# Copyright (c) Microsoft. All rights reserved.

"""Shared test fixtures and stubs for AG-UI tests."""

import sys
from collections.abc import AsyncIterable, AsyncIterator, Awaitable, Callable, Mapping, MutableSequence, Sequence
from pathlib import Path
from types import SimpleNamespace
from typing import Any, Generic, Literal, cast, overload

import pytest
from agent_framework import (
    AgentResponse,
    AgentResponseUpdate,
    AgentSession,
    BaseChatClient,
    ChatOptions,
    ChatResponse,
    ChatResponseUpdate,
    Content,
    Message,
    SupportsAgentRun,
    SupportsChatGetResponse,
)
from agent_framework._clients import OptionsCoT
from agent_framework._middleware import ChatMiddlewareLayer
from agent_framework._tools import FunctionInvocationLayer
from agent_framework._types import ResponseStream
from agent_framework.observability import ChatTelemetryLayer

if sys.version_info >= (3, 12):
    from typing import override  # type: ignore # pragma: no cover
else:
    from typing_extensions import override  # type: ignore[import] # pragma: no cover

StreamFn = Callable[..., AsyncIterable[ChatResponseUpdate]]
ResponseFn = Callable[..., Awaitable[ChatResponse]]


def pytest_configure() -> None:
    """Ensure this test directory is on sys.path so helper modules can be imported by name."""
    test_dir = str(Path(__file__).resolve().parent)
    if test_dir not in sys.path:
        sys.path.insert(0, test_dir)


class StreamingChatClientStub(
    FunctionInvocationLayer[OptionsCoT],
    ChatMiddlewareLayer[OptionsCoT],
    ChatTelemetryLayer[OptionsCoT],
    BaseChatClient[OptionsCoT],
    Generic[OptionsCoT],
):
    """Typed streaming stub that satisfies SupportsChatGetResponse."""

    def __init__(self, stream_fn: StreamFn, response_fn: ResponseFn | None = None) -> None:
        super().__init__(middleware=[])
        self._stream_fn = stream_fn
        self._response_fn = response_fn
        self.last_session: AgentSession | None = None
        self.last_service_session_id: str | None = None

    @overload
    def get_response(
        self,
        messages: Sequence[Message],
        *,
        stream: Literal[False] = ...,
        options: ChatOptions[Any],
        **kwargs: Any,
    ) -> Awaitable[ChatResponse[Any]]: ...

    @overload
    def get_response(
        self,
        messages: Sequence[Message],
        *,
        stream: Literal[False] = ...,
        options: OptionsCoT | ChatOptions[None] | None = ...,
        **kwargs: Any,
    ) -> Awaitable[ChatResponse[Any]]: ...

    @overload
    def get_response(
        self,
        messages: Sequence[Message],
        *,
        stream: Literal[True],
        options: OptionsCoT | ChatOptions[Any] | None = ...,
        **kwargs: Any,
    ) -> ResponseStream[ChatResponseUpdate, ChatResponse[Any]]: ...

    def get_response(
        self,
        messages: Sequence[Message],
        *,
        stream: bool = False,
        options: OptionsCoT | ChatOptions[Any] | None = None,
        **kwargs: Any,
    ) -> Awaitable[ChatResponse[Any]] | ResponseStream[ChatResponseUpdate, ChatResponse[Any]]:
        client_kwargs = kwargs.get("client_kwargs")
        if isinstance(client_kwargs, Mapping):
            self.last_session = cast(AgentSession | None, client_kwargs.get("session"))
        else:
            self.last_session = None
        self.last_service_session_id = self.last_session.service_session_id if self.last_session else None
        return cast(
            Awaitable[ChatResponse[Any]] | ResponseStream[ChatResponseUpdate, ChatResponse[Any]],
            super().get_response(
                messages=messages,
                stream=cast(Literal[True, False], stream),
                options=options,
                **kwargs,
            ),
        )

    @override
    def _inner_get_response(
        self,
        *,
        messages: Sequence[Message],
        stream: bool = False,
        options: Mapping[str, Any],
        **kwargs: Any,
    ) -> Awaitable[ChatResponse] | ResponseStream[ChatResponseUpdate, ChatResponse]:
        if stream:

            def _finalize(updates: Sequence[ChatResponseUpdate]) -> ChatResponse:
                return ChatResponse.from_updates(updates)

            return ResponseStream(self._stream_fn(messages, options, **kwargs), finalizer=_finalize)

        return self._get_response_impl(messages, options, **kwargs)

    async def _get_response_impl(
        self, messages: Sequence[Message], options: Mapping[str, Any], **kwargs: Any
    ) -> ChatResponse:
        """Non-streaming implementation."""
        if self._response_fn is not None:
            return await self._response_fn(messages, options, **kwargs)

        contents: list[Any] = []
        async for update in self._stream_fn(list(messages), dict(options), **kwargs):
            contents.extend(update.contents)

        return ChatResponse(
            messages=[Message(role="assistant", contents=contents)],
            response_id="stub-response",
        )


def stream_from_updates(updates: list[ChatResponseUpdate]) -> StreamFn:
    """Create a stream function that yields from a static list of updates."""

