"""Grafting similarity onto existing methods: where it works and where not.

The project's one clear success was a graft - the credit safeguard turned
regula falsi, the secant rule and inverse quadratic interpolation into methods
that solve 193 of 199 with a near-bisection worst case.  This file pins the
graft that FAILED, and the boundary the two of them mark out.
"""
from __future__ import annotations

import math
import os
import sys

import pytest

sys.path.insert(0, os.path.dirname(os.path.dirname(os.path.abspath(__file__))))

from simroot.baselines import brent, chandrupatla
from stage16_blend import brent_blend, chandrupatla_blend, load, measure

PROBS = load()


def both(m):
    t, ok, worst = measure(m, PROBS)
    return t["APS"] + t["CHA"], ok["APS"] + ok["CHA"], worst


def test_the_controls_reproduce_the_published_methods_exactly():
    """Without this the experiment is void: a blend must be compared against
    the same code with the blend switched off, not against a different
    implementation."""
    pub_b = both(lambda f, a, b, xt, mx: brent(f, a, b, xt, mx))
    off_b = both(lambda f, a, b, xt, mx: brent_blend(f, a, b, xt, mx,
                                                     mode="off"))
    assert pub_b == off_b, (pub_b, off_b)
    pub_c = both(lambda f, a, b, xt, mx: chandrupatla(f, a, b, xt, mx))
    off_c = both(lambda f, a, b, xt, mx: chandrupatla_blend(f, a, b, xt, mx,
                                                            mode="off"))
    assert pub_c == off_c, (pub_c, off_c)


def test_softening_brents_acceptance_test_makes_it_worse():
    base, _s, _w = both(lambda f, a, b, xt, mx: brent(f, a, b, xt, mx))
    blend, _s2, _w2 = both(lambda f, a, b, xt, mx: brent_blend(f, a, b, xt, mx,
                                                               mode="blend"))
    assert blend > 1.2 * base, (base, blend)


def test_softening_chandrupatlas_acceptance_test_makes_it_worse():
    base, s_base, _w = both(lambda f, a, b, xt, mx: chandrupatla(f, a, b, xt,
                                                                 mx))
    blend, s_blend, _w2 = both(
        lambda f, a, b, xt, mx: chandrupatla_blend(f, a, b, xt, mx,
                                                   mode="blend"))
    assert blend > 1.2 * base, (base, blend)
    assert s_blend < s_base, (s_base, s_blend)   # and it breaks problems


def test_projecting_onto_brents_bound_also_fails():
    """The move that worked inside our own method - project, do not replace -
    does not transfer to somebody else's acceptance condition.  Clamping to
    the boundary produces the most aggressive still-permitted step, which is
    exactly where the interpolation has stopped carrying information."""
    base, s_base, _w = both(lambda f, a, b, xt, mx: brent(f, a, b, xt, mx))
    proj, s_proj, _w2 = both(lambda f, a, b, xt, mx: brent_blend(
        f, a, b, xt, mx, mode="project"))
    assert proj > base, (base, proj)
    assert s_proj < s_base, (s_base, s_proj)


def test_the_boundary_this_marks_out():
    """Three failures against one success, and they differ in kind.

    The safeguard graft succeeded where the quantity being controlled is a
    GRADED QUALITY - how much margin to leave, how bold a step to take.  The
    blend graft failed where the quantity is a VALIDITY CONDITION - whether
    the interpolation model applies at all.  Near such a boundary a point is
    not partly good; it is where the model has just stopped holding, which is
    why Brent and Chandrupatla discard it rather than shrink it."""
    from stage14_is_anything_reusable import RULES, load as load14, measure as m14
    p14 = load14()
    for name, rule in RULES:
        t_raw, s_raw, _w = m14(rule, False, p14)
        t_g, s_g, _w2 = m14(rule, True, p14)
        assert s_g > s_raw and t_g < t_raw, name      # the graft that works
    base, _s, _w = both(lambda f, a, b, xt, mx: brent(f, a, b, xt, mx))
    blend, _s2, _w2 = both(lambda f, a, b, xt, mx: brent_blend(
        f, a, b, xt, mx, mode="blend"))
    assert blend > base                                # the graft that does not