"""Contract tests for get_predecessors 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 TestGetPredecessorsContract:
    """Contract tests verifying get_predecessors tool interface."""

    async def test_get_predecessors_returns_list(self, sample_xer_single_project: Path) -> None:
        """get_predecessors returns predecessor activities."""
        from xer_mcp.tools.get_predecessors import get_predecessors
        from xer_mcp.tools.load_xer import load_xer

        await load_xer(file_path=str(sample_xer_single_project))

        # A1010 (2002) has one predecessor: A1000 (2001)
        result = await get_predecessors(activity_id="2002")

        assert "activity_id" in result
        assert result["activity_id"] == "2002"
        assert "predecessors" in result
        assert len(result["predecessors"]) == 1
        assert result["predecessors"][0]["task_id"] == "2001"

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

        await load_xer(file_path=str(sample_xer_single_project))

        result = await get_predecessors(activity_id="2002")

        pred = result["predecessors"][0]
        assert "relationship_type" in pred
        assert "lag_hr_cnt" in pred
        assert pred["relationship_type"] in ["FS", "SS", "FF", "SF"]

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

        await load_xer(file_path=str(sample_xer_single_project))

        # A1000 (2001) has no predecessors
        result = await get_predecessors(activity_id="2001")

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

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

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

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

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

        await load_xer(file_path=str(sample_xer_single_project))

        # A1010 (2002) has one predecessor: A1000 (2001)
        result = await get_predecessors(activity_id="2002")

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