"""
aiosched: Yet another Python async scheduler

Copyright (C) 2022 nocturn9x

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   https:www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
"""
import traceback
from aiosched.task import Task


class SchedulerError(Exception):
    """
    A generic scheduler error
    """


class InternalError(SchedulerError):
    """
    Internal exception
    """


class ResourceBusy(SchedulerError):
    """
    Exception that is raised when a resource is
    accessed by more than one task at a time
    """


class ResourceClosed(SchedulerError):
    """
    Raised when I/O is attempted on a closed
    resource
    """


class ResourceBroken(SchedulerError):
    """
    Raised when I/O is attempted on a broken
    resource
    """


class TimedOutError(SchedulerError):
    """
    This is raised if a timeout expires
    """

    task: Task


class Cancelled(BaseException):
    """
    A cancellation exception.
    Inherits from BaseException as
    it is not meant to be caught
    """

    task: Task


class ErrorStack(SchedulerError):
    """
    This exception wraps multiple exceptions and
    shows each individual traceback of them when
    printed. This is to ensure that no exception is
    lost even if 2 or more tasks raise at the
    same time or during cancellation of other
    tasks
    """

    def __init__(self, errors: list[BaseException]):
        """
        Object constructor
        """

        super().__init__()
        self.errors = errors

    def __str__(self):
        """
        Returns str(self)
        """

        tracebacks = ""
        for i, err in enumerate(self.errors):
            if i not in (1, len(self.errors)):
                tracebacks += f"\n{''.join(traceback.format_exception(type(err), err, err.__traceback__))}\n{'-' * 32}\n"
            else:
                tracebacks += f"\n{''.join(traceback.format_exception(type(err), err, err.__traceback__))}"
        return f"Multiple errors occurred:\n{tracebacks}"