import os
import pathlib
import logging
import asyncio
import pandas as pd
from datetime import datetime
from typing import Optional

from core.storage_manager import StorageManager
from connectors.kite_client import KiteBrokerClient

logger = logging.getLogger("bqe.engine.instrument_parser")

class MarketInstrumentParser:
    """
    Downloads daily master option instrument lists from Zerodha Kite,
    filters them for liquid index options (NIFTY & BANKNIFTY), and archives
    them as Parquet files partitioned by date in Hive structure.
    """
    
    def __init__(self, storage_manager: Optional[StorageManager] = None):
        """
        Initializes the parser with BQE storage structures and broker clients.
        """
        self.storage_manager = storage_manager or StorageManager()
        self.broker_client = KiteBrokerClient()
        
    async def download_and_archive_instruments(self) -> pathlib.Path:
        """
        Retrieves all instruments, filters for NFO liquid indices,
        and saves the snapshot to a partitioned Parquet file.
        
        Returns:
            pathlib.Path: Absolute path to the saved Parquet file.
        """
        if not self.broker_client.kite_connect:
            raise ValueError("No active Kite session. Authentication is required.")
            
        logger.info("Fetching master instruments from Zerodha...")
        
        # Offload blocking network call to separate thread
        loop = asyncio.get_event_loop()
        raw_instruments = await loop.run_in_executor(
            None,
            lambda: self.broker_client.kite_connect.instruments()
        )
        
        logger.info(f"Downloaded {len(raw_instruments)} total instruments. Processing...")
        
        # Convert to Pandas DataFrame
        df = pd.DataFrame(raw_instruments)
        if df.empty:
            raise ValueError("Downloaded instruments payload is empty.")
            
        # Standardize exchange and name column types
        df['exchange'] = df['exchange'].astype(str)
        df['name'] = df['name'].astype(str)
        
        # Filter for NFO index options (NIFTY & BANKNIFTY)
        filtered_df = df[
            (df['exchange'] == 'NFO') & 
            (df['name'].isin(['NIFTY', 'BANKNIFTY']))
        ].copy()
        
        logger.info(f"Filtered down to {len(filtered_df)} liquid NFO derivative instruments.")
        
        # Determine today's date in 2026
        today = datetime.now()
        year_str = today.strftime("%Y")
        month_str = today.strftime("%m")
        day_str = today.strftime("%d")
        
        # Construct Hive partition path layout:
        # data_lake/derivatives/instruments/year=YYYY/month=MM/day=DD/master_instruments.parquet
        partition_dir = os.path.join(
            self.storage_manager.data_lake_dir,
            "derivatives",
            "instruments",
            f"year={year_str}",
            f"month={month_str}",
            f"day={day_str}"
        )
        
        # Ensure directories exist
        pathlib.Path(partition_dir).mkdir(parents=True, exist_ok=True)
        
        target_path = pathlib.Path(os.path.join(partition_dir, "master_instruments.parquet")).resolve()
        
        logger.info(f"Writing derivative master snapshot to: {target_path}...")
        
        # Offload blocking write to thread pool
        await loop.run_in_executor(
            None,
            lambda: filtered_df.to_parquet(str(target_path), engine='pyarrow', index=False)
        )
        
        logger.info("Derivative master instruments snapshot archived successfully.")
        return target_path