"""Timezone utilities for converting between UTC and user timezones."""
from datetime import datetime
from typing import Optional
import pytz
from dateutil import parser


def convert_to_utc(dt: datetime, from_timezone: str = "UTC") -> datetime:
    """Convert datetime from user timezone to UTC.

    Args:
        dt: Datetime to convert (naive or aware)
        from_timezone: IANA timezone name (e.g., "Europe/Bucharest")

    Returns:
        Naive datetime in UTC
    """
    if dt.tzinfo is None:
        # Naive datetime, assume it's in user timezone
        tz = pytz.timezone(from_timezone)
        dt = tz.localize(dt)

    # Convert to UTC
    return dt.astimezone(pytz.UTC).replace(tzinfo=None)


def convert_from_utc(dt: datetime, to_timezone: str = "UTC") -> datetime:
    """Convert datetime from UTC to user timezone.

    Args:
        dt: Datetime in UTC (naive or aware)
        to_timezone: IANA timezone name (e.g., "Europe/Bucharest")

    Returns:
        Timezone-aware datetime in target timezone
    """
    if dt.tzinfo is None:
        # Add UTC timezone if naive
        dt = pytz.UTC.localize(dt)

    # Convert to target timezone
    tz = pytz.timezone(to_timezone)
    return dt.astimezone(tz)


def format_datetime_tz(dt: datetime, timezone: str = "UTC", format_str: str = "%Y-%m-%d %H:%M %Z") -> str:
    """Format datetime with timezone abbreviation.

    Args:
        dt: Datetime in UTC (naive or aware)
        timezone: IANA timezone name for display
        format_str: Format string (default includes timezone abbreviation)

    Returns:
        Formatted datetime string with timezone
    """
    dt_tz = convert_from_utc(dt, timezone)
    return dt_tz.strftime(format_str)


def get_available_timezones():
    """Get list of common timezones for user selection."""
    common_timezones = [
        "UTC",
        "Europe/Bucharest",
        "Europe/London",
        "Europe/Paris",
        "Europe/Berlin",
        "Europe/Amsterdam",
        "America/New_York",
        "America/Los_Angeles",
        "America/Chicago",
        "America/Denver",
        "Asia/Tokyo",
        "Asia/Shanghai",
        "Asia/Dubai",
        "Australia/Sydney",
    ]
    return common_timezones