"""Regression tests for Client.Python-005: streaming hierarchy iteration.

`GalaxyRepositoryClient.iter_hierarchy` yields objects page by page instead of
buffering the entire Galaxy hierarchy in memory, and `discover_hierarchy`
remains a convenience wrapper built on top of it.
"""

from __future__ import annotations

from typing import Any

import pytest

from mxgateway import ClientOptions, GalaxyRepositoryClient
from mxgateway.generated import galaxy_repository_pb2 as galaxy_pb


class _FakeUnary:
    def __init__(self, replies: list[Any]) -> None:
        self.replies = list(replies)
        self.requests: list[Any] = []
        self.metadata: tuple[tuple[str, str], ...] | None = None

    async def __call__(
        self,
        request: Any,
        *,
        metadata: tuple[tuple[str, str], ...],
        timeout: float | None = None,
    ) -> Any:
        self.requests.append(request)
        self.metadata = metadata
        return self.replies.pop(0)


class _FakeGalaxyStub:
    def __init__(self, discover_replies: list[Any]) -> None:
        self.DiscoverHierarchy = _FakeUnary(discover_replies)


def _two_page_replies() -> list[galaxy_pb.DiscoverHierarchyReply]:
    return [
        galaxy_pb.DiscoverHierarchyReply(
            next_page_token="page-2",
            total_object_count=3,
            objects=[
                galaxy_pb.GalaxyObject(gobject_id=1, tag_name="Area_001", is_area=True),
                galaxy_pb.GalaxyObject(gobject_id=2, tag_name="Pump_001"),
            ],
        ),
        galaxy_pb.DiscoverHierarchyReply(
            total_object_count=3,
            objects=[
                galaxy_pb.GalaxyObject(gobject_id=3, tag_name="Pump_002"),
            ],
        ),
    ]


@pytest.mark.asyncio
async def test_iter_hierarchy_yields_objects_across_pages() -> None:
    stub = _FakeGalaxyStub(_two_page_replies())
    client = await GalaxyRepositoryClient.connect(
        ClientOptions(endpoint="fake", plaintext=True),
        stub=stub,
    )

    tags = [obj.tag_name async for obj in client.iter_hierarchy()]

    assert tags == ["Area_001", "Pump_001", "Pump_002"]
    assert len(stub.DiscoverHierarchy.requests) == 2
    assert stub.DiscoverHierarchy.requests[0].page_token == ""
    assert stub.DiscoverHierarchy.requests[1].page_token == "page-2"


@pytest.mark.asyncio
async def test_iter_hierarchy_is_lazy_and_does_not_prefetch_next_page() -> None:
    """Pulling only the first object must not have requested the second page."""

    stub = _FakeGalaxyStub(_two_page_replies())
    client = await GalaxyRepositoryClient.connect(
        ClientOptions(endpoint="fake", plaintext=True),
        stub=stub,
    )

    iterator = client.iter_hierarchy()
    first = await iterator.__anext__()

    assert first.tag_name == "Area_001"
    # Only the first page should have been fetched so far.
    assert len(stub.DiscoverHierarchy.requests) == 1

    await iterator.aclose()


@pytest.mark.asyncio
async def test_iter_hierarchy_rejects_repeated_page_token() -> None:
    stub = _FakeGalaxyStub(
        [
            galaxy_pb.DiscoverHierarchyReply(next_page_token="7:1"),
            galaxy_pb.DiscoverHierarchyReply(next_page_token="7:1"),
        ],
    )
    client = await GalaxyRepositoryClient.connect(
        ClientOptions(endpoint="fake", plaintext=True),
        stub=stub,
    )

    with pytest.raises(Exception, match="repeated page token"):
        async for _ in client.iter_hierarchy():
            pass


@pytest.mark.asyncio
async def test_discover_hierarchy_still_returns_full_list() -> None:
    """The convenience wrapper must keep returning a buffered list."""

    stub = _FakeGalaxyStub(_two_page_replies())
    client = await GalaxyRepositoryClient.connect(
        ClientOptions(endpoint="fake", plaintext=True),
        stub=stub,
    )

    objects = await client.discover_hierarchy()

    assert isinstance(objects, list)
    assert [obj.tag_name for obj in objects] == ["Area_001", "Pump_001", "Pump_002"]