from collections.abc import Generator

from sqlalchemy import create_engine, inspect, text
from sqlalchemy.orm import DeclarativeBase, Session, sessionmaker

from app.config import get_settings


class Base(DeclarativeBase):
    pass


def _connect_args(database_url: str) -> dict[str, object]:
    if database_url.startswith("sqlite"):
        return {"check_same_thread": False}
    return {}


settings = get_settings()
engine = create_engine(settings.database_url, connect_args=_connect_args(settings.database_url))
SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False)


def init_db() -> None:
    import app.models  # noqa: F401

    Base.metadata.create_all(bind=engine)
    _ensure_runtime_schema()


def _ensure_runtime_schema() -> None:
    import app.models as models

    inspector = inspect(engine)
    table_names = set(inspector.get_table_names())
    if "employees" in table_names and "employee_publications" not in table_names:
        models.EmployeePublication.__table__.create(bind=engine, checkfirst=True)
        inspector = inspect(engine)
        table_names = set(inspector.get_table_names())
    if "employees" in table_names and "employee_news_links" not in table_names:
        models.EmployeeNewsLink.__table__.create(bind=engine, checkfirst=True)
        inspector = inspect(engine)
        table_names = set(inspector.get_table_names())
    if "crawl_runs" not in table_names:
        return
    crawl_run_columns = {column["name"] for column in inspector.get_columns("crawl_runs")}
    if "skipped_count" not in crawl_run_columns:
        with engine.begin() as connection:
            connection.execute(text("ALTER TABLE crawl_runs ADD COLUMN skipped_count INTEGER NOT NULL DEFAULT 0"))


def get_db() -> Generator[Session, None, None]:
    db = SessionLocal()
    try:
        yield db
    finally:
        db.close()