bambuddy/backend/tests/unit/test_code_quality.py

"""
Code quality tests for BamBuddy backend.

These tests check for common anti-patterns and code quality issues
that could cause runtime errors but aren't caught by normal tests.
"""

import ast
import os
import pytest
from pathlib import Path


# Get the backend source directory
BACKEND_DIR = Path(__file__).parent.parent.parent / "app"


# Safe imports that are commonly re-imported in functions without issues
# These are typically imported at the START of a function, not midway through
SAFE_REIMPORT_NAMES = {
    'logging', 're', 'os', 'sys', 'json', 'Path', 'datetime', 'timedelta',
    'asyncio', 'time', 'typing', 'Optional', 'List', 'Dict', 'Any', 'Union',
}


class DangerousImportVisitor(ast.NodeVisitor):
    """AST visitor that detects dangerous import patterns.

    Specifically looks for cases where:
    1. A name is imported at module level
    2. The same name is imported locally in a function
    3. The name is USED before the local import in that function

    This pattern causes 'cannot access local variable' errors.
    """

    def __init__(self):
        self.module_imports: set[str] = set()
        self.dangerous_imports: list[tuple[str, int, str, int]] = []  # (name, import_line, function, first_use_line)
        self.current_function: str | None = None
        self.function_start_line: int = 0
        self.in_function = False

    def visit_Import(self, node: ast.Import):
        for alias in node.names:
            name = alias.asname or alias.name
            if not self.in_function:
                self.module_imports.add(name)
        self.generic_visit(node)

    def visit_ImportFrom(self, node: ast.ImportFrom):
        for alias in node.names:
            name = alias.asname or alias.name
            if not self.in_function:
                self.module_imports.add(name)
        self.generic_visit(node)

    def _check_function(self, node):
        """Check a function for dangerous import patterns."""
        if not self.in_function:
            return

        # Skip safe reimports
        # Collect all local imports in this function
        local_imports: dict[str, int] = {}  # name -> line number
        name_uses: dict[str, int] = {}  # name -> first use line number

        for child in ast.walk(node):
            # Find local imports
            if isinstance(child, (ast.Import, ast.ImportFrom)):
                if isinstance(child, ast.Import):
                    for alias in child.names:
                        name = alias.asname or alias.name
                        if name in self.module_imports and name not in SAFE_REIMPORT_NAMES:
                            local_imports[name] = child.lineno
                elif isinstance(child, ast.ImportFrom):
                    for alias in child.names:
                        name = alias.asname or alias.name
                        if name in self.module_imports and name not in SAFE_REIMPORT_NAMES:
                            local_imports[name] = child.lineno

            # Find name uses
            if isinstance(child, ast.Name):
                if child.id not in name_uses:
                    name_uses[child.id] = child.lineno

        # Check for dangerous pattern: use before import
        for name, import_line in local_imports.items():
            if name in name_uses:
                first_use = name_uses[name]
                if first_use < import_line:
                    self.dangerous_imports.append((name, import_line, self.current_function, first_use))

    def visit_FunctionDef(self, node: ast.FunctionDef):
        old_function = self.current_function
        old_in_function = self.in_function
        old_start_line = self.function_start_line

        self.current_function = node.name
        self.in_function = True
        self.function_start_line = node.lineno

        self._check_function(node)
        self.generic_visit(node)

        self.current_function = old_function
        self.in_function = old_in_function
        self.function_start_line = old_start_line

    def visit_AsyncFunctionDef(self, node: ast.AsyncFunctionDef):
        old_function = self.current_function
        old_in_function = self.in_function
        old_start_line = self.function_start_line

        self.current_function = node.name
        self.in_function = True
        self.function_start_line = node.lineno

        self._check_function(node)
        self.generic_visit(node)

        self.current_function = old_function
        self.in_function = old_in_function
        self.function_start_line = old_start_line


def find_import_shadowing(file_path: Path) -> list[tuple[str, int, str]]:
    """Find cases where local imports shadow module-level imports AND are used before import.

