"""Runtime configuration loader — reads secrets from a gitignored ``.env``.

Broker login lives in ``.env`` (gitignored). The bridge reads these at runtime
and injects them into ``tester.ini``'s ``[Common]`` section **without printing
them** (doc 07 §5). Never hard-code credentials and never print them.
"""
from __future__ import annotations

import os
from pathlib import Path
from typing import Optional

try:
    from dotenv import load_dotenv  # type: ignore
    _HAS_DOTENV = True
except ImportError:
    _HAS_DOTENV = False


def load_env(project_root: Optional[str | Path] = None) -> dict[str, str]:
    """Load ``.env`` from ``project_root`` (defaults to this file's parent).

    Returns the MT5 credential keys without their values exposed in logs.
    Falls back to plain line parsing if ``python-dotenv`` isn't installed.
    """
    root = Path(project_root) if project_root else Path(__file__).resolve().parent.parent
    env_path = root / ".env"
    if _HAS_DOTENV and env_path.exists():
        load_dotenv(env_path)
    elif env_path.exists():
        _parse_plain(env_path)
    return {
        "MT5_DEMO_LOGIN": os.environ.get("MT5_DEMO_LOGIN", ""),
        "MT5_DEMO_SERVER": os.environ.get("MT5_DEMO_SERVER", ""),
        # Password is intentionally not returned here; read via get_secret().
        "MT5_TERMINAL_PATH": os.environ.get(
            "MT5_TERMINAL_PATH",
            r"C:\Program Files\MetaTrader 5 IC Markets Global\terminal64.exe",
        ),
    }


def get_secret(name: str) -> str:
    """Read a secret from the environment (load_env must be called first)."""
    return os.environ.get(name, "")


def _parse_plain(env_path: Path) -> None:
    """Minimal ``.env`` parser (KEY=VALUE) without python-dotenv."""
    for line in env_path.read_text(encoding="utf-8").splitlines():
        line = line.strip()
        if not line or line.startswith("#") or "=" not in line:
            continue
        k, _, v = line.partition("=")
        k, v = k.strip(), v.strip()
        # Strip optional surrounding quotes.
        if len(v) >= 2 and v[0] == v[-1] and v[0] in ("'", '"'):
            v = v[1:-1]
        os.environ.setdefault(k, v)