How to write below case statements in DAX

There are three tables involved in below statement. Table a, Table b, Table c.

COUNT (
DISTINCT CASE
WHEN a.PARTICIPANT_STATUS = 'No Show'
AND b.EVT_END_DT >= c.WEEK_END_DT
OR a.PARTICIPANT_STATUS NOT IN ('No Show')
AND NVL (
a.reg_dt,
ADD_MONTHS (
TO_DATE ('2019-06-21', 'YYYY-MM-DD'),
73)) >= c.WEEK_END_DT
AND a.cancel_dt <=
c.WEEK_END_DT
AND NVL (
a.transfer_dt
ADD_MONTHS (
TO_DATE ('2019-06-21', 'YYYY-MM-DD'),
73)) >= c.WEEK_END_DT
THEN
a.ROW_WID
END)