    Returns list of (name, line_number, function_name) tuples.
    """
    try:
        with open(file_path, 'r') as f:
            source = f.read()
        tree = ast.parse(source)
        visitor = DangerousImportVisitor()
        visitor.visit(tree)
        # Convert (name, import_line, function, first_use_line) to (name, import_line, function)
        return [(name, import_line, func) for name, import_line, func, _ in visitor.dangerous_imports]
    except SyntaxError:
        return []  # Skip files with syntax errors


def get_python_files(directory: Path) -> list[Path]:
    """Get all Python files in a directory recursively."""
    return list(directory.rglob("*.py"))


class TestImportShadowing:
    """Tests for import shadowing anti-pattern."""

    def test_no_import_shadowing_in_main(self):
        """Check main.py has no import shadowing issues.

        This test would have caught the ArchiveService scoping bug.
        """
        main_file = BACKEND_DIR / "main.py"
        if not main_file.exists():
            pytest.skip("main.py not found")

        shadows = find_import_shadowing(main_file)

        if shadows:
            error_msg = "Import shadowing detected in main.py:\n"
            for name, line, func in shadows:
                error_msg += f"  - '{name}' at line {line} in function '{func}' shadows module-level import\n"
            error_msg += "\nThis can cause 'cannot access local variable' errors."
            pytest.fail(error_msg)

    def test_no_import_shadowing_in_services(self):
        """Check service files have no import shadowing issues."""
        services_dir = BACKEND_DIR / "services"
        if not services_dir.exists():
            pytest.skip("services directory not found")

        all_shadows = []
        for py_file in get_python_files(services_dir):
            shadows = find_import_shadowing(py_file)
            for name, line, func in shadows:
                all_shadows.append((py_file.name, name, line, func))

        if all_shadows:
            error_msg = "Import shadowing detected in services:\n"
            for filename, name, line, func in all_shadows:
                error_msg += f"  - {filename}: '{name}' at line {line} in function '{func}'\n"
            pytest.fail(error_msg)

    def test_no_import_shadowing_in_routes(self):
        """Check route files have no import shadowing issues."""
        routes_dir = BACKEND_DIR / "api" / "routes"
        if not routes_dir.exists():
            pytest.skip("routes directory not found")

        all_shadows = []
        for py_file in get_python_files(routes_dir):
            shadows = find_import_shadowing(py_file)
            for name, line, func in shadows:
                all_shadows.append((py_file.name, name, line, func))

        if all_shadows:
            error_msg = "Import shadowing detected in routes:\n"
            for filename, name, line, func in all_shadows:
                error_msg += f"  - {filename}: '{name}' at line {line} in function '{func}'\n"
            pytest.fail(error_msg)


class TestModuleImports:
    """Tests for module import health."""

    def test_all_modules_importable(self):
        """Verify all Python modules can be imported without errors.

        This catches syntax errors and missing dependencies.
        """
        import importlib
        import sys

        # Modules to test importing
        modules = [
            "backend.app.main",
            "backend.app.services.bambu_mqtt",
            "backend.app.services.printer_manager",
            "backend.app.services.archive",
            "backend.app.services.notification_service",
            "backend.app.services.smart_plug_manager",
        ]

        errors = []
        for module_name in modules:
            try:
                # Remove from cache first to ensure fresh import
                if module_name in sys.modules:
                    del sys.modules[module_name]
                importlib.import_module(module_name)
            except Exception as e:
                errors.append(f"{module_name}: {type(e).__name__}: {e}")

        if errors:
            pytest.fail("Failed to import modules:\n" + "\n".join(errors))


class TestLogErrorPatterns:
    """Tests that use log capture to detect runtime errors."""

    def test_mqtt_message_processing_no_errors(self, capture_logs):
        """Test that MQTT message processing doesn't log errors."""
        from backend.app.services.bambu_mqtt import BambuMQTTClient

        client = BambuMQTTClient(
            ip_address="192.168.1.100",
            serial_number="TEST123",
            access_code="12345678",
        )
        client.on_print_start = lambda data: None
        client.on_print_complete = lambda data: None

        # Process a realistic print lifecycle
        messages = [
            {"print": {"gcode_state": "RUNNING", "gcode_file": "/test.gcode", "subtask_name": "Test"}},
            {"print": {"gcode_state": "RUNNING", "gcode_file": "/test.gcode", "mc_percent": 50}},
            {"print": {"gcode_state": "FINISH", "gcode_file": "/test.gcode", "subtask_name": "Test"}},
        ]

        for msg in messages:
            client._process_message(msg)

        assert not capture_logs.has_errors(), f"Errors during MQTT processing:\n{capture_logs.format_errors()}"