Using loop to insert values from one table to another - oracle

Question

I have the following table named screening_plan:
plan_id movie_id plan_start_day plan_end_day plan_min_start_hh24 plan_max_start_hh24 screenings
1 1 1/06/2015 28/06/2015 9 17 5
2 2 1/06/2015 28/06/2015 9 22 4
3 3 1/06/2015 28/06/2015 9 22 5
4 4 1/06/2015 28/06/2015 9 17 4
And another tables theatre:
THEATRE_ID THEATRE_DESCRIPTION THEATRE_TOTAL_ROWS
1 2
2 2
3 3
4 2
There is a total of 18 screenings per day. I have to insert the details in the screening table as follows:
screening_id plan_id theatre_id screening_date screening_start_hh24 screening_start_mm60
1 1 3 1/06/2015 9 0
2 1 3 1/06/2015 11 30
3 1 3 1/06/2015 14 0
4 1/06/2015
plan_id is a foreign key referring table screening and theatre_id is a foreign key referring table theatre.
Each movie should be screened as per the screening number is defined
in the table screening_plan.
There is a break of 30 minutes between 2 consecutive screenings in
the same theatre.
The screening_start_hh24 should be less than plan_max_start_hh24.
Please note that the number of screenings for the first movie won't
fit into the provided time interval,so the second screening should be done
in an alternate theatre(preferably in theatre_id=2 starting from 11:30).
Each movie has a lenght of 2 hours.
I am stuck with this since yesterday. Tried doing it using the If-Else block, but that requires defining every condition. How can I do this using a loop?Please help.
My code(I have skipped the declaration part here):
BEGIN
SELECT plan_id INTO s_plan_id FROM screening_plan WHERE plan_id=1;
SELECT theatre_id INTO s_theatre_id FROM theatre WHERE theatre_id=1;
SELECT PLAN_START_DATE INTO s_screening_date FROM screening_plan WHERE plan_id=1;
SELECT Count(*) INTO s_count_theatre_id FROM screening;
IF s_count_theatre_id = 0
THEN
s_screening_start_hh24:=9;
s_screening_start_mm60:=0;
ELSIF s_count_theatre_id >0 AND s_count_theatre_id <=4
THEN
s_screening_start_hh24:=11 ;
s_screening_start_mm60:=30 ;
ELSE
Dbms_Output.put_line('---');
END IF;
INSERT INTO screening (plan_id, theatre_id, screening_date, screening_start_hh24, screening_start_mm60)
VALUES( s_plan_id,
s_theatre_id,
s_screening_date,
s_screening_start_hh24,
s_screening_start_mm60);
END;
There should be a total of 18 record in the table screening.5 for movie_id=1, 4 for movie_id=2, 5 for movie_id=3 and 4 for movie_id=3.