import asyncio
import queue
import threading
from concurrent.futures import ThreadPoolExecutor
from datetime import datetime
from enum import Enum
from functools import partial
from typing import Callable, Iterable

from openhands.core.logger import openhands_logger as logger
from openhands.core.utils import json
from openhands.events.event import Event, EventSource
from openhands.events.serialization.event import event_from_dict, event_to_dict
from openhands.storage import FileStore
from openhands.storage.locations import (
    get_conversation_dir,
    get_conversation_event_filename,
    get_conversation_events_dir,
)
from openhands.utils.async_utils import call_sync_from_async
from openhands.utils.shutdown_listener import should_continue


class EventStreamSubscriber(str, Enum):
    AGENT_CONTROLLER = 'agent_controller'
    SECURITY_ANALYZER = 'security_analyzer'
    RESOLVER = 'openhands_resolver'
    SERVER = 'server'
    RUNTIME = 'runtime'
    MAIN = 'main'
    TEST = 'test'


async def session_exists(sid: str, file_store: FileStore) -> bool:
    try:
        await call_sync_from_async(file_store.list, get_conversation_dir(sid))
        return True
    except FileNotFoundError:
        return False


class AsyncEventStreamWrapper:
    def __init__(self, event_stream, *args, **kwargs):
        self.event_stream = event_stream
        self.args = args
        self.kwargs = kwargs

    async def __aiter__(self):
        loop = asyncio.get_running_loop()

        # Create an async generator that yields events
        for event in self.event_stream.get_events(*self.args, **self.kwargs):
            # Run the blocking get_events() in a thread pool
            yield await loop.run_in_executor(None, lambda e=event: e)  # type: ignore


class EventStream:
    sid: str
    file_store: FileStore
    # For each subscriber ID, there is a map of callback functions - useful
    # when there are multiple listeners
    _subscribers: dict[str, dict[str, Callable]]
    _cur_id: int = 0
    _lock: threading.Lock
    _queue: queue.Queue[Event]
    _queue_thread: threading.Thread
    _queue_loop: asyncio.AbstractEventLoop | None
    _thread_pools: dict[str, dict[str, ThreadPoolExecutor]]
    _thread_loops: dict[str, dict[str, asyncio.AbstractEventLoop]]

    def __init__(self, sid: str, file_store: FileStore):
        self.sid = sid
        self.file_store = file_store
        self._stop_flag = threading.Event()
        self._queue: queue.Queue[Event] = queue.Queue()
        self._thread_pools = {}
        self._thread_loops = {}
        self._queue_loop = None
        self._queue_thread = threading.Thread(target=self._run_queue_loop)
        self._queue_thread.daemon = True
        self._queue_thread.start()
        self._subscribers = {}
        self._lock = threading.Lock()
        self._cur_id = 0

        # load the stream
        self.__post_init__()

    def __post_init__(self) -> None:
        try:
            events = self.file_store.list(get_conversation_events_dir(self.sid))
        except FileNotFoundError:
            logger.debug(f'No events found for session {self.sid}')
            self._cur_id = 0
            return

        # if we have events, we need to find the highest id to prepare for new events
        for event_str in events:
            id = self._get_id_from_filename(event_str)
            if id >= self._cur_id:
                self._cur_id = id + 1

    def _init_thread_loop(self, subscriber_id: str, callback_id: str):
        loop = asyncio.new_event_loop()
        asyncio.set_event_loop(loop)
        if subscriber_id not in self._thread_loops:
            self._thread_loops[subscriber_id] = {}
        self._thread_loops[subscriber_id][callback_id] = loop

    def close(self):
        self._stop_flag.set()
        if self._queue_thread.is_alive():
            self._queue_thread.join()

        subscriber_ids = list(self._subscribers.keys())
        for subscriber_id in subscriber_ids:
            callback_ids = list(self._subscribers[subscriber_id].keys())
            for callback_id in callback_ids:
                self._clean_up_subscriber(subscriber_id, callback_id)

