import asyncio
import collections
import contextlib
import os
from logging import getLogger

from defence360agent.api import inactivity
from defence360agent.contracts.messages import MessageType, Splittable
from defence360agent.contracts.plugins import (
    MessageSink,
    MessageSource,
    expect,
)
from defence360agent.utils import recurring_check

logger = getLogger(__name__)


class Accumulate(MessageSink, MessageSource):
    PROCESSING_ORDER = MessageSink.ProcessingOrder.POST_PROCESS_MESSAGE
    DEFAULT_AGGREGATE_TIMEOUT = int(
        os.environ.get("IMUNIFY360_AGGREGATE_MESSAGES_TIMEOUT", 60)
    )
    SHUTDOWN_SEND_TIMEOUT = int(
        os.environ.get("IMUNIFY360_AGGREGATE_SHUTDOWN_SEND_TIMEOUT", 50)
    )

    def __init__(
        self,
        period=DEFAULT_AGGREGATE_TIMEOUT,
        shutdown_timeout=SHUTDOWN_SEND_TIMEOUT,
        **kwargs,
    ):
        super().__init__(**kwargs)
        self._period = period
        self._shutdown_timeout = shutdown_timeout
        self._data = collections.defaultdict(list)

    async def create_source(self, loop, sink):
        self._loop = loop
        self._sink = sink
        self._task = (
            None
            if self._period == 0
            else loop.create_task(recurring_check(self._period)(self._flush)())
        )

    async def create_sink(self, loop):
        self._loop = loop

    async def shutdown(self):
        try:
            await asyncio.wait_for(self.stop(), self._shutdown_timeout)
        except asyncio.TimeoutError:
            # Used logger.error to notify sentry
            logger.error(
                "Timeout (%ss) sending messages to server on shutdown.",
                self._shutdown_timeout,
            )
            if self._task is not None:
                self._task.cancel()
                with contextlib.suppress(asyncio.CancelledError):
                    await self._task

    async def stop(self):
        logger.info("Accumulate.stop cancel _task")
        if self._task is not None:
            self._task.cancel()
            with contextlib.suppress(asyncio.CancelledError):
                await self._task
        logger.info("Accumulate.stop wait lock")
        # send pending messages
        await self._flush()

    @expect(MessageType.Accumulatable)
    async def collect(self, message):
        list_types = (
            message.LIST_CLASS
            if isinstance(message.LIST_CLASS, tuple)
            else (message.LIST_CLASS,)
        )
        if message.do_accumulate():
            with inactivity.track.task("accumulate"):
                for list_type in list_types:
                    self._data[list_type].append(message)

    async def _flush(self):
        copy_data = self._data
        self._data = collections.defaultdict(list)

        for list_type, messages in copy_data.items():
            batched = (
                list_type.batched(messages)
                if issubclass(list_type, Splittable)
                else (messages,)
            )

            for batch in batched:
                logger.info(
                    f"Prepare {list_type.__name__}(<items={len(batch)}>) "
                    "for further processing"
                )
                try:
                    # FIXME: remove this try..except block after
                    #  we have forbidden to create Accumulatable class
                    #  without LIST_CLASS.
                    await self._sink.process_message(list_type(items=batch))
                except TypeError:
                    logger.error("%s, %s", list_type, batch)
                    raise