holidayspl/holidays.go

package holidayspl

import (
	"time"
)

type Holidays struct {
	list  []Holiday
	cache map[int][]Holiday
}

func New() *Holidays {
	return &Holidays{
		list:  createList(),
		cache: make(map[int][]Holiday),
	}
}

func (hol *Holidays) GetEasterDate(year int) time.Time {
	a := year % 19
	b := year / 100
	c := year % 100
	d := b / 4
	e := b % 4
	f := (b + 8) / 25
	g := (b - f + 1) / 3
	h := (19*a + b - d - g + 15) % 30
	i := c / 4
	k := c % 4
	l := (32 + 2*e + 2*i - h - k) % 7
	m := (a + 11*h + 22*l) / 451
	n := (h + l - 7*m + 114) / 31
	o := (h + l - 7*m + 114) % 31
	return time.Date(year, time.Month(n), o+1, 0, 0, 0, 0, time.UTC)
}

func (hol *Holidays) GetHolidaysList(year int) []Holiday {
	// Check if the holiday list for this year is already cached
	if holidays, ok := hol.cache[year]; ok {
		return holidays
	}

	// Calculate and store holidays in the cache
	easter := hol.GetEasterDate(year)
	for i, h := range hol.list {
		if h.HolidayType == FIXED {
			hol.list[i].Date = time.Date(year, h.Month, h.Day, 0, 0, 0, 0, time.UTC)
		} else if h.HolidayType == MOVABLE {
			hol.list[i].Date = easter.AddDate(0, 0, h.PlusEaster)
		}
	}

	// Cache the computed holiday list
	hol.cache[year] = hol.list
	return hol.list
}

func (hol *Holidays) GetByDate(d time.Time) (Holiday, bool) {
	for _, h := range hol.GetHolidaysList(d.Year()) {
		if h.Date.Equal(d) {
			return h, true
		}
	}
	return Holiday{}, false
}

func (hol *Holidays) GetCache() map[int][]Holiday {
	return hol.cache
}

func createList() []Holiday {

	return []Holiday{
		{
			Name:        "New Year",
			NamePL:      "Nowy Rok",
			Month:       time.Month(1),
			Day:         1,
			HolidayType: FIXED,
		},
		{
			Name:        "Three Kings' Day",
			NamePL:      "Święto Trzech Króli",
			Month:       time.Month(1),
			Day:         6,
			HolidayType: FIXED,
		},
		{
			Name:        "Labour Day",
			NamePL:      "Święto Pracy",
			Month:       time.Month(5),
			Day:         1,
			HolidayType: FIXED,
		},
		{
			Name:        "3 May Constitution Day",
			NamePL:      "Narodowe Święto Konstytucji Trzeciego Maja",
			Month:       time.Month(5),
			Day:         3,
			HolidayType: FIXED,
		},
		{
			Name:        "Assumption of Mary",
			NamePL:      "Wniebowzięcie Najświętszej Maryi Panny",
			Month:       time.Month(8),
			Day:         15,
			HolidayType: FIXED,
		},
		{
			Name:        "All Saints' Day",
			NamePL:      "Wszystkich Świętych",
			Month:       time.Month(11),
			Day:         1,
			HolidayType: FIXED,
		},
		{
			Name:        "National Independence Day",
			NamePL:      "Narodowe Święto Niepodległości",
			Month:       time.Month(11),
			Day:         11,
			HolidayType: FIXED,
		},
		{
			Name:        "Christmas",
			NamePL:      "Boże Narodzenie",
			Month:       time.Month(12),
			Day:         25,
			HolidayType: FIXED,
		},
		{
			Name:        "Second Day of Christmas",
			NamePL:      "Boże Narodzenie - drugi dzień",
			Month:       time.Month(12),
			Day:         26,
			HolidayType: FIXED,
		},
		{
			Name:        "Easter Sunday",
			NamePL:      "Niedziela Wielkanocna",
			Month:       time.Month(5),
			Day:         3,
			HolidayType: MOVABLE,
			PlusEaster:  0,
		},
		{
			Name:        "Easter Monday",
			NamePL:      "Poniedziałek Wielkanocny",
			Month:       time.Month(5),
			Day:         3,
			HolidayType: MOVABLE,
			PlusEaster:  1,
		},
		{
			Name:        "Green Week",
			NamePL:      "Zielone Świątki",
			Month:       time.Month(5),
			Day:         3,
			HolidayType: MOVABLE,
			PlusEaster:  49,
		},
		{
			Name:        "Feast of Corpus Christi",
			NamePL:      "Boże Ciało",
			Month:       time.Month(5),
			Day:         3,
			HolidayType: MOVABLE,
			PlusEaster:  60,
		},
	}
}