"""Runs the authenticator simulator and exposes it as a python-fido2 HID device."""

import os
import pathlib
import subprocess
import threading

import pytest
from fido2.hid import CtapHidDevice
from fido2.hid.base import CtapHidConnection, HidDescriptor

ROOT = pathlib.Path(__file__).resolve().parent.parent
SIMULATOR = pathlib.Path(os.environ.get("SKEY_SIM", ROOT / "build-host" / "skey_sim"))
PACKET_SIZE = 64


class PipeConnection(CtapHidConnection):
    """Carries HID reports over the simulator's stdin/stdout."""

    def __init__(self, proc: subprocess.Popen):
        self.proc = proc

    def write_packet(self, data: bytes) -> None:
        assert len(data) == PACKET_SIZE
        self.proc.stdin.write(data)
        self.proc.stdin.flush()

    def read_packet(self) -> bytes:
        data = self.proc.stdout.read(PACKET_SIZE)
        if len(data) != PACKET_SIZE:
            raise OSError(f"simulator exited with {self.proc.wait()}")
        return data

    def close(self) -> None:
        self.proc.stdin.close()
        assert self.proc.wait(timeout=10) == 0, "simulator crashed"


class Simulator:
    """One simulated key. Restarting keeps its flash, like unplugging a real one.

    Without a button file every request is approved; with one, press() is a
    touch of the button.
    """

    def __init__(self, flash_file: pathlib.Path, button_file: pathlib.Path | None = None):
        self.flash_file = flash_file
        self.button_file = button_file
        self.device = None

    def start(self) -> CtapHidDevice:
        if not SIMULATOR.exists():
            pytest.fail(f"{SIMULATOR} not found; build it with: cmake -B build-host -DSKEY_HOST=ON && cmake --build build-host")
        env = {**os.environ, "SKEY_FLASH_FILE": str(self.flash_file)}
        if self.button_file:
            env["SKEY_BUTTON_FILE"] = str(self.button_file)
        proc = subprocess.Popen([SIMULATOR], stdin=subprocess.PIPE, stdout=subprocess.PIPE, env=env)
        descriptor = HidDescriptor(
            path="skey-sim",
            vid=0x1209,
            pid=0x0001,
            report_size_in=PACKET_SIZE,
            report_size_out=PACKET_SIZE,
            product_name="Skey simulator",
            serial_number="sim",
        )
        self.device = CtapHidDevice(descriptor, PipeConnection(proc))
        return self.device

    def stop(self) -> None:
        if self.device:
            self.device.close()
            self.device = None

    def restart(self) -> CtapHidDevice:
        self.stop()
        return self.start()

    def press(self) -> None:
        self.button_file.touch()

    def press_after(self, seconds: float) -> threading.Timer:
        timer = threading.Timer(seconds, self.press)
        timer.start()
        return timer


@pytest.fixture
def sim(tmp_path):
    simulator = Simulator(tmp_path / "flash.bin")
    simulator.start()
    yield simulator
    simulator.stop()


@pytest.fixture
def device(sim):
    return sim.device


@pytest.fixture
def button_sim(tmp_path):
    simulator = Simulator(tmp_path / "flash.bin", tmp_path / "button")
    simulator.start()
    yield simulator
    simulator.stop()