Week to month converter

backend/Core/Weeks/Week.cs

@@ -169,6 +169,7 @@ private bool DateIsInWeek(DateOnly day)
         return FromDateOnly(day).Equals(this);
     }
 
+
     public static bool operator ==(Week left, Week right)
     {
         if (ReferenceEquals(left, right)) return true;

backend/Core/Weeks/WeekExtensions.cs

@@ -0,0 +1,49 @@
+namespace Core.Weeks;
+public static class WeekExtensions
+{
+
+    public struct MonthsOfWeek
+    {
+        public int Month { get; init; }
+        public int? SecondMonth { get; init; }
+        public int Distribution { get; init; }
+    }
+
+    public static MonthsOfWeek GetMonthOfWeek(this Week week)
+    {
+        int daysFromStartOfYear = 1 + (week.WeekNumber - 1) * 7;
+        var dayOfWeek = new DateOnly(week.Year, 1, 1).AddDays(daysFromStartOfYear - 1); // Adjust start of year to the calculated day
+        var monday = dayOfWeek.GetPreviousOrCurrentMonday();
+        int month = monday.Month;
+
+        double distribution = 100;
+        int? secondMonth = null;
+
+        for (int i = 1; i < 7; i++)
+        {
+            var addedDayDate = monday.AddDays(i);
+            if (addedDayDate.Month != month)
+            {
+                distribution = distribution / 7 * i;
+                secondMonth = addedDayDate.Month;
+                break;
+            }
+        }
+
+        return new MonthsOfWeek
+        {
+            Month = month,
+            SecondMonth = secondMonth,
+            Distribution = (int)distribution
+        };
+    }
+    public static DateOnly GetPreviousOrCurrentMonday(this DateOnly date)
+    {
+        if (date.DayOfWeek == DayOfWeek.Monday)
+        {
+            return date;
+        }
+        int daysToSubtract = (date.DayOfWeek - DayOfWeek.Monday + 7) % 7;
+        return date.AddDays(-daysToSubtract);
+    }
+}

frontend/src/app/[organisation]/kunder/weekToMonthConverter.tsx

@@ -0,0 +1,56 @@
+import { addDays, isMonday, previousMonday } from "date-fns";
+
+export default async function WeekToMonth() {
+  type Week = {
+    week: number;
+    year: number;
+  };
+
+  type MonthDistributionOfWeek = {
+    week: number;
+    year: number;
+    month: number;
+    secondMonth?: number;
+    distribution: number;
+  };
+
+  function weekToWeekType(weekInput: number) {
+    const weekInputStr = weekInput.toString();
+    return {
+      week: Number(weekInputStr.slice(-2)),
+      year: Number(weekInputStr.slice(0, 4)),
+    } as Week;
+  }
+
+  function getMonthOfWeek(week: Week) {
+    const weekNumber = week.week;
+    const year = week.year;
+    var daysFromStartOfYear = 1 + (weekNumber - 1) * 7;
+
+    const dayOfSelectedWeek = new Date(year, 0, daysFromStartOfYear);
+    const mondayOfSelectedWeek = !isMonday(dayOfSelectedWeek)
+      ? previousMonday(dayOfSelectedWeek)
+      : dayOfSelectedWeek;
+    const month = mondayOfSelectedWeek.getMonth();
+
+    var distribution = 100;
+    var endDate = null;
+    for (let i = 1; i < 7; i++) {
+      const addedDayDate = addDays(mondayOfSelectedWeek, i);
+      if (addedDayDate.getMonth() != month) {
+        distribution = (distribution / 7) * i;
+        endDate = addedDayDate;
+        break;
+      }
+    }
+    const weekToMonthInstance = {
+      week: weekNumber,
+      year: year,
+      month: month,
+      secondMonth: endDate?.getMonth(),
+      distribution: distribution,
+    } as MonthDistributionOfWeek;
+
+    return weekToMonthInstance;
+  }
+}