    def _clean_up_subscriber(self, subscriber_id: str, callback_id: str):
        if subscriber_id not in self._subscribers:
            logger.warning(f'Subscriber not found during cleanup: {subscriber_id}')
            return
        if callback_id not in self._subscribers[subscriber_id]:
            logger.warning(f'Callback not found during cleanup: {callback_id}')
            return
        if (
            subscriber_id in self._thread_loops
            and callback_id in self._thread_loops[subscriber_id]
        ):
            loop = self._thread_loops[subscriber_id][callback_id]
            try:
                loop.stop()
                loop.close()
            except Exception as e:
                logger.warning(
                    f'Error closing loop for {subscriber_id}/{callback_id}: {e}'
                )
            del self._thread_loops[subscriber_id][callback_id]

        if (
            subscriber_id in self._thread_pools
            and callback_id in self._thread_pools[subscriber_id]
        ):
            pool = self._thread_pools[subscriber_id][callback_id]
            pool.shutdown()
            del self._thread_pools[subscriber_id][callback_id]

        del self._subscribers[subscriber_id][callback_id]

    def _get_filename_for_id(self, id: int) -> str:
        return get_conversation_event_filename(self.sid, id)

    @staticmethod
    def _get_id_from_filename(filename: str) -> int:
        try:
            return int(filename.split('/')[-1].split('.')[0])
        except ValueError:
            logger.warning(f'get id from filename ({filename}) failed.')
            return -1

    def get_events(
        self,
        start_id: int = 0,
        end_id: int | None = None,
        reverse: bool = False,
        filter_out_type: tuple[type[Event], ...] | None = None,
        filter_hidden=False,
    ) -> Iterable[Event]:
        """
        Retrieve events from the event stream, optionally filtering out events of a given type
        and events marked as hidden.

        Args:
            start_id: The ID of the first event to retrieve. Defaults to 0.
            end_id: The ID of the last event to retrieve. Defaults to the last event in the stream.
            reverse: Whether to retrieve events in reverse order. Defaults to False.
            filter_out_type: A tuple of event types to filter out. Typically used to filter out backend events from the agent.
            filter_hidden: If True, filters out events with the 'hidden' attribute set to True.

        Yields:
            Events from the stream that match the criteria.
        """

        def should_filter(event: Event):
            if filter_hidden and hasattr(event, 'hidden') and event.hidden:
                return True
            if filter_out_type is not None and isinstance(event, filter_out_type):
                return True
            return False

        if reverse:
            if end_id is None:
                end_id = self._cur_id - 1
            event_id = end_id
            while event_id >= start_id:
                try:
                    event = self.get_event(event_id)
                    if not should_filter(event):
                        yield event
                except FileNotFoundError:
                    logger.debug(f'No event found for ID {event_id}')
                event_id -= 1
        else:
            event_id = start_id
            while should_continue():
                if end_id is not None and event_id > end_id:
                    break
                try:
                    event = self.get_event(event_id)
                    if not should_filter(event):
                        yield event
                except FileNotFoundError:
                    break
                event_id += 1

    def get_event(self, id: int) -> Event:
        filename = self._get_filename_for_id(id)
        content = self.file_store.read(filename)
        data = json.loads(content)
        return event_from_dict(data)

    def get_latest_event(self) -> Event:
        return self.get_event(self._cur_id - 1)

    def get_latest_event_id(self) -> int:
        return self._cur_id - 1

    def subscribe(
        self, subscriber_id: EventStreamSubscriber, callback: Callable, callback_id: str
    ):
        initializer = partial(self._init_thread_loop, subscriber_id, callback_id)
        pool = ThreadPoolExecutor(max_workers=1, initializer=initializer)
        if subscriber_id not in self._subscribers:
            self._subscribers[subscriber_id] = {}
            self._thread_pools[subscriber_id] = {}

        if callback_id in self._subscribers[subscriber_id]:
            raise ValueError(
                f'Callback ID on subscriber {subscriber_id} already exists: {callback_id}'
            )

        self._subscribers[subscriber_id][callback_id] = callback
        self._thread_pools[subscriber_id][callback_id] = pool

    def unsubscribe(self, subscriber_id: EventStreamSubscriber, callback_id: str):
        if subscriber_id not in self._subscribers:
            logger.warning(f'Subscriber not found during unsubscribe: {subscriber_id}')
            return

        if callback_id not in self._subscribers[subscriber_id]:
            logger.warning(f'Callback not found during unsubscribe: {callback_id}')
            return

        self._clean_up_subscriber(subscriber_id, callback_id)

