"""
Service for fetching and processing price data from Yahoo Finance using yfinance-plus
"""

from datetime import datetime, timezone, timedelta, date
from typing import Dict, List, Optional, Tuple, Union
import logging
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import select, and_, desc
import asyncio
import sys
import os

# Add parent directory to path for imports
sys.path.append(os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__)))))

from app.models.financial import PriceData
from app.schemas.financial import DataSource, ErrorType
from app.utils.date_utils import parse_period, quarters_to_date_range, resolve_time_parameters
from app.core.config import settings

logger = logging.getLogger(__name__)


async def _run_with_timeout(coro, timeout_seconds: float, description: str):
    try:
        return await asyncio.wait_for(coro, timeout=timeout_seconds)
    except asyncio.TimeoutError:
        raise TimeoutError(f"yfinance timed out after {timeout_seconds}s: {description}")


# Import yfinance-plus for price data only
try:
    import yfinance_plus as yf
    YFINANCE_AVAILABLE = True
    logger.info("yfinance-plus imported successfully for price data")
except ImportError:
    logger.error("yfinance-plus not available for price data")
    YFINANCE_AVAILABLE = False

class PriceDataService:
    def __init__(self):
        self.yf_available = YFINANCE_AVAILABLE
        if not self.yf_available:
            logger.warning("Yahoo Finance (yfinance-plus) data will not be available")
    
    async def get_or_update_price_data(
        self,
        db: AsyncSession,
        ticker: str,
        start_date: datetime,
        end_date: datetime,
        interval: str = "1d",
        force_refresh: bool = False
    ) -> List[PriceData]:
        """
        Get price data from database or fetch from Yahoo Finance if needed
        
        Args:
            db: Database session
            ticker: Stock ticker symbol
            start_date: Start date for data retrieval
            end_date: End date for data retrieval
            interval: Data interval (1d, 1w, 1m, 1h, etc.)
            force_refresh: Force refresh data from Yahoo Finance
            
        Returns:
            List of PriceData objects
        """
        ticker = ticker.upper()
        
        # Check if we need to fetch new data
        missing_periods = await self._check_missing_periods(
            db, ticker, start_date, end_date, interval
        )
        
        if missing_periods or force_refresh:
            if not self.yf_available:
                raise ValueError("Yahoo Finance (yfinance-plus) data source not available")

            # Fetch data from Yahoo Finance using yfinance-plus
            await self._fetch_and_store_price_data(
                db, ticker, start_date, end_date, interval
            )
        
        # Retrieve data from database
        price_data = await self._get_price_data_from_db(
            db, ticker, start_date, end_date, interval
        )
        
        return price_data
    
    async def _check_missing_periods(
        self,
        db: AsyncSession,
        ticker: str,
        start_date: datetime,
        end_date: datetime,
        interval: str
    ) -> List[datetime]:
        """Check which periods are missing in the database"""
        # If no date range provided, assume we need to fetch data
        if start_date is None or end_date is None:
            return [datetime.now()]  # Return a dummy date to trigger fetch
            
        # Check if we have any data for this ticker and interval
        result = await db.execute(
            select(PriceData.date)
            .where(
                and_(
                    PriceData.ticker == ticker,
                    PriceData.date >= start_date,
                    PriceData.date <= end_date
                )
            )
            .order_by(PriceData.date)
        )
        
        existing_dates = {row[0].date() for row in result.fetchall()}
        
        # Generate expected dates based on interval
        expected_dates = self._generate_expected_dates(start_date, end_date, interval)
        
        # Find missing dates
        missing_dates = [date for date in expected_dates if date not in existing_dates]
        
        # If more than 10% of dates are missing, consider it as needing refresh
        if len(missing_dates) > len(expected_dates) * 0.1:
            return missing_dates
        
        return []
    
    def _generate_expected_dates(
        self,
        start_date: datetime,
        end_date: datetime,
        interval: str
    ) -> List[datetime]:
        """Generate expected trading dates based on interval"""
        expected_dates = []
        current_date = start_date
        
