src/utils/sleep.py

from datetime import datetime, date, time, timedelta

def calculate_sleep_duration(yesterday_date: date, yesterday_sleep: time, today_date: date, today_wake: time) -> float:
    sleep_dt = datetime.combine(yesterday_date, yesterday_sleep)
    
    # If the user went to sleep past midnight (e.g., 01:00 AM), 
    # it actually belongs to 'today_date' chronologically.
    if yesterday_sleep < time(12, 0): # Assuming any sleep time before noon is past midnight
        sleep_dt += timedelta(days=1)
        
    wake_dt = datetime.combine(today_date, today_wake)
    
    duration_td = wake_dt - sleep_dt
    
    # Fallback in case of weird overlapping data
    if duration_td.total_seconds() < 0:
        return 0.0 
        
    return round(duration_td.total_seconds() / 3600.0, 2)