Assigning task to team members as per their availability

Hi Team,

I have a team of 20 people & have to distribute task to them every month, is there any formula or VBA code through which it can be done.
In attached images, i have two task to be performed :
1) In tracker have to Mark Implement & Preparation.
2) For Implement have to assign it to person who is available in same shift on same date.
3) For Preparation have to assign that task to people present in shift 1 day before & that too except Night Shift.
Is there any way this can be automated?TrackerRoster