from __future__ import annotations

import os
from pathlib import Path
from typing import Optional
from dotenv import load_dotenv

load_dotenv()

ROOT_DIR = Path(__file__).resolve().parents[1]


def _resolve_path(value: Optional[str], default: Path) -> Path:
    if value:
        return Path(value).expanduser().resolve()
    return default.resolve()


def _get_int(name: str, default: int) -> int:
    value = os.getenv(name)
    if value is None:
        return default
    try:
        return int(value)
    except ValueError:
        return default


def _get_float(name: str, default: float) -> float:
    value = os.getenv(name)
    if value is None:
        return default
    try:
        return float(value)
    except ValueError:
        return default


class Settings:
    def __init__(self) -> None:
        self.faq_data_path: Path = _resolve_path(
            os.getenv("FAQ_DATA_PATH"), ROOT_DIR / "faq_kb.json"
        )
        self.vectorstore_dir: Path = _resolve_path(
            os.getenv("VECTORSTORE_DIR"), ROOT_DIR / "vectorstore"
        )
        self.vectorstore_index_name: str = os.getenv("VECTORSTORE_INDEX_NAME", "index")
        self.top_k: int = _get_int("TOP_K", 5)
        self.google_genai_model: str = os.getenv(
            "GOOGLE_GENAI_MODEL", "gemini-2.5-flash"
        )
        self.google_genai_temperature: float = _get_float(
            "GOOGLE_GENAI_TEMPERATURE", 0.0
        )
        self.google_genai_api_key: Optional[str] = os.getenv("GOOGLE_GENAI_API_KEY")
        self.hf_token: Optional[str] = os.getenv("HF_TOKEN")

        self._validate()
        self.vectorstore_dir.mkdir(parents=True, exist_ok=True)
        if self.hf_token:
            os.environ.setdefault("HUGGINGFACEHUB_API_TOKEN", self.hf_token)

    def _validate(self) -> None:
        if not self.faq_data_path.exists():
            raise FileNotFoundError(
                f"FAQ file not found: {self.faq_data_path}. "
                "Please put faq_kb.json in the repo root or set FAQ_DATA_PATH in .env."
            )

settings = Settings()