package carbon

import (
	"time"
)

// Now returns a Carbon instance for now.
// 当前
func (c Carbon) Now(timezone ...string) Carbon {
	if len(timezone) > 0 {
		c.loc, c.Error = getLocationByTimezone(timezone[0])
	}
	if c.Error != nil {
		return c
	}
	if c.IsSetTestNow() {
		now := CreateFromTimestampNano(c.testNow, c.Location())
		now.testNow = c.testNow
		return now
	}
	c.time = time.Now().In(c.loc)
	return c
}

// Now returns a Carbon instance for now.
// 当前
func Now(timezone ...string) Carbon {
	return NewCarbon().Now(timezone...)
}

// Tomorrow returns a Carbon instance for tomorrow.
// 明天
func (c Carbon) Tomorrow(timezone ...string) Carbon {
	if len(timezone) > 0 {
		c.loc, c.Error = getLocationByTimezone(timezone[0])
	}
	if c.Error != nil {
		return c
	}
	if !c.IsZero() {
		return c.AddDay()
	}
	return c.Now().AddDay()
}

// Tomorrow returns a Carbon instance for tomorrow.
// 明天
func Tomorrow(timezone ...string) Carbon {
	return NewCarbon().Tomorrow(timezone...)
}

// Yesterday returns a Carbon instance for yesterday.
// 昨天
func (c Carbon) Yesterday(timezone ...string) Carbon {
	if len(timezone) > 0 {
		c.loc, c.Error = getLocationByTimezone(timezone[0])
	}
	if c.Error != nil {
		return c
	}
	if !c.IsZero() {
		return c.SubDay()
	}
	return c.Now().SubDay()
}

// Yesterday returns a Carbon instance for yesterday.
// 昨天
func Yesterday(timezone ...string) Carbon {
	return NewCarbon().Yesterday(timezone...)
}

// AddDuration adds one duration.
// 按照时长增加时间,支持整数/浮点数和符号ns(纳秒)、us(微妙)、ms(毫秒)、s(秒)、m(分钟)、h(小时)的组合
func (c Carbon) AddDuration(duration string) Carbon {
	if c.IsInvalid() {
		return c
	}
	td, err := parseByDuration(duration)
	c.time, c.Error = c.StdTime().Add(td), err
	return c
}

// SubDuration subtracts one duration.
// 按照时长减少时间,支持整数/浮点数和符号ns(纳秒)、us(微妙)、ms(毫秒)、s(秒)、m(分钟)、h(小时)的组合
func (c Carbon) SubDuration(duration string) Carbon {
	return c.AddDuration("-" + duration)
}

// AddCenturies adds some centuries.
// N个世纪后
func (c Carbon) AddCenturies(centuries int) Carbon {
	return c.AddYears(centuries * YearsPerCentury)
}

// AddCenturiesNoOverflow adds some centuries without overflowing month.
// N个世纪后(月份不溢出)
func (c Carbon) AddCenturiesNoOverflow(centuries int) Carbon {
	return c.AddYearsNoOverflow(centuries * YearsPerCentury)
}

// AddCentury adds one century.
// 1个世纪后
func (c Carbon) AddCentury() Carbon {
	return c.AddCenturies(1)
}

// AddCenturyNoOverflow adds one century without overflowing month.
// 1个世纪后(月份不溢出)
func (c Carbon) AddCenturyNoOverflow() Carbon {
	return c.AddCenturiesNoOverflow(1)
}

// SubCenturies subtracts some centuries.
// N个世纪前
func (c Carbon) SubCenturies(centuries int) Carbon {
	return c.SubYears(centuries * YearsPerCentury)
}

// SubCenturiesNoOverflow subtracts some centuries without overflowing month.
// N个世纪前(月份不溢出)
func (c Carbon) SubCenturiesNoOverflow(centuries int) Carbon {
	return c.SubYearsNoOverflow(centuries * YearsPerCentury)
}

// SubCentury subtracts one century.
// 1个世纪前
func (c Carbon) SubCentury() Carbon {
	return c.SubCenturies(1)
}

// SubCenturyNoOverflow subtracts one century without overflowing month.
// 1个世纪前(月份不溢出)
func (c Carbon) SubCenturyNoOverflow() Carbon {
	return c.SubCenturiesNoOverflow(1)
}

// AddDecades adds some decades.
// N个年代后
func (c Carbon) AddDecades(decades int) Carbon {
	return c.AddYears(decades * YearsPerDecade)
}

