from datetime import datetime, timezone
from typing import Optional, Dict, Union
from sqlalchemy.orm import Session
from sqlalchemy import func
from models.server_time import ServerTime

def get_current_utc_time() -> datetime:
    """
    Get current UTC timestamp.
    
    Returns:
        datetime: Current UTC datetime
    """
    return datetime.now(timezone.utc)

def validate_timestamp(timestamp: datetime) -> bool:
    """
    Validate if timestamp is a valid datetime and not in future.
    
    Args:
        timestamp: Datetime to validate
        
    Returns:
        bool: True if valid, False otherwise
    """
    current_time = get_current_utc_time()
    return timestamp <= current_time

def record_server_time(db: Session) -> ServerTime:
    """
    Record current server time in database.
    
    Args:
        db: Database session
        
    Returns:
        ServerTime: Recorded server time entry
    """
    server_time = ServerTime(server_time=func.now())
    db.add(server_time)
    db.commit()
    db.refresh(server_time)
    return server_time

def get_latest_server_time(db: Session) -> Optional[ServerTime]:
    """
    Get most recent server time record.
    
    Args:
        db: Database session
        
    Returns:
        Optional[ServerTime]: Latest server time record if exists
    """
    return db.query(ServerTime).order_by(ServerTime.server_time.desc()).first()

def get_time_difference(time1: datetime, time2: datetime) -> float:
    """
    Calculate time difference in seconds between two timestamps.
    
    Args:
        time1: First timestamp
        time2: Second timestamp
        
    Returns:
        float: Time difference in seconds
    """
    return abs((time1 - time2).total_seconds())

def format_server_time(server_time: datetime, format: str = "%Y-%m-%d %H:%M:%S") -> str:
    """
    Format server time to string representation.
    
    Args:
        server_time: Datetime to format
        format: Output format string
        
    Returns:
        str: Formatted datetime string
    """
    return server_time.strftime(format)