Generate Available 30-Minute Time Slots

Problem Statement

Given a recurring weekly working schedule, a list of existing booked appointments, and a requested date range, generate all available 30-minute time slots.

Definitions

• Working Schedule: A dictionary where keys are days of the week (0=Monday, 6=Sunday) and values are lists of [start_time, end_time] strings in HH:MM format (e.g., {"0": [["09:00", "17:00"]]}).
• Booked Appointments: A list of datetime strings in ISO format: YYYY-MM-DDTHH:MM:SS representing the start and end of each booking.
• Requested Range: A [start_date, end_date] pair as ISO date strings.

Function Signature

def get_available_slots(working_schedule, booked_appointments, start_date, end_date):
    # Return a list of tuples: (slot_start_iso, slot_end_iso)

Constraints

• Time slots must be exactly 30 minutes long.
• Time slots must be aligned to the hour (e.g., :00 or :30).
• start_date and end_date are inclusive.
• If a booking overlaps with a working hour, that time is unavailable.

Example

• Schedule: {"0": [["09:00", "10:00"]]} (Mondays 9-10 AM only).
• Bookings: [["2023-10-02T09:30:00", "2023-10-02T10:00:00"]].
• Range: ["2023-10-02", "2023-10-02"].
• Output: [["2023-10-02T09:00:00", "2023-10-02T09:30:00"]].

Edge Cases

• Range spans multiple weeks.
• Working hours end at midnight.
• Bookings that span across the boundary of working hours.