"""Environment helpers for LLM provider configuration."""

from __future__ import annotations

import os
import shlex
from pathlib import Path


def load_project_dotenv(dotenv_path: str | Path = ".env", *, override: bool = False) -> Path | None:
    """Load simple shell-style KEY=value lines into ``os.environ``."""

    path = Path(dotenv_path).expanduser().resolve()
    if not path.exists():
        return None

    for raw_line in path.read_text(encoding="utf-8").splitlines():
        parsed = parse_dotenv_line(raw_line)
        if parsed is None:
            continue
        key, value = parsed
        if not override and key in os.environ:
            continue
        os.environ[key] = value
    return path


def parse_dotenv_line(raw_line: str) -> tuple[str, str] | None:
    line = raw_line.strip()
    if not line or line.startswith("#"):
        return None
    if line.startswith("export "):
        line = line[len("export ") :].strip()
    if "=" not in line:
        return None

    key, value = line.split("=", 1)
    key = key.strip()
    if not key:
        return None
    return key, _parse_env_value(value.strip())


def _parse_env_value(value: str) -> str:
    if not value:
        return ""
    try:
        parsed = shlex.split(value, posix=True)
    except ValueError:
        return value
    if len(parsed) == 1:
        return parsed[0]
    return value