#!/usr/bin/env python3
"""
market_series.py

Fetch historical series and print CSV to stdout.

Stocks/ETFs/indices: yfinance history (daily)
FX: derived from ExchangeRate-API open endpoint (daily snapshots not provided here),
    so we return a simple "latest only" line unless you add a historical FX provider.

Usage:
  python scripts/market_series.py AAPL --days 30
  python scripts/market_series.py ^GSPC --days 120
  python scripts/market_series.py USD/ZAR --days 30
"""

from __future__ import annotations

import argparse
import sys
import re
from datetime import datetime, timedelta
from typing import Optional, Tuple

import pandas as pd


def _parse_fx_pair(s: str) -> Optional[Tuple[str, str]]:
    s = s.strip().upper()
    s = s.replace(" ", "")
    s = s.replace("-", "/")
    if "/" in s:
        parts = s.split("/")
        if len(parts) == 2 and len(parts[0]) == 3 and len(parts[1]) == 3:
            return parts[0], parts[1]
        return None
    if len(s) == 6 and s.isalpha():
        return s[:3], s[3:]
    return None


def _stock_series(symbol: str, days: int) -> pd.DataFrame:
    import yfinance as yf

    end = datetime.utcnow()
    start = end - timedelta(days=days)

    df = yf.download(symbol, start=start.date().isoformat(), end=end.date().isoformat(), progress=False)
    if df is None or len(df) == 0:
        raise RuntimeError(f"No data returned for symbol: {symbol}")

    df = df.reset_index()
    # Normalize column names (handle MultiIndex tuples from yfinance)
    cols = {}
    for c in df.columns:
        if isinstance(c, tuple):
            # Flatten tuple to string (e.g., ('Close', 'AAPL') -> 'close')
            name = "_".join(str(x) for x in c if x).lower().replace(" ", "_")
        else:
            name = str(c).lower().replace(" ", "_")
        cols[c] = name
    df = df.rename(columns=cols)
    return df


def main() -> None:
    ap = argparse.ArgumentParser()
    ap.add_argument("symbol", help="Ticker or FX pair")
    ap.add_argument("--days", type=int, default=30)
    args = ap.parse_args()

    fx = _parse_fx_pair(args.symbol)
    if fx:
        # Open access endpoint does not provide true historical in this mode.
        # We intentionally fail loudly so the agent explains the limitation.
        raise SystemExit(
            "FX historical series is not supported with the no-key open endpoint. "
            "Use latest quotes, or add a historical FX provider (paid or other source)."
        )

    df = _stock_series(args.symbol, args.days)
    df.to_csv(sys.stdout, index=False)


if __name__ == "__main__":
    main()