"""Unit tests for checkpointer config and singleton factory."""

import sys
from unittest.mock import AsyncMock, MagicMock, patch

import pytest

import deerflow.config.app_config as app_config_module
from deerflow.config.checkpointer_config import (
    CheckpointerConfig,
    get_checkpointer_config,
    load_checkpointer_config_from_dict,
    set_checkpointer_config,
)
from deerflow.runtime.checkpointer import get_checkpointer, reset_checkpointer


@pytest.fixture(autouse=True)
def reset_state():
    """Reset singleton state before each test."""
    app_config_module._app_config = None
    set_checkpointer_config(None)
    reset_checkpointer()
    yield
    app_config_module._app_config = None
    set_checkpointer_config(None)
    reset_checkpointer()


# ---------------------------------------------------------------------------
# Config tests
# ---------------------------------------------------------------------------


class TestCheckpointerConfig:
    def test_load_memory_config(self):
        load_checkpointer_config_from_dict({"type": "memory"})
        config = get_checkpointer_config()
        assert config is not None
        assert config.type == "memory"
        assert config.connection_string is None

    def test_load_sqlite_config(self):
        load_checkpointer_config_from_dict({"type": "sqlite", "connection_string": "/tmp/test.db"})
        config = get_checkpointer_config()
        assert config is not None
        assert config.type == "sqlite"
        assert config.connection_string == "/tmp/test.db"

    def test_load_postgres_config(self):
        load_checkpointer_config_from_dict({"type": "postgres", "connection_string": "postgresql://localhost/db"})
        config = get_checkpointer_config()
        assert config is not None
        assert config.type == "postgres"
        assert config.connection_string == "postgresql://localhost/db"

    def test_default_connection_string_is_none(self):
        config = CheckpointerConfig(type="memory")
        assert config.connection_string is None

    def test_set_config_to_none(self):
        load_checkpointer_config_from_dict({"type": "memory"})
        set_checkpointer_config(None)
        assert get_checkpointer_config() is None

    def test_invalid_type_raises(self):
        with pytest.raises(Exception):
            load_checkpointer_config_from_dict({"type": "unknown"})


# ---------------------------------------------------------------------------
# Factory tests
# ---------------------------------------------------------------------------


class TestGetCheckpointer:
    def test_returns_in_memory_saver_when_not_configured(self):
        """get_checkpointer should return InMemorySaver when not configured."""
        from langgraph.checkpoint.memory import InMemorySaver

        with patch("deerflow.runtime.checkpointer.provider.get_app_config", side_effect=FileNotFoundError):
            cp = get_checkpointer()
        assert cp is not None
        assert isinstance(cp, InMemorySaver)

    def test_memory_returns_in_memory_saver(self):
        load_checkpointer_config_from_dict({"type": "memory"})
        from langgraph.checkpoint.memory import InMemorySaver

        cp = get_checkpointer()
        assert isinstance(cp, InMemorySaver)

    def test_memory_singleton(self):
        load_checkpointer_config_from_dict({"type": "memory"})
        cp1 = get_checkpointer()
        cp2 = get_checkpointer()
        assert cp1 is cp2

    def test_reset_clears_singleton(self):
        load_checkpointer_config_from_dict({"type": "memory"})
        cp1 = get_checkpointer()
        reset_checkpointer()
        cp2 = get_checkpointer()
        assert cp1 is not cp2

    def test_sqlite_raises_when_package_missing(self):
        load_checkpointer_config_from_dict({"type": "sqlite", "connection_string": "/tmp/test.db"})
        with patch.dict(sys.modules, {"langgraph.checkpoint.sqlite": None}):
            reset_checkpointer()
            with pytest.raises(ImportError, match="langgraph-checkpoint-sqlite"):
                get_checkpointer()

    def test_postgres_raises_when_package_missing(self):
        load_checkpointer_config_from_dict({"type": "postgres", "connection_string": "postgresql://localhost/db"})
        with patch.dict(sys.modules, {"langgraph.checkpoint.postgres": None}):
            reset_checkpointer()
            with pytest.raises(ImportError, match="langgraph-checkpoint-postgres"):
                get_checkpointer()

    def test_postgres_raises_when_connection_string_missing(self):
        load_checkpointer_config_from_dict({"type": "postgres"})
        mock_saver = MagicMock()
        mock_module = MagicMock()
        mock_module.PostgresSaver = mock_saver
        with patch.dict(sys.modules, {"langgraph.checkpoint.postgres": mock_module}):
            reset_checkpointer()
            with pytest.raises(ValueError, match="connection_string is required"):
                get_checkpointer()

    def test_sqlite_creates_saver(self):
        """SQLite checkpointer is created when package is available."""
        load_checkpointer_config_from_dict({"type": "sqlite", "connection_string": "/tmp/test.db"})

