"""
Plugin Code Validators

Ensures safety and correctness of plugin code before execution.
"""

import ast
import re
from typing import List, Set
import logging

logger = logging.getLogger(__name__)


class PluginValidationError(Exception):
    """Raised when plugin code fails validation."""
    pass


# Whitelist of safe modules for plugin imports
SAFE_MODULES = {
    'math', 'numpy', 'scipy', 'pandas',
    'pathlib', 'json', 'csv', 'datetime',
    'logging', 'typing', 'dataclasses',
    'optuna', 