add alternative holidays

ausholiday.go

@@ -99,3 +99,81 @@ func init() {
 		xholidays = days.Holidays
 	})
 }
+
+// Holiday alternative
+type HolidayAlt struct {
+	HolidayName     string
+	Information     string
+	MoreInformation string
+	Jurisdiction    State
+	Timezone        string
+
+	Month   time.Month
+	Week    int
+	Weekday time.Weekday
+}
+
+var holidayAlts = []*HolidayAlt{
+	{
+		HolidayName:     "Dawin Show Day",
+		Information:     "",
+		MoreInformation: "",
+		Jurisdiction:    NT,
+		Timezone:        "Australia/Darwin",
+
+		Month:   time.July,
+		Week:    4,
+		Weekday: time.Friday,
+	},
+}
+
+func IsHolidayAlt(state State, date time.Time) bool {
+
+	for _, holidayAlt := range holidayAlts {
+		if holidayAlt.Jurisdiction != state {
+			continue
+		}
+
+		location, err := time.LoadLocation(holidayAlt.Timezone)
+		if err != nil {
+			continue
+		}
+
+		// convert time in the timezone
+		timeWithTimezone := date.In(location)
+
+		y := timeWithTimezone.Year()
+		m := timeWithTimezone.Month()
+		d := timeWithTimezone.Day()
+		wd := timeWithTimezone.Weekday()
+
+		// check month
+		if holidayAlt.Month != m {
+			continue
+		}
+
+		// check weekday
+		if holidayAlt.Weekday != wd {
+			continue
+		}
+
+		// check date
+		firstDayOfTheMonth := time.Date(y, m, 1, 0, 0, 0, 0, time.UTC)
+
+		firstWeekdayOfTheMonth := int(firstDayOfTheMonth.Weekday())
+
+		diffOfTheDays := int(wd) - firstWeekdayOfTheMonth
+		if diffOfTheDays < 0 {
+			diffOfTheDays += 7
+		}
+
+		if d != firstDayOfTheMonth.Add(time.Duration(diffOfTheDays*24)*time.Hour).Add(time.Duration((holidayAlt.Week-1)*7*24)*time.Hour).Day() {
+			continue
+		}
+
+		return true
+
+	}
+
+	return false
+}

ausholiday_test.go

@@ -104,6 +104,38 @@ func testIsHolidayFunc(hday *AusHoliday, t1 time.Time, expect bool) func(t *test
 	}
 }
 
+func TestIsHolidayAlt(t *testing.T) {
+	var t1 time.Time
+
+	t1 = ezTime(2022, 7, 22)
+	t.Run("Darwin Show Day Check 2022", testIsHolidayAlt(NT, t1, true))
+
+	t1 = ezTime(2023, 7, 28)
+	t.Run("Darwin Show Day Check 2023", testIsHolidayAlt(NT, t1, true))
+
+	t1 = ezTime(2024, 7, 26)
+	t.Run("Darwin Show Day Check 2024", testIsHolidayAlt(NT, t1, true))
+
+	t1 = ezTime(2025, 7, 25)
+	t.Run("Darwin Show Day Check 2025", testIsHolidayAlt(NT, t1, true))
+
+	t1 = ezTime(2026, 7, 24)
+	t.Run("Darwin Show Day Check 2026", testIsHolidayAlt(NT, t1, true))
+
+	t1 = ezTime(2026, 7, 25)
+	t.Run("Darwin Show Day Check False", testIsHolidayAlt(NT, t1, false))
+}
+
+func testIsHolidayAlt(state State, date time.Time, expect bool) func(t *testing.T) {
+	return func(t *testing.T) {
+		b := IsHolidayAlt(state, date)
+		if b != expect {
+			t.Errorf("IsHoliday was incorrect, got: %t, want: %t", b, expect)
+		}
+	}
+
+}
+
 func TestBusinessDays(t *testing.T) {
 	var t1, t2 time.Time
 

builtin.go

@@ -127,7 +127,8 @@ func IsHoliday(state State, t time.Time, holidays ...*Holiday) bool {
 		}
 	}
 
-	return false
+	// final check if it is a alt holiday
+	return IsHolidayAlt(state, t)
 }
 
 // IsHolidayAny is it a holiday in any state