        mock_saver_instance = MagicMock()
        mock_cm = MagicMock()
        mock_cm.__enter__ = MagicMock(return_value=mock_saver_instance)
        mock_cm.__exit__ = MagicMock(return_value=False)

        mock_saver_cls = MagicMock()
        mock_saver_cls.from_conn_string = MagicMock(return_value=mock_cm)

        mock_module = MagicMock()
        mock_module.SqliteSaver = mock_saver_cls

        with patch.dict(sys.modules, {"langgraph.checkpoint.sqlite": mock_module}):
            reset_checkpointer()
            cp = get_checkpointer()

        assert cp is mock_saver_instance
        mock_saver_cls.from_conn_string.assert_called_once()
        mock_saver_instance.setup.assert_called_once()

    def test_sqlite_creates_parent_dir(self):
        """Sync SQLite checkpointer should call ensure_sqlite_parent_dir before connecting.

        This mirrors the async checkpointer's behaviour and prevents
        'sqlite3.OperationalError: unable to open database file' when the
        parent directory for the database file does not yet exist (e.g. when
        using the harness package from an external virtualenv where the
        .deer-flow directory has not been created).
        """
        load_checkpointer_config_from_dict({"type": "sqlite", "connection_string": "relative/test.db"})

        mock_saver_instance = MagicMock()
        mock_cm = MagicMock()
        mock_cm.__enter__ = MagicMock(return_value=mock_saver_instance)
        mock_cm.__exit__ = MagicMock(return_value=False)

        mock_saver_cls = MagicMock()
        mock_saver_cls.from_conn_string = MagicMock(return_value=mock_cm)

        mock_module = MagicMock()
        mock_module.SqliteSaver = mock_saver_cls

        with (
            patch.dict(sys.modules, {"langgraph.checkpoint.sqlite": mock_module}),
            patch("deerflow.runtime.checkpointer.provider.ensure_sqlite_parent_dir") as mock_ensure,
            patch(
                "deerflow.runtime.checkpointer.provider.resolve_sqlite_conn_str",
                return_value="/tmp/resolved/relative/test.db",
            ),
        ):
            reset_checkpointer()
            cp = get_checkpointer()

        assert cp is mock_saver_instance
        mock_ensure.assert_called_once_with("/tmp/resolved/relative/test.db")
        mock_saver_cls.from_conn_string.assert_called_once_with("/tmp/resolved/relative/test.db")

    def test_sqlite_ensure_parent_dir_before_connect(self):
        """ensure_sqlite_parent_dir must be called before from_conn_string."""
        load_checkpointer_config_from_dict({"type": "sqlite", "connection_string": "relative/test.db"})

        call_order = []

        mock_saver_instance = MagicMock()
        mock_cm = MagicMock()
        mock_cm.__enter__ = MagicMock(return_value=mock_saver_instance)
        mock_cm.__exit__ = MagicMock(return_value=False)

        mock_saver_cls = MagicMock()
        mock_saver_cls.from_conn_string = MagicMock(side_effect=lambda *a, **kw: (call_order.append("connect"), mock_cm)[1])

        mock_module = MagicMock()
        mock_module.SqliteSaver = mock_saver_cls

        def record_ensure(*a, **kw):
            call_order.append("ensure")

        with (
            patch.dict(sys.modules, {"langgraph.checkpoint.sqlite": mock_module}),
            patch(
                "deerflow.runtime.checkpointer.provider.ensure_sqlite_parent_dir",
                side_effect=record_ensure,
            ),
            patch(
                "deerflow.runtime.checkpointer.provider.resolve_sqlite_conn_str",
                return_value="/tmp/resolved/relative/test.db",
            ),
        ):
            reset_checkpointer()
            get_checkpointer()

        assert call_order == ["ensure", "connect"]

    def test_postgres_creates_saver(self):
        """Postgres checkpointer is created when packages are available."""
        load_checkpointer_config_from_dict({"type": "postgres", "connection_string": "postgresql://localhost/db"})

        mock_saver_instance = MagicMock()
        mock_cm = MagicMock()
        mock_cm.__enter__ = MagicMock(return_value=mock_saver_instance)
        mock_cm.__exit__ = MagicMock(return_value=False)

        mock_saver_cls = MagicMock()
        mock_saver_cls.from_conn_string = MagicMock(return_value=mock_cm)

        mock_pg_module = MagicMock()
        mock_pg_module.PostgresSaver = mock_saver_cls

        with patch.dict(sys.modules, {"langgraph.checkpoint.postgres": mock_pg_module}):
            reset_checkpointer()
            cp = get_checkpointer()

        assert cp is mock_saver_instance
        mock_saver_cls.from_conn_string.assert_called_once_with("postgresql://localhost/db")
        mock_saver_instance.setup.assert_called_once()


class TestAsyncCheckpointer:
    @pytest.mark.anyio
    async def test_sqlite_creates_parent_dir_via_to_thread(self):
        """Async SQLite setup should move mkdir off the event loop."""
        from deerflow.runtime.checkpointer.async_provider import make_checkpointer