    def add_event(self, event: Event, source: EventSource):
        if hasattr(event, '_id') and event.id is not None:
            raise ValueError(
                f'Event already has an ID:{event.id}. It was probably added back to the EventStream from inside a handler, triggering a loop.'
            )
        with self._lock:
            event._id = self._cur_id  # type: ignore [attr-defined]
            self._cur_id += 1
        logger.debug(f'Adding {type(event).__name__} id={event.id} from {source.name}')
        event._timestamp = datetime.now().isoformat()
        event._source = source  # type: ignore [attr-defined]
        data = event_to_dict(event)
        if event.id is not None:
            self.file_store.write(self._get_filename_for_id(event.id), json.dumps(data))
        self._queue.put(event)

    def _run_queue_loop(self):
        self._queue_loop = asyncio.new_event_loop()
        asyncio.set_event_loop(self._queue_loop)
        try:
            self._queue_loop.run_until_complete(self._process_queue())
        finally:
            self._queue_loop.close()

    async def _process_queue(self):
        while should_continue() and not self._stop_flag.is_set():
            event = None
            try:
                event = self._queue.get(timeout=0.1)
            except queue.Empty:
                continue

            # pass each event to each callback in order
            for key in sorted(self._subscribers.keys()):
                callbacks = self._subscribers[key]
                for callback_id in callbacks:
                    callback = callbacks[callback_id]
                    pool = self._thread_pools[key][callback_id]
                    future = pool.submit(callback, event)
                    future.add_done_callback(self._make_error_handler(callback_id, key))

    def _make_error_handler(self, callback_id: str, subscriber_id: str):
        def _handle_callback_error(fut):
            try:
                # This will raise any exception that occurred during callback execution
                fut.result()
            except Exception as e:
                logger.error(
                    f'Error in event callback {callback_id} for subscriber {subscriber_id}: {str(e)}',
                )
                # Re-raise in the main thread so the error is not swallowed
                raise e

        return _handle_callback_error

    def filtered_events_by_source(self, source: EventSource):
        for event in self.get_events():
            if event.source == source:
                yield event

    def _should_filter_event(
        self,
        event,
        query: str | None = None,
        event_type: str | None = None,
        source: str | None = None,
        start_date: str | None = None,
        end_date: str | None = None,
    ) -> bool:
        """Check if an event should be filtered out based on the given criteria.

        Args:
            event: The event to check
            query (str, optional): Text to search for in event content
            event_type (str, optional): Filter by event type (e.g., "FileReadAction")
            source (str, optional): Filter by event source
            start_date (str, optional): Filter events after this date (ISO format)
            end_date (str, optional): Filter events before this date (ISO format)

        Returns:
            bool: True if the event should be filtered out, False if it matches all criteria
        """
        if event_type and not event.__class__.__name__ == event_type:
            return True

        if source and not event.source.value == source:
            return True

        if start_date and event.timestamp < start_date:
            return True

        if end_date and event.timestamp > end_date:
            return True

        # Text search in event content if query provided
        if query:
            event_dict = event_to_dict(event)
            event_str = str(event_dict).lower()
            if query.lower() not in event_str:
                return True

        return False

    def get_matching_events(
        self,
        query: str | None = None,
        event_type: str | None = None,
        source: str | None = None,
        start_date: str | None = None,
        end_date: str | None = None,
        start_id: int = 0,
        limit: int = 100,
    ) -> list:
        """Get matching events from the event stream based on filters.

        Args:
            query (str, optional): Text to search for in event content
            event_type (str, optional): Filter by event type (e.g., "FileReadAction")
            source (str, optional): Filter by event source
            start_date (str, optional): Filter events after this date (ISO format)
            end_date (str, optional): Filter events before this date (ISO format)
            start_id (int): Starting ID in the event stream. Defaults to 0
            limit (int): Maximum number of events to return. Must be between 1 and 100. Defaults to 100

        Returns:
            list: List of matching events (as dicts)

        Raises:
            ValueError: If limit is less than 1 or greater than 100
        """
        if limit < 1 or limit > 100:
            raise ValueError('Limit must be between 1 and 100')

        matching_events: list = []

        for event in self.get_events(start_id=start_id):
            if self._should_filter_event(
                event, query, event_type, source, start_date, end_date
            ):
                continue

            matching_events.append(event_to_dict(event))

            # Stop if we have enough events
            if len(matching_events) >= limit:
                break

        return matching_events