// AddDecadesNoOverflow adds some decades without overflowing month.
// N个年代后(月份不溢出)
func (c Carbon) AddDecadesNoOverflow(decades int) Carbon {
	return c.AddYearsNoOverflow(decades * YearsPerDecade)
}

// AddDecade adds one decade.
// 1个年代后
func (c Carbon) AddDecade() Carbon {
	return c.AddDecades(1)
}

// AddDecadeNoOverflow adds one decade without overflowing month.
// 1个年代后(月份不溢出)
func (c Carbon) AddDecadeNoOverflow() Carbon {
	return c.AddDecadesNoOverflow(1)
}

// SubDecades subtracts some decades.
// N个年代后
func (c Carbon) SubDecades(decades int) Carbon {
	return c.SubYears(decades * YearsPerDecade)
}

// SubDecadesNoOverflow subtracts some decades without overflowing month.
// N个年代后(月份不溢出)
func (c Carbon) SubDecadesNoOverflow(decades int) Carbon {
	return c.SubYearsNoOverflow(decades * YearsPerDecade)
}

// SubDecade subtracts one decade.
// 1个年代后
func (c Carbon) SubDecade() Carbon {
	return c.SubDecades(1)
}

// SubDecadeNoOverflow subtracts one decade without overflowing month.
// 1个年代后(月份不溢出)
func (c Carbon) SubDecadeNoOverflow() Carbon {
	return c.SubDecadesNoOverflow(1)
}

// AddYears adds some years.
// N年后
func (c Carbon) AddYears(years int) Carbon {
	if c.IsInvalid() {
		return c
	}
	c.time = c.StdTime().AddDate(years, 0, 0)
	return c
}

// AddYearsNoOverflow adds some years without overflowing month.
// N年后(月份不溢出)
func (c Carbon) AddYearsNoOverflow(years int) Carbon {
	if c.IsInvalid() {
		return c
	}
	nanosecond := c.Nanosecond()
	year, month, day, hour, minute, second := c.DateTime()
	// 获取N年后本月的最后一天
	lastYear, lastMonth, lastDay := c.create(year+years, month+1, 0, hour, minute, second, nanosecond).Date()
	if day > lastDay {
		day = lastDay
	}
	return c.create(lastYear, lastMonth, day, hour, minute, second, nanosecond)
}

// AddYear adds one year.
// 1年后
func (c Carbon) AddYear() Carbon {
	return c.AddYears(1)
}

// AddYearNoOverflow adds one year without overflowing month.
// 1年后(月份不溢出)
func (c Carbon) AddYearNoOverflow() Carbon {
	return c.AddYearsNoOverflow(1)
}

// SubYears subtracts some years.
// N年前
func (c Carbon) SubYears(years int) Carbon {
	if c.IsInvalid() {
		return c
	}
	return c.AddYears(-years)
}

// SubYearsNoOverflow subtracts some years without overflowing month.
// N年前(月份不溢出)
func (c Carbon) SubYearsNoOverflow(years int) Carbon {
	return c.AddYearsNoOverflow(-years)
}

// SubYear subtracts one year.
// 1年前
func (c Carbon) SubYear() Carbon {
	return c.SubYears(1)
}

// SubYearNoOverflow subtracts one year without overflowing month.
// 1年前(月份不溢出)
func (c Carbon) SubYearNoOverflow() Carbon {
	return c.SubYearsNoOverflow(1)
}

// AddQuarters adds some quarters
// N个季度后
func (c Carbon) AddQuarters(quarters int) Carbon {
	return c.AddMonths(quarters * MonthsPerQuarter)
}

// AddQuartersNoOverflow adds quarters without overflowing month.
// N个季度后(月份不溢出)
func (c Carbon) AddQuartersNoOverflow(quarters int) Carbon {
	return c.AddMonthsNoOverflow(quarters * MonthsPerQuarter)
}

// AddQuarter adds one quarter
// 1个季度后
func (c Carbon) AddQuarter() Carbon {
	return c.AddQuarters(1)
}

// AddQuarterNoOverflow adds one quarter without overflowing month.
// 1个季度后(月份不溢出)
func (c Carbon) AddQuarterNoOverflow() Carbon {
	return c.AddQuartersNoOverflow(1)
}