        mock_config = MagicMock()
        mock_config.checkpointer = CheckpointerConfig(type="sqlite", connection_string="relative/test.db")

        mock_saver = AsyncMock()
        mock_cm = AsyncMock()
        mock_cm.__aenter__.return_value = mock_saver
        mock_cm.__aexit__.return_value = False

        mock_saver_cls = MagicMock()
        mock_saver_cls.from_conn_string.return_value = mock_cm

        mock_module = MagicMock()
        mock_module.AsyncSqliteSaver = mock_saver_cls

        with (
            patch("deerflow.runtime.checkpointer.async_provider.get_app_config", return_value=mock_config),
            patch.dict(sys.modules, {"langgraph.checkpoint.sqlite.aio": mock_module}),
            patch("deerflow.runtime.checkpointer.async_provider.asyncio.to_thread", new_callable=AsyncMock) as mock_to_thread,
            patch(
                "deerflow.runtime.checkpointer.async_provider.resolve_sqlite_conn_str",
                return_value="/tmp/resolved/test.db",
            ),
        ):
            async with make_checkpointer() as saver:
                assert saver is mock_saver

        mock_to_thread.assert_awaited_once()
        called_fn, called_path = mock_to_thread.await_args.args
        assert called_fn.__name__ == "ensure_sqlite_parent_dir"
        assert called_path == "/tmp/resolved/test.db"
        mock_saver_cls.from_conn_string.assert_called_once_with("/tmp/resolved/test.db")
        mock_saver.setup.assert_awaited_once()


# ---------------------------------------------------------------------------
# app_config.py integration
# ---------------------------------------------------------------------------


class TestAppConfigLoadsCheckpointer:
    def test_load_checkpointer_section(self):
        """load_checkpointer_config_from_dict populates the global config."""
        set_checkpointer_config(None)
        load_checkpointer_config_from_dict({"type": "memory"})
        cfg = get_checkpointer_config()
        assert cfg is not None
        assert cfg.type == "memory"


# ---------------------------------------------------------------------------
# DeerFlowClient falls back to config checkpointer
# ---------------------------------------------------------------------------


class TestClientCheckpointerFallback:
    def test_client_uses_config_checkpointer_when_none_provided(self):
        """DeerFlowClient._ensure_agent falls back to get_checkpointer() when checkpointer=None."""
        from langgraph.checkpoint.memory import InMemorySaver

        from deerflow.client import DeerFlowClient

        load_checkpointer_config_from_dict({"type": "memory"})

        captured_kwargs = {}

        def fake_create_agent(**kwargs):
            captured_kwargs.update(kwargs)
            return MagicMock()

        model_mock = MagicMock()
        config_mock = MagicMock()
        config_mock.models = [model_mock]
        config_mock.get_model_config.return_value = MagicMock(supports_vision=False)
        config_mock.checkpointer = None

        with (
            patch("deerflow.client.get_app_config", return_value=config_mock),
            patch("deerflow.client.create_agent", side_effect=fake_create_agent),
            patch("deerflow.client.create_chat_model", return_value=MagicMock()),
            patch("deerflow.client._build_middlewares", return_value=[]),
            patch("deerflow.client.apply_prompt_template", return_value=""),
            patch("deerflow.client.DeerFlowClient._get_tools", return_value=[]),
        ):
            client = DeerFlowClient(checkpointer=None)
            config = client._get_runnable_config("test-thread")
            client._ensure_agent(config)

        assert "checkpointer" in captured_kwargs
        assert isinstance(captured_kwargs["checkpointer"], InMemorySaver)

    def test_client_explicit_checkpointer_takes_precedence(self):
        """An explicitly provided checkpointer is used even when config checkpointer is set."""
        from deerflow.client import DeerFlowClient

        load_checkpointer_config_from_dict({"type": "memory"})

        explicit_cp = MagicMock()
        captured_kwargs = {}

        def fake_create_agent(**kwargs):
            captured_kwargs.update(kwargs)
            return MagicMock()

        model_mock = MagicMock()
        config_mock = MagicMock()
        config_mock.models = [model_mock]
        config_mock.get_model_config.return_value = MagicMock(supports_vision=False)
        config_mock.checkpointer = None

        with (
            patch("deerflow.client.get_app_config", return_value=config_mock),
            patch("deerflow.client.create_agent", side_effect=fake_create_agent),
            patch("deerflow.client.create_chat_model", return_value=MagicMock()),
            patch("deerflow.client._build_middlewares", return_value=[]),
            patch("deerflow.client.apply_prompt_template", return_value=""),
            patch("deerflow.client.DeerFlowClient._get_tools", return_value=[]),
        ):
            client = DeerFlowClient(checkpointer=explicit_cp)
            config = client._get_runnable_config("test-thread")
            client._ensure_agent(config)

        assert captured_kwargs["checkpointer"] is explicit_cp
