"""Typed cost-IR tests (method-spec §7.1).

Schema invariants are enforced at IR construction, so a malformed proposal can never
exist as a value (§3 Step 2). Loading the IR projection from a bundle is FAIL-FAST:
a missing file raises (required input — contrast the tolerant inbox, §5). Pure
config/file-layer — no model client, no API key, no network.
"""

from __future__ import annotations

from pathlib import Path
from typing import Any

import pytest
from pydantic import ValidationError

from portfolio_optimiser_claude.ir import SavingsProposal, load_validator_input

BUNDLE = Path(__file__).resolve().parents[1] / "shared" / "examples" / "bygg-energi-mikro"

VALID: dict[str, Any] = {
    "project_id": "P1",
    "measure": "LED retrofit",
    "affected_items": [{"code": "EL", "quantity": 1000, "unit_cost": 1.0}],
    "claimed_saving_nok": 200,
    "assumptions": {"EL": [0.8, 1.2]},
}


def build(**overrides: Any) -> SavingsProposal:
    return SavingsProposal(**{**VALID, **overrides})


class TestSchemaInvariants:
    """§7.1: invariants hold at construction — a schema error, never a validator call."""

    def test_valid_proposal_constructs(self) -> None:
        proposal = build()
        assert proposal.project_id == "P1"
        assert proposal.assumptions["EL"] == (0.8, 1.2)

    def test_empty_affected_items_rejected(self) -> None:
        with pytest.raises(ValidationError):
            build(affected_items=[])

    def test_negative_quantity_rejected(self) -> None:
        with pytest.raises(ValidationError):
            build(affected_items=[{"code": "EL", "quantity": -1, "unit_cost": 1.0}])

    @pytest.mark.parametrize("bad", [0, -0.5])
    def test_nonpositive_unit_cost_rejected(self, bad: float) -> None:
        with pytest.raises(ValidationError):
            build(affected_items=[{"code": "EL", "quantity": 1000, "unit_cost": bad}])

    @pytest.mark.parametrize("bad", [0, -100])
    def test_nonpositive_claimed_saving_rejected(self, bad: float) -> None:
        with pytest.raises(ValidationError):
            build(claimed_saving_nok=bad)

    def test_claim_above_affected_total_is_schema_error(self) -> None:
        # The claimed saving MUST NOT exceed the affected items' own total
        # (Σ quantity·unit_cost = 1000) — a schema error, not a validator rejection.
        with pytest.raises(ValidationError):
            build(claimed_saving_nok=1001)

    def test_claim_equal_to_affected_total_allowed(self) -> None:
        assert build(claimed_saving_nok=1000).claimed_saving_nok == 1000

    def test_assumptions_default_to_empty(self) -> None:
        # Empty assumptions = degenerate band, no spread (§7.1).
        proposal = build(assumptions={})
        assert proposal.assumptions == {}


class TestFailFastLoader:
    """§7.1: the IR projection is required input — a missing file raises."""

    def test_loads_shared_bundle_projection_unchanged(self) -> None:
        proposal = load_validator_input(BUNDLE)
        assert proposal.project_id == "BYGG-KONTOR-NORD"
        assert [item.code for item in proposal.affected_items] == ["ENERGI-TOTAL-EL"]
        assert proposal.assumptions["ENERGI-TOTAL-EL"] == (0.70, 1.40)

    def test_missing_projection_raises(self, tmp_path: Path) -> None:
        with pytest.raises(FileNotFoundError):
            load_validator_input(tmp_path)