# maubot - A plugin-based Matrix bot system.
# Copyright (C) 2022 Tulir Asokan
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.
from __future__ import annotations

from typing import TYPE_CHECKING, TypeVar
from abc import ABC, abstractmethod
import asyncio

from ..plugin_base import Plugin
from .meta import PluginMeta

if TYPE_CHECKING:
    from ..instance import PluginInstance

PluginClass = TypeVar("PluginClass", bound=Plugin)


class IDConflictError(Exception):
    pass


class BasePluginLoader(ABC):
    meta: PluginMeta

    @property
    @abstractmethod
    def source(self) -> str:
        pass

    def sync_read_file(self, path: str) -> bytes:
        raise NotImplementedError("This loader doesn't support synchronous operations")

    @abstractmethod
    async def read_file(self, path: str) -> bytes:
        pass

    def sync_list_files(self, directory: str) -> list[str]:
        raise NotImplementedError("This loader doesn't support synchronous operations")

    @abstractmethod
    async def list_files(self, directory: str) -> list[str]:
        pass


class PluginLoader(BasePluginLoader, ABC):
    id_cache: dict[str, PluginLoader] = {}

    meta: PluginMeta
    references: set[PluginInstance]

    def __init__(self):
        self.references = set()

    @classmethod
    def find(cls, plugin_id: str) -> PluginLoader:
        return cls.id_cache[plugin_id]

    def to_dict(self) -> dict:
        return {
            "id": self.meta.id,
            "version": str(self.meta.version),
            "instances": [instance.to_dict() for instance in self.references],
        }

    async def stop_instances(self) -> None:
        await asyncio.gather(
            *[instance.stop() for instance in self.references if instance.started]
        )

    async def start_instances(self) -> None:
        await asyncio.gather(
            *[instance.start() for instance in self.references if instance.enabled]
        )

    @abstractmethod
    async def load(self) -> type[PluginClass]:
        pass

    @abstractmethod
    async def reload(self) -> type[PluginClass]:
        pass

    @abstractmethod
    async def delete(self) -> None:
        pass