"""Monitored tasks"""
from dataclasses import dataclass, field
from datetime import datetime
from enum import Enum
from typing import Any, Dict, List, Optional

from celery import Task
from django.core.cache import cache


class TaskResultStatus(Enum):
    """Possible states of tasks"""

    SUCCESSFUL = 1
    WARNING = 2
    ERROR = 4


@dataclass
class TaskResult:
    """Result of a task run, this class is created by the task itself
    and used by self.set_status"""

    status: TaskResultStatus

    messages: List[str] = field(default_factory=list)

    error: Optional[Exception] = field(default=None)

    # Optional UID used in cache for tasks that run in different instances
    uid: Optional[str] = field(default=None)


@dataclass
class TaskInfo:
    """Info about a task run"""

    task_name: str
    finish_timestamp: datetime

    result: TaskResult

    task_call_module: str
    task_call_func: str
    task_call_args: List[Any] = field(default_factory=list)
    task_call_kwargs: Dict[str, Any] = field(default_factory=dict)

    task_description: Optional[str] = field(default=None)

    @staticmethod
    def all() -> Dict[str, "TaskInfo"]:
        """Get all TaskInfo objects"""
        return cache.get_many(cache.keys("task_*"))

    @staticmethod
    def by_name(name: str) -> Optional["TaskInfo"]:
        """Get TaskInfo Object by name"""
        return cache.get(f"task_{name}")

    def save(self):
        """Save task into cache"""
        key = f"task_{self.task_name}"
        if self.result.uid:
            key += f"_{self.result.uid}"
            self.task_name += f"_{self.result.uid}"
        cache.set(key, self, timeout=6 * 60 * 60)


class MonitoredTask(Task):
    """Task which can save its state to the cache"""

    _result: TaskResult

    def __init__(self, *args, **kwargs) -> None:
        super().__init__(*args, **kwargs)
        self._result = TaskResult(status=TaskResultStatus.ERROR, messages=[])

    def set_status(self, result: TaskResult):
        """Set result for current run, will overwrite previous result."""
        self._result = result

    # pylint: disable=too-many-arguments
    def after_return(
        self, status, retval, task_id, args: List[Any], kwargs: Dict[str, Any], einfo
    ):
        TaskInfo(
            task_name=self.__name__,
            task_description=self.__doc__,
            finish_timestamp=datetime.now(),
            result=self._result,
            task_call_module=self.__module__,
            task_call_func=self.__name__,
            task_call_args=args,
            task_call_kwargs=kwargs,
        ).save()
        return super().after_return(status, retval, task_id, args, kwargs, einfo=einfo)

    # pylint: disable=too-many-arguments
    def on_failure(self, exc, task_id, args, kwargs, einfo):
        TaskInfo(
            task_name=self.__name__,
            task_description=self.__doc__,
            finish_timestamp=datetime.now(),
            result=self._result,
            task_call_module=self.__module__,
            task_call_func=self.__name__,
            task_call_args=args,
            task_call_kwargs=kwargs,
        ).save()
        return super().on_failure(exc, task_id, args, kwargs, einfo=einfo)

    def run(self, *args, **kwargs):
        raise NotImplementedError