holiday.go

package flagday

import (
	"sync"
	"time"
)

var (
	jstLocation *time.Location
	jstOnce     sync.Once
)

// HolidayKind is kind of holiday.
type HolidayKind int

const (
	// PublicHoliday means that holiday is public holiday.
	PublicHoliday HolidayKind = iota
	// NationalHoliday means that holiday is national holiday.
	NationalHoliday
	// SubstituteHoliday means that holiday is substitute holiday.
	SubstituteHoliday
	// ImperialRelated means that holiday is Imperial related holiday.
	ImperialRelated
)

// Holiday holds public holiday information.
type Holiday interface {
	// Def returns definition of holiday.
	Def() *Definition
	// Year of holiday.
	Year() int
	// Month of holiday.
	Month() int
	// Day of holiday.
	Day() int
	// Name of holiday.
	Name() string
	// Kind of holiday.
	Kind() HolidayKind
	// Time is time.Time instance of holiday (JST)
	Time() time.Time
	// Original is original holiday.
	// This field is only set when holiday is substitute holiday.
	Original() Holiday
	// IsSubstituted returns that this holiday is substituted by substitute holiday.
	IsSubstituted() bool
}

type substitutedSetter interface {
	SetSubstituted(b bool)
}

type holiday struct {
	def         *Definition
	year        int
	month       int
	day         int
	name        string
	kind        HolidayKind
	time        time.Time
	original    Holiday
	substituted bool
}

func (d *holiday) Def() *Definition {
	return d.def
}

func (d *holiday) Year() int {
	return d.year
}

func (d *holiday) Month() int {
	return d.month
}

func (d *holiday) Day() int {
	return d.day
}

func (d *holiday) Name() string {
	return d.name
}

func (d *holiday) Kind() HolidayKind {
	return d.kind
}

func (d *holiday) Time() time.Time {
	return d.time
}

func (d *holiday) Original() Holiday {
	return d.original
}

func (d *holiday) IsSubstituted() bool {
	return d.substituted
}

func (d *holiday) SetSubstituted(b bool) {
	d.substituted = b
}

// NewHoliday returns new date with time.
func NewHoliday(def *Definition, year, month, day int, name string, kind HolidayKind, original Holiday) Holiday {
	return &holiday{
		def:      def,
		year:     year,
		month:    month,
		day:      day,
		name:     name,
		kind:     kind,
		time:     timeFrom(year, month, day),
		original: original,
	}
}

func newPublicHoliday(def Definition, year, day int) Holiday {
	return NewHoliday(&def, year, def.Month(), day, def.Name(), PublicHoliday, nil)
}

func newNationalHoliday(year, month, day int) Holiday {
	return NewHoliday(nil, year, month, day, "国民の休日", NationalHoliday, nil)
}

func newSubstituteHoliday(year, month, day int, original Holiday) Holiday {
	return NewHoliday(nil, year, month, day, "振替休日", SubstituteHoliday, original)
}

func newImperialRelatedHoliday(def Definition, year, day int) Holiday {
	return NewHoliday(&def, year, def.Month(), day, def.Name(), ImperialRelated, nil)
}

func jst() *time.Location {
	jstOnce.Do(func() {
		loc, err := time.LoadLocation("Asia/Tokyo")
		if err != nil {
			loc = time.FixedZone("Asia/Tokyo", 9*60*60)
		}
		jstLocation = loc
	})
	return jstLocation
}

func timeFrom(year, month, day int) time.Time {
	return time.Date(year, time.Month(month), day, 0, 0, 0, 0, jst())
}