"""Tests for diff generation."""


from i18n_guardian.diff.diff_generator import DiffGenerator, DiffChange, DiffResult


class TestDiffGenerator:
    """Tests for DiffGenerator."""

    def test_generate_diff_basic(self, temp_dir):
        """Test basic diff generation."""
        file_path = temp_dir / "test.py"
        old_content = 'message = "Hello"'
        new_content = 'message = t("Hello")'

        generator = DiffGenerator()
        diff = generator.generate_diff(file_path, old_content, new_content)

        assert isinstance(diff, str)
        assert len(diff) > 0
        assert "---" in diff
        assert "+++" in diff
        assert "-" in diff
        assert "+" in diff

    def test_generate_diff_multiple_lines(self, temp_dir):
        """Test diff generation for multiple lines."""
        file_path = temp_dir / "test.py"
        old_content = '''def greet():
    return "Hello"
'''
        new_content = '''def greet():
    return t("Hello")
'''

        generator = DiffGenerator()
        diff = generator.generate_diff(file_path, old_content, new_content)

        assert "Hello" in diff

    def test_create_replacement(self):
        """Test creating replacement string with i18n function."""
        generator = DiffGenerator()
        replacement = generator.create_replacement("Hello World", "t")

        assert 't("Hello World")' in replacement
        assert "\\n" not in replacement or replacement.count('\\n') == 0

    def test_create_replacement_escaping(self):
        """Test that special characters are escaped."""
        generator = DiffGenerator()
        replacement = generator.create_replacement('Hello "World"', "t")

        assert '\\"' in replacement

    def test_diff_result_structure(self):
        """Test DiffResult has correct structure."""
        result = DiffResult()
        assert hasattr(result, "changes")
        assert hasattr(result, "files_modified")
        assert hasattr(result, "total_changes")
        assert result.changes == []

    def test_diff_change_structure(self, temp_dir):
        """Test DiffChange has correct structure."""
        change = DiffChange(
            file_path=temp_dir / "test.py",
            original_line=1,
            original_text='"Hello"',
            new_text='t("Hello")',
        )

        assert hasattr(change, "file_path")
        assert hasattr(change, "original_line")
        assert hasattr(change, "original_text")
        assert hasattr(change, "new_text")

    def test_empty_diff(self, temp_dir):
        """Test diff with no changes."""
        file_path = temp_dir / "test.py"
        content = 'message = "Hello"'

        generator = DiffGenerator()
        diff = generator.generate_diff(file_path, content, content)

        assert isinstance(diff, str)

    def test_apply_diff_creates_backup(self, temp_dir):
        """Test that applying diff creates backup."""
        file_path = temp_dir / "test.py"
        file_path.write_text('message = "Hello"', encoding="utf-8")

        old_content = file_path.read_text(encoding="utf-8")
        new_content = 'message = t("Hello")'

        generator = DiffGenerator()
        diff = generator.generate_diff(file_path, old_content, new_content)
        result = generator.apply_diff(file_path, diff, backup=True)

        assert result
        assert file_path.with_suffix(".bak").exists()

    def test_apply_diff_modifies_file(self, temp_dir):
        """Test that applying diff modifies file."""
        file_path = temp_dir / "test.py"
        file_path.write_text('message = "Hello"', encoding="utf-8")

        old_content = file_path.read_text(encoding="utf-8")
        new_content = 'message = t("Hello")'

        generator = DiffGenerator()
        diff = generator.generate_diff(file_path, old_content, new_content)
        generator.apply_diff(file_path, diff, backup=False)

        content = file_path.read_text(encoding="utf-8")
        assert 't("Hello")' in content