"""Runtime configuration loaded from environment variables / .env.

Portable across self-host setups: defaults to a local SQLite file so the app
runs with zero external services, and switches to PostgreSQL automatically
when DATABASE_URL points at postgres (e.g. inside docker-compose).
"""
from __future__ import annotations

import os
from functools import lru_cache
from pathlib import Path

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


def _load_dotenv(path: Path = ROOT / ".env") -> None:
    if not path.exists():
        return
    for raw in path.read_text(encoding="utf-8").splitlines():
        line = raw.strip()
        if not line or line.startswith("#") or "=" not in line:
            continue
        key, value = line.split("=", 1)
        key = key.strip()
        value = value.strip().strip('"').strip("'")
        if key and key not in os.environ:
            os.environ[key] = value


_load_dotenv()


class Settings:
    """Plain settings container (no extra dependency)."""

    def __init__(self) -> None:
        # Storage. Default = local SQLite (zero-config). Docker sets postgres URL.
        default_db = f"sqlite+aiosqlite:///{ROOT / 'data' / 'lograg.db'}"
        self.database_url: str = os.getenv("DATABASE_URL", default_db)

        # Optional LLM (RAG answer). System works fully offline without these.
        self.openrouter_api_key: str = os.getenv("OPENROUTER_API_KEY", "")
        self.openrouter_model: str = os.getenv("OPENROUTER_MODEL", "openrouter/free")
        self.openrouter_embed_model: str = os.getenv(
            "OPENROUTER_EMBED_MODEL", "nvidia/llama-nemotron-embed-vl-1b-v2:free"
        )

        # Server
        self.host: str = os.getenv("HOST", "0.0.0.0")
        self.port: int = int(os.getenv("PORT", "8000"))

        # Realtime mock stream guardrails
        self.max_mock_burst: int = int(os.getenv("MAX_MOCK_BURST", "500"))
        self.max_csv_rows: int = int(os.getenv("MAX_CSV_ROWS", "50000"))

    @property
    def llm_ready(self) -> bool:
        return bool(self.openrouter_api_key)

    @property
    def is_postgres(self) -> bool:
        return self.database_url.startswith("postgres")


@lru_cache(maxsize=1)
def get_settings() -> Settings:
    settings = Settings()
    # Ensure local sqlite directory exists.
    if settings.database_url.startswith("sqlite"):
        (ROOT / "data").mkdir(parents=True, exist_ok=True)
    return settings