Rolling 4 Weeks Average by Weekno

Hi All,

I am new user to Power BI and trying to calculate 4 Week Rolling avg by Weeknumbers.

i have gone through quite a lot of articles and videos, tried in built DAX functions like DATESINPERIOD etc but no luck,

Since POWERBI doesnt have inbuilt function in DAX for ROlling Weekly Avg.

Roll4AVg = 
Var CurrentWeek = SELECTEDVALUE(tbl_SalesDaily[tbl_Calendar.TYWN])
Var Currentyear = SELECTEDVALUE(tbl_SalesDaily[tbl_Calendar.TYN])
Var MaxWeekNo = CALCULATE(MAX(tbl_SalesDaily[tbl_Calendar.TYWN]), ALL(tbl_SalesDaily))          
RETURN	
AVERAGEX(
            FILTER(tbl_SalesDaily, 
                          if (CurrentWeek = 1,
tbl_SalesDaily[tbl_Calendar.TYWN] = MaxWeekNo - 3 && tbl_SalesDaily[tbl_Calendar.TYN] = Currentyear - 1,
tbl_SalesDaily[tbl_Calendar.TYWN] = CurrentWeek - 4 && tbl_SalesDaily[tbl_Calendar.TYN] = Currentyear)), [Selected Category])

ended up writing this code after going through lots of articles, since Week numbers go upto 52 or 53 in some of the years and then reset to 1 for new commencing year.

Also attaching DUmmy data at below location:

https://1drv.ms/x/s!AoKR2AuKbWtQg06k3bVNAkNd-wd2

looking forward for solution...

Regards,

Vishal.