"""
    Module to manage all the workflow of the service. From http request to http response
"""

from django.conf import settings

from tools import const
from tools.exceptions import SystemException
from monitorT.task import Task
from monitorT.task import KillingThread
from .http_loaders import json_in, json_out


class Service:
    """
        Main class to service management

    Attributes
    ----------
    conf: dict
        Service configuration,
            {'task': ..,
            'function': ...,
            'http_rm': ...,
            'http_p': ...,
            'parser': ...}
    """
    __slots__ = ['conf']
    required_fields = ['function']
    optional_fields = {'task': Task,
                       'http_p': json_in,
                       'http_rm': json_out,
                       'parser': const.PARSER_DEFAULT}

    SERVICE_EXCEPTION = type('ServiceException', (SystemException, ), {})

    def __init__(self, conf):
        """
        Parameters
        ----------
        conf: dict
        Service configuration,
            {'task': ..,
            'function': ...,
            'http_rm': ...,
            'http_p': ...,
            'parser': ...}
        """
        self.conf = conf

    def check(self):
        """
            Check required values and fill with the defaults values the optional fields
        Returns
        -------
        success: True
        fails: SystemException
        """
        not_in = [item for item in self.required_fields if item not in self.conf.keys()]
        if not_in:
            return self.SERVICE_EXCEPTION('{} field not in conf'
                                          .format(','.join(not_in)))
        for optional in self.optional_fields:
            if optional not in self.conf.keys() or not self.conf[optional]:
                settings.LOG('Optional field ({}) not found, setting default'.format(optional),
                             settings.LOG.WARNING_KEY)
                self.conf[optional] = self.optional_fields[optional]
        return True

    def run(self, request, **kwargs):
        """
            Run workflow of service
        Parameters
        ----------
        request: HttpRequest

        Returns
        -------
        success: HttpResponse
        """
        data = self.conf['http_p'](request)
        kwargs.update(data)
        data = kwargs
        if 'user' not in data.keys():
            data['user'] = None
        task_obj = settings.MASTER_TASK_LIST.add_task(data['user'],
                                                      self.conf['function'],
                                                      data,
                                                      self.conf['task'],
                                                      self.conf['parser'])
        thread = KillingThread(target=task_obj.run, name=task_obj.task_id)
        thread.start()

        if task_obj.CONTROL:
            result = {'task_id': task_obj.task_id}
            return json_out(result)
        thread.join()
        result = task_obj.result
        settings.MASTER_TASK_LIST.remove_task(task_obj.task_id)
        return self.conf['http_rm'](result)