"""Structural-block tests (method-spec §3 Step 4).

A claim above the optimistic feasible bound (p90) yields a ``Rejection`` that is a
DISTINCT type from ``ValidatedProposal`` — carrying the claimed and feasible figures
in its reason, and NO percentiles — so it can never be consumed as validated.
"""

from __future__ import annotations

import pytest

from portfolio_optimiser_claude.ir import SavingsProposal
from portfolio_optimiser_claude.validator import (
    Rejection,
    ValidatedProposal,
    validate_proposal,
)


def proposal_claiming(claimed: float) -> SavingsProposal:
    # Degenerate band (no assumptions): every Monte Carlo sample equals the fixed
    # cost, so the feasible bound is exactly 0.30 × 1000 = 300 at every percentile.
    return SavingsProposal(
        project_id="P1",
        measure="test measure",
        affected_items=[{"code": "EL", "quantity": 1000, "unit_cost": 1.0}],
        claimed_saving_nok=claimed,
    )


class TestStructuralBlock:
    """§3 Step 4: the deterministic validator gates the numbers — blocking."""

    def test_claim_above_p90_yields_rejection(self) -> None:
        outcome = validate_proposal(proposal_claiming(500))
        assert isinstance(outcome, Rejection)

    def test_claim_within_p90_yields_validated(self) -> None:
        outcome = validate_proposal(proposal_claiming(200))
        assert isinstance(outcome, ValidatedProposal)
        assert outcome.validates is True
        # Degenerate band: no spread, all percentiles collapse to the fixed bound.
        assert outcome.p10 == outcome.p50 == outcome.p90 == pytest.approx(300.0)

    def test_rejection_reason_carries_claimed_and_feasible_figures(self) -> None:
        outcome = validate_proposal(proposal_claiming(500))
        assert isinstance(outcome, Rejection)
        assert "500" in outcome.reason
        assert "300" in outcome.reason


class TestRejectionIsUnconsumable:
    """§3 Step 4: a distinct type with no percentiles — never consumable as validated."""

    def test_rejection_is_not_a_validated_proposal(self) -> None:
        outcome = validate_proposal(proposal_claiming(500))
        assert not isinstance(outcome, ValidatedProposal)
        assert not issubclass(Rejection, ValidatedProposal)
        assert not issubclass(ValidatedProposal, Rejection)

    def test_rejection_has_no_percentiles(self) -> None:
        outcome = validate_proposal(proposal_claiming(500))
        assert isinstance(outcome, Rejection)
        for field in ("p10", "p50", "p90", "validates"):
            assert not hasattr(outcome, field)