// SubQuarters subtracts some quarters.
// N个季度前
func (c Carbon) SubQuarters(quarters int) Carbon {
	return c.AddQuarters(-quarters)
}

// SubQuartersNoOverflow subtracts some quarters without overflowing month.
// N个季度前(月份不溢出)
func (c Carbon) SubQuartersNoOverflow(quarters int) Carbon {
	return c.AddMonthsNoOverflow(-quarters * MonthsPerQuarter)
}

// SubQuarter subtracts one quarter.
// 1个季度前
func (c Carbon) SubQuarter() Carbon {
	return c.SubQuarters(1)
}

// SubQuarterNoOverflow subtracts one quarter without overflowing month.
// 1个季度前(月份不溢出)
func (c Carbon) SubQuarterNoOverflow() Carbon {
	return c.SubQuartersNoOverflow(1)
}

// AddMonths adds some months.
// N个月后
func (c Carbon) AddMonths(months int) Carbon {
	if c.IsInvalid() {
		return c
	}
	c.time = c.StdTime().AddDate(0, months, 0)
	return c
}

// AddMonthsNoOverflow adds some months without overflowing month.
// N个月后(月份不溢出)
func (c Carbon) AddMonthsNoOverflow(months int) Carbon {
	if c.IsInvalid() {
		return c
	}
	nanosecond := c.Nanosecond()
	year, month, day, hour, minute, second := c.DateTime()
	// 获取N月后的最后一天
	lastYear, lastMonth, lastDay := c.create(year, month+months+1, 0, hour, minute, second, nanosecond).Date()
	if day > lastDay {
		day = lastDay
	}
	return c.create(lastYear, lastMonth, day, hour, minute, second, nanosecond)
}

// AddMonth adds one month.
// 1个月后
func (c Carbon) AddMonth() Carbon {
	return c.AddMonths(1)
}

// AddMonthNoOverflow adds one month without overflowing month.
// 1个月后(月份不溢出)
func (c Carbon) AddMonthNoOverflow() Carbon {
	return c.AddMonthsNoOverflow(1)
}

// SubMonths subtracts some months.
// N个月前
func (c Carbon) SubMonths(months int) Carbon {
	return c.AddMonths(-months)
}

// SubMonthsNoOverflow subtracts some months without overflowing month.
// N个月前(月份不溢出)
func (c Carbon) SubMonthsNoOverflow(months int) Carbon {
	return c.AddMonthsNoOverflow(-months)
}

// SubMonth subtracts one month.
// 1个月前
func (c Carbon) SubMonth() Carbon {
	return c.SubMonths(1)
}

// SubMonthNoOverflow subtracts one month without overflowing month.
// 1个月前(月份不溢出)
func (c Carbon) SubMonthNoOverflow() Carbon {
	return c.SubMonthsNoOverflow(1)
}

// AddWeeks adds some weeks.
// N周后
func (c Carbon) AddWeeks(weeks int) Carbon {
	return c.AddDays(weeks * DaysPerWeek)
}

// AddWeek adds one week.
// 1周后
func (c Carbon) AddWeek() Carbon {
	return c.AddWeeks(1)
}

// SubWeeks subtracts some weeks.
// N周前
func (c Carbon) SubWeeks(weeks int) Carbon {
	return c.SubDays(weeks * DaysPerWeek)
}

// SubWeek subtracts one week.
// 1周前
func (c Carbon) SubWeek() Carbon {
	return c.SubWeeks(1)
}

// AddDays adds some days.
// N天后
func (c Carbon) AddDays(days int) Carbon {
	if c.IsInvalid() {
		return c
	}
	c.time = c.StdTime().AddDate(0, 0, days)
	return c
}

// AddDay adds one day.
// 1天后
func (c Carbon) AddDay() Carbon {
	return c.AddDays(1)
}

// SubDays subtracts some days.
// N天前
func (c Carbon) SubDays(days int) Carbon {
	return c.AddDays(-days)
}

// SubDay subtracts one day.
// 1天前
func (c Carbon) SubDay() Carbon {
	return c.SubDays(1)
}

// AddHours adds some hours.
// N小时后
func (c Carbon) AddHours(hours int) Carbon {
	if c.IsInvalid() {
		return c
	}
	td := time.Duration(hours) * time.Hour
	c.time = c.StdTime().Add(td)
	return c
}

// AddHour adds one hour.
// 1小时后
func (c Carbon) AddHour() Carbon {
	return c.AddHours(1)
}