        # Simple date generation (doesn't account for market holidays)
        if interval == "1d":
            while current_date <= end_date:
                # Skip weekends for daily data
                if current_date.weekday() < 5:  # Monday = 0, Friday = 4
                    expected_dates.append(current_date)
                current_date += timedelta(days=1)
        elif interval == "1w":
            while current_date <= end_date:
                expected_dates.append(current_date)
                current_date += timedelta(weeks=1)
        elif interval == "1m":
            # Monthly data - first day of each month
            while current_date <= end_date:
                expected_dates.append(current_date)
                # Move to next month
                if current_date.month == 12:
                    current_date = current_date.replace(year=current_date.year + 1, month=1)
                else:
                    current_date = current_date.replace(month=current_date.month + 1)
        else:
            # For other intervals, just return the date range
            expected_dates = [start_date, end_date]
        
        return expected_dates
    
    async def _fetch_and_store_price_data(
        self,
        db: AsyncSession,
        ticker: str,
        start_date: datetime,
        end_date: datetime,
        interval: str
    ):
        """Fetch price data from Yahoo Finance using yfinance-plus and store in database"""
        try:
            logger.info(f"Fetching price data for {ticker} from {start_date} to {end_date}")
            
            # Create yfinance-plus ticker object
            yf_ticker = yf.Ticker(ticker)
            
            # Fetch historical data
            # Convert dates to strings in YYYY-MM-DD format
            start_str = start_date.strftime('%Y-%m-%d')
            # yfinance's `end` parameter is exclusive for daily data when using date strings.
            # Add +1 day to include the intended end_date day in the results.
            from datetime import timedelta
            end_inclusive = end_date + timedelta(days=1)
            end_str = end_inclusive.strftime('%Y-%m-%d')
            
            # Run yfinance-plus in executor to avoid blocking
            loop = asyncio.get_event_loop()
            hist_data = await _run_with_timeout(
                loop.run_in_executor(
                    None,
                    lambda: yf_ticker.history(
                        start=start_str,
                        end=end_str,
                        interval=interval,
                        auto_adjust=True,
                        prepost=False,
                        period=None  # Explicitly set period to None when using start/end dates
                    )
                ),
                timeout_seconds=30,
                description=f"history {ticker} {start_str}:{end_str}"
            )
            
            if hist_data.empty:
                logger.warning(f"No price data returned for {ticker}")
                return
            
            # Store data in database
            await self._store_price_data(db, ticker, hist_data, interval)
            
            await db.commit()
            
            logger.info(f"Successfully stored {len(hist_data)} price records for {ticker}")
            
        except Exception as e:
            logger.error(f"Error fetching price data for {ticker}: {str(e)}")
            await db.rollback()
            raise

    async def get_quote(self, ticker: str, use_prepost: bool = True) -> Dict:
        """Get latest quote using yfinance-plus .info fields with fallback to fast history last row."""
        if not self.yf_available:
            raise ValueError("Yahoo Finance (yfinance-plus) data source not available")
        try:
            yf_ticker = yf.Ticker(ticker)
            loop = asyncio.get_event_loop()
            info = await _run_with_timeout(
                loop.run_in_executor(None, lambda: yf_ticker.info),
                timeout_seconds=20,
                description=f"info {ticker}"
            )
            # Prefer regular/post/pre values
            regular = info.get("regularMarketPrice")
            post = info.get("postMarketPrice") if use_prepost else None
            pre = info.get("preMarketPrice") if use_prepost else None
            price = post or pre or regular
            currency = info.get("currency")
            exchange = info.get("exchange") or info.get("fullExchangeName")
            market_state = info.get("marketState")
            ts = info.get("regularMarketTime") or info.get("postMarketTime") or info.get("preMarketTime")
            if isinstance(ts, (int, float)):
                ts = datetime.fromtimestamp(ts, tz=timezone.utc)
            elif isinstance(ts, datetime):
                if ts.tzinfo is None:
                    ts = ts.replace(tzinfo=timezone.utc)
            else:
                ts = datetime.now(timezone.utc)
            return {
                "ticker": ticker.upper(),
                "price": float(price) if price is not None else None,
                "regular_price": float(regular) if regular is not None else None,
                "pre_market_price": float(pre) if pre is not None else None,
                "post_market_price": float(post) if post is not None else None,
                "currency": currency,
                "exchange": exchange,
                "market_state": market_state,
                "timestamp": ts,
                "source": DataSource.YAHOO_FINANCE,
                "delayed": True,
            }
        except Exception as e:
            logger.error(f"Error fetching quote for {ticker}: {str(e)}")
            raise

