import logging
import time
import json
import pika
import subprocess
import sys
import threading
import os
from distutils.util import strtobool

class JixelBackgroundTaskHandler():

	def __init__(
		self, rabbitmq_username, rabbitmq_password, 
		rabbitmq_host, rabbitmq_port, rabbitmq_queue, 
		rabbitmq_heartbeat, execution_path, logger,
		discarding_mode=False
		):
		self.rabbitmq_username = rabbitmq_username
		self.rabbitmq_password = rabbitmq_password
		self.rabbitmq_host = rabbitmq_host
		self.rabbitmq_port = rabbitmq_port
		self.rabbitmq_queue = rabbitmq_queue
		self.rabbitmq_heartbeat = int(rabbitmq_heartbeat)
		self.execution_path = execution_path
		self.logger = logger
		self.discarding_mode = strtobool(discarding_mode)
		self.logger.info("JixelBackgroundTaskHandler - Initialization...")
		self.credentials = pika.PlainCredentials(
			self.rabbitmq_username , 
			self.rabbitmq_password
		)
		self.connection = pika.BlockingConnection(
			pika.ConnectionParameters(
				host=self.rabbitmq_host, 
				port=int(self.rabbitmq_port),
				credentials=self.credentials,heartbeat=self.rabbitmq_heartbeat
			)
		)
		self.channel = self.connection.channel()
		self.logger.info("JixelBackgroundTaskHandler - Initialization completed successfully")
		self.channel.queue_declare(queue=self.rabbitmq_queue, durable=True)
		self.logger.info("JixelBackgroundTaskHandler - " + self.rabbitmq_queue + " queue declared")
		self.channel.queue_declare(queue=self.rabbitmq_queue+'_errors', durable=True)
		self.logger.info("JixelBackgroundTaskHandler - " + self.rabbitmq_queue + "_errors queue declared")
		self.channel.basic_qos(prefetch_count=1)
		self.logger.info("JixelBackgroundTaskHandler - Queue handler declared")
		self.channel.basic_consume(
			on_message_callback=self.__data_handler, 
			queue=self.rabbitmq_queue
		)
		
	def consume(self):

		try:
			self.channel.start_consuming()
		except KeyboardInterrupt:
			self.channel.stop_consuming()
		
		self.channel.close()

	def __execute_command(self, mr):
		self.logger.info('JixelBackgroundTaskHandler - Processing thread is running:')
		command = [self.execution_path + 'cake']
		command +=  mr['command'].split(' ')
		command += [mr['data']]
		self.logger.info('JixelBackgroundTaskHandler - Executing shell command:')
		self.logger.info(command)

		try:
			subprocess.check_call(command)
			self.result = True
		except subprocess.CalledProcessError as error:
			self.logger.error('JixelBackgroundTaskHandler - An error as occured during processing:')
			self.logger.error(error)
			self.result = False
		
	def __data_processing(self, channel, mr):
		self.logger.info(mr)
		self.logger.info('JixelBackgroundTaskHandler - Starting processing thread:')
		self.result = None
		thread = threading.Thread(target=self.__execute_command, args=(mr,))
		thread.start()

		while thread.is_alive():
			self.connection.process_data_events()

		self.logger.info("JixelBackgroundTaskHandler - Result received:")
		self.logger.info(self.result)
		if (self.result is not True):
			self.__send_error(json.dumps(mr))
		return self.result

	def __send_ack_nack(self, ack, channel, method):
		if ack is True:
			self.logger.info("JixelBackgroundTaskHandler - Ack performed")
			channel.basic_ack(delivery_tag=method.delivery_tag)
		else:
			self.logger.info("JixelBackgroundTaskHandler - Nack performed BECAUSE ERRORS OCCURRED!")
			channel.basic_reject(delivery_tag=method.delivery_tag)

	def __data_handler(self, channel, method, properties, body):
		self.logger.info('JixelBackgroundTaskHandler - New message received:')
		error = False

		try:
			mr = json.loads(body.decode())
			error = not self.__data_processing(channel, mr)
		except json.JSONDecodeError as error:
			self.logger.error("JixelBackgroundTaskHandler - Malformed message")
			self.logger.error(error)
			self.logger.error("JixelBackgroundTaskHandler - This message will be removed from the queue")
			self.__send_ack_nack(False, channel, method)
			time.sleep(60)
			return

		if self.result is True and error is False:
			self.__send_ack_nack(True, channel, method)
		else:
			self.logger.error("JixelBackgroundTaskHandler - An error has occured during processing")
			if self.discarding_mode is True:
				self.logger.error("JixelBackgroundTaskHandler - Discarding mode enabled.")
				self.__send_ack_nack(True, channel, method)
			else:
				self.__send_ack_nack(False, channel, method)

			time.sleep(5)
		
		self.logger.info("JixelBackgroundTaskHandler - Data handling complete. Waiting for new messages")

	def __send_error(self, message):
		self.channel.basic_publish(exchange='', routing_key=self.rabbitmq_queue+'_errors', body=message)

if __name__ == '__main__':
	logger = logging.getLogger("JixelBackgroundTaskHandler")
	logger.setLevel(logging.INFO)
	formatter = logging.Formatter("%(asctime)s - %(name)s - %(levelname)s - %(message)s")
	terminal_log = logging.StreamHandler(sys.stdout)
	terminal_log.setFormatter(formatter)
	logger.addHandler(terminal_log)
	app = JixelBackgroundTaskHandler(
		os.environ['RABBITMQ_USERNAME'],
		os.environ['RABBITMQ_PASSWORD'],
		os.environ['rabbitmq_host'],
		os.environ['rabbitmq_port'],
		os.environ['rabbitmq_queue'],
		os.environ['rabbitmq_heartbeat'],
		os.environ['execution_path'],
		logger,
		os.environ['discarding_mode']
	)
	app.consume()