"""Download XAUUSD M5 history to Parquet (doc 02 §3, doc 07 §6).

Pulls the full M5 window from the running MT5 terminal and saves it as a
Parquet file in ``data/``. Re-runs of the engine then load from Parquet (fast,
compact, no MT5 connection needed). M5 is the EA's signal timeframe — higher
timeframes are resampled in Python from this M1/M5 base.

Connects to the already-running, manually-logged-in terminal (initialize()
with no path → reuse). Keep the terminal UI open while this runs.
"""
from __future__ import annotations

import sys
import time
from datetime import datetime, timedelta
from pathlib import Path

PROJECT = Path(__file__).resolve().parent.parent
sys.path.insert(0, str(PROJECT))

from shared.config import get_secret, load_env

load_env(PROJECT)

import MetaTrader5 as mt5  # type: ignore
import pandas as pd

SYMBOL = "XAUUSD"
TIMEFRAME = "M5"
# Full window: 2 years back to today (matches the history depth probe).
START = (datetime.now() - timedelta(days=730)).strftime("%Y-%m-%d")
END = datetime.now().strftime("%Y-%m-%d")
OUT = PROJECT / "data" / f"{SYMBOL}_{TIMEFRAME}_{START}_{END}.parquet"


def connect(retries: int = 5, sleep_s: float = 5.0) -> bool:
    """Connect to the running terminal (initialize() with no path → reuse)."""
    for attempt in range(1, retries + 1):
        if not mt5.initialize():
            print(f"  initialize() attempt {attempt}/{retries} failed: {mt5.last_error()}")
            time.sleep(sleep_s)
            continue
        login = int(get_secret("MT5_DEMO_LOGIN") or 0)
        password = get_secret("MT5_DEMO_PASSWORD")
        server = get_secret("MT5_DEMO_SERVER")
        if not mt5.login(login, password=password, server=server):
            print(f"  login() attempt {attempt}/{retries} failed: {mt5.last_error()}")
            mt5.shutdown()
            time.sleep(sleep_s)
            continue
        print(f"  connected: login={login} server={server}")
        return True
    return False


def main() -> int:
    if not connect():
        print("could not connect — is the terminal running and logged in?")
        return 1
    try:
        tf = getattr(mt5, f"TIMEFRAME_{TIMEFRAME}")
        print(f"downloading {SYMBOL} {TIMEFRAME} {START} → {END} ...")
        rates = mt5.copy_rates_range(
            SYMBOL, tf, pd.Timestamp(START), pd.Timestamp(END)
        )
        if rates is None or len(rates) == 0:
            print(f"  no bars returned: {mt5.last_error()}")
            return 2
        df = pd.DataFrame(rates)
        df["timestamp"] = pd.to_datetime(df["time"], unit="s", utc=False)
        df = df[["timestamp", "open", "high", "low", "close", "spread"]]
        df = df.sort_values("timestamp").reset_index(drop=True)
        # Deduplicate (MT5 occasionally returns overlapping bars near boundaries).
        df = df.drop_duplicates(subset=["timestamp"]).reset_index(drop=True)
        OUT.parent.mkdir(parents=True, exist_ok=True)
        df.to_parquet(OUT, index=False)
        print(f"saved {len(df):,} bars → {OUT.relative_to(PROJECT)}")
        print(f"range: {df['timestamp'].iloc[0]} → {df['timestamp'].iloc[-1]}")
        print(f"spread stats: min={df['spread'].min()} max={df['spread'].max()} "
              f"median={df['spread'].median():.1f}")
        return 0
    finally:
        mt5.shutdown()


if __name__ == "__main__":
    raise SystemExit(main())