"""Application Logger.

======================

Creates application logger instance, that will send the logs to Loggly.
If config.LOGGER_DSN value is not set, the logs will be sent to stdout.

"""
import threading
import uuid
from contextlib import contextmanager

from owslogger import logger as ows_logger

from notifications_delivery import config

app_logger = ows_logger.setup(
    config.ENVIRONMENT, config.APP_NAME, config.LOGGER_LEVEL,
    config.APP_NAME, config.APP_VERSION
)


# Create a thread-local data space
_thread_local = threading.local()


def _init_logger(correlation_id=None):
    """Initialize logger with correlation_id.

    Args:
        correlation_id: correlation_id that will be sent along with log record.
    Returns:
        logger.OwsLoggingAdapter: instance of OwsLoggingAdapter with
        correlation_id attached.
    """
    if not correlation_id:
        correlation_id = str(uuid.uuid1())
        message = f'correlation_id ({correlation_id}) created.'
    else:
        message = f'correlation_id ({correlation_id}) received.'

    logger_ = ows_logger.OwsLoggingAdapter(app_logger, {
        'correlation_id': correlation_id
    })

    logger_.debug(message)
    return logger_


class _ProxyLogger:
    """Proxy class that provide logger with proper correlation id."""

    @staticmethod
    def __get_logger():
        if hasattr(_thread_local, 'logger'):
            logger_ = _thread_local.logger
        else:
            logger_ = _init_logger()

        return logger_

    def __getattr__(self, item):
        return getattr(self.__get_logger(), item)

    def __dir__(self):
        return dir(self.__get_logger())


_proxy_logger = _ProxyLogger()


@contextmanager
def set_correlation_id(correlation_id):
    """Context manager to set and clear the correlation_id and logger in thread-local storage.

    Args:
        correlation_id: correlation_id that will be sent along with log record.
    """
    # Set the correlation_id and logger for the current thread
    _thread_local.correlation_id = correlation_id
    _thread_local.logger = _init_logger(correlation_id)
    try:
        yield
    finally:
        # Clear the correlation_id and logger from thread-local storage
        delattr(_thread_local, 'correlation_id')
        delattr(_thread_local, 'logger')


def get_current_logger():
    """Get logger with a correlation_id attached.

    Returns:
        logger.OwsLoggingAdapter: instance of OwsLoggingAdapter with
        correlation_id attached.
    """
    return _proxy_logger