"
	"math/rand"
	"strconv"
	"time"

	"github.com/jinzhu/now"
)

const (
	Day = time.Hour * 24

	MinuteSeconds = 60
	HourSeconds   = 60 * MinuteSeconds
	DaySeconds    = 24 * HourSeconds
)

// MonthStartEndTime 返回这月1号的0点和下月1号的0点
// 2006-02-02 12:34:56 => 2016-01-01 00:00:00, 2016-02-01 00:00:00
func MonthStartEndTime(t time.Time) (time.Time, time.Time) {
	start := now.New(t).BeginningOfMonth()
	end := start.AddDate(0, 1, 0)
	return start, end
}

// Age 计算年龄
func Age(birthday time.Time, t time.Time) int {
	btm := birthday
	now_ := t
	if btm.After(now_) {
		return 0
	}
	age := now_.Year() - btm.Year()
	if now_.Month() < btm.Month() {
		age--
	} else if now_.Month() == btm.Month() {
		if now_.Day() < btm.Day() {
			age--
		}
	}
	return age
}

// MidnoonOfDay 一天正午12点
func MidnoonOfDay(t time.Time) time.Time {
	return BeginningOfDay(t).Add(12 * time.Hour)
}

func Now() time.Time {
	return time.Now().Local()
}

func BeginOfToday() time.Time {
	t := Now()
	return BeginOfTime(t)
}

func BeginOfTime(t time.Time) time.Time {
	year, month, day := t.Date()
	return time.Date(year, month, day, 0, 0, 0, 0, t.Location())
}

// BeginningOfDay 一天的开始
func BeginningOfDay(t time.Time) time.Time {
	return now.New(t).BeginningOfDay()
}

// BeginningOfTomorrow 明天的开始
func BeginningOfTomorrow(t time.Time) time.Time {
	return BeginningOfDay(t).AddDate(0, 0, 1)
}

// BeginningOfMonth 月的开始
func BeginningOfMonth(t time.Time) time.Time {
	return now.New(t).BeginningOfMonth()
}

// BeginningOfWeek 周的开始  当前时间的周一零点
func BeginningOfWeek(t time.Time) time.Time {
	return now.New(t.Add(-time.Hour * 24)).BeginningOfWeek().Add(+time.Hour * 24)
}

// TailOfWeek 周的结束  当前时间的周一零点
func TailOfWeek(t time.Time) time.Time {

	return now.New(t.Add(-time.Hour * 24)).BeginningOfWeek()
}

// StrTimeToTime 时间字符串转时间
func StrTimeToTime(strTime string) (t time.Time) {
	timeLayout := "2006-01-02T15:04:05-07:00"
	loc, _ := time.LoadLocation("Local")
	t, _ = time.ParseInLocation(timeLayout, strTime, loc)
	return
}

// 多少分之前
func BeforeMinute(min int) time.Time {
	negativeM, _ := time.ParseDuration("-" + strconv.Itoa(min) + "m")
	return time.Now().Add(negativeM)
}

// 近几个月 返回时间的上两个月的月初 只支持向前12月
func NearMonth(t time.Time, m time.Month) time.Time {
	tM := t.Month() - m
	if tM < 0 {
		tM = 12 + tM
		return time.Date(t.Year()-1, tM, 1, 0, 0, 0, 0, time.Local)
	}
	return time.Date(t.Year(), tM, 1, 0, 0, 0, 0, time.Local)
}

// MillisecondConsistency 毫秒为000时毫秒+1保证毫米精度不丢失
func MillisecondConsistency(s time.Time) time.Time {
	timestamp := s.UnixNano() / 1e6
	if timestamp%1000 == 0 {
		return time.Unix(0, (timestamp+1)*1e6)
	}
	return s
}

// MonthStartEndTime 返回这月1号的0点和下月1号的0点
// 2006-02-02 12:34:56 => 2016-01-01 00:00:00, 2016-02-01 00:00:00
func EarlyLastMonth(t time.Time) (time.Time, time.Time) {
	start := now.New(t).BeginningOfMonth()
	end := start.AddDate(0, 1, 0)
	return start, end
}

// MonthStartEndTime 返回当天的0点和后一天的0点
// 2006-02-02 12:34:56 => 2016-02-02 00:00:00, 2016-02-03 00:00:00
func EarlyLastDay(t time.Time) (time.Time, time.Time) {
	start := now.New(t).BeginningOfDay()
	end := start.AddDate(0, 0, 1)
	return start, end
}

// MonthStartEndTime 返回前一天的0点和今天的0点
// 2006-02-02 12:34:56 => 2016-02-02 00:00:00, 2016-02-03 00:00:00
func YesterdayDay(t time.Time) (time.Time, time.Time) {
	tmp := t.AddDate(0, 0, -1)
	start := BeginningOfDay(tmp)
	end := start.AddDate(0, 0, 1)
	return start, end
}

// 按指定的基础时间,指定的范围随机一个时间 向前随机一个时间
func RandAddTime(baseTime time.Time, max time.Duration) time.Time {
	sum := int64(rand.Intn(int(math.Ceil(max.Seconds()))))
	return time.Unix(baseTime.Unix()+sum, 0)
}

// 按指定的基础时间,指定的范围随机一个时间 向后随机一个时间
func RandReduceTime(baseTime time.Time, max time.Duration) time.Time {
	sum := int64(rand.Intn(int(math.Ceil(max.Seconds()))))
	return time.Unix(baseTime.Unix()-sum, 0)
}

// 根据月份和年返回当月0点和下月0点
func GetTimeByMonthAndYear(m int, y int) (time.Time, time.Time) {
	t := time.Date(y, time.Month(m), 1, 0, 0, 0, 0, time.Local)
	nextM := t.AddDate(0, 1, 0)
	return t, nextM
}

// 增加时间, 年、月、日
func AddTimeByCombo(tm *time.Time, typ string, duration int) *time.Time {
	if tm == nil {
		return tm
	}
	date := time.Time{}
	switch typ {
	case "day":
		date = tm.AddDate(0, 0, duration)
	case "month":
		date = tm.AddDate(0, duration, 0)
	case "year":
		date = tm.AddDate(duration, 0, 0)
	}
	return &date
}