goext/timeext/weekcount.go

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2022-10-27 16:00:57 +02:00
package timeext
import (
"time"
)
var isoWeekCountAggregate map[int]int
func init() {
isoWeekCountAggregate = make(map[int]int)
for y := 1900; y <= time.Now().Year(); y++ {
GetAggregateIsoWeekCount(y)
}
}
func GetAggregateIsoWeekCount(year int) int {
if v, ok := isoWeekCountAggregate[year]; ok {
return v
}
if year == 1900 {
isoWeekCountAggregate[year] = 0
return 0
}
if year < 1900 {
s := 0
for yy := year; yy < 1900; yy++ {
s += GetIsoWeekCount(yy)
}
w := -s
isoWeekCountAggregate[year] = w
return w
}
w := GetIsoWeekCount(year)
w += GetAggregateIsoWeekCount(year - 1)
isoWeekCountAggregate[year] = w
return w
}
func GetIsoWeekCount(year int) int {
_, w1 := time.Date(year+0, 12, 27, 0, 0, 0, 0, TimezoneBerlin).ISOWeek()
_, w2 := time.Date(year+0, 12, 31, 0, 0, 0, 0, TimezoneBerlin).ISOWeek()
_, w3 := time.Date(year+1, 1, 4, 0, 0, 0, 0, TimezoneBerlin).ISOWeek()
w1 -= 1
w2 -= 1
w3 -= 1
w := w1
if w2 > w {
w = w2
}
if w3 > w {
w = w3
}
return w
}
func GetGlobalWeeknumber(t time.Time) int {
y, w := t.ISOWeek()
w -= 1
if y <= 1900 {
w -= 1
}
return GetAggregateIsoWeekCount(y-1) + w
}