"""Golden tests for IMMUTABLE_DECISION_LEDGER_V1 (governance/todo/v8_9_p2_adoption_plan.yaml P2-C).

Maps to v8.9 proposal golden case V89_039 (operator_override -- immutable log required)
plus duplicate-id and missing-field rejection paths.
"""
from __future__ import annotations

import importlib.util
from pathlib import Path

ROOT = Path(__file__).resolve().parents[3]
MODULE_PATH = ROOT / "tools" / "build_immutable_decision_ledger_v1.py"


def _load_module():
    spec = importlib.util.spec_from_file_location("build_immutable_decision_ledger_v1", MODULE_PATH)
    module = importlib.util.module_from_spec(spec)
    assert spec.loader is not None
    spec.loader.exec_module(module)
    return module


def _decision(decision_id="D1"):
    return {
        "decision_id": decision_id,
        "engine_version": "PORTFOLIO_TRANSITION_UTILITY_V1",
        "input_hash_bundle": "abc123",
        "execution_mode": "NO_TRADE",
        "candidate_ids": ["A"],
    }


def test_v89_039_new_decision_appends_successfully() -> None:
    mod = _load_module()
    ledger = {"formula_id": "IMMUTABLE_DECISION_LEDGER_V1", "records": []}
    new_ledger, status = mod.append_decision(ledger, _decision())
    assert status == "APPENDED"
    assert len(new_ledger["records"]) == 1


def test_duplicate_decision_id_rejected_original_unchanged() -> None:
    mod = _load_module()
    ledger = {"formula_id": "IMMUTABLE_DECISION_LEDGER_V1", "records": []}
    ledger, _ = mod.append_decision(ledger, _decision())
    original_record = ledger["records"][0]

    new_ledger, status = mod.append_decision(ledger, _decision())
    assert status == "DUPLICATE_DECISION_ID"
    assert new_ledger["records"][0] == original_record
    assert len(new_ledger["records"]) == 1


def test_missing_required_field_rejected_not_filled_with_default() -> None:
    mod = _load_module()
    ledger = {"formula_id": "IMMUTABLE_DECISION_LEDGER_V1", "records": []}
    incomplete = _decision()
    incomplete["decision_id"] = None
    new_ledger, status = mod.append_decision(ledger, incomplete)
    assert status == "REJECTED_MISSING_FIELDS"
    assert new_ledger["records"] == []