import pytest

from src.api.endpoints import chat
from src.backends.chat import ChatInput, ChatResult, FormUpdate, TextDelta
from src.schemas.models import ProcessRequest_chat


class FakeBackend:
    def __init__(self):
        self.received = []

    async def stream(self, chat_input: ChatInput):
        self.received.append(chat_input)
        yield TextDelta("<sta")
        yield TextDelta("te>1002</state>你")
        yield FormUpdate({"jdcsl": 2})
        yield TextDelta("好")

    async def complete(self, chat_input: ChatInput):
        self.received.append(chat_input)
        return ChatResult(
            content="<state>1002</state>你好",
            status_code="1002",
            form_update={"jdcsl": 2},
        )


def make_request():
    return ProcessRequest_chat(
        sessionId="session-001",
        timeStamp="20260725120000",
        text="发生了交通事故",
        needFormUpdate=True,
    )


@pytest.mark.asyncio
async def test_non_stream_chat_uses_backend_neutral_result():
    backend = FakeBackend()

    response = await chat(make_request(), stream=False, backend=backend)

    assert response.outputText == "你好"
    assert response.nextStageCode == "1002"
    assert response.formUpdate == {"jdcsl": 2}
    assert backend.received == [
        ChatInput(
            session_id="session-001",
            text="发生了交通事故",
            need_form_update=True,
        )
    ]


@pytest.mark.asyncio
async def test_stream_chat_keeps_state_prefix_buffering_in_fastapi_layer():
    backend = FakeBackend()

    response = await chat(make_request(), stream=True, backend=backend)
    chunks = []
    async for chunk in response.body_iterator:
        chunks.append(chunk.decode() if isinstance(chunk, bytes) else chunk)
    body = "".join(chunks)

    assert body.index("event: stage_code") < body.index("event: text_delta")
    assert '"nextStageCode": "1002"' in body
    assert '"text": "你"' in body
    assert '"text": "好"' in body
    assert "event: formUpdate" in body
    assert "event: done" in body