import xml.etree.ElementTree as ET
from datetime import datetime, timedelta

import httpx
from sqlmodel import Session, col, select

from app.config import settings
from app.models.models import ExchangeRate

# BCCR indicators: 317 = buy, 318 = sell
BCCR_URL = "https://gee.bccr.fi.cr/Indicadores/Suscripciones/WS/wsindicadoreseconomicos.asmx/ObtenerIndicadoresEconomicos"

_cache: dict[str, tuple[ExchangeRate, datetime]] = {}
CACHE_TTL = timedelta(hours=1)


def _fetch_bccr_rate(indicator: int, date_str: str) -> float | None:
    """Fetch a single indicator from BCCR API."""
    try:
        params = {
            "Indicador": str(indicator),
            "FechaInicio": date_str,
            "FechaFinal": date_str,
            "Nombre": settings.BCCR_API_EMAIL or "WealthySmart",
            "SubNiveles": "N",
            "CorreoElectronico": settings.BCCR_API_EMAIL or "no-reply@example.com",
            "Token": settings.BCCR_API_TOKEN or "",
        }
        resp = httpx.get(BCCR_URL, params=params, timeout=10)
        resp.raise_for_status()

        # Parse XML response
        root = ET.fromstring(resp.text)
        # The value is in INGC011_DES_DATOS > NUM_VALOR
        ns = {"": "http://ws.sdde.bccr.fi.cr"}
        for datos in root.iter():
            if datos.tag.endswith("NUM_VALOR"):
                return float(datos.text.strip().replace(",", "."))
    except Exception:
        pass
    return None


def get_current_rate(session: Session) -> ExchangeRate | None:
    """Get current USD/CRC rate. Uses in-memory cache + DB fallback."""
    # Check memory cache
    cached = _cache.get("current")
    if cached and datetime.utcnow() - cached[1] < CACHE_TTL:
        return cached[0]

    # Check DB for recent rate
    one_hour_ago = datetime.utcnow() - CACHE_TTL
    db_rate = session.exec(
        select(ExchangeRate)
        .where(ExchangeRate.fetched_at > one_hour_ago)
        .order_by(col(ExchangeRate.fetched_at).desc())
    ).first()
    if db_rate:
        _cache["current"] = (db_rate, datetime.utcnow())
        return db_rate

    # Fetch from BCCR
    today = datetime.now().strftime("%d/%m/%Y")
    buy = _fetch_bccr_rate(317, today)
    sell = _fetch_bccr_rate(318, today)

    if buy is None or sell is None:
        # Fallback: return most recent DB rate regardless of age
        fallback = session.exec(
            select(ExchangeRate).order_by(col(ExchangeRate.fetched_at).desc())
        ).first()
        return fallback

    rate = ExchangeRate(
        date=datetime.utcnow(),
        buy_rate=buy,
        sell_rate=sell,
    )
    session.add(rate)
    session.commit()
    session.refresh(rate)
    _cache["current"] = (rate, datetime.utcnow())
    return rate


def get_rate_history(session: Session, days: int = 30) -> list[ExchangeRate]:
    """Get historical exchange rates."""
    cutoff = datetime.utcnow() - timedelta(days=days)
    return list(
        session.exec(
            select(ExchangeRate)
            .where(ExchangeRate.date > cutoff)
            .order_by(col(ExchangeRate.date).desc())
        ).all()
    )