"""Pins the regime findings of stage 7.

Three conclusions were drawn from that analysis and used to decide what to do
next.  Each is asserted here so that a re-run of the sweep which moves them
fails the build instead of quietly invalidating the conclusion.
"""
from __future__ import annotations

import json
import os
import sys

import pytest

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

SWEEP = os.path.join(ROOT, "sweep_full.json")
pytestmark = pytest.mark.skipif(not os.path.exists(SWEEP),
                                reason="sweep_full.json not present")

SCALES = ("start", "bracket", "derived", "derived3")
MAXFEV = 200


def load():
    with open(SWEEP, encoding="utf8") as fh:
        return {r["label"]: r for r in json.load(fh)}


def cost(rows, sim, scale, pid):
    r = rows[f"pure.{sim}.{scale}.project"]
    d = r["APS"]["per"].get(pid) or r["CHA"]["per"].get(pid)
    return d[0] if d[1] else MAXFEV


def all_pids(rows):
    r = rows["pure.ratio.derived3.project"]
    return list(r["APS"]["per"]) + list(r["CHA"]["per"])


def test_the_scale_axis_has_little_headroom():
    """5.3%.  If this ever grows a lot, the scale is worth revisiting; as it
    stands it is not where the regimes live."""
    rows = load()
    pids = all_pids(rows)
    ours = sum(cost(rows, "ratio", "derived3", p) for p in pids)
    oracle = sum(min(cost(rows, "ratio", s, p) for s in SCALES) for p in pids)
    head = (ours - oracle) / ours
    assert 0.0 <= head < 0.10, head


def test_cbrt_beats_us_consistently_on_the_fun4_family():
    """The signature of a real regime rather than luck: the same function at
    five different parameters all prefer the same similarity, by a wide
    margin.  This is the finding that keeps the line open."""
    rows = load()
    fam = [f"fun4.{i}" for i in range(1, 6)]
    better = 0
    for pid in fam:
        ours = cost(rows, "ratio", "derived3", pid)
        cb = cost(rows, "cbrt", "derived3", pid)
        if cb < ours:
            better += 1
    assert better == 5, f"only {better}/5 of the fun4 family prefer cbrt"
    tot_ours = sum(cost(rows, "ratio", "derived3", p) for p in fam)
    tot_cb = sum(cost(rows, "cbrt", "derived3", p) for p in fam)
    assert tot_cb < 0.6 * tot_ours, (tot_cb, tot_ours)


def test_switching_by_benchmark_set_is_worse_than_not_switching():
    """The finding that closed the obvious exploit: cbrt wins the fun3/4/5
    families but loses the rest of Chandrupatla, so a set-level switch costs
    more than a single fixed choice.  Any future 'regime' proposal has to beat
    this, not merely beat one family."""
    rows = load()
    single = (rows["pure.ratio.derived3.project"]["APS"]["total"]
              + rows["pure.ratio.derived3.project"]["CHA"]["total"])
    switched = (rows["pure.ratio.derived3.project"]["APS"]["total"]
                + rows["pure.cbrt.derived3.project"]["CHA"]["total"])
    assert switched > single, (switched, single)


def test_the_proposed_similarity_wins_most_problems_outright():
    """155 of 199.  The per-problem oracle over similarities is an upper
    bound on regime detection, not a method, and most of the field is already
    ours without it."""
    rows = load()
    pids = all_pids(rows)
    sims = ("ratio", "sqrt", "cbrt", "rational", "ratio_soft", "exp_abs",
            "rat_sq", "exp_sq", "cosine")
    wins = 0
    for p in pids:
        c = {s: cost(rows, s, "derived3", p) for s in sims}
        if c["ratio"] == min(c.values()):
            wins += 1
    assert wins >= 150, wins


def test_stage7_runs():
    """The analysis script itself must still execute against the current
    sweep file."""
    import subprocess
    r = subprocess.run([sys.executable, "stage7_regimes.py"], cwd=ROOT,
                       capture_output=True, text=True, timeout=600)
    assert r.returncode == 0, r.stderr[-800:]
    assert "SETTLING THE TWO SUSPICIONS" in r.stdout