"""MySQL Connector.

Manages interactions with MySQL.
"""

from collections.abc import Generator
from contextlib import contextmanager

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

from video import config


def _create_engine(db_url: str) -> Engine:
    """Create engine based on config settings."""
    db_engine = create_engine(
        db_url,
        pool_size=config.SQLALCHEMY_POOL_SIZE,
        max_overflow=config.SQLALCHEMY_POOL_MAX_OVERFLOW,
        pool_recycle=config.SQLALCHEMY_POOL_RECYCLE_MS,
        pool_pre_ping=config.SQLALCHEMY_POOL_PRE_PING,
        pool_timeout=config.SQLALCHEMY_POOL_TIMEOUT,
    )

    return db_engine


_db_engine = _create_engine(config.VIDEO_DB_URL)
_db_session = sessionmaker(bind=_db_engine)

ar_db_engine = _create_engine(config.AR_DB_URL)
ar_database_session = sessionmaker(bind=ar_db_engine)


class BaseModel(DeclarativeBase):
    pass


class ArModel(DeclarativeBase):
    pass


@contextmanager
def db_session(
    turn_off_foreign_key_constraint: bool = False,
) -> Generator[Session, None, None]:
    """Provide a transactional scope around a series of operations.

    Taken from http://docs.sqlalchemy.org/en/latest/orm/session_basics.html.
    This handles rollback and closing of session, so there is no need
    to do that throughout the code.
    Usage:
        with db_session() as session:
            session.execute(query)
    """
    session = _db_session()
    try:
        if turn_off_foreign_key_constraint:
            session.execute(text("SET FOREIGN_KEY_CHECKS = 0;"))
        yield session
        session.commit()
    except Exception:
        session.rollback()
        raise
    finally:
        if turn_off_foreign_key_constraint:
            session.execute(text("SET FOREIGN_KEY_CHECKS = 1;"))
        session.close()


@contextmanager
def ar_db_session(
    turn_off_foreign_key_constraint: bool = False,
) -> Generator[Session, None, None]:
    """Provide transactional scope around series of operations for art_relations.

    Taken from http://docs.sqlalchemy.org/en/latest/orm/session_basics.html.
    This handles rollback and closing of session, so there is no need
    to do that throughout the code.
    Usage:
        with ar_database_session() as session:
            session.execute(query)
    """
    session = ar_database_session()
    try:
        if turn_off_foreign_key_constraint:
            session.execute(text("SET FOREIGN_KEY_CHECKS = 0;"))
        yield session
        session.commit()
    except Exception:
        session.rollback()
        raise
    finally:
        if turn_off_foreign_key_constraint:
            session.execute(text("SET FOREIGN_KEY_CHECKS = 1;"))
        session.close()