"""
Price service for fetching stock prices.

This is a mock implementation that uses DB data.
Can be replaced with real OpenAPI implementation later.
"""
from datetime import date, timedelta
from decimal import Decimal
from typing import Dict, List, Optional

from sqlalchemy.orm import Session
from sqlalchemy import func

from app.models.stock import Price


class PriceData:
    """Price data point."""

    def __init__(
        self,
        ticker: str,
        date: date,
        open: Decimal,
        high: Decimal,
        low: Decimal,
        close: Decimal,
        volume: int,
    ):
        self.ticker = ticker
        self.date = date
        self.open = open
        self.high = high
        self.low = low
        self.close = close
        self.volume = volume


class PriceService:
    """
    Service for fetching stock prices.

    Current implementation uses DB data (prices table).
    Can be extended to use real-time OpenAPI in the future.
    """

    def __init__(self, db: Session):
        self.db = db

    def get_current_price(self, ticker: str) -> Optional[Decimal]:
        """
        Get current price for a single ticker.

        Returns the most recent closing price from DB.
        """
        result = (
            self.db.query(Price.close)
            .filter(Price.ticker == ticker)
            .order_by(Price.date.desc())
            .first()
        )
        return Decimal(str(result[0])) if result else None

    def get_current_prices(self, tickers: List[str]) -> Dict[str, Decimal]:
        """
        Get current prices for multiple tickers.

        Returns a dict mapping ticker to most recent closing price.
        """
        if not tickers:
            return {}

        # Subquery to get max date for each ticker
        subquery = (
            self.db.query(
                Price.ticker,
                func.max(Price.date).label('max_date')
            )
            .filter(Price.ticker.in_(tickers))
            .group_by(Price.ticker)
            .subquery()
        )

        # Get prices at max date
        results = (
            self.db.query(Price.ticker, Price.close)
            .join(
                subquery,
                (Price.ticker == subquery.c.ticker) &
                (Price.date == subquery.c.max_date)
            )
            .all()
        )

        return {ticker: Decimal(str(close)) for ticker, close in results}

    def get_price_history(
        self,
        ticker: str,
        start_date: date,
        end_date: date,
    ) -> List[PriceData]:
        """
        Get price history for a ticker within date range.
        """
        results = (
            self.db.query(Price)
            .filter(
                Price.ticker == ticker,
                Price.date >= start_date,
                Price.date <= end_date,
            )
            .order_by(Price.date)
            .all()
        )

        return [
            PriceData(
                ticker=p.ticker,
                date=p.date,
                open=Decimal(str(p.open)),
                high=Decimal(str(p.high)),
                low=Decimal(str(p.low)),
                close=Decimal(str(p.close)),
                volume=p.volume,
            )
            for p in results
        ]

    def get_price_at_date(self, ticker: str, target_date: date) -> Optional[Decimal]:
        """
        Get closing price at specific date.

        If no price on exact date, returns most recent price before that date.
        """
        result = (
            self.db.query(Price.close)
            .filter(
                Price.ticker == ticker,
                Price.date <= target_date,
            )
            .order_by(Price.date.desc())
            .first()
        )
        return Decimal(str(result[0])) if result else None

    def get_prices_at_date(
        self,
        tickers: List[str],
        target_date: date,
    ) -> Dict[str, Decimal]:
        """
        Get closing prices for multiple tickers at specific date.
        """
        if not tickers:
            return {}

        # Subquery to get max date <= target_date for each ticker
        subquery = (
            self.db.query(
                Price.ticker,
                func.max(Price.date).label('max_date')
            )
            .filter(
                Price.ticker.in_(tickers),
                Price.date <= target_date,
            )
            .group_by(Price.ticker)
            .subquery()
        )

        # Get prices at those dates
        results = (
            self.db.query(Price.ticker, Price.close)
            .join(
                subquery,
                (Price.ticker == subquery.c.ticker) &
                (Price.date == subquery.c.max_date)
            )
            .all()
        )

        return {ticker: Decimal(str(close)) for ticker, close in results}