    async def get_intraday(self, ticker: str, interval: str = "1m", period: str = "1d") -> List[Dict]:
        """Get intraday candles using yfinance-plus history with period/interval."""
        if not self.yf_available:
            raise ValueError("Yahoo Finance (yfinance-plus) data source not available")
        try:
            yf_ticker = yf.Ticker(ticker)
            loop = asyncio.get_event_loop()
            df = await _run_with_timeout(
                loop.run_in_executor(
                    None,
                    lambda: yf_ticker.history(period=period, interval=interval, auto_adjust=True, prepost=True)
                ),
                timeout_seconds=30,
                description=f"intraday {ticker} {period}/{interval}"
            )
            candles = []
            if not df.empty:
                for ts, row in df.iterrows():
                    dt = ts.to_pydatetime()
                    if dt.tzinfo is None:
                        dt = dt.replace(tzinfo=timezone.utc)
                    candles.append({
                        "timestamp": dt,
                        "open": float(row.get("Open", 0)) if not pd.isna(row.get("Open")) else None,
                        "high": float(row.get("High", 0)) if not pd.isna(row.get("High")) else None,
                        "low": float(row.get("Low", 0)) if not pd.isna(row.get("Low")) else None,
                        "close": float(row.get("Close", 0)) if not pd.isna(row.get("Close")) else 0.0,
                        "volume": float(row.get("Volume", 0)) if not pd.isna(row.get("Volume")) else None,
                    })
            return candles
        except Exception as e:
            logger.error(f"Error fetching intraday for {ticker}: {str(e)}")
            raise

    async def get_today_ohlc(self, ticker: str) -> Dict:
        """Get today's OHLC. If daily not yet finalized, aggregate from intraday 1m."""
        if not self.yf_available:
            raise ValueError("Yahoo Finance (yfinance-plus) data source not available")
        try:
            # First try daily with period=1d
            yf_ticker = yf.Ticker(ticker)
            loop = asyncio.get_event_loop()
            daily = await _run_with_timeout(
                loop.run_in_executor(
                    None, lambda: yf_ticker.history(period="1d", interval="1d", auto_adjust=True, prepost=False)
                ),
                timeout_seconds=30,
                description=f"today_ohlc {ticker}"
            )
            if daily is not None and not daily.empty:
                ts, row = list(daily.iterrows())[-1]
                d = ts.to_pydatetime().date()
                return {
                    "ticker": ticker.upper(),
                    "date": d,
                    "open": float(row.get("Open", 0)) if not pd.isna(row.get("Open")) else None,
                    "high": float(row.get("High", 0)) if not pd.isna(row.get("High")) else None,
                    "low": float(row.get("Low", 0)) if not pd.isna(row.get("Low")) else None,
                    "close": float(row.get("Close", 0)) if not pd.isna(row.get("Close")) else 0.0,
                    "volume": float(row.get("Volume", 0)) if not pd.isna(row.get("Volume")) else None,
                    "source": DataSource.YAHOO_FINANCE,
                    "method": "daily",
                }
            # Fallback to intraday aggregation
            intraday = await self.get_intraday(ticker, interval="1m", period="1d")
            if not intraday:
                raise ValueError("No intraday data available for today")
            o = next((c["open"] for c in intraday if c.get("open") is not None), None)
            h = max((c.get("high") or c.get("close") or 0.0) for c in intraday)
            l = min((c.get("low") or c.get("close") or float("inf")) for c in intraday)
            c = next((candle.get("close") for candle in reversed(intraday) if candle.get("close") is not None), 0.0)
            v = sum((c.get("volume") or 0.0) for c in intraday)
            today_date = intraday[0]["timestamp"].date()
            return {
                "ticker": ticker.upper(),
                "date": today_date,
                "open": o,
                "high": h if h != 0.0 else None,
                "low": l if l != float("inf") else None,
                "close": c,
                "volume": v or None,
                "source": DataSource.YAHOO_FINANCE,
                "method": "intraday_aggregate",
            }
        except Exception as e:
            logger.error(f"Error fetching today OHLC for {ticker}: {str(e)}")
            raise
    
