"""Tests for the LLMService."""

from __future__ import annotations

import asyncio
import json
import time
from unittest import mock

import pytest

from py.services import llm_service as llm_module
from py.services.errors import LLMNotConfiguredError, LLMRateLimitError, LLMResponseError
from py.services.llm_service import LLMService, fetch_ollama_models


class MockSettings:
    """Minimal settings mock for LLMService tests."""

    def __init__(self, **kwargs):
        self._data = {
            "llm_enabled": False,
            "llm_provider": "openai",
            "llm_api_key": "",
            "llm_api_base": "",
            "llm_model": "",
        }
        self._data.update(kwargs)

    def get(self, key, default=None):
        return self._data.get(key, default)


class MockResponse:
    """Mock aiohttp response."""

    def __init__(self, status, json_data=None, text_data="", headers=None):
        self.status = status
        self._json_data = json_data
        self._text_data = text_data
        self.headers = headers or {}

    async def json(self):
        return self._json_data

    async def text(self):
        return self._text_data

    async def __aenter__(self):
        return self

    async def __aexit__(self, *args):
        pass


class MockSession:
    """Mock aiohttp ClientSession."""

    def __init__(self, response):
        self._response = response
        self.closed = False
        self.last_url = None
        self.last_json = None
        self.last_headers = None

    def post(self, url, json=None, headers=None):
        self.last_url = url
        self.last_json = json
        self.last_headers = headers
        return self._response

    async def __aenter__(self):
        return self

    async def __aexit__(self, *args):
        pass


class RecordingSession:
    """Mock session that records each request payload and replays responses."""

    def __init__(self, responses):
        self._responses = list(responses)
        self.payloads = []

    def post(self, url, json=None, headers=None):
        self.payloads.append(json)
        index = min(len(self.payloads) - 1, len(self._responses) - 1)
        return self._responses[index]

    async def __aenter__(self):
        return self

    async def __aexit__(self, *args):
        pass


@pytest.fixture
def llm_service():
    """Create an LLMService with mock settings."""
    LLMService.reset_instance()
    settings = MockSettings(
        llm_enabled=True,
        llm_provider="openai",
        llm_api_key="sk-test-key",
        llm_api_base="",
        llm_model="gpt-4o-mini",
    )
    return LLMService(settings)


class TestLLMServiceConfiguration:
    def test_is_configured_when_enabled_with_key_and_model(self, llm_service):
        assert llm_service.is_configured() is True

    def test_not_configured_when_disabled(self):
        settings = MockSettings(
            llm_enabled=False, llm_api_key="sk-test", llm_model="gpt-4o"
        )
        service = LLMService(settings)
        # Lenient: model + API key is treated as configured even without
        # the toggle, because the user clearly intends to use the feature.
        assert service.is_configured() is True

    def test_not_configured_without_model(self):
        settings = MockSettings(llm_enabled=True, llm_api_key="sk-test", llm_model="")
        service = LLMService(settings)
        assert service.is_configured() is False

    def test_not_configured_without_api_key_for_openai(self):
        settings = MockSettings(llm_enabled=True, llm_api_key="", llm_model="gpt-4o")
        service = LLMService(settings)
        assert service.is_configured() is False

    def test_ollama_configured_without_api_key(self):
        settings = MockSettings(
            llm_enabled=True, llm_provider="ollama", llm_api_key="", llm_model="llama3"
        )
        service = LLMService(settings)
        assert service.is_configured() is True

    def test_resolve_api_base_openai_default(self, llm_service):
        assert llm_service._resolve_api_base("openai", "") == "https://api.openai.com/v1"

    def test_resolve_api_base_ollama_default(self, llm_service):
        assert llm_service._resolve_api_base("ollama", "") == "http://localhost:11434/v1"

    def test_resolve_api_base_custom_override(self, llm_service):
        assert llm_service._resolve_api_base("custom", "https://my.api.com/v1/") == "https://my.api.com/v1"

    def test_ensure_configured_raises_when_disabled(self):
        settings = MockSettings(llm_enabled=False)
        service = LLMService(settings)
        with pytest.raises(LLMNotConfiguredError):
            service._ensure_configured()

    def test_ensure_configured_raises_without_model(self):
        settings = MockSettings(llm_enabled=True, llm_api_key="sk-test", llm_model="")
        service = LLMService(settings)
        with pytest.raises(LLMNotConfiguredError):
            service._ensure_configured()

    def test_not_configured_custom_without_api_base(self):
        settings = MockSettings(
            llm_enabled=True, llm_provider="custom",
            llm_api_key="sk-test", llm_api_base="", llm_model="gpt-4o",
        )
        service = LLMService(settings)
        assert service.is_configured() is False

