from __future__ import annotations

from app.core.errors import UnsupportedEngineError
from app.core.interface import EngineBackend
from app.models import (
    CapabilitySet,
    EngineKind,
    EngineState,
    RuntimeRequest,
    RuntimeSnapshot,
    RuntimeStats,
)


class FreeTurnBackend(EngineBackend):
    """FreeTurn adapter contract.

    The actual Android calls (`Mobile.Start`, `StartTunnel`, `SetProtect`, events,
    CAPTCHA) are owned by the native service. Desktop support is intentionally not
    claimed until a desktop build of the core is selected.
    """

    name = "freeturn"
    capabilities = CapabilitySet(
        supports_vpn=False,
        supports_proxy=True,
        supports_socks=False,
        supports_http=False,
        supports_udp=True,
        supports_mobile=True,
        supports_desktop=False,
        supports_stats=True,
        supports_hot_reload=False,
        supports_both=False,
    )

    def __init__(self) -> None:
        self._state = RuntimeSnapshot(engine=EngineKind.FREETURN)

    async def start(self, request: RuntimeRequest) -> RuntimeSnapshot:
        self._state = RuntimeSnapshot(
            state=EngineState.UNSUPPORTED,
            engine=EngineKind.FREETURN,
            mode=request.mode,
            profile_id=request.profile_id,
            message="FreeTurn is available only through the Android native mobile binding",
        )
        raise UnsupportedEngineError(
            self._state.message or "FreeTurn is unsupported on this platform"
        )

    async def stop(self) -> RuntimeSnapshot:
        self._state = self._state.model_copy(update={"state": EngineState.STOPPED})
        return self._state

    async def restart(self, request: RuntimeRequest) -> RuntimeSnapshot:
        await self.stop()
        return await self.start(request)

    async def get_state(self) -> RuntimeSnapshot:
        return self._state

    async def get_stats(self) -> RuntimeStats:
        return self._state.stats