    async def _store_price_data(
        self,
        db: AsyncSession,
        ticker: str,
        hist_data,
        interval: str
    ):
        """Store price data in database using batch upsert (INSERT ... ON CONFLICT DO NOTHING)."""
        from sqlalchemy.dialects.postgresql import insert as pg_insert
        import uuid as _uuid

        def _safe(val):
            """Return float or None, handling NaN/None safely."""
            if val is None:
                return None
            try:
                v = float(val)
                return None if pd.isna(v) else v
            except (TypeError, ValueError):
                return None

        now = datetime.now(timezone.utc)
        rows = []
        for date_idx, row in hist_data.iterrows():
            price_date = date_idx.to_pydatetime()
            if price_date.tzinfo is None:
                price_date = price_date.replace(tzinfo=timezone.utc)

            rows.append({
                'id': _uuid.uuid4(),
                'ticker': ticker,
                'date': price_date,
                'open': _safe(row.get('Open')),
                'high': _safe(row.get('High')),
                'low': _safe(row.get('Low')),
                'close': _safe(row.get('Close')) or 0.0,
                'volume': _safe(row.get('Volume')),
                'adjusted_close': _safe(row.get('Close')),
                'data_source': DataSource.YAHOO_FINANCE.value,
                'created_at': now,
                'updated_at': now,
            })

        if not rows:
            return

        # Single batch INSERT — skip rows that violate the unique constraint (ticker, date)
        stmt = pg_insert(PriceData).values(rows)
        stmt = stmt.on_conflict_do_nothing(constraint='uq_price_data')
        await db.execute(stmt)
    
    async def _get_price_data_from_db(
        self,
        db: AsyncSession,
        ticker: str,
        start_date: datetime,
        end_date: datetime,
        interval: str
    ) -> List[PriceData]:
        """Get price data from database"""
        # Build query conditions
        conditions = [PriceData.ticker == ticker]
        
        if start_date is not None:
            conditions.append(PriceData.date >= start_date)
        if end_date is not None:
            conditions.append(PriceData.date <= end_date)
        
        result = await db.execute(
            select(PriceData)
            .where(and_(*conditions))
            .order_by(PriceData.date)
        )
        
        return result.scalars().all()
    
    async def get_latest_price(
        self,
        db: AsyncSession,
        ticker: str
    ) -> Optional[PriceData]:
        """Get the latest price for a ticker"""
        result = await db.execute(
            select(PriceData)
            .where(PriceData.ticker == ticker.upper())
            .order_by(desc(PriceData.date))
            .limit(1)
        )
        
        return result.scalar_one_or_none()
    
    async def get_ticker_info(self, ticker: str) -> Dict:
        """Get ticker information from Yahoo Finance using yfinance-plus"""
        if not self.yf_available:
            raise ValueError("Yahoo Finance (yfinance-plus) data source not available")
        
        try:
            yf_ticker = yf.Ticker(ticker)

            # Run in executor to avoid blocking
            loop = asyncio.get_event_loop()
            info = await _run_with_timeout(
                loop.run_in_executor(None, lambda: yf_ticker.info),
                timeout_seconds=20,
                description=f"ticker_info {ticker}"
            )

            return info
            
        except Exception as e:
            logger.error(f"Error fetching ticker info for {ticker}: {str(e)}")
            raise
    
    async def get_multiple_tickers_data(
        self,
        db: AsyncSession,
        tickers: List[str],
        start_date: datetime,
        end_date: datetime,
        interval: str = "1d",
        force_refresh: bool = False
    ) -> Dict[str, List[PriceData]]:
        """Get price data for multiple tickers (legacy method)"""
        results = {}
        
