"""Explicit, isolated low-Mach GPU test configuration."""
import json
from pathlib import Path
from tempfile import TemporaryDirectory

from CelerisLab.simulation import Simulation


def make_sim(nx=128, ny=64, *, streaming="double_buffer", precision="FP32",
             shifted=False, collision="SRT", y_wall="bounce_back", **physics):
    config_path = Path(__file__).resolve().parents[2] / "src/CelerisLab/configs/config_lbm.json"
    cfg = json.loads(config_path.read_text())
    cfg["grid"].update(nx=nx, ny=ny, nz=1, lattice_model="D2Q9")
    cfg["physics"].update(viscosity=0.05, velocity=0.02, rho=1.0)
    cfg["physics"].update(physics)
    cfg["method"].update(collision=collision, streaming=streaming,
                          store_precision=precision, ddf_shifting=shifted, y_wall_bc=y_wall)
    cfg["method"]["les"]["enabled"] = False
    with TemporaryDirectory(prefix="celeris-test-config-") as temp:
        lbm = Path(temp) / "lbm.json"
        bodies = Path(temp) / "bodies.json"
        lbm.write_text(json.dumps(cfg))
        bodies.write_text('{"objects": []}')
        return Simulation(lbm_config_path=str(lbm), body_config_path=str(bodies))