"""Contract tests for get_successors MCP tool."""

from pathlib import Path

import pytest

from xer_mcp.db import db


@pytest.fixture(autouse=True)
def setup_db():
    """Initialize and clear database for each test."""
    db.initialize()
    yield
    db.clear()


class TestGetSuccessorsContract:
    """Contract tests verifying get_successors tool interface."""

    async def test_get_successors_returns_list(self, sample_xer_single_project: Path) -> None:
        """get_successors returns successor activities."""
        from xer_mcp.tools.get_successors import get_successors
        from xer_mcp.tools.load_xer import load_xer

        await load_xer(file_path=str(sample_xer_single_project))

        # A1010 (2002) has two successors: A1020 (2003) and A1030 (2004)
        result = await get_successors(activity_id="2002")

        assert "activity_id" in result
        assert result["activity_id"] == "2002"
        assert "successors" in result
        assert len(result["successors"]) == 2

    async def test_get_successors_includes_relationship_details(
        self, sample_xer_single_project: Path
    ) -> None:
        """get_successors includes relationship type and lag."""
        from xer_mcp.tools.get_successors import get_successors
        from xer_mcp.tools.load_xer import load_xer

        await load_xer(file_path=str(sample_xer_single_project))

        result = await get_successors(activity_id="2001")

        succ = result["successors"][0]
        assert "relationship_type" in succ
        assert "lag_hr_cnt" in succ
        assert succ["relationship_type"] in ["FS", "SS", "FF", "SF"]

    async def test_get_successors_empty_list_for_no_successors(
        self, sample_xer_single_project: Path
    ) -> None:
        """get_successors returns empty list when no successors exist."""
        from xer_mcp.tools.get_successors import get_successors
        from xer_mcp.tools.load_xer import load_xer

        await load_xer(file_path=str(sample_xer_single_project))

        # A1040 (2005) has no successors
        result = await get_successors(activity_id="2005")

        assert "successors" in result
        assert len(result["successors"]) == 0

    async def test_get_successors_no_file_loaded_returns_error(self) -> None:
        """get_successors without loaded file returns NO_FILE_LOADED error."""
        from xer_mcp.server import set_file_loaded
        from xer_mcp.tools.get_successors import get_successors

        set_file_loaded(False)
        result = await get_successors(activity_id="2002")

        assert "error" in result
        assert result["error"]["code"] == "NO_FILE_LOADED"

    async def test_get_successors_includes_driving_flag(
        self, sample_xer_single_project: Path
    ) -> None:
        """get_successors includes driving flag for each successor."""
        from xer_mcp.tools.get_successors import get_successors
        from xer_mcp.tools.load_xer import load_xer

        await load_xer(file_path=str(sample_xer_single_project))

        # A1000 (2001) has one successor: A1010 (2002)
        result = await get_successors(activity_id="2001")

        assert "successors" in result
        assert len(result["successors"]) >= 1
        # All successors should have a driving flag
        for succ in result["successors"]:
            assert "driving" in succ
            assert isinstance(succ["driving"], bool)