from collections.abc import Iterator

from sqlalchemy import create_engine, event, inspect, text
from sqlalchemy.engine import Engine
from sqlalchemy.orm import Session, sessionmaker

from app.db.models import Base


def create_session_factory(database_url: str) -> tuple[Engine, sessionmaker[Session]]:
    engine = create_engine(database_url, connect_args={"check_same_thread": False})

    @event.listens_for(engine, "connect")
    def enable_sqlite_foreign_keys(dbapi_connection, _connection_record) -> None:
        cursor = dbapi_connection.cursor()
        cursor.execute("PRAGMA foreign_keys=ON")
        cursor.close()

    return engine, sessionmaker(bind=engine, autoflush=False, expire_on_commit=False)


def init_db(engine) -> None:
    Base.metadata.create_all(bind=engine)
    _add_missing_project_columns(engine)


def _add_missing_project_columns(engine: Engine) -> None:
    inspector = inspect(engine)
    if "projects" not in inspector.get_table_names():
        return
    columns = {column["name"] for column in inspector.get_columns("projects")}
    if "drug_name" in columns:
        return
    with engine.begin() as connection:
        connection.execute(text("ALTER TABLE projects ADD COLUMN drug_name TEXT"))


def get_session(session_factory) -> Iterator[Session]:
    with session_factory() as session:
        yield session