"""Check a two-dimensional kernel worked example; no ECG training."""
import json
import math
from pathlib import Path

ROOT = Path(__file__).resolve().parent if "__file__" in globals() else Path.cwd()


def reproduce():
    source = json.loads((ROOT / "source.json").read_text(encoding="utf-8"))
    x = math.radians(source["x_degrees"]) / 2
    y = math.radians(source["y_degrees"]) / 2
    alpha = source["fidelity_weight"]
    fidelity = math.cos(x - y) ** 2
    reference_gap = (math.cos(x) - math.cos(y)) ** 2
    return {"fidelity": fidelity, "reference_gap": reference_gap,
            "combined_kernel": alpha * fidelity + (1 - alpha) * reference_gap}


if __name__ == "__main__":
    result = reproduce()
    expected = json.loads((ROOT / "expected.json").read_text(encoding="utf-8"))
    for key, value in expected.items():
        assert math.isclose(result[key], value, rel_tol=0, abs_tol=1e-12), key
    print(json.dumps(result, indent=2))
    print("PASS: kernel worked example checked; no ECG model trained.")