from collections.abc import Generator
from pathlib import Path

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

from app.config import get_settings


class Base(DeclarativeBase):
    pass


def create_sqlite_engine(database_url: str):
    if database_url.startswith("sqlite:///") and database_url != "sqlite:///:memory:":
        db_path = Path(database_url.removeprefix("sqlite:///"))
        if db_path.parent != Path("."):
            db_path.parent.mkdir(parents=True, exist_ok=True)

    connect_args = {"check_same_thread": False, "timeout": 10}
    engine = create_engine(database_url, connect_args=connect_args)
    engine.dialect.connect_args = connect_args

    @event.listens_for(engine, "connect")
    def set_sqlite_pragma(dbapi_connection, _connection_record):
        cursor = dbapi_connection.cursor()
        cursor.execute("PRAGMA journal_mode=WAL")
        cursor.close()

    return engine


engine = create_sqlite_engine(get_settings().database_url)
SessionLocal = sessionmaker(bind=engine, autoflush=False, autocommit=False)


def check_database_integrity(target_engine: Engine = engine) -> str:
    raw_connection = target_engine.raw_connection()
    try:
        cursor = raw_connection.driver_connection.cursor()
        try:
            cursor.execute("PRAGMA integrity_check")
            result = cursor.fetchone()
        finally:
            cursor.close()
    finally:
        raw_connection.close()

    status = result[0] if result else "missing_result"
    if status != "ok":
        raise RuntimeError(f"SQLite integrity check failed: {status}")
    return status


def checkpoint_sqlite_wal(target_engine: Engine = engine) -> bool:
    if str(target_engine.url) == "sqlite:///:memory:":
        return False
    if target_engine.url.get_backend_name() != "sqlite":
        return False

    with target_engine.begin() as connection:
        connection.exec_driver_sql("PRAGMA wal_checkpoint(TRUNCATE)")
    return True


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

    Base.metadata.create_all(engine)
    check_database_integrity(engine)
    checkpoint_sqlite_wal(engine)


def get_db_session() -> Generator[Session]:
    with SessionLocal() as session:
        yield session