from datetime import date, timedelta
import pandas_market_calendars as _mcal  # optional dep — fall back gracefully
from typing import Optional
import logging

logger = logging.getLogger(__name__)

_NYSE_CAL = None


def _get_nyse():
    global _NYSE_CAL
    if _NYSE_CAL is None:
        try:
            import pandas_market_calendars as mcal
            _NYSE_CAL = mcal.get_calendar("NYSE")
        except ImportError:
            pass
    return _NYSE_CAL


def is_trading_day(d: date) -> bool:
    """Return True if d is a NYSE trading day."""
    cal = _get_nyse()
    if cal is None:
        return d.weekday() < 5
    import pandas as pd
    schedule = cal.schedule(start_date=str(d), end_date=str(d))
    return not schedule.empty


def next_trading_day(d: date) -> date:
    """Return the next trading day after d."""
    candidate = d + timedelta(days=1)
    while not is_trading_day(candidate):
        candidate += timedelta(days=1)
    return candidate


def next_friday(from_date: Optional[date] = None) -> date:
    """Return the next Friday on or after from_date."""
    d = from_date or date.today()
    days_ahead = 4 - d.weekday()  # Friday is weekday 4
    if days_ahead < 0:
        days_ahead += 7
    elif days_ahead == 0:
        pass  # today is Friday
    return d + timedelta(days=days_ahead)


def nearest_monthly_expiry(from_date: Optional[date] = None, target_dte: int = 30) -> date:
    """Return the standard monthly expiry (third Friday) closest to target_dte from from_date."""
    d = from_date or date.today()
    target = d + timedelta(days=target_dte)

    # Find third Friday of that month
    year, month = target.year, target.month
    third_friday = _third_friday(year, month)

    # If the third Friday of target month is already past relative to today, advance one month
    if third_friday <= d:
        if month == 12:
            year += 1
            month = 1
        else:
            month += 1
        third_friday = _third_friday(year, month)

    return third_friday


def _third_friday(year: int, month: int) -> date:
    """Return the third Friday of the given month."""
    first = date(year, month, 1)
    # Find first Friday
    days_to_friday = (4 - first.weekday()) % 7
    first_friday = first + timedelta(days=days_to_friday)
    return first_friday + timedelta(weeks=2)


def market_is_open_now() -> bool:
    """Best-effort check: is the US market currently open (9:30–16:00 ET)?"""
    from datetime import datetime
    import zoneinfo
    now_et = datetime.now(tz=zoneinfo.ZoneInfo("America/New_York"))
    if not is_trading_day(now_et.date()):
        return False
    open_time = now_et.replace(hour=9, minute=30, second=0, microsecond=0)
    close_time = now_et.replace(hour=16, minute=0, second=0, microsecond=0)
    return open_time <= now_et <= close_time


def within_dte_window_for_0dte() -> bool:
    """True if it's a trading day and between 9:30 AM and 2:00 PM ET."""
    from datetime import datetime
    import zoneinfo
    now_et = datetime.now(tz=zoneinfo.ZoneInfo("America/New_York"))
    if not is_trading_day(now_et.date()):
        return False
    open_time = now_et.replace(hour=9, minute=30, second=0, microsecond=0)
    cutoff = now_et.replace(hour=14, minute=0, second=0, microsecond=0)
    return open_time <= now_et <= cutoff