from collections.abc import Generator
from pathlib import Path

from alembic import command
from alembic.config import Config
from sqlalchemy import create_engine, event, inspect
from sqlalchemy.orm import DeclarativeBase, Session, sessionmaker

DATABASE_URL = "sqlite:////data/app.db"
LOCAL_DATABASE_URL = "sqlite:///./app.db"


class Base(DeclarativeBase):
    pass


def _database_url() -> str:
    return DATABASE_URL if Path("/data").exists() else LOCAL_DATABASE_URL


engine = create_engine(
    _database_url(),
    connect_args={"check_same_thread": False},
)


@event.listens_for(engine, "connect")
def set_sqlite_pragma(dbapi_conn, _connection_record) -> None:
    cursor = dbapi_conn.cursor()
    cursor.execute("PRAGMA journal_mode=WAL")
    cursor.execute("PRAGMA foreign_keys=ON")
    cursor.close()


SessionLocal = sessionmaker(bind=engine, autocommit=False, autoflush=False)


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


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

    Base.metadata.create_all(bind=engine)


def run_migrations() -> None:
    config = Config(str(Path(__file__).parent / "alembic.ini"))
    config.set_main_option("sqlalchemy.url", _database_url())
    inspector = inspect(engine)
    table_names = set(inspector.get_table_names())
    if "users" in table_names and "alembic_version" not in table_names:
        command.stamp(config, "head")
        return
    command.upgrade(config, "head")