import unittest
from unittest.mock import patch

from sn_basis.functions import variable_wrapper


class _Scope:
    def __init__(self, value: str):
        self._value = value

    def variable(self, _name: str) -> str:
        return self._value


class TestVariableWrapper(unittest.TestCase):

    @patch("sn_basis.functions.variable_wrapper.QgsProject.instance")
    @patch("sn_basis.functions.variable_wrapper.QgsExpressionContextUtils.setProjectVariable")
    @patch("sn_basis.functions.variable_wrapper.QgsExpressionContextUtils.projectScope")
    def test_set_variable_project_noop_write_is_skipped(
        self,
        mock_project_scope,
        mock_set_project_variable,
        mock_project_instance,
    ):
        mock_project_instance.return_value = object()
        mock_project_scope.return_value = _Scope("layer_1")

        variable_wrapper.set_variable("verfahrensgebiet_layer", "layer_1", scope="project")

        mock_set_project_variable.assert_not_called()

    @patch("sn_basis.functions.variable_wrapper.QgsProject.instance")
    @patch("sn_basis.functions.variable_wrapper.QgsExpressionContextUtils.setProjectVariable")
    @patch("sn_basis.functions.variable_wrapper.QgsExpressionContextUtils.projectScope")
    def test_set_variable_project_changed_value_is_written(
        self,
        mock_project_scope,
        mock_set_project_variable,
        mock_project_instance,
    ):
        fake_project = object()
        mock_project_instance.return_value = fake_project
        mock_project_scope.return_value = _Scope("old_value")

        variable_wrapper.set_variable("verfahrensgebiet_layer", "new_value", scope="project")

        mock_set_project_variable.assert_called_once_with(
            fake_project,
            "sn_verfahrensgebiet_layer",
            "new_value",
        )

    @patch("sn_basis.functions.variable_wrapper.QgsExpressionContextUtils.setGlobalVariable")
    def test_set_variable_global_writes_prefixed_name(self, mock_set_global):
        variable_wrapper.set_variable("verfahrensnummer", "123", scope="global")

        mock_set_global.assert_called_once_with("sn_verfahrensnummer", "123")

    @patch("sn_basis.functions.variable_wrapper.QgsExpressionContextUtils.globalScope")
    def test_get_variable_global_returns_empty_string_fallback(self, mock_global_scope):
        mock_global_scope.return_value = _Scope("")

        value = variable_wrapper.get_variable("nicht_vorhanden", scope="global")

        self.assertEqual(value, "")

    def test_get_variable_invalid_scope_raises(self):
        with self.assertRaises(ValueError):
            variable_wrapper.get_variable("foo", scope="invalid")

    def test_set_variable_invalid_scope_raises(self):
        with self.assertRaises(ValueError):
            variable_wrapper.set_variable("foo", "bar", scope="invalid")


if __name__ == "__main__":
    unittest.main()