"""Exchange-rate retrieval and Stripe currency conversion."""


from datetime import datetime
import requests
from runtime_config import (
    CACHE_DURATION,
    EXCHANGE_RATE_CACHE,
    EXCHANGE_RATE_LOCK,
    logger,
)

__all__ = ['calculate_stripe_amount', 'fetch_exchange_rates', 'get_cached_exchange_rates']



def calculate_stripe_amount(credits: int, currency: str) -> int:
    """
    Calculate amount in smallest currency unit (cents, pence, etc.)
    Base rate: 100 credits = 1.00 USD
    """
    # Get USD price
    usd_price = credits / 100  # $1 per 100 credits

    # Get exchange rate
    rates = get_cached_exchange_rates()
    rate = rates.get(currency, 1.0)

    # Convert to target currency
    currency_price = usd_price * rate

    # Convert to smallest unit (cents)
    # Most currencies use 2 decimal places, but some don't
    if currency in ['JPY', 'KRW']:  # Zero decimal currencies
        return int(currency_price)
    else:
        return int(currency_price * 100)

def fetch_exchange_rates():
    """
    Fetch exchange rates from the free currency API
    Uses EUR as base currency
    """
    try:
        # Using the fawazahmed0 currency API - EUR as base
        url = 'https://cdn.jsdelivr.net/npm/@fawazahmed0/currency-api@latest/v1/currencies/eur.json'

        logger.info("Fetching exchange rates from API...")
        response = requests.get(url, timeout=10)
        response.raise_for_status()

        data = response.json()

        if 'eur' in data:
            rates_data = data['eur']

            # Extract rates for currencies we support - all relative to EUR
            new_rates = {
                'EUR': 1.00,  # Base currency
                'USD': rates_data.get('usd', 1.5),  # EUR->USD rate
                'GBP': rates_data.get('gbp', 0.85),  # EUR->GBP rate
                'PLN': rates_data.get('pln', 4.32),  # EUR->PLN rate
                'PHP': rates_data.get('php', 60.50),  # EUR->PHP rate
                'CZK': rates_data.get('czk', 24.65)   # EUR->CZK rate
            }

            with EXCHANGE_RATE_LOCK:
                EXCHANGE_RATE_CACHE['rates'] = new_rates
                EXCHANGE_RATE_CACHE['last_updated'] = datetime.now().isoformat()

            logger.info(f"✅ Exchange rates updated successfully: {new_rates}")
            return True
        else:
            logger.error("Invalid response format from currency API")
            return False

    except requests.exceptions.Timeout:
        logger.error("❌ Timeout fetching exchange rates")
        return False
    except requests.exceptions.RequestException as e:
        logger.error(f"❌ Error fetching exchange rates: {e}")
        return False
    except Exception as e:
        logger.error(f"❌ Unexpected error fetching exchange rates: {e}")
        return False

def get_cached_exchange_rates():
    """Get cached exchange rates, fetch new ones if cache is stale"""
    with EXCHANGE_RATE_LOCK:
        last_updated = EXCHANGE_RATE_CACHE.get('last_updated')

        # If never updated or cache is stale, fetch new rates
        if last_updated is None:
            logger.info("Exchange rates cache is empty, fetching...")
            # Release lock before fetching to avoid deadlock
        elif (datetime.now() - datetime.fromisoformat(last_updated)).total_seconds() > CACHE_DURATION:
            logger.info("Exchange rates cache is stale, fetching...")
        else:
            # Cache is fresh, return it
            return EXCHANGE_RATE_CACHE['rates']

    # Fetch new rates (outside lock to avoid blocking)
    fetch_exchange_rates()

    # Return rates (either newly fetched or fallback)
    with EXCHANGE_RATE_LOCK:
        return EXCHANGE_RATE_CACHE['rates']