Implementing days/weeks system

Hello, I am interested in how the logic for implementing having different days would work. No blueprints right now, just the design.

What are the days in my game and what they should do:

-Days count is infinite. Hours are not counted, tho one day is ~30 minutes, and the night is skipped.
Months contain weeks and days, weeks contain days, and their number in the year. How to implement that, and should days count add-up automatically, should the days be new levels or be an integer in the save file that will affect things? Is that done with a multi-D array with different data types? I could not find such array in UE

-Each day there is a short-summary of what have been done today (gets updated whenever something gets added to it). For example, kill count (if there were any during the day). The information must be stored in this day to be accessed from future.

-The days will be displayed on a calendar. You can select a date and see what happened on that date. The information from days will be also needed for showing the progress of skills over time.
-Days will be used to regenerate from diseases. For example, you ll need exactly 2 days to regenerate from a disease

If you have some ideas on how that would work, please share them I am very interested, and as always,
Please halp!

If one day is 30 minutes, the logic is that you gradually increase a variable (every second, for example) until it reaches 1800 (1800 seconds = 30 minutes). Then it’s considered a “day”.
So if the “seconds” variable == 1800, increment the day integer variable.

You can save completed/failed objectives as a text string in the save blueprint, under an array, for each particular day (along with any other stuff the player did that day).

Hi, thanks for your reply!
As array for each day, should new arrays be created each day or something like that?