from __future__ import annotations

import os
from pathlib import Path
from typing import Optional


def load_dotenv_into_environ(dotenv_path: os.PathLike[str] | str, *, override: bool = False) -> bool:
    """
    Load KEY=VALUE lines from a .env file into os.environ.

    - Supports lines like: KEY=VALUE, export KEY=VALUE
    - Ignores blank lines and # comments
    - Handles single/double-quoted values
    - Does not expand ${VARS} or handle multiline values

    Returns True if the file existed and was read.
    """
    path = Path(dotenv_path)
    if not path.is_file():
        return False

    content = path.read_text(encoding="utf-8")
    # Remove UTF-8 BOM if present
    if content.startswith("\ufeff"):
        content = content.lstrip("\ufeff")

    for raw_line in content.splitlines():
        line = raw_line.strip()
        if not line or line.startswith("#"):
            continue
        if line.startswith("export "):
            line = line[len("export ") :].lstrip()

        if "=" not in line:
            continue

        key, value = line.split("=", 1)
        key = key.strip()
        value = value.strip()

        if not key:
            continue

        if len(value) >= 2 and value[0] == value[-1] and value[0] in ("'", '"'):
            value = value[1:-1]

        if not override and key in os.environ:
            continue

        os.environ[key] = value

    return True


def load_llm_fsm_dotenv(*, override: bool = False, filename: str = ".env") -> bool:
    """
    Convenience loader for `.env` next to `scripts/llm_fsm` runner scripts.
    """
    dotenv_path = Path(__file__).resolve().parent / filename
    return load_dotenv_into_environ(dotenv_path, override=override)