"""
Timezone utilities for consistent timestamp handling across the gateway.
Ensures all timestamps are properly handled as UTC.
"""

from datetime import datetime, timezone, timedelta
from typing import Union, Optional

def get_utc_now() -> datetime:
    """
    Get current time in UTC with timezone info.
    
    Returns:
        datetime: Current UTC time with timezone info
    """
    return datetime.now(timezone.utc)

def get_utc_timestamp() -> float:
    """
    Get current UTC timestamp (seconds since epoch).
    
    Returns:
        float: Current UTC timestamp in seconds
    """
    return datetime.now(timezone.utc).timestamp()

def to_utc_timestamp(dt: datetime) -> float:
    """
    Convert datetime object to UTC timestamp.
    
    Args:
        dt (datetime): Datetime object to convert
        
    Returns:
        float: UTC timestamp in seconds
    """
    if dt.tzinfo is None:
        # If naive datetime, assume it's UTC
        dt = dt.replace(tzinfo=timezone.utc)
    return dt.timestamp()

def from_utc_timestamp(timestamp: Union[int, float]) -> datetime:
    """
    Convert UTC timestamp to datetime object.
    
    Args:
        timestamp (Union[int, float]): UTC timestamp in seconds
        
    Returns:
        datetime: Datetime object in UTC
    """
    return datetime.fromtimestamp(timestamp, tz=timezone.utc)

def add_seconds_to_utc(seconds: int) -> datetime:
    """
    Add seconds to current UTC time.
    
    Args:
        seconds (int): Seconds to add (can be negative)
        
    Returns:
        datetime: UTC time with seconds added
    """
    return get_utc_now() + timedelta(seconds=seconds)

def add_seconds_to_utc_timestamp(seconds: int) -> float:
    """
    Add seconds to current UTC timestamp.
    
    Args:
        seconds (int): Seconds to add (can be negative)
        
    Returns:
        float: UTC timestamp with seconds added
    """
    return get_utc_timestamp() + seconds

def format_utc_for_display(dt: datetime, format_str: str = "%Y-%m-%d %H:%M:%S UTC") -> str:
    """
    Format UTC datetime for display.
    
    Args:
        dt (datetime): UTC datetime to format
        format_str (str): Format string (default: ISO-like with UTC indicator)
        
    Returns:
        str: Formatted datetime string
    """
    if dt.tzinfo is None:
        # If naive datetime, assume it's UTC
        dt = dt.replace(tzinfo=timezone.utc)
    return dt.strftime(format_str)

def is_expired_utc(expires_at: Union[datetime, float, str]) -> bool:
    """
    Check if a UTC timestamp has expired.
    
    Args:
        expires_at (Union[datetime, float, str]): Expiration timestamp
        
    Returns:
        bool: True if expired, False otherwise
    """
    if not expires_at:
        return False
    
    current_utc = get_utc_timestamp()
    
    if isinstance(expires_at, datetime):
        expires_timestamp = to_utc_timestamp(expires_at)
    elif isinstance(expires_at, str):
        try:
            # Try to parse ISO string
            dt = datetime.fromisoformat(expires_at.replace('Z', '+00:00'))
            expires_timestamp = to_utc_timestamp(dt)
        except ValueError:
            # If parsing fails, try float conversion
            expires_timestamp = float(expires_at)
    else:
        expires_timestamp = float(expires_at)
    
    return current_utc > expires_timestamp

def get_expires_in_seconds(expires_at: Union[datetime, float, str]) -> Optional[int]:
    """
    Get seconds until expiration (negative if expired).
    
    Args:
        expires_at (Union[datetime, float, str]): Expiration timestamp
        
    Returns:
        Optional[int]: Seconds until expiration, None if no expiration
    """
    if not expires_at:
        return None
    
    current_utc = get_utc_timestamp()
    
    if isinstance(expires_at, datetime):
        expires_timestamp = to_utc_timestamp(expires_at)
    elif isinstance(expires_at, str):
        try:
            # Try to parse ISO string
            dt = datetime.fromisoformat(expires_at.replace('Z', '+00:00'))
            expires_timestamp = to_utc_timestamp(dt)
        except ValueError:
            # If parsing fails, try float conversion
            expires_timestamp = float(expires_at)
    else:
        expires_timestamp = float(expires_at)
    
    return int(expires_timestamp - current_utc)

def create_expiration_timestamp(expires_in_seconds: int) -> float:
    """
    Create a new expiration timestamp from seconds until expiration.
    
    Args:
        expires_in_seconds (int): Seconds until expiration
        
    Returns:
        float: UTC timestamp in seconds
    """
    return get_utc_timestamp() + expires_in_seconds