    def test_custom_configured_with_api_base(self):
        settings = MockSettings(
            llm_enabled=True, llm_provider="custom",
            llm_api_key="sk-test",
            llm_api_base="https://my.api.com/v1", llm_model="gpt-4o",
        )
        service = LLMService(settings)
        assert service.is_configured() is True

    def test_ensure_configured_raises_custom_without_api_base(self):
        settings = MockSettings(
            llm_enabled=True, llm_provider="custom",
            llm_api_key="sk-test", llm_api_base="", llm_model="gpt-4o",
        )
        service = LLMService(settings)
        with pytest.raises(LLMNotConfiguredError, match="API base URL"):
            service._ensure_configured()


class TestLLMServiceChatCompletion:
    @pytest.mark.asyncio
    async def test_chat_completion_success(self, llm_service):
        mock_response = MockResponse(
            200,
            json_data={
                "choices": [{"message": {"content": "Hello!"}}],
                "usage": {"total_tokens": 10},
                "model": "gpt-4o-mini",
            },
        )
        mock_session = MockSession(mock_response)

        with mock.patch("aiohttp.ClientSession", return_value=mock_session):
            result = await llm_service.chat_completion(
                messages=[{"role": "user", "content": "Hi"}],
            )

        assert result["content"] == "Hello!"
        assert result["usage"]["total_tokens"] == 10
        assert result["model"] == "gpt-4o-mini"

    @pytest.mark.asyncio
    async def test_chat_completion_raises_on_not_configured(self):
        settings = MockSettings(llm_enabled=False)
        service = LLMService(settings)
        with pytest.raises(LLMNotConfiguredError):
            await service.chat_completion(messages=[])

    @pytest.mark.asyncio
    async def test_chat_completion_raises_on_http_error(self, llm_service):
        mock_response = MockResponse(500, text_data="Internal Server Error")
        mock_session = MockSession(mock_response)

        with mock.patch("aiohttp.ClientSession", return_value=mock_session):
            with pytest.raises(LLMResponseError, match="HTTP 500"):
                await llm_service.chat_completion(messages=[])

    @pytest.mark.asyncio
    async def test_chat_completion_raises_on_rate_limit(self, llm_service):
        mock_response = MockResponse(429, text_data="Rate limited", headers={"Retry-After": "0"})
        mock_session = MockSession(mock_response)

        with mock.patch("aiohttp.ClientSession", return_value=mock_session):
            with pytest.raises(LLMRateLimitError):
                await llm_service.chat_completion(
                    messages=[], retry_on_rate_limit=False
                )

    @pytest.mark.asyncio
    async def test_chat_completion_raises_on_bad_response_structure(self, llm_service):
        mock_response = MockResponse(200, json_data={"unexpected": "data"})
        mock_session = MockSession(mock_response)

        with mock.patch("aiohttp.ClientSession", return_value=mock_session):
            with pytest.raises(LLMResponseError, match="Unexpected LLM response"):
                await llm_service.chat_completion(messages=[])


class TestLLMServiceChatCompletionJson:
    @pytest.mark.asyncio
    async def test_chat_completion_json_parses_json(self, llm_service):
        mock_response = MockResponse(
            200,
            json_data={
                "choices": [{"message": {"content": '{"key": "value"}'}}],
                "usage": {},
                "model": "gpt-4o-mini",
            },
        )
        mock_session = MockSession(mock_response)

        with mock.patch("aiohttp.ClientSession", return_value=mock_session):
            result = await llm_service.chat_completion_json(
                system_prompt="You are helpful.",
                user_prompt="Return JSON.",
            )

        assert result == {"key": "value"}

    @pytest.mark.asyncio
    async def test_chat_completion_json_falls_back_on_response_format_rejection(
        self, llm_service,
    ):
        """Retry without response_format when provider rejects it (HTTP 400)."""
        error_response = MockResponse(
            400,
            text_data=(
                '{"error":"\'response_format.type\' must be '
                '\'json_schema\' or \'text\'"}'
            ),
        )
        success_response = MockResponse(
            200,
            json_data={
                "choices": [{"message": {"content": '{"key": "value"}'}}],
                "usage": {},
                "model": "local-model",
            },
        )

        call_index = 0

        class FallbackMockSession:
            def __init__(self):
                self.last_url = None
                self.last_json = None

            def post(self, url, json=None, headers=None):
                nonlocal call_index
                self.last_url = url
                self.last_json = json
                call_index += 1
                return error_response if call_index == 1 else success_response

            async def __aenter__(self):
                return self

            async def __aexit__(self, *args):
                pass

        with mock.patch("aiohttp.ClientSession", return_value=FallbackMockSession()):
            result = await llm_service.chat_completion_json(
                system_prompt="You are helpful.",
                user_prompt="Return JSON.",
            )

        assert result == {"key": "value"}
        assert call_index == 2

    @pytest.mark.asyncio
    async def test_chat_completion_json_prefers_json_object_for_deepseek(self):
        """DeepSeek rejects json_schema, so json_object is used first.

