"""Tests for the glass-box per-prediction confidence (dee.core.confidence).

The signal is ESM-2's own posterior sharpness at a position, reconstructed
from the ΔLL table (softmax shift-invariant) — a peaked distribution ⇒ high
confidence, a flat one ⇒ low. Weakest-link aggregation across a variant's
mutated positions.
"""
import pandas as pd
import pytest

from dee.core.confidence import (
    attach_confidence,
    position_confidence_from_scores,
    variant_confidence,
)


def _scores(rows):
    """rows: list of (position, mut_aa, delta_ll) — wt_aa fixed 'A'."""
    return pd.DataFrame(
        [{"position": p, "wt_aa": "A", "mut_aa": m, "delta_ll": float(d)} for (p, m, d) in rows]
    )


_MUTS = "CDEFGHIKLMNPQRSTVWY"   # 19 non-Ala AAs


def test_peaked_position_is_high_confidence():
    # One substitution dominates, the rest strongly disfavored → model is sure.
    rows = [(0, m, (5.0 if m == "C" else -10.0)) for m in _MUTS]
    conf = position_confidence_from_scores(_scores(rows))
    assert conf[0] > 0.7


def test_flat_position_is_low_confidence():
    # All substitutions equal to WT → uniform posterior over 20 → confidence ~0.
    rows = [(0, m, 0.0) for m in _MUTS]
    conf = position_confidence_from_scores(_scores(rows))
    assert conf[0] < 0.05


def test_confidence_is_bounded():
    rows = [(0, m, 3.0) for m in _MUTS] + [(1, m, -3.0) for m in _MUTS]
    conf = position_confidence_from_scores(_scores(rows))
    for c in conf.values():
        assert 0.0 <= c <= 1.0


def test_variant_confidence_is_weakest_link():
    pos_conf = {0: 0.9, 5: 0.3, 9: 0.7}
    score, weakest = variant_confidence("A1C,A6D,A10E", pos_conf)
    assert score == pytest.approx(0.3)      # min, not mean
    assert weakest == "A6D"


def test_variant_confidence_none_when_no_scorable_site():
    score, weakest = variant_confidence("A99Z", {0: 0.9})   # position not in map
    assert score is None
    assert weakest == ""


def test_attach_confidence_sets_fields_and_skips_wt():
    pos_conf = {0: 0.8, 1: 0.4}
    rows = [
        {"Variant_ID": "WT", "Mutations_AA": ""},
        {"Variant_ID": "V1", "Mutations_AA": "A1C,A2D"},
    ]
    attach_confidence(rows, pos_conf)
    assert rows[0]["Confidence"] is None
    assert rows[1]["Confidence"] == pytest.approx(0.4)      # weakest of {0.8, 0.4}
    assert rows[1]["Confidence_Weakest"] == "A2D"