// SubHours subtracts some hours.
// N小时前
func (c Carbon) SubHours(hours int) Carbon {
	return c.AddHours(-hours)
}

// SubHour subtracts one hour.
// 1小时前
func (c Carbon) SubHour() Carbon {
	return c.SubHours(1)
}

// AddMinutes adds some minutes.
// N分钟后
func (c Carbon) AddMinutes(minutes int) Carbon {
	if c.IsInvalid() {
		return c
	}
	td := time.Duration(minutes) * time.Minute
	c.time = c.StdTime().Add(td)
	return c
}

// AddMinute adds one minute.
// 1分钟后
func (c Carbon) AddMinute() Carbon {
	return c.AddMinutes(1)
}

// SubMinutes subtracts some minutes.
// N分钟前
func (c Carbon) SubMinutes(minutes int) Carbon {
	return c.AddMinutes(-minutes)
}

// SubMinute subtracts one minute.
// 1分钟前
func (c Carbon) SubMinute() Carbon {
	return c.SubMinutes(1)
}

// AddSeconds adds some seconds.
// N秒钟后
func (c Carbon) AddSeconds(seconds int) Carbon {
	if c.IsInvalid() {
		return c
	}
	td := time.Duration(seconds) * time.Second
	c.time = c.StdTime().Add(td)
	return c
}

// AddSecond adds one second.
// 1秒钟后
func (c Carbon) AddSecond() Carbon {
	return c.AddSeconds(1)
}

// SubSeconds subtracts some seconds.
// N秒钟前
func (c Carbon) SubSeconds(seconds int) Carbon {
	return c.AddSeconds(-seconds)
}

// SubSecond subtracts one second.
// 1秒钟前
func (c Carbon) SubSecond() Carbon {
	return c.SubSeconds(1)
}

// AddMilliseconds adds some milliseconds.
// N毫秒后
func (c Carbon) AddMilliseconds(milliseconds int) Carbon {
	if c.IsInvalid() {
		return c
	}
	td := time.Duration(milliseconds) * time.Millisecond
	c.time = c.StdTime().Add(td)
	return c
}

// AddMillisecond adds one millisecond.
// 1毫秒后
func (c Carbon) AddMillisecond() Carbon {
	return c.AddMilliseconds(1)
}

// SubMilliseconds subtracts some milliseconds.
// N毫秒前
func (c Carbon) SubMilliseconds(milliseconds int) Carbon {
	return c.AddMilliseconds(-milliseconds)
}

// SubMillisecond subtracts one millisecond.
// 1毫秒前
func (c Carbon) SubMillisecond() Carbon {
	return c.SubMilliseconds(1)
}

// AddMicroseconds adds some microseconds.
// N微秒后
func (c Carbon) AddMicroseconds(microseconds int) Carbon {
	if c.IsInvalid() {
		return c
	}
	td := time.Duration(microseconds) * time.Microsecond
	c.time = c.StdTime().Add(td)
	return c
}

// AddMicrosecond adds one microsecond.
// 1微秒后
func (c Carbon) AddMicrosecond() Carbon {
	return c.AddMicroseconds(1)
}

// SubMicroseconds subtracts some microseconds.
// N微秒前
func (c Carbon) SubMicroseconds(microseconds int) Carbon {
	return c.AddMicroseconds(-microseconds)
}

// SubMicrosecond subtracts one microsecond.
// 1微秒前
func (c Carbon) SubMicrosecond() Carbon {
	return c.SubMicroseconds(1)
}

// AddNanoseconds adds some nanoseconds.
// N纳秒后
func (c Carbon) AddNanoseconds(nanoseconds int) Carbon {
	if c.IsInvalid() {
		return c
	}
	td := time.Duration(nanoseconds) * time.Nanosecond
	c.time = c.StdTime().Add(td)
	return c
}

// AddNanosecond adds one nanosecond.
// 1纳秒后
func (c Carbon) AddNanosecond() Carbon {
	return c.AddNanoseconds(1)
}

// SubNanoseconds subtracts some nanoseconds.
// N纳秒前
func (c Carbon) SubNanoseconds(nanoseconds int) Carbon {
	return c.AddNanoseconds(-nanoseconds)
}

// SubNanosecond subtracts one nanosecond.
// 1纳秒前
func (c Carbon) SubNanosecond() Carbon {
	return c.SubNanoseconds(1)
}