from time import sleep
from logging import Logger
from threading import Event, Thread
from collections import deque

from cloudsync.handlers.error import Error
from cloudsync.common.enums import *
from cloudsync.utils.globals import *
from cloudsync.utils.helpers import *


class ErrorHandler:
    def __init__(self, logger: Logger, max_size, output_channel):
        self.logger = logger
        self.output_channel = output_channel
        self.queue = deque(maxlen=max_size)  # Thread safe
        self.thread = Thread(target=self.scheduler, daemon=True)
        self.event = Event()
        self.thread.start()

        self.logger.info('Created Error Handler')

    def scheduler(self) -> None:
        """
        Continuously monitors the event flag to check for new errors
        :return: None
        """
        while True:
            flag = self.event.wait()
            if flag:
                while len(self.queue) > 0:
                    error = self.queue.popleft()
                    self.handle_error(error)
                self.event.clear()

    def enqueue_error(self, error: Error) -> bool:
        """
        :param error: the error to add to the queue
        :return: True upon success, False otherwise
        """
        if len(self.queue) < self.queue.maxlen:
            self.queue.append(error)
            self.event.set()
            return True
        else:
            return False

    def handle_error(self, error: Error):
        if InboundMessageIDs.mapped_str_value(error.ID) == InboundMessageIDs.UI2CS_ERROR:
            self.logger.error('UI App Error {0}: {1}'.format(error.code, error.parameters))
            return  # TODO Add specific UI error message handling when necessary

        if OutboundMessageIDs.mapped_str_value(error.ID) == OutboundMessageIDs.CS2UI_ERROR:
            self.logger.error('CS App Error {0} - {1}: {2}'.format(error.code, 
                                                                   ErrorIDs.mapped_str_value(error.code),
                                                                   error.parameters))
            parameter_string = ""
            for parameter in error.parameters:
                parameter_string += ","
                parameter_string += parameter

            message_body = str(OutboundMessageIDs.CS2UI_ERROR.value) + ',' + error.size + ',' + error.code + parameter_string
            self.output_channel.enqueue_message(message_body)