        for ticker in tickers:
            try:
                data = await self.get_or_update_price_data(
                    db, ticker, start_date, end_date, interval, force_refresh
                )
                results[ticker] = data
            except Exception as e:
                logger.error(f"Error fetching data for {ticker}: {str(e)}")
                results[ticker] = []
        
        return results
    
    async def get_multiple_tickers_data_optimized(
        self,
        db: AsyncSession,
        tickers: List[str],
        start_date: datetime,
        end_date: datetime,
        interval: str = "1d",
        force_refresh: bool = False
    ) -> Tuple[List, int, int]:
        """
        Optimized bulk processing for multiple tickers with chunking for 100+ tickers:
        1. Smart chunking to handle 100+ tickers efficiently
        2. Parallel processing using asyncio with concurrency limits
        3. Bulk yfinance queries using yfinance-plus bulk features
        4. Optimized database operations with batch processing
        5. Progress tracking for large requests
        
        Supports unlimited ticker count with intelligent chunking:
        - Small batches (≤50): Process in single chunk
        - Medium batches (51-200): Process in 2-4 chunks
        - Large batches (200+): Process in optimal chunks with progress tracking
        
        Returns:
            Tuple of (results, successful_count, failed_count) for API response
        """
        from app.schemas.financial import BulkPriceDataItem, PriceDataResponse, PriceDataPoint
        
        results = []
        successful_count = 0
        failed_count = 0
        
        # Normalize tickers and validate
        tickers = [t.upper().strip() for t in tickers if t.strip()]
        total_tickers = len(tickers)
        
        logger.info(f"Starting bulk processing for {total_tickers} tickers")
        
        # Determine optimal chunking strategy based on ticker count
        if total_tickers <= 50:
            chunk_size = total_tickers  # Single chunk for small requests
            max_concurrent = 1
        elif total_tickers <= 200:
            chunk_size = 50  # Moderate chunks for medium requests
            max_concurrent = 4
        else:
            chunk_size = 75  # Larger chunks for big requests
            max_concurrent = 6
        
        try:
            # Process tickers in chunks to avoid overwhelming APIs and memory
            all_results = []
            all_successful = 0
            all_failed = 0
            
            for chunk_start in range(0, total_tickers, chunk_size):
                chunk_end = min(chunk_start + chunk_size, total_tickers)
                chunk_tickers = tickers[chunk_start:chunk_end]
                chunk_num = (chunk_start // chunk_size) + 1
                total_chunks = (total_tickers + chunk_size - 1) // chunk_size
                
                logger.info(f"Processing chunk {chunk_num}/{total_chunks}: {len(chunk_tickers)} tickers")
                
                # Step 1: Batch check missing periods for chunk
                missing_tickers = []
                if force_refresh:
                    missing_tickers = chunk_tickers.copy()
                else:
                    missing_tickers = await self._batch_check_missing_periods(
                        db, chunk_tickers, start_date, end_date, interval
                    )
                
                # Step 2: If we have missing data, use bulk yfinance fetch
                if missing_tickers and self.yf_available:
                    logger.info(f"Bulk fetching price data for {len(missing_tickers)} tickers in chunk {chunk_num}")
                    await self._bulk_fetch_and_store_price_data(
                        db, missing_tickers, start_date, end_date, interval
                    )
                
                # Step 3: Batch retrieve all data from database for this chunk
                ticker_data_map = await self._batch_get_price_data_from_db(
                    db, chunk_tickers, start_date, end_date, interval
                )
                
                # Step 4: Process results for this chunk
                chunk_results = []
                chunk_successful = 0
                chunk_failed = 0
                
                for ticker in chunk_tickers:
                    try:
                        price_data = ticker_data_map.get(ticker, [])
                        
                        # Convert to response models
                        price_points = [
                            PriceDataPoint.model_construct(
                                date=pd.date.date() if isinstance(pd.date, datetime) else pd.date,
                                open=pd.open, high=pd.high, low=pd.low, close=pd.close,
                                volume=pd.volume, adjusted_close=pd.adjusted_close,
                                data_source=pd.data_source.value if hasattr(pd.data_source, 'value') else pd.data_source,
                            ) for pd in price_data
                        ]
                        
