"""Unit tests for M02 — the ``response_format`` payload builder.

These assert the OpenAI-standard ``json_schema`` wrapper shape (the only form
empirically verified to enforce on the current llama.cpp server image; see Q2)
and the fail-closed schema hardening (inline enum, ``additionalProperties: false``,
no surviving ``$defs`` indirection). No live server is required.
"""

from __future__ import annotations

import json
from typing import Any

import pytest
from loosecanvas.contracts import SceneAction, SceneActionType, ScenePlan
from loosecanvas.response_format import SCENEPLAN_RESPONSE_FORMAT


def _nested_schema() -> dict[str, Any]:
    return SCENEPLAN_RESPONSE_FORMAT["json_schema"]["schema"]


def test_response_format_is_json_serializable() -> None:
    # Must not raise — fed verbatim to the server as JSON.
    json.dumps(SCENEPLAN_RESPONSE_FORMAT)


def test_response_format_wrapper_shape() -> None:
    assert SCENEPLAN_RESPONSE_FORMAT["type"] == "json_schema"
    json_schema = SCENEPLAN_RESPONSE_FORMAT["json_schema"]
    assert json_schema["name"] == "scene_plan"
    assert json_schema["strict"] is True
    # The schema is nested under json_schema["schema"], not at the top level.
    assert "schema" in json_schema


def test_nested_schema_forbids_additional_properties() -> None:
    schema = _nested_schema()
    assert schema["additionalProperties"] is False
    action_schema = schema["properties"]["actions"]["items"]
    assert action_schema["additionalProperties"] is False


def test_nested_schema_has_no_defs_indirection() -> None:
    schema = _nested_schema()
    assert "$defs" not in schema


def test_action_type_enum_is_inline_and_complete() -> None:
    schema = _nested_schema()
    type_schema = schema["properties"]["actions"]["items"]["properties"]["type"]
    assert "$ref" not in type_schema
    assert set(type_schema["enum"]) == {t.value for t in SceneActionType}


def test_schema_validates_a_real_sceneplan_instance() -> None:
    instance = ScenePlan(
        actions=[
            SceneAction(
                type=SceneActionType.explain_no_change, reasoning="nothing to do"
            )
        ],
        summary="no change",
    ).model_dump(mode="json")

    jsonschema = pytest.importorskip("jsonschema")
    jsonschema.validate(instance=instance, schema=_nested_schema())