"""Application settings.

Configuration is read from the environment. For the MVP the two knobs are the
database URL and the ``USE_FAKE_DATA`` flag.
"""

from __future__ import annotations

from functools import lru_cache

from pydantic_settings import BaseSettings, SettingsConfigDict


class Settings(BaseSettings):
    """Runtime settings, populated from environment variables.

    ``DATABASE_URL`` and ``USE_FAKE_DATA`` (case-insensitive) override defaults.
    """

    model_config = SettingsConfigDict(env_file=".env", extra="ignore")

    # Async SQLAlchemy URL. asyncpg driver is required for the async engine.
    database_url: str = "postgresql+asyncpg://hsdata:hsdata@localhost:5432/hsdata"

    # PostgreSQL schema holding the拼团 funnel tables. Real source is `ads`
    # (tables ads.ads_trd_group_funnel_*); set via connection search_path so the
    # schema-less ORM table names resolve there. Empty = leave default (public).
    db_schema: str = "ads"

    # When true, the funnel API serves a realistic in-memory snapshot instead of
    # querying Postgres. Default ON so `uvicorn app.main:app` works with zero
    # infrastructure. Set USE_FAKE_DATA=false to read the real wide table.
    use_fake_data: bool = True


@lru_cache
def get_settings() -> Settings:
    """Return a cached Settings instance."""
    return Settings()