"""Error injection tests for constraints.py to improve coverage.

Targets uncovered error handling paths in lines 197-202, 242-244, 263-266.
"""

import unittest
from unittest.mock import Mock, patch, MagicMock
import z3

from model_checker.iterate.constraints import ConstraintGenerator


class TestConstraintErrorPaths(unittest.TestCase):
    """Test error handling paths in ConstraintGenerator."""
    
    def setUp(self):
        """Set up test fixtures."""
        self.mock_example = Mock()
        self.mock_example.premises = ["P"]
        self.mock_example.conclusions = ["Q"]
        self.mock_example.settings = {'N': 3}
        
        # Setup mock model constraints with required attributes
        self.mock_example.model_constraints = Mock()
        self.mock_example.model_constraints.semantics = Mock()
        self.mock_example.model_constraints.all_constraints = []
        
        # Setup mock model structure with solver
        mock_solver = Mock()
        mock_solver.assertions = Mock(return_value=[])
        mock_solver.add = Mock()
        self.mock_example.model_structure = Mock()
        self.mock_example.model_structure.solver = mock_solver
        
        self.generator = ConstraintGenerator(self.mock_example)
    
    def test_state_difference_with_z3_exception(self):
        """Test error handling when Z3 evaluation fails (lines 197-198)."""
        # Setup mock model
        mock_prev_model = Mock()
        # Make eval raise Z3Exception
        mock_prev_model.eval = Mock(side_effect=z3.Z3Exception("Z3 evaluation error"))
        
        # Setup semantics with is_world
        semantics = Mock()
        semantics.is_world = Mock(return_value=z3.Bool('is_world_test'))
        self.generator.build_example.model_constraints.semantics = semantics
        
        # Store current model in generator
        self.generator.current_model = Mock()
        self.generator.current_model.solver = Mock()
        self.generator.current_model.solver.model = Mock(return_value=Mock())
        
        # Call the method - should handle Z3Exception gracefully
        constraints = self.generator._create_state_difference_constraints(mock_prev_model)
        
        # Should return list (possibly empty) without raising
        self.assertIsInstance(constraints, list)
    
    def test_state_difference_with_attribute_error(self):
        """Test error handling for AttributeError in state differences (lines 201-202)."""
        # Setup mock model with missing attributes
        mock_prev_model = Mock()
        # Make eval raise AttributeError
        mock_prev_model.eval = Mock(side_effect=AttributeError("Missing attribute"))
        
        # Setup semantics
        semantics = Mock()
        semantics.is_world = Mock(return_value=z3.Bool('is_world_test'))
        self.generator.build_example.model_constraints.semantics = semantics
        
        # Store current model
        self.generator.current_model = Mock()
        self.generator.current_model.solver = Mock()
        self.generator.current_model.solver.model = Mock(return_value=Mock())
        
        # Call the method - should handle AttributeError gracefully
        constraints = self.generator._create_state_difference_constraints(mock_prev_model)
        
        # Should return empty list without raising
        self.assertEqual(constraints, [])
    
    def test_non_isomorphic_constraint_z3_exception(self):
        """Test Z3Exception handling in isomorphism checking (lines 242-244)."""
        # Setup isomorphic model that raises Z3Exception on eval
        mock_iso_model = Mock()
        mock_iso_model.eval = Mock(side_effect=z3.Z3Exception("Z3 error in isomorphism"))
        
        # Setup semantics
        semantics = Mock()
        semantics.is_world = Mock(return_value=z3.Bool('is_world_test'))
        self.mock_example.model_constraints.semantics = semantics
        
        # Call the method - should handle exception gracefully
        result = self.generator._create_non_isomorphic_constraint(mock_iso_model)
        
        # Should return None when all evaluations fail
        self.assertIsNone(result)
    
    def test_non_isomorphic_constraint_attribute_error(self):
        """Test AttributeError handling in non-isomorphic constraints (lines 263-264)."""
        # Setup model with missing attributes
        mock_iso_model = Mock()
        
        # Remove build_example attributes to cause AttributeError
        self.generator.build_example = Mock()
        del self.generator.build_example.model_constraints
        
        # Call the method - should handle AttributeError gracefully
        result = self.generator._create_non_isomorphic_constraint(mock_iso_model)
        
        # Should return None without raising
        self.assertIsNone(result)
    
    def test_constraint_generation_with_invalid_model(self):
        """Test constraint generation with corrupted model data."""
        # Create a model that returns invalid constraint types
        mock_iso_model = Mock()
        mock_iso_model.eval = Mock(return_value="not_a_z3_value")
        
        # Setup semantics
        semantics = Mock()
        # Return something that will fail Z3 operations
        semantics.is_world = Mock(return_value="invalid_constraint")
        self.mock_example.model_constraints.semantics = semantics
        
        # Reset build_example
        self.generator.build_example = self.mock_example
        
        # Call the method - should handle invalid data gracefully
        result = self.generator._create_non_isomorphic_constraint(mock_iso_model)
        
        # Should return None for invalid constraints
        self.assertIsNone(result)
    
    def test_state_difference_with_type_error(self):
        """Test TypeError handling in state difference constraints (line 201)."""
        # Setup mock model that causes TypeError
        mock_prev_model = Mock()
        mock_prev_model.eval = Mock(side_effect=TypeError("Type error in model"))
        
        # Setup semantics
        semantics = Mock()
        semantics.is_world = Mock(return_value=z3.Bool('is_world_test'))
        self.generator.build_example.model_constraints.semantics = semantics
        
        # Store current model
        self.generator.current_model = Mock()
        self.generator.current_model.solver = Mock()
        self.generator.current_model.solver.model = Mock(return_value=Mock())
        
        # Call the method - should handle TypeError gracefully  
        constraints = self.generator._create_state_difference_constraints(mock_prev_model)
        
        # Should return empty list without raising
        self.assertEqual(constraints, [])
    
    def test_non_isomorphic_constraint_key_error(self):
        """Test KeyError handling in non-isomorphic constraints (line 263)."""
        mock_iso_model = Mock()
        
        # Setup build_example.settings to raise KeyError
        self.generator.build_example.settings = Mock()
        self.generator.build_example.settings.get = Mock(side_effect=KeyError("Missing key"))
        
        # Call the method - should handle KeyError gracefully
        result = self.generator._create_non_isomorphic_constraint(mock_iso_model)
        
        # Should return None without raising
        self.assertIsNone(result)
    
    def test_z3_and_operation_failure(self):
        """Test handling of invalid Z3 And operation (lines 253-256)."""
        mock_iso_model = Mock()
        mock_iso_model.eval = Mock(return_value=z3.BoolVal(False))
        
        # Setup semantics to return mock that fails And operation
        semantics = Mock()
        invalid_constraint = Mock()
        # Make And operation with this constraint fail
        invalid_constraint.__and__ = Mock(side_effect=z3.Z3Exception("Invalid And"))
        semantics.is_world = Mock(return_value=invalid_constraint)
        self.mock_example.model_constraints.semantics = semantics
        
        # Patch z3.And to raise exception for our invalid constraint
        with patch('z3.And', side_effect=z3.Z3Exception("Invalid constraint")):
            result = self.generator._create_non_isomorphic_constraint(mock_iso_model)
        
        # Should handle the error and return None
        self.assertIsNone(result)


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