from __future__ import annotations

import pytest

from app.core.llm_gateway import LlmGateway, LlmUseCase


class _FakeProvider:
    def __init__(self, name: str) -> None:
        self.name = name
        self.langchain_llm = f"lc-{name}"
        self.complete_calls: list[dict] = []

    async def complete(self, messages, **kwargs) -> str:
        self.complete_calls.append({"messages": messages, **kwargs})
        return f"ok-{self.name}"


def test_llm_gateway_selects_default_or_fast_provider(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    from app.core import llm_gateway as gateway_mod

    default = _FakeProvider("default")
    fast = _FakeProvider("fast")
    monkeypatch.setattr(gateway_mod, "get_llm_provider", lambda: default)
    monkeypatch.setattr(gateway_mod, "get_llm_provider_fast", lambda: fast)

    gateway = LlmGateway()

    assert gateway.langchain_llm_for() == "lc-default"
    assert gateway.langchain_llm_for(LlmUseCase("memory", fast=True)) == "lc-fast"


@pytest.mark.asyncio
async def test_llm_gateway_chat_text_applies_use_case_defaults(
    monkeypatch: pytest.MonkeyPatch,
) -> None:
    from app.core import llm_gateway as gateway_mod

    provider = _FakeProvider("default")
    monkeypatch.setattr(gateway_mod, "get_llm_provider", lambda: provider)

    text = await LlmGateway().chat_text(
        [{"role": "user", "content": "hi"}],
        use_case=LlmUseCase(
            "chat",
            max_tokens=99,
            temperature=0.2,
            model="model-a",
        ),
    )

    assert text == "ok-default"
    assert provider.complete_calls == [
        {
            "messages": [{"role": "user", "content": "hi"}],
            "temperature": 0.2,
            "model": "model-a",
            "max_tokens": 99,
        }
    ]