"""Explicit startup backends for real hardware and isolated MuJoCo deployment.

The real entry point never exposes the simulation backend.  The simulation
entry point cannot attach the production SHM name and cannot manufacture the
real MotionSwitcher-attestation bit.
"""

from __future__ import annotations

from dataclasses import dataclass
from pathlib import Path
import subprocess
import sys
import time
from typing import Protocol

from .h2_contract import H2_JOINT_MAP_REVISION
from .h2_shm_bridge import (
    H2SharedMemoryBridge,
    SHM_NAME,
    SIMULATION_ACK,
    SIM_SHM_PREFIX,
)
from .motion_attestation import (
    MOTION_SWITCHER_ACK,
    consume_attestation,
    require_interface_up,
)


class RunnerStartupBackend(Protocol):
    @property
    def identity(self) -> str: ...

    def validate_before_model_load(self, *, shm_name: str, config_revision: str) -> None: ...

    def attach_after_model_load(self, *, shm_name: str) -> tuple[H2SharedMemoryBridge, str]: ...


@dataclass(frozen=True)
class RealRunnerStartup:
    network_interface: str
    joint_map_ack: str
    motion_switcher_ack: str
    check_motion_switcher_on_attach: bool = False

    @property
    def identity(self) -> str:
        return str(self.network_interface)

    def validate_before_model_load(self, *, shm_name: str, config_revision: str) -> None:
        if str(shm_name).lstrip("/") != SHM_NAME:
            raise RuntimeError(
                f"real H2 control accepts only the production SHM name {SHM_NAME!r}"
            )
        if config_revision != H2_JOINT_MAP_REVISION:
            raise RuntimeError(
                "config H2 joint-map revision does not match this executable: "
                f"{config_revision!r} != {H2_JOINT_MAP_REVISION!r}"
            )
        if str(self.joint_map_ack) != H2_JOINT_MAP_REVISION:
            raise RuntimeError(
                "real H2 control requires explicit --ack-joint-map-revision "
                f"{H2_JOINT_MAP_REVISION} after suspended ID verification"
            )
        if str(self.motion_switcher_ack) != MOTION_SWITCHER_ACK:
            raise RuntimeError(
                "real H2 control requires explicit --ack-motion-switcher-attestation "
                f"{MOTION_SWITCHER_ACK} after a fresh successful CheckMode"
            )
        require_interface_up(self.network_interface)

    def attach_after_model_load(self, *, shm_name: str) -> tuple[H2SharedMemoryBridge, str]:
        if self.check_motion_switcher_on_attach:
            started = time.monotonic()
            print("[STARTUP] CheckMode begin (models ready; read-only, no release)", flush=True)
            guard = Path(__file__).resolve().parents[1] / "scripts/motion_switcher_guard.py"
            try:
                subprocess.run([sys.executable, str(guard), "--network-interface",
                                self.network_interface, "--write-attestation"],
                               check=True, timeout=15)
            except (subprocess.SubprocessError, OSError) as error:
                raise RuntimeError(f"startup CheckMode failed after {time.monotonic()-started:.2f}s: {error}") from error
            print(f"[STARTUP] CheckMode complete elapsed_s={time.monotonic()-started:.3f}", flush=True)
        bridge = H2SharedMemoryBridge(name=shm_name, claim_writer=True)
        try:
            age_s = consume_attestation(self.network_interface)
            bridge.attest_motion_switcher_released(self.network_interface)
        except BaseException:
            bridge.close()
            raise
        return bridge, (
            f"consumed MotionSwitcher attestation age={age_s:.3f}s "
            f"interface={self.network_interface}"
        )


@dataclass(frozen=True)
class SimulationRunnerStartup:
    acknowledgement: str

    @property
    def identity(self) -> str:
        return "MuJoCo simulation only"

    def validate_before_model_load(self, *, shm_name: str, config_revision: str) -> None:
        normalized = str(shm_name).lstrip("/")
        if normalized == SHM_NAME or not normalized.startswith(SIM_SHM_PREFIX):
            raise RuntimeError(
                f"simulation runner requires a random {SIM_SHM_PREFIX}<run-id> SHM name"
            )
        if config_revision != H2_JOINT_MAP_REVISION:
            raise RuntimeError(
                "simulation and real runner must use the same pinned H2 joint-map revision"
            )
        if str(self.acknowledgement) != SIMULATION_ACK:
            raise RuntimeError(
                "simulation deployment requires explicit --ack-simulation-only "
                f"{SIMULATION_ACK}"
            )

    def attach_after_model_load(self, *, shm_name: str) -> tuple[H2SharedMemoryBridge, str]:
        bridge = H2SharedMemoryBridge(name=shm_name, claim_writer=True)
        try:
            bridge.attest_simulation_runner()
        except BaseException:
            bridge.close()
            raise
        return bridge, "validated isolated MuJoCo H2BR owner and simulation-only command gate"


__all__ = [
    "RealRunnerStartup",
    "RunnerStartupBackend",
    "SimulationRunnerStartup",
]