                        # Calculate actual date range from returned data
                        actual_start_date = start_date
                        actual_end_date = end_date
                        
                        if price_points:
                            # Get actual start and end dates from the data
                            actual_start_date = min(point.date for point in price_points)
                            actual_end_date = max(point.date for point in price_points)
                        
                        response = PriceDataResponse(
                            ticker=ticker,
                            interval=interval,
                            data=price_points,
                            metadata={
                                "request_id": str(ticker),
                                "data_points": len(price_points),
                                "interval": interval,
                                "date_range": {
                                    "start": actual_start_date.isoformat(),
                                    "end": actual_end_date.isoformat()
                                },
                                "last_updated": datetime.now(timezone.utc).isoformat()
                            }
                        )
                        
                        chunk_results.append(BulkPriceDataItem(
                            ticker=ticker,
                            success=True,
                            data=response,
                            error=None
                        ))
                        chunk_successful += 1
                        
                    except Exception as e:
                        # Handle individual ticker failure
                        error_message = str(e)
                        if "No price data found" in error_message or "No data returned" in error_message:
                            error_message = f"No price data found for ticker {ticker}"
                        elif "Invalid ticker" in error_message:
                            error_message = f"Invalid or unknown ticker: {ticker}"
                        elif "Yahoo Finance data source not available" in error_message:
                            error_message = "Yahoo Finance data source not available"
                        
                        chunk_results.append(BulkPriceDataItem(
                            ticker=ticker,
                            success=False,
                            data=None,
                            error=error_message
                        ))
                        chunk_failed += 1
                
                # Aggregate chunk results
                all_results.extend(chunk_results)
                all_successful += chunk_successful
                all_failed += chunk_failed
                
                logger.info(f"Chunk {chunk_num} completed: {chunk_successful} successful, {chunk_failed} failed")
                
                # Small delay between chunks to avoid overwhelming APIs
                if chunk_num < total_chunks:
                    await asyncio.sleep(0.2)
            
            logger.info(f"Bulk processing completed: {all_successful} successful, {all_failed} failed out of {total_tickers} total")
            return all_results, all_successful, all_failed
                    
        except Exception as e:
            logger.error(f"Error in optimized bulk processing: {str(e)}")
            # Fallback to individual processing
            return await self._fallback_individual_processing(
                db, tickers, start_date, end_date, interval, force_refresh
            )
    
    async def _batch_check_missing_periods(
        self,
        db: AsyncSession,
        tickers: List[str],
        start_date: datetime,
        end_date: datetime,
        interval: str
    ) -> List[str]:
        """Batch check which tickers have missing periods"""
        # Single query to check all tickers at once
        from sqlalchemy import func, case
        
        result = await db.execute(
            select(
                PriceData.ticker,
                func.count(PriceData.date).label('count'),
                func.min(PriceData.date).label('min_date'),
                func.max(PriceData.date).label('max_date')
            )
            .where(
                and_(
                    PriceData.ticker.in_(tickers),
                    PriceData.date >= start_date,
                    PriceData.date <= end_date
                )
            )
            .group_by(PriceData.ticker)
        )
        
        existing_tickers = {}
        for row in result.fetchall():
            ticker, count, min_date, max_date = row
            existing_tickers[ticker] = {
                'count': count,
                'min_date': min_date,
                'max_date': max_date
            }
        
        # Determine expected count based on interval
        expected_days = (end_date - start_date).days
        if interval == "1d":
            expected_count = expected_days * 0.7  # Rough estimate for trading days
        elif interval == "1w":
            expected_count = expected_days / 7
        else:
            expected_count = 1
        
        missing_tickers = []
        for ticker in tickers:
            ticker_data = existing_tickers.get(ticker)
            if not ticker_data or ticker_data['count'] < expected_count * 0.8:
                missing_tickers.append(ticker)
        
        logger.info(f"Found {len(missing_tickers)} tickers needing data refresh out of {len(tickers)}")
        return missing_tickers
    
    async def _bulk_fetch_and_store_price_data(
        self,
        db: AsyncSession,
        tickers: List[str],
        start_date: datetime,
        end_date: datetime,
        interval: str
    ):
        """Optimized bulk fetch using yfinance-plus bulk features"""
        try:
            logger.info(f"Starting bulk fetch for {len(tickers)} tickers")
            
