wglass/lighthouse

import logging
import os

from watchdog import events, observers

from .handler import ConfigFileChangeHandler


logger = logging.getLogger(__name__)


class ConfigFileMonitor(object):
    """
    Config file monitoring class.

    This class monitors the proper config directory of a target class and
    fires given callbacks whenever a file is added, updated or removed.
    """

    def __init__(self, target_class, base_path):
        self.target_class = target_class

        path = [base_path]
        if target_class.config_subdirectory:
            path.append(target_class.config_subdirectory)

        self.file_path = os.path.join(*path)

    def start(self, on_add, on_update, on_delete):
        """
        Starts monitoring the file path, passing along on_(add|update|delete)
        callbacks to a watchdog observer.

        Iterates over the files in the target path before starting the observer
        and calls the on_created callback before starting the observer, so
        that existing files aren't missed.
        """
        handler = ConfigFileChangeHandler(
            self.target_class, on_add, on_update, on_delete
        )

        for file_name in os.listdir(self.file_path):
            if os.path.isdir(os.path.join(self.file_path, file_name)):
                continue
            if (
                not self.target_class.config_subdirectory and
                not (
                    file_name.endswith(".yaml") or file_name.endswith(".yml")
                )
            ):
                continue

            handler.on_created(
                events.FileCreatedEvent(
                    os.path.join(self.file_path, file_name)
                )
            )

        observer = observers.Observer()
        observer.schedule(handler, self.file_path)
        observer.start()

        return observer