"""CE-Gate e-process 纯函数单元测试。

覆盖 compute_e_value、gate_decision、probation_verdict 三个公共函数
的核心路径与边界条件。
"""

import math

import pytest

from core.evolution.gate import compute_e_value, gate_decision, probation_verdict
from core.evolution.types import GateParams, GateVerdict

_PARAMS = GateParams(
    e_confirm=20.0,
    e_provisional=3.0,
    w_net_min=2,
    delta_min=0.02,
    lambda_dir=-0.642,
    e_rollback=10.0,
)


class TestComputeEValue:
    """compute_e_value 的数学正确性与边界校验。"""

    def test_zero_zero_returns_one(self) -> None:
        """W=L=0 时 e 值应为 1（无证据，中性）。"""
        assert compute_e_value(0, 0) == pytest.approx(1.0)

    def test_negative_w_raises(self) -> None:
        """负 W 应立即报错。"""
        with pytest.raises(ValueError):
            compute_e_value(-1, 0)

    def test_negative_l_raises(self) -> None:
        """负 L 应立即报错。"""
        with pytest.raises(ValueError):
            compute_e_value(0, -1)

    def test_heavy_loss_returns_near_zero(self) -> None:
        """重度失败时 e 值趋近于零。"""
        assert compute_e_value(0, 20) < 0.05

    def test_heavy_win_returns_large(self) -> None:
        """重度胜利时 e 值远大于 100。"""
        assert compute_e_value(10, 0) > 100

    def test_symmetric(self) -> None:
        """W>L 时 e 值应大于 W<L 时。"""
        assert compute_e_value(5, 3) > compute_e_value(3, 5)


class TestGateDecision:
    """gate_decision 四出口优先级链测试。"""

    def test_confirmed_needs_both_e_and_delta(self) -> None:
        """高 e 值 + 足够 delta → accept_confirmed。"""
        v = gate_decision(10, 0, 10, 10, params=_PARAMS)
        assert v.decision == "accept_confirmed"

    def test_continue_on_balanced(self) -> None:
        """平衡局面且题未尽 → continue。"""
        v = gate_decision(3, 3, 6, 20, params=_PARAMS)
        assert v.decision == "continue"

    def test_reject_inertia_on_exhaustion(self) -> None:
        """题尽且证据不足 → reject_inertia。"""
        v = gate_decision(1, 1, 2, 0, params=_PARAMS)
        assert v.decision == "reject_inertia"

    def test_n_used_zero_raises(self) -> None:
        """n_used=0 应立即报错。"""
        with pytest.raises(ValueError):
            gate_decision(0, 0, 0, 10, params=_PARAMS)

    def test_n_remaining_negative_raises(self) -> None:
        """n_remaining<0 应立即报错。"""
        with pytest.raises(ValueError):
            gate_decision(1, 0, 1, -1, params=_PARAMS)


class TestProbationVerdict:
    """probation_verdict 试用期结算测试。"""

    def test_strong_win_confirmed(self) -> None:
        """强烈胜利 → confirmed 转正。"""
        assert probation_verdict(10, 0, params=_PARAMS) == "confirmed"

    def test_strong_loss_rollback(self) -> None:
        """强烈失败 → rollback 回滚。"""
        assert probation_verdict(0, 10, params=_PARAMS) == "rollback"

    def test_balanced_unverified(self) -> None:
        """平衡局面 → unverified 惯性转正。"""
        assert probation_verdict(3, 3, params=_PARAMS) == "unverified"
