"""
会议调度器 - 实现栅栏同步（Barrier Synchronization）
"""

import asyncio
from datetime import datetime
from typing import Dict, List, Optional, Set
from dataclasses import dataclass, asdict

from .storage import get_storage


@dataclass
class MeetingQueue:
    """会议等待队列"""
    meeting_id: str
    title: str
    expected_attendees: List[str]
    arrived_attendees: List[str]
    status: str = "waiting"
    created_at: str = ""
    started_at: str = ""
    min_required: int = 2

    def __post_init__(self):
        if not self.created_at:
            self.created_at = datetime.now().isoformat()

    @property
    def is_ready(self) -> bool:
        expected = set(self.expected_attendees)
        arrived = set(self.arrived_attendees)
        return expected.issubset(arrived) and len(arrived) >= self.min_required

    @property
    def missing_attendees(self) -> List[str]:
        return list(set(self.expected_attendees) - set(self.arrived_attendees))

    @property
    def progress(self) -> str:
        return f"{len(self.arrived_attendees)}/{len(self.expected_attendees)}"


class MeetingScheduler:
    """会议调度器 - 栅栏同步实现"""

    QUEUES_FILE = "cache/meeting_queue.json"

    def __init__(self):
        self._storage = get_storage()
        self._lock = asyncio.Lock()
        self._events: Dict[str, asyncio.Event] = {}

    async def _load_queues(self) -> Dict[str, Dict]:
        return await self._storage.read_json(self.QUEUES_FILE)

    async def _save_queues(self, queues: Dict[str, Dict]) -> None:
        await self._storage.write_json(self.QUEUES_FILE, queues)

    async def create_meeting(
        self,
        meeting_id: str,
        title: str,
        expected_attendees: List[str],
        min_required: int = None
    ) -> MeetingQueue:
        async with self._lock:
            queue = MeetingQueue(
                meeting_id=meeting_id,
                title=title,
                expected_attendees=expected_attendees,
                arrived_attendees=[],
                min_required=min_required or len(expected_attendees)
            )
            queues = await self._load_queues()
            queues[meeting_id] = asdict(queue)
            await self._save_queues(queues)
            return queue

    async def get_queue(self, meeting_id: str) -> Optional[MeetingQueue]:
        queues = await self._load_queues()
        return MeetingQueue(**queues[meeting_id]) if meeting_id in queues else None

    async def wait_for_meeting(
        self,
        agent_id: str,
        meeting_id: str,
        timeout: int = 300
    ) -> str:
        async with self._lock:
            queues = await self._load_queues()

            if meeting_id not in queues:
                await self.create_meeting(
                    meeting_id=meeting_id,
                    title=f"Meeting: {meeting_id}",
                    expected_attendees=[agent_id],
                    min_required=1
                )
                return "started"

            queue_data = queues[meeting_id]
            if agent_id not in queue_data.get("arrived_attendees", []):
                queue_data["arrived_attendees"].append(agent_id)
                queue_data["arrived_attendees"].sort()

            await self._save_queues(queues)
            queue = MeetingQueue(**queue_data)
            is_ready = queue.is_ready

        if is_ready:
            await self._start_meeting(meeting_id)
            return "started"

        # 等待会议开始
        event = self._events.setdefault(meeting_id, asyncio.Event())
        try:
            await asyncio.wait_for(event.wait(), timeout=timeout)
            return "started"
        except asyncio.TimeoutError:
            return "timeout"

    async def _start_meeting(self, meeting_id: str) -> None:
        async with self._lock:
            queues = await self._load_queues()
            if meeting_id in queues:
                queues[meeting_id]["status"] = "ready"
                queues[meeting_id]["started_at"] = datetime.now().isoformat()
                await self._save_queues(queues)

        # 唤醒所有等待者
        event = self._events.get(meeting_id)
        if event:
            event.set()

    async def end_meeting(self, meeting_id: str) -> bool:
        async with self._lock:
            queues = await self._load_queues()
            if meeting_id not in queues:
                return False

            queues[meeting_id]["status"] = "ended"
            await self._save_queues(queues)
            self._events.pop(meeting_id, None)
            return True

    async def get_all_queues(self) -> List[MeetingQueue]:
        queues = await self._load_queues()
        return [MeetingQueue(**data) for data in queues.values()]

    async def add_attendee(self, meeting_id: str, agent_id: str) -> bool:
        async with self._lock:
            queues = await self._load_queues()
            if meeting_id not in queues:
                return False

            if agent_id not in queues[meeting_id]["expected_attendees"]:
                queues[meeting_id]["expected_attendees"].append(agent_id)
                await self._save_queues(queues)
                return True
            return False


# 简化单例实现
_scheduler_instance: Optional[MeetingScheduler] = None


def get_meeting_scheduler() -> MeetingScheduler:
    global _scheduler_instance
    if _scheduler_instance is None:
        _scheduler_instance = MeetingScheduler()
    return _scheduler_instance