fix: weekbased calculation pdf report

with this change the time calculations for pdf reports should be better
line with the reports send as "week_report"

Backend/helper/time.go

@@ -4,6 +4,7 @@ package helper
 
 import (
 	"fmt"
+	"slices"
 	"time"
 )
 
@@ -18,6 +19,64 @@ func GetMonday(ts time.Time) time.Time {
 	return ts
 }
 
+func GetMondays(allDays []time.Time, onlyInRange bool) []time.Time {
+	var mondays []time.Time
+	var start, end time.Time
+
+	for _, day := range allDays {
+		mondays = append(mondays, GetMonday(day))
+
+		if start.IsZero() || day.Before(start) {
+			start = day
+		}
+		if end.IsZero() || day.After(end) {
+			end = day
+		}
+	}
+	mondays = slices.Compact(mondays)
+	if onlyInRange {
+		return DaysInRange(mondays, start, end)
+	}
+	return mondays
+}
+
+func DaysInRange(days []time.Time, startDate, endDate time.Time) []time.Time {
+	filtered := []time.Time{}
+	startDate = startDate.Add(-time.Minute)
+	endDate = endDate.Add(time.Minute)
+
+	for _, day := range days {
+		if day.After(startDate) && day.Before(endDate) {
+			filtered = append(filtered, day)
+		}
+	}
+	return filtered
+}
+
+func IsMonday(day time.Time) bool {
+	return day.Weekday() == time.Monday
+}
+
+// GenerateDateRange returns a slice of all dates between start and end (inclusive).
+func GenerateDateRange(start, end time.Time) []time.Time {
+	var dates []time.Time
+
+	// Ensure start is before or equal to end
+	if start.After(end) {
+		return dates
+	}
+
+	// Normalize times to midnight
+	current := start.Truncate(time.Hour * 24)
+	end = end.Truncate(time.Hour * 24)
+
+	for !current.After(end) {
+		dates = append(dates, current)
+		current = current.AddDate(0, 0, 1) // Add one day
+	}
+	return dates
+}
+
 func GetFirstOfMonth(ts time.Time) time.Time {
 	if ts.Day() > 1 {
 		return ts.AddDate(0, 0, -(ts.Day() - 1))