        Regression: DeepSeek answers json_schema with
        "This response_format type is unavailable now", which the old
        substring check did not recognise, so enrichment failed outright.
        """
        settings = MockSettings(
            llm_enabled=True,
            llm_provider="deepseek",
            llm_api_key="sk-test-key",
            llm_api_base="https://api.deepseek.com/v1",
            llm_model="deepseek-v4-flash",
        )
        service = LLMService(settings)

        session = RecordingSession(
            [
                MockResponse(
                    200,
                    json_data={
                        "choices": [{"message": {"content": '{"key": "value"}'}}],
                        "usage": {},
                    },
                )
            ]
        )

        with mock.patch("aiohttp.ClientSession", return_value=session):
            result = await service.chat_completion_json(
                system_prompt="You are helpful.",
                user_prompt="Return JSON.",
            )

        assert result == {"key": "value"}
        assert len(session.payloads) == 1
        assert session.payloads[0]["response_format"] == {"type": "json_object"}

    @pytest.mark.asyncio
    async def test_chat_completion_json_downgrades_from_json_schema(
        self, llm_service,
    ):
        """json_schema → json_object when the provider rejects json_schema."""
        session = RecordingSession(
            [
                MockResponse(
                    400,
                    text_data=(
                        '{"error":{"message":"This response_format type is '
                        'unavailable now","type":"invalid_request_error"}}'
                    ),
                ),
                MockResponse(
                    200,
                    json_data={
                        "choices": [{"message": {"content": '{"key": "value"}'}}],
                        "usage": {},
                    },
                ),
            ]
        )

        with mock.patch("aiohttp.ClientSession", return_value=session):
            result = await llm_service.chat_completion_json(
                system_prompt="You are helpful.",
                user_prompt="Return JSON.",
            )

        assert result == {"key": "value"}
        assert [p.get("response_format") for p in session.payloads] == [
            {
                "type": "json_schema",
                "json_schema": {"name": "metadata", "schema": {"type": "object"}},
            },
            {"type": "json_object"},
        ]

    @pytest.mark.asyncio
    async def test_chat_completion_json_does_not_retry_unrelated_errors(
        self, llm_service,
    ):
        """Unrelated 400s are surfaced unchanged, without format downgrades."""
        session = RecordingSession(
            [
                MockResponse(
                    400,
                    text_data='{"error":{"message":"Model not found"}}',
                )
            ]
        )

        with mock.patch("aiohttp.ClientSession", return_value=session):
            with pytest.raises(LLMResponseError, match="HTTP 400"):
                await llm_service.chat_completion_json(
                    system_prompt="You are helpful.",
                    user_prompt="Return JSON.",
                )

        assert len(session.payloads) == 1

    @pytest.mark.asyncio
    async def test_chat_completion_json_raises_on_non_json(self, llm_service):
        # Non-JSON content raises LLMResponseError (salvage also fails)
        mock_response = MockResponse(
            200,
            json_data={
                "choices": [{"message": {"content": "not json at all"}}],
                "usage": {},
            },
        )
        mock_session = MockSession(mock_response)

        with mock.patch("aiohttp.ClientSession", return_value=mock_session):
            with pytest.raises(LLMResponseError, match="could not be parsed as JSON"):
                await llm_service.chat_completion_json(
                    system_prompt="test",
                    user_prompt="test",
                )


class MockGetSession:
    """Minimal aiohttp session mock supporting get() for catalog tests."""

    def __init__(self, response):
        self._response = response
        self.last_url = None
        self.last_headers = None

    def get(self, url, headers=None):
        self.last_url = url
        self.last_headers = headers
        return self._response

    async def __aenter__(self):
        return self

    async def __aexit__(self, *args):
        pass


class CorruptJsonResponse(MockResponse):
    """Response whose body cannot be decoded as UTF-8 (like the issue's 0x9a byte)."""

    async def json(self):
        raise UnicodeDecodeError("utf-8", b"\x9a", 0, 1, "invalid start byte")


class SlowResponse(MockResponse):
    """Response whose body takes a moment to read, to force contention."""

    async def json(self):
        await asyncio.sleep(0.05)
        return self._json_data


class TestModelCatalog:
    """Tests for _load_model_catalog / fetch_ollama_models error handling."""