    async def _stream(
        messages: MutableSequence[Message], options: dict[str, Any], **kwargs: Any
    ) -> AsyncIterator[ChatResponseUpdate]:
        for update in updates:
            yield update

    return _stream


class StubAgent(SupportsAgentRun):
    """Minimal SupportsAgentRun stub for orchestrator tests."""

    def __init__(
        self,
        updates: list[AgentResponseUpdate] | None = None,
        *,
        agent_id: str = "stub-agent",
        agent_name: str | None = "stub-agent",
        default_options: Any | None = None,
        client: Any | None = None,
    ) -> None:
        self.id = agent_id
        self.name = agent_name
        self.description = "stub agent"
        self.updates = updates or [AgentResponseUpdate(contents=[Content.from_text(text="response")], role="assistant")]
        self.default_options: dict[str, Any] = (
            default_options if isinstance(default_options, dict) else {"tools": None, "response_format": None}
        )
        self.client = client or SimpleNamespace(function_invocation_configuration=None)
        self.messages_received: list[Any] = []
        self.tools_received: list[Any] | None = None
        self.last_session: AgentSession | None = None

    @overload
    def run(
        self,
        messages: str | Content | Message | Sequence[str | Content | Message] | None = None,
        *,
        stream: Literal[False] = ...,
        session: AgentSession | None = None,
        **kwargs: Any,
    ) -> Awaitable[AgentResponse[Any]]: ...

    @overload
    def run(
        self,
        messages: str | Content | Message | Sequence[str | Content | Message] | None = None,
        *,
        stream: Literal[True],
        session: AgentSession | None = None,
        **kwargs: Any,
    ) -> ResponseStream[AgentResponseUpdate, AgentResponse[Any]]: ...

    def run(
        self,
        messages: str | Content | Message | Sequence[str | Content | Message] | None = None,
        *,
        stream: bool = False,
        session: AgentSession | None = None,
        **kwargs: Any,
    ) -> Awaitable[AgentResponse[Any]] | ResponseStream[AgentResponseUpdate, AgentResponse[Any]]:
        if stream:

            async def _stream() -> AsyncIterator[AgentResponseUpdate]:
                self.messages_received = [] if messages is None else list(messages)  # type: ignore[arg-type]
                self.last_session = session
                self.tools_received = kwargs.get("tools")
                for update in self.updates:
                    yield update

            def _finalize(updates: Sequence[AgentResponseUpdate]) -> AgentResponse:
                return AgentResponse.from_updates(updates)

            return ResponseStream(_stream(), finalizer=_finalize)

        async def _get_response() -> AgentResponse[Any]:
            return AgentResponse(messages=[], response_id="stub-response")

        return _get_response()

    def create_session(self, **kwargs: Any) -> AgentSession:
        return AgentSession()


# Fixtures


@pytest.fixture
def streaming_chat_client_stub() -> type[SupportsChatGetResponse]:
    """Return the StreamingChatClientStub class for creating test instances."""
    return StreamingChatClientStub  # type: ignore[return-value]


@pytest.fixture
def stream_from_updates_fixture() -> Callable[[list[ChatResponseUpdate]], StreamFn]:
    """Return the stream_from_updates helper function."""
    return stream_from_updates


@pytest.fixture
def stub_agent() -> type[SupportsAgentRun]:
    """Return the StubAgent class for creating test instances."""
    return StubAgent  # type: ignore[return-value]


# ── Fixtures for golden / integration tests ──


@pytest.fixture
def collect_events() -> Callable[..., Any]:
    """Return an async helper that collects all events from an async generator."""

    async def _collect(async_gen: AsyncIterable[Any]) -> list[Any]:
        return [event async for event in async_gen]

    return _collect


@pytest.fixture
def make_agent_wrapper() -> Callable[..., Any]:
    """Factory that builds an AgentFrameworkAgent from a stream function.

    Usage::

        agent = make_agent_wrapper(
            stream_fn=stream_from_updates(updates),
            state_schema=...,
        )
        events = [e async for e in agent.run(payload)]
    """
    from agent_framework_ag_ui import AgentFrameworkAgent

    def _factory(
        stream_fn: StreamFn,
        *,
        state_schema: Any | None = None,
        predict_state_config: dict[str, dict[str, str]] | None = None,
        require_confirmation: bool = True,
    ) -> Any:
        client = StreamingChatClientStub(stream_fn)
        stub = StubAgent(client=client)
        return AgentFrameworkAgent(
            agent=stub,
            state_schema=state_schema,
            predict_state_config=predict_state_config,
            require_confirmation=require_confirmation,
        )

    return _factory


@pytest.fixture
def make_app() -> Callable[..., Any]:
    """Factory that builds a FastAPI app with an AG-UI endpoint.

    Usage::

        app = make_app(agent_or_wrapper, path="/test")
    """
    from fastapi import FastAPI

    from agent_framework_ag_ui import add_agent_framework_fastapi_endpoint

    def _factory(
        agent: Any,
        *,
        path: str = "/",
        state_schema: Any | None = None,
        predict_state_config: dict[str, dict[str, str]] | None = None,
        default_state: dict[str, Any] | None = None,
    ) -> FastAPI:
        app = FastAPI()
        add_agent_framework_fastapi_endpoint(
            app,
            agent,
            path=path,
            state_schema=state_schema,
            predict_state_config=predict_state_config,
            default_state=default_state,
        )
        return app

    return _factory
