"""PREREG_estimated_transform_2026-09-22: the control K3 must be Chandrupatla's method itself when
no order is estimated, and must stay a bracketing method when one is."""
from __future__ import annotations

import math

import pytest

from simroot.baselines import chandrupatla
from simroot.transformed import chandrupatla_transformed
from sweep_full import load_problems

PROBS = load_problems()


def test_without_an_estimate_it_is_chandrupatla_bit_for_bit():
    bad = []
    for s, pid, f, a, b, _r in PROBS:
        r1 = chandrupatla(f, a, b, 1e-12, 200)
        r2 = chandrupatla_transformed(f, a, b, 1e-12, 200, estimator="none")
        if (float(r1[0]).hex(), r1[1], r1[2]) != (float(r2[0]).hex(), r2[1], r2[2]):
            bad.append(pid)
    assert not bad, bad[:5]


@pytest.mark.parametrize("estimator", ("lag", "analogy"))
def test_with_an_estimate_it_still_brackets(estimator):
    for s, pid, f, a, b, _r in PROBS:
        x, n, ok = chandrupatla_transformed(f, a, b, 1e-12, 200, estimator=estimator)
        assert min(a, b) <= x <= max(a, b), pid
        assert n <= 200


def test_the_estimate_is_read_and_used_on_a_pure_power():
    """The analogy estimator must reach m_hat on (t - 1)^9 and pay.  Lagouanelle's is NOT asserted:
    on Chandrupatla's iterates, which alternate sides of the root, its three-point parabola reads
    m ~ 1 at every step - an outcome of the experiment, reported by the run, not a property
    to pin here."""
    f = lambda t: (t - 1.0) ** 9  # noqa: E731
    plain = chandrupatla_transformed(f, -2.0, 5.0, 1e-12, 200, estimator="none")[1]
    st = {}
    x, n, ok = chandrupatla_transformed(f, -2.0, 5.0, 1e-12, 200, estimator="analogy", stats=st)
    assert ok and abs(x - 1.0) < 1e-6
    assert st.get("updates", 0) >= 1
    assert n < plain, (n, plain)
    x, n, ok = chandrupatla_transformed(f, -2.0, 5.0, 1e-12, 200, estimator="lag")
    assert ok and abs(x - 1.0) < 1e-6


def test_an_overflowing_transform_halves_instead_of_raising():
    """Found 2026-09-22: on the fractional branch 1/m_hat > 1 and |f|^(1/m_hat) overflowed with
    an OverflowError that escaped the solver.  Now it is inf, the interpolation is refused, and
    the step halves."""
    from simroot.transformed import _G
    assert _G(1e300, 3.0) == math.inf and _G(-1e300, 3.0) == -math.inf


def test_unknown_estimator_is_refused():
    with pytest.raises(ValueError):
        chandrupatla_transformed(math.sin, 3.0, 4.0, 1e-12, 200, estimator="guess")