"""One execution boundary shared by XML API and native validation tools."""
from __future__ import annotations

import os

from app.simulation.config import SolveIVPConfig


DEFAULT_NUMERIC_ENGINE = "native"


def numeric_engine_name(backend: str | None = None) -> str:
    configured = backend or os.environ.get("SIMULATION_NUMERIC_ENGINE", "")
    selected = configured.strip().lower() or DEFAULT_NUMERIC_ENGINE
    if selected == "native-c":
        return "native"
    if selected == "native":
        return selected
    if selected == "python":
        raise ValueError("The Python numerical backend has been removed. Use SIMULATION_NUMERIC_ENGINE=native.")
    raise ValueError(f"Unknown simulation engine: {selected}.")


def simulation_config(simulation) -> SolveIVPConfig:
    # Match the validated native pipe/chamber accuracy. Per-state SI absolute
    # floors are emitted by native_codegen.tolerances; XML tolerance fields
    # remain a separate protocol change.
    return SolveIVPConfig(t_start=simulation.t_start, t_stop=simulation.t_stop,
                         method=simulation.method, rtol=1e-8, max_step=simulation.max_step)


def simulate_network(network, simulation, *, progress_callback=None,
                     cancel_check=None, activity_tracker=None, backend=None, raw_series=False):
    numeric_engine_name(backend)
    config = simulation_config(simulation)
    from app.simulation.native_codegen.runner import simulate_native
    return simulate_native(network, config, sample_step=simulation.sample_step, progress_callback=progress_callback,
               cancel_check=cancel_check, activity_tracker=activity_tracker, raw_series=raw_series)