    @pytest.fixture(autouse=True)
    def _reset_catalog_cache(self):
        """Reset the module-level catalog cache around each test."""
        llm_module._catalog_cache = None
        llm_module._model_output_limits = {}
        llm_module._catalog_last_failure = None
        yield
        llm_module._catalog_cache = None
        llm_module._model_output_limits = {}
        llm_module._catalog_last_failure = None

    @pytest.mark.asyncio
    async def test_load_model_catalog_falls_back_on_unicode_decode_error(self):
        """Corrupted catalog body must not raise — fall back to an empty dict."""
        response = CorruptJsonResponse(200)
        session = MockGetSession(response)

        with mock.patch("aiohttp.ClientSession", return_value=session):
            catalog = await llm_module._load_model_catalog()

        assert catalog == {}

    @pytest.mark.asyncio
    async def test_fetch_ollama_models_falls_back_on_unicode_decode_error(self):
        """Corrupted Ollama response must not raise — fall back to an empty list."""
        response = CorruptJsonResponse(200)
        session = MockGetSession(response)

        with mock.patch("aiohttp.ClientSession", return_value=session):
            models = await fetch_ollama_models("http://localhost:11434/v1")

        assert models == []

    @pytest.mark.asyncio
    async def test_catalog_request_disables_brotli_encoding(self):
        """The catalog request must not advertise br — a corrupt brotli stream
        can crash the native decoder (Windows access violation, issue #1099)."""
        response = MockResponse(200, json_data={})
        session = MockGetSession(response)

        with mock.patch("aiohttp.ClientSession", return_value=session):
            await llm_module._load_model_catalog()

        assert session.last_headers == {"Accept-Encoding": "gzip, deflate"}

    @pytest.mark.asyncio
    async def test_ollama_request_disables_brotli_encoding(self):
        """The Ollama models request must not advertise br either."""
        response = MockResponse(200, json_data={"data": [{"id": "llama3"}]})
        session = MockGetSession(response)

        with mock.patch("aiohttp.ClientSession", return_value=session):
            models = await fetch_ollama_models("http://localhost:11434/v1")

        assert models == ["llama3"]
        assert session.last_headers == {"Accept-Encoding": "gzip, deflate"}

    @pytest.mark.asyncio
    async def test_failed_fetch_is_negatively_cached(self):
        """A failed fetch is not retried until the cooldown elapses."""
        created = []

        def factory(*args, **kwargs):
            session = MockGetSession(MockResponse(500, text_data="error"))
            created.append(session)
            return session

        with mock.patch("aiohttp.ClientSession", side_effect=factory):
            first = await llm_module._load_model_catalog()
            second = await llm_module._load_model_catalog()

        assert first == {}
        assert second == {}
        assert len(created) == 1
        assert llm_module._catalog_last_failure is not None

    @pytest.mark.asyncio
    async def test_fetch_retries_after_cooldown(self):
        """Once the cooldown elapses, the next call fetches again."""
        bad = MockGetSession(MockResponse(500, text_data="error"))
        with mock.patch("aiohttp.ClientSession", return_value=bad):
            assert await llm_module._load_model_catalog() == {}

        # Simulate the cooldown having elapsed.
        llm_module._catalog_last_failure = (
            time.monotonic() - llm_module._CATALOG_FAILURE_COOLDOWN - 1
        )

        good = MockGetSession(
            MockResponse(200, json_data={"openai": {"models": {"gpt-4o": {}}}})
        )
        with mock.patch("aiohttp.ClientSession", return_value=good):
            catalog = await llm_module._load_model_catalog()

        assert catalog == {"openai": ["gpt-4o"]}

    @pytest.mark.asyncio
    async def test_concurrent_fetches_are_deduplicated(self):
        """Concurrent callers share a single in-flight fetch."""
        created = []

        def factory(*args, **kwargs):
            session = MockGetSession(
                SlowResponse(200, json_data={"openai": {"models": {"gpt-4o": {}}}})
            )
            created.append(session)
            return session

        with mock.patch("aiohttp.ClientSession", side_effect=factory):
            results = await asyncio.gather(
                *(llm_module._load_model_catalog() for _ in range(3))
            )

        assert len(created) == 1
        assert all(r == {"openai": ["gpt-4o"]} for r in results)