import pytest

from sentence_api.ai_tutor import AITutor, AITutorError


class FakeResponse:
    def __init__(self, status_code=200, body=None):
        self.status_code = status_code
        self.text = str(body)
        self._body = body or {}

    def json(self):
        if self._body is None:
            raise ValueError("invalid JSON")
        return self._body


def test_ai_tutor_parses_chat_completion(monkeypatch):
    requests_payloads = []

    def fake_post(endpoint, headers, json, timeout):
        requests_payloads.append((endpoint, headers, json, timeout))
        return FakeResponse(
            body={
                "choices": [
                    {"message": {"content": " 这句话的意思是…… "}}
                ]
            }
        )

    monkeypatch.setattr("sentence_api.ai_tutor.requests.post", fake_post)
    tutor = AITutor("https://ai.test/chat", "secret", "test-model", 1.5)

    explanation = tutor.explain(
        "The early bird catches the worm.",
        course_title="English idioms",
        sentence_index=1,
        language="en",
    )

    endpoint, headers, payload, timeout = requests_payloads[0]
    assert explanation == "这句话的意思是……"
    assert endpoint == "https://ai.test/chat"
    assert headers["Authorization"] == "Bearer secret"
    assert payload["model"] == "test-model"
    assert "The early bird catches the worm." in payload["messages"][1]["content"]
    assert timeout == 1.5


def test_ai_tutor_resolves_openai_compatible_base_url(monkeypatch):
    endpoints = []

    def fake_post(endpoint, **kwargs):
        endpoints.append(endpoint)
        return FakeResponse(body={"choices": [{"message": {"content": "ok"}}]})

    monkeypatch.setattr("sentence_api.ai_tutor.requests.post", fake_post)
    tutor = AITutor("https://ai.test:8080/v1", "secret", "test-model", 1)

    assert tutor.explain("Hello.") == "ok"
    assert endpoints == ["https://ai.test:8080/v1/chat/completions"]
    assert tutor.request_url == "https://ai.test:8080/v1/chat/completions"


def test_ai_tutor_rejects_unexpected_response(monkeypatch):
    monkeypatch.setattr(
        "sentence_api.ai_tutor.requests.post",
        lambda *args, **kwargs: FakeResponse(body={"choices": []}),
    )
    tutor = AITutor("https://ai.test/chat", "secret", "test-model", 1)

    with pytest.raises(AITutorError):
        tutor.explain("Hello.")