"""镜像生成：成功造出正解相反的镜像；正解相同/生成 null → 返回 None。"""

import pytest

from app.question_gen.adversarial_filter import generate_mirror_question
from core.types import GeneratedQuestion, LLMResponse


class _FakeVLM:
    def __init__(self, content: str):
        self._content = content

    async def chat_with_images(self, messages, images, *, session_id=None, parent_call_id=None):
        return LLMResponse(
            content=self._content, thinking="", model="fake", provider="fake",
            prompt_tokens=0, completion_tokens=0, latency_ms=0,
            ttft_ms=None, max_inter_token_ms=None, cache_hit=False, call_id="c",
        )


def _q():
    return GeneratedQuestion(
        question_id="q1", video_id="v1", task_type="Action Recognition",
        question="X 之前做了什么？", options=("A. 蒸", "B. 炒", "C. 煮", "D. 炸"),
        answer="A", source_nodes=("n1",), difficulty="hard",
        sub_pattern="temporal_reasoning_failure",
    )


@pytest.mark.asyncio
async def test_mirror_distinct_correct_ok():
    vlm = _FakeVLM('{"mirror": {"question": "X 之后做了什么？", '
                   '"options": ["A. 炒", "B. 蒸", "C. 煮", "D. 炸"], "answer": "A"}}')
    mirror = await generate_mirror_question(
        _q(), flip_axis="before/after", vlm=vlm, material=_FakeMaterial(), session_id="s",
    )
    assert mirror is not None
    # 原正解 canonical="蒸"，镜像正解 canonical="炒" → 相异，有效
    assert mirror.answer == "A"
    assert mirror.options[0] == "A. 炒"


@pytest.mark.asyncio
async def test_mirror_same_correct_rejected():
    # 镜像正解 canonical 仍是"蒸" → 造不出有效对 → None
    vlm = _FakeVLM('{"mirror": {"question": "X 之后？", '
                   '"options": ["A. 蒸", "B. 炒", "C. 煮", "D. 炸"], "answer": "A"}}')
    mirror = await generate_mirror_question(
        _q(), flip_axis="before/after", vlm=vlm, material=_FakeMaterial(), session_id="s",
    )
    assert mirror is None


@pytest.mark.asyncio
async def test_mirror_null_returns_none():
    vlm = _FakeVLM('{"mirror": null}')
    mirror = await generate_mirror_question(
        _q(), flip_axis="before/after", vlm=vlm, material=_FakeMaterial(), session_id="s",
    )
    assert mirror is None


@pytest.mark.asyncio
async def test_mirror_malformed_response_returns_none():
    # 畸形 VLM 响应（连 json_repair 都救不回）不得抛异常中断本轮，须返 None
    vlm = _FakeVLM("对不起，我无法完成这个请求。")
    mirror = await generate_mirror_question(
        _q(), flip_axis="before/after", vlm=vlm, material=_FakeMaterial(), session_id="s",
    )
    assert mirror is None


class _FakeMaterial:
    subtitle_sentences = ["先炒后蒸"]
    frame_paths = ["/f1.jpg"]