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# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
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# specific language governing permissions and limitations
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import logging
from datetime import timedelta

from flask import Flask

from superset.engines.manager import EngineManager, EngineModes

logger = logging.getLogger(__name__)


class EngineManagerExtension:
    """
    Flask extension for managing SQLAlchemy engines in Superset.

    This extension creates and configures an EngineManager instance based on
    Flask configuration, handling startup and shutdown of background cleanup
    threads as needed.
    """

    def __init__(self) -> None:
        self.engine_manager: EngineManager | None = None

    def init_app(self, app: Flask) -> None:
        """
        Initialize the EngineManager with Flask app configuration.
        """
        engine_context_manager = app.config["ENGINE_CONTEXT_MANAGER"]
        db_connection_mutator = app.config["DB_CONNECTION_MUTATOR"]
        mode = app.config["ENGINE_MANAGER_MODE"]
        cleanup_interval = app.config["ENGINE_MANAGER_CLEANUP_INTERVAL"]
        local_bind_address = app.config["SSH_TUNNEL_LOCAL_BIND_ADDRESS"]
        tunnel_timeout = timedelta(seconds=app.config["SSH_TUNNEL_TIMEOUT_SEC"])
        ssh_timeout = timedelta(seconds=app.config["SSH_TUNNEL_PACKET_TIMEOUT_SEC"])
        auto_start_cleanup = app.config["ENGINE_MANAGER_AUTO_START_CLEANUP"]

        # Create the engine manager
        self.engine_manager = EngineManager(
            engine_context_manager,
            db_connection_mutator,
            mode,
            cleanup_interval,
            local_bind_address,
            tunnel_timeout,
            ssh_timeout,
        )

        # Start cleanup thread if requested and in SINGLETON mode
        if auto_start_cleanup and mode == EngineModes.SINGLETON:
            self.engine_manager.start_cleanup_thread()
            logger.info("Started EngineManager cleanup thread")

        # Register shutdown handler
        def shutdown_engine_manager() -> None:
            if self.engine_manager:
                self.engine_manager.stop_cleanup_thread()
                # Use a try-except to handle closed log file handlers during tests
                try:
                    logger.info("Stopped EngineManager cleanup thread")
                except ValueError:
                    # Ignore logging errors during test shutdown when file handles are closed
                    pass

        app.teardown_appcontext_funcs.append(lambda exc: None)

        # Register with atexit for clean shutdown
        import atexit

        atexit.register(shutdown_engine_manager)

        logger.info(
            "Initialized EngineManager with mode=%s, cleanup_interval=%ds",
            mode,
            cleanup_interval.total_seconds(),
        )

    @property
    def manager(self) -> EngineManager:
        """
        Get the EngineManager instance.

        Raises:
            RuntimeError: If the extension hasn't been initialized with an app.
        """
        if self.engine_manager is None:
            raise RuntimeError(
                "EngineManager extension not initialized. "
                "Call init_app() with a Flask app first."
            )
        return self.engine_manager