            # Convert dates to strings
            start_str = start_date.strftime('%Y-%m-%d')
            end_str = end_date.strftime('%Y-%m-%d')
            
            # Use yfinance-plus bulk download feature
            loop = asyncio.get_event_loop()
            
            # Use adaptive chunk size for yfinance API calls based on ticker count
            # Smaller chunks for yfinance API calls to avoid overwhelming the service
            total_tickers = len(tickers)
            if total_tickers <= 10:
                chunk_size = total_tickers  # Single chunk for very small batches
            elif total_tickers <= 50:
                chunk_size = 15  # Small chunks for moderate batches
            else:
                chunk_size = 20  # Standard chunks for large batches
            for i in range(0, len(tickers), chunk_size):
                chunk_tickers = tickers[i:i + chunk_size]
                
                logger.info(f"Processing chunk {i//chunk_size + 1}: {len(chunk_tickers)} tickers")
                
                # Use yfinance-plus bulk download
                _chunk_str = ' '.join(chunk_tickers)
                bulk_data = await _run_with_timeout(
                    loop.run_in_executor(
                        None,
                        lambda: yf.download(
                            tickers=_chunk_str,
                            start=start_str,
                            end=end_str,
                            interval=interval,
                            auto_adjust=True,
                            prepost=False,
                            group_by='ticker',
                            threads=True  # Enable multi-threading
                        )
                    ),
                    timeout_seconds=60,
                    description=f"bulk_download {len(chunk_tickers)} tickers"
                )
                
                # Process and store data for each ticker in the chunk
                await self._process_bulk_data(db, chunk_tickers, bulk_data, interval)
                
                # Small delay to be nice to the API
                await asyncio.sleep(0.1)
            
            await db.commit()
            logger.info(f"Successfully completed bulk fetch for {len(tickers)} tickers")
            
        except Exception as e:
            logger.error(f"Error in bulk fetch: {str(e)}")
            await db.rollback()
            raise
    
    async def _process_bulk_data(
        self,
        db: AsyncSession,
        tickers: List[str],
        bulk_data,
        interval: str
    ):
        """Process bulk data returned from yfinance and store in database"""
        if bulk_data.empty:
            logger.warning("No bulk data returned from yfinance")
            return
        
        # Handle different data structures from yfinance bulk download
        if len(tickers) == 1:
            # Single ticker - data is a simple DataFrame
            await self._store_ticker_data(db, tickers[0], bulk_data, interval)
        else:
            # Multiple tickers - data is grouped by ticker
            for ticker in tickers:
                try:
                    if ticker in bulk_data.columns.get_level_values(0):
                        ticker_data = bulk_data[ticker]
                        if not ticker_data.empty:
                            await self._store_ticker_data(db, ticker, ticker_data, interval)
                except Exception as e:
                    logger.error(f"Error processing data for {ticker}: {str(e)}")
                    continue
    
    async def _store_ticker_data(
        self,
        db: AsyncSession,
        ticker: str,
        ticker_data,
        interval: str
    ):
        """Store individual ticker data using batch upsert (INSERT ... ON CONFLICT DO NOTHING)."""
        from sqlalchemy.dialects.postgresql import insert as pg_insert
        import uuid as _uuid

        def _safe(val):
            if val is None:
                return None
            try:
                v = float(val)
                return None if pd.isna(v) else v
            except (TypeError, ValueError):
                return None

        now = datetime.now(timezone.utc)
        rows = []
        for date_idx, row in ticker_data.iterrows():
            price_date = date_idx.to_pydatetime()
            if price_date.tzinfo is None:
                price_date = price_date.replace(tzinfo=timezone.utc)

            rows.append({
                'id': _uuid.uuid4(),
                'ticker': ticker,
                'date': price_date,
                'open': _safe(row.get('Open')),
                'high': _safe(row.get('High')),
                'low': _safe(row.get('Low')),
                'close': _safe(row.get('Close')) or 0.0,
                'volume': _safe(row.get('Volume')),
                'adjusted_close': _safe(row.get('Close')),
                'data_source': DataSource.YAHOO_FINANCE.value,
                'created_at': now,
                'updated_at': now,
            })

        if not rows:
            return

        stmt = pg_insert(PriceData).values(rows)
        stmt = stmt.on_conflict_do_nothing(constraint='uq_price_data')
        await db.execute(stmt)
        logger.info(f"Batch upserted {len(rows)} price records for {ticker}")
    
    async def _get_existing_dates_for_ticker(
        self,
        db: AsyncSession,
        ticker: str
    ) -> set:
        """Get existing dates for a ticker to avoid duplicates"""
        result = await db.execute(
            select(PriceData.date)
            .where(PriceData.ticker == ticker)
        )
        return {row[0].date() for row in result.fetchall()}
    
    async def _batch_get_price_data_from_db(
        self,
        db: AsyncSession,
        tickers: List[str],
        start_date: datetime,
        end_date: datetime,
        interval: str
    ) -> Dict[str, List[PriceData]]:
        """Batch retrieve price data for multiple tickers"""
        # Single query to get data for all tickers
        result = await db.execute(
            select(PriceData)
            .where(
                and_(
                    PriceData.ticker.in_(tickers),
                    PriceData.date >= start_date,
                    PriceData.date <= end_date
                )
            )
            .order_by(PriceData.ticker, PriceData.date)
        )
        
        # Group results by ticker
        ticker_data_map = {}
        for ticker in tickers:
            ticker_data_map[ticker] = []
        
        for record in result.scalars().all():
            if record.ticker in ticker_data_map:
                ticker_data_map[record.ticker].append(record)
        
        return ticker_data_map
    
    async def _fallback_individual_processing(
        self,
        db: AsyncSession,
        tickers: List[str],
        start_date: datetime,
        end_date: datetime,
        interval: str,
        force_refresh: bool
    ) -> Tuple[List, int, int]:
        """Fallback to individual processing if bulk processing fails"""
        from app.schemas.financial import BulkPriceDataItem, PriceDataResponse, PriceDataPoint
        
        logger.warning("Falling back to individual ticker processing")
        
        results = []
        successful_count = 0
        failed_count = 0
        
        for ticker in tickers:
            try:
                # Get price data
                price_data = await self.get_or_update_price_data(
                    db, ticker, start_date, end_date, interval, force_refresh
                )
                
                # Convert to response models
                price_points = [
                    PriceDataPoint.model_construct(
                        date=pd.date.date() if isinstance(pd.date, datetime) else pd.date,
                        open=pd.open, high=pd.high, low=pd.low, close=pd.close,
                        volume=pd.volume, adjusted_close=pd.adjusted_close,
                        data_source=pd.data_source.value if hasattr(pd.data_source, 'value') else pd.data_source,
                    ) for pd in price_data
                ]
                
                # Calculate actual date range from returned data
                actual_start_date = start_date
                actual_end_date = end_date
                
                if price_points:
                    actual_start_date = min(point.date for point in price_points)
                    actual_end_date = max(point.date for point in price_points)
                
                response = PriceDataResponse(
                    ticker=ticker,
                    interval=interval,
                    data=price_points,
                    metadata={
                        "request_id": str(ticker),
                        "data_points": len(price_points),
                        "interval": interval,
                        "date_range": {
                            "start": actual_start_date.isoformat(),
                            "end": actual_end_date.isoformat()
                        },
                        "last_updated": datetime.now(timezone.utc).isoformat()
                    }
                )
                
                results.append(BulkPriceDataItem(
                    ticker=ticker,
                    success=True,
                    data=response,
                    error=None
                ))
                successful_count += 1
                
            except Exception as e:
                error_message = str(e)
                results.append(BulkPriceDataItem(
                    ticker=ticker,
                    success=False,
                    data=None,
                    error=error_message
                ))
                failed_count += 1
        
        return results, successful_count, failed_count


# Import pandas for data processing
try:
    import pandas as pd
except ImportError:
    logger.error("pandas not available - price data service will not work")
    pd = None