v0.0.268 added WeekStart() and WeekEnd()

goextVersion.go

@@ -1,5 +1,5 @@
 package goext
 
-const GoextVersion = "0.0.267"
+const GoextVersion = "0.0.268"
 
-const GoextVersionTimestamp = "2023-09-21T14:15:02+0200"
+const GoextVersionTimestamp = "2023-09-21T16:29:23+0200"

timeext/calendarweek.go

@@ -0,0 +1,28 @@
+package timeext
+
+import "time"
+
+func WeekStart(year, week int) time.Time {
+
+	// https://stackoverflow.com/a/52303730/1761622
+
+	// Start from the middle of the year:
+	t := time.Date(year, 7, 1, 0, 0, 0, 0, time.UTC)
+
+	// Roll back to Monday:
+	if wd := t.Weekday(); wd == time.Sunday {
+		t = t.AddDate(0, 0, -6)
+	} else {
+		t = t.AddDate(0, 0, -int(wd)+1)
+	}
+
+	// Difference in weeks:
+	_, w := t.ISOWeek()
+	t = t.AddDate(0, 0, (week-w)*7)
+
+	return t
+}
+
+func WeekEnd(year, week int) time.Time {
+	return WeekStart(year, week).AddDate(0, 0, 7).Add(time.Duration(-1))
+}

timeext/calendarweek_test.go

@@ -0,0 +1,25 @@
+package timeext
+
+import (
+	"gogs.mikescher.com/BlackForestBytes/goext/tst"
+	"testing"
+	"time"
+)
+
+func TestWeekStart(t *testing.T) {
+
+	tst.AssertEqual(t, WeekStart(2018, 1).Format(time.RFC3339Nano), "2018-01-01T00:00:00Z")
+	tst.AssertEqual(t, WeekStart(2018, 2).Format(time.RFC3339Nano), "2018-01-08T00:00:00Z")
+	tst.AssertEqual(t, WeekStart(2019, 1).Format(time.RFC3339Nano), "2018-12-31T00:00:00Z")
+	tst.AssertEqual(t, WeekStart(2019, 2).Format(time.RFC3339Nano), "2019-01-07T00:00:00Z")
+
+}
+
+func TestWeekEnd(t *testing.T) {
+
+	tst.AssertEqual(t, WeekEnd(2018, 1).Format(time.RFC3339Nano), "2018-01-07T23:59:59.999999999Z")
+	tst.AssertEqual(t, WeekEnd(2018, 2).Format(time.RFC3339Nano), "2018-01-14T23:59:59.999999999Z")
+	tst.AssertEqual(t, WeekEnd(2019, 1).Format(time.RFC3339Nano), "2019-01-06T23:59:59.999999999Z")
+	tst.AssertEqual(t, WeekEnd(2019, 2).Format(time.RFC3339Nano), "2019-01-13T23:59:59.999999999Z")
+
+}