"""
Index Constituents Service
S&P 500 / Nasdaq 100 구성 종목을 Wikipedia에서 조회
"""

import asyncio
import logging
from io import StringIO
from typing import Optional
from urllib.request import Request, urlopen

import pandas as pd

logger = logging.getLogger("app.services.index_constituents")


class IndexConstituentsService:
    INDEXES = {
        "sp500": {
            "url": "https://en.wikipedia.org/wiki/List_of_S%26P_500_companies",
            "table_index": 0,
            "ticker_col": "Symbol",
            "name_col": "Security",
            "sector_col": "GICS Sector",
            "industry_col": "GICS Sub-Industry",
        },
        "nasdaq100": {
            "url": "https://en.wikipedia.org/wiki/Nasdaq-100",
            "table_index": 4,
            "ticker_col": "Ticker",
            "name_col": "Company",
            "sector_col": "GICS Sector",
            "industry_col": "GICS Sub-Industry",
        },
    }

    def _fetch_constituents_sync(self, index_name: str) -> dict:
        config = self.INDEXES[index_name]
        url = config["url"]
        ticker_col = config["ticker_col"]
        name_col = config["name_col"]
        sector_col = config["sector_col"]
        industry_col = config["industry_col"]

        logger.info(f"Fetching Wikipedia tables from {url}")
        req = Request(url, headers={"User-Agent": "Mozilla/5.0 (compatible; StockOracle/1.0)"})
        with urlopen(req, timeout=25) as resp:
            html = resp.read().decode("utf-8")
        tables = pd.read_html(StringIO(html), flavor="lxml")

        # Try configured table index first
        df = None
        table_index = config["table_index"]
        if table_index < len(tables) and ticker_col in tables[table_index].columns:
            df = tables[table_index]
            logger.info(f"Using configured table index {table_index}")
        else:
            # Fallback: scan all tables for ticker column
            for i, tbl in enumerate(tables):
                if ticker_col in tbl.columns:
                    df = tbl
                    logger.info(f"Fallback: found ticker column '{ticker_col}' in table {i}")
                    break

        if df is None:
            raise ValueError(
                f"Could not find table with column '{ticker_col}' in any of the {len(tables)} tables"
            )

        constituents = []
        for _, row in df.iterrows():
            symbol = str(row.get(ticker_col, "")).strip()
            if not symbol or symbol == "nan":
                continue
            constituents.append({
                "symbol": symbol,
                "name": str(row.get(name_col, "")).strip(),
                "sector": str(row.get(sector_col, "")).strip() if sector_col in df.columns else None,
                "industry": str(row.get(industry_col, "")).strip() if industry_col in df.columns else None,
            })

        return {
            "success": True,
            "index": index_name,
            "count": len(constituents),
            "constituents": constituents,
        }

    async def get_constituents(self, index_name: str) -> dict:
        if index_name not in self.INDEXES:
            raise ValueError(f"Unknown index '{index_name}'. Supported: {list(self.INDEXES.keys())}")

        loop = asyncio.get_event_loop()
        result = await loop.run_in_executor(None, self._fetch_constituents_sync, index_name)
        logger.info(f"Retrieved {result['count']} constituents for {index_name}")
        return result


index_constituents_service = IndexConstituentsService()