from datetime import timedelta
from typing import Optional

def format_human_readable_time(seconds: float) -> str:
    """
    Convert seconds to human-readable time format using datetime.timedelta
    
    Args:
        seconds: Number of seconds to format
        
    Returns:
        Human-readable time string (e.g., "1 day 2 hours 3 minutes 4 seconds")
    """
    td = timedelta(seconds=seconds)
    
    # Extract components
    days = td.days
    hours, remainder = divmod(td.seconds, 3600)
    minutes, seconds_remaining = divmod(remainder, 60)
    
    # Build the human-readable string
    parts = []
    if days > 0:
        parts.append(f"{days} day" if days == 1 else f"{days} days")
    if hours > 0:
        parts.append(f"{hours} hour" if hours == 1 else f"{hours} hours")
    if minutes > 0:
        parts.append(f"{minutes} minute" if minutes == 1 else f"{minutes} minutes")
    if seconds_remaining > 0 or not parts:  # Include seconds if no other parts or if seconds exist
        parts.append(f"{seconds_remaining} second" if seconds_remaining == 1 else f"{seconds_remaining} seconds")
    
    return " ".join(parts)

def calculate_time_remaining(start_time: float, duration_required: float, current_time: Optional[float] = None) -> float:
    """
    Calculate remaining time for a duration requirement
    
    Args:
        start_time: When the timer started
        duration_required: Total duration required
        current_time: Current time (defaults to time.time())
        
    Returns:
        Remaining time in seconds (0 if elapsed time exceeds requirement)
    """
    import time
    current = current_time or time.time()
    elapsed = current - start_time
    return max(0, duration_required - elapsed)