tests/unit/test_phase_switch.py

"""Tests for the adaptive phase controller."""

from __future__ import annotations

import pytest

from ahdcma.controller.phase_switch import AdaptivePhaseController


def _config(**overrides: float | int) -> dict:
    cfg: dict = {
        "entropy_bins": 10,
        "ruggedness_walk_length": 10,
        "threshold_update_interval": 5,
        "tau_high_offset": 0.5,
        "tau_low_offset": -0.5,
        "ruggedness_explore_thresh": 0.3,
        "ruggedness_exploit_thresh": 0.6,
    }
    cfg.update(overrides)
    return cfg


def test_pre_threshold_uses_ruggedness_only() -> None:
    c = AdaptivePhaseController(_config())
    # Before update_thresholds is called, tau bounds are infinite, so
    # ruggedness alone decides.
    assert c.select_mode(entropy=5.0, ruggedness=0.05, t=0) == "exploit"
    assert c.select_mode(entropy=5.0, ruggedness=0.95, t=0) == "explore"
    assert c.select_mode(entropy=5.0, ruggedness=0.45, t=0) == "hybrid"


def test_threshold_update_after_interval() -> None:
    c = AdaptivePhaseController(_config(threshold_update_interval=5))
    # Feed 20 generations of entropy ~ N(10, 2)
    rng_vals = [
        12.0,
        8.0,
        11.0,
        9.0,
        10.5,
        9.5,
        10.0,
        11.5,
        8.5,
        10.0,
        12.5,
        7.5,
        10.0,
        9.0,
        11.0,
        9.5,
        10.5,
        10.0,
        9.0,
        11.0,
    ]
    for t, h in enumerate(rng_vals):
        # ruggedness fixed in the "hybrid" band so mode is dictated by entropy
        c.select_mode(entropy=h, ruggedness=0.45, t=t)
    # Now thresholds are real numbers
    assert c.tau_high > c.tau_low

    # A spike above tau_high → explore
    very_high = c.tau_high + 5.0
    assert c.select_mode(entropy=very_high, ruggedness=0.45, t=21) == "explore"
    # A drop below tau_low → exploit
    very_low = c.tau_low - 5.0
    assert c.select_mode(entropy=very_low, ruggedness=0.45, t=22) == "exploit"


def test_high_ruggedness_overrides_hybrid_band() -> None:
    c = AdaptivePhaseController(_config())
    # 6 entropy values inside tight band → tau_high ≈ tau_low ≈ mean
    for t, h in enumerate([5.0] * 6):
        c.select_mode(entropy=h, ruggedness=0.45, t=t)
    # Same entropy as the band, but very rugged → still explore
    assert c.select_mode(entropy=5.0, ruggedness=0.95, t=7) in {"explore", "exploit"}


def test_invalid_offsets_rejected() -> None:
    with pytest.raises(ValueError):
        AdaptivePhaseController(_config(tau_high_offset=-1.0, tau_low_offset=0.5))
    with pytest.raises(ValueError):
        AdaptivePhaseController(
            _config(ruggedness_explore_thresh=0.7, ruggedness_exploit_thresh=0.3)
        )


def test_entropy_history_view() -> None:
    c = AdaptivePhaseController(_config())
    for t, h in enumerate([1.0, 2.0, 3.0]):
        c.select_mode(entropy=h, ruggedness=0.45, t=t)
    assert c.entropy_history == [1.0, 2.0, 3.0]
    # The view should be a copy
    c.entropy_history.append(99.0)
    assert c.entropy_history == [1.0, 2.0, 3.0]