"""Load simple project-local environment files without overriding the process environment."""

from __future__ import annotations

import os
import re
from pathlib import Path


_ENV_KEY_RE = re.compile(r"^[A-Za-z_][A-Za-z0-9_]*$")


def load_project_env(path: Path) -> None:
    """Load KEY=VALUE entries from a project-local env file if it exists."""
    if not path.is_file():
        return
    try:
        lines = path.read_text(encoding="utf-8-sig").splitlines()
    except OSError:
        return
    for raw_line in lines:
        line = raw_line.strip()
        if not line or line.startswith("#"):
            continue
        if line.startswith("export "):
            line = line[7:].lstrip()
        key, separator, value = line.partition("=")
        key = key.strip()
        if not separator or not _ENV_KEY_RE.fullmatch(key):
            continue
        value = value.strip()
        if len(value) >= 2 and value[0] == value[-1] and value[0] in {"'", '"'}:
            value = value[1:-1]
        os.environ.setdefault(key, value)