from __future__ import annotations

from abc import ABC, abstractmethod

from app.models import CapabilitySet, RuntimeRequest, RuntimeSnapshot, RuntimeStats


class EngineBackend(ABC):
    """Platform-independent lifecycle contract.

    Platform adapters may implement this through a desktop process or through the
    Android native bridge. Python never owns Android VPN process lifetime.
    """

    name: str
    capabilities: CapabilitySet

    @abstractmethod
    async def start(self, request: RuntimeRequest) -> RuntimeSnapshot: ...

    @abstractmethod
    async def stop(self) -> RuntimeSnapshot: ...

    @abstractmethod
    async def restart(self, request: RuntimeRequest) -> RuntimeSnapshot: ...

    @abstractmethod
    async def get_state(self) -> RuntimeSnapshot: ...

    @abstractmethod
    async def get_stats(self) -> RuntimeStats: ...