import asyncio
from uuid import UUID, uuid4

from app.models import CurrentStatus, Monitor, MonitorCreate, MonitorUpdate, utcnow


class MonitorStore:
    """Lock-protected process-local storage returning defensive copies."""

    def __init__(self) -> None:
        self._lock = asyncio.Lock()
        self._items: dict[UUID, Monitor] = {}
        self._revisions: dict[UUID, int] = {}

    async def create(self, data: MonitorCreate) -> Monitor:
        now = utcnow()
        item = Monitor(id=uuid4(), name=data.name, url=data.url, created_at=now,
                       updated_at=now, current_status=CurrentStatus())
        async with self._lock:
            self._items[item.id] = item
            self._revisions[item.id] = 0
            return item.model_copy(deep=True)

    async def list(self) -> list[Monitor]:
        async with self._lock:
            values = sorted(self._items.values(), key=lambda item: item.created_at)
            return [item.model_copy(deep=True) for item in values]

    async def get(self, monitor_id: UUID) -> Monitor | None:
        async with self._lock:
            item = self._items.get(monitor_id)
            return item.model_copy(deep=True) if item else None

    async def snapshot(self, monitor_id: UUID) -> tuple[Monitor, int] | None:
        async with self._lock:
            item = self._items.get(monitor_id)
            if item is None:
                return None
            return item.model_copy(deep=True), self._revisions[monitor_id]

    async def update(self, monitor_id: UUID, data: MonitorUpdate) -> Monitor | None:
        async with self._lock:
            item = self._items.get(monitor_id)
            if item is None:
                return None
            changes = data.model_dump(exclude_none=True)
            changes["updated_at"] = utcnow()
            updated = item.model_copy(update=changes, deep=True)
            self._items[monitor_id] = updated
            self._revisions[monitor_id] += 1
            return updated.model_copy(deep=True)

    async def delete(self, monitor_id: UUID) -> bool:
        async with self._lock:
            existed = self._items.pop(monitor_id, None) is not None
            self._revisions.pop(monitor_id, None)
            return existed

    async def record_status(self, monitor_id: UUID, revision: int,
                            status: CurrentStatus) -> Monitor | None:
        async with self._lock:
            item = self._items.get(monitor_id)
            if item is None or self._revisions[monitor_id] != revision:
                return None
            updated = item.model_copy(update={"current_status": status,
                                              "updated_at": utcnow()}, deep=True)
            self._items[monitor_id] = updated
            return updated.model_copy(deep=True)