from __future__ import annotations

import os
from pathlib import Path
from typing import Dict

from openai import OpenAI

ENV_FILE_NAME = ".env"
_ENV_KEY_CANDIDATES = (
    "OPENAI_API_KEY",
    "OpenAI_API_KEY",
    "OpenAI-API",
    "OpenAI_API",
    "OPENAIKEY",
)

_OPENAI_CLIENT: OpenAI | None = None


def _read_env_file(path: Path) -> Dict[str, str]:
    entries: Dict[str, str] = {}
    if not path.exists():
        return entries
    for raw_line in path.read_text().splitlines():
        line = raw_line.strip()
        if not line or line.startswith("#"):
            continue
        if "=" in line:
            key, value = line.split("=", 1)
        elif ":" in line:
            key, value = line.split(":", 1)
        else:
            continue
        entries[key.strip()] = value.strip().strip('"').strip("'")
    return entries


def ensure_openai_api_key() -> str:
    key = os.getenv("OPENAI_API_KEY")
    if key:
        return key

    env_path = Path(__file__).resolve().parent.parent / ENV_FILE_NAME
    env_entries = _read_env_file(env_path)
    for candidate in _ENV_KEY_CANDIDATES:
        if env_entries.get(candidate):
            key = env_entries[candidate]
            break
    else:
        key = None

    if not key:
        raise RuntimeError(
            "OpenAI API key is not configured. Set OPENAI_API_KEY or add it to .env (e.g., 'OpenAI-API: sk-...')."
        )

    os.environ["OPENAI_API_KEY"] = key
    return key


def get_openai_client() -> OpenAI:
    global _OPENAI_CLIENT
    if _OPENAI_CLIENT is None:
        api_key = ensure_openai_api_key()
        _OPENAI_CLIENT = OpenAI(api_key=api_key)
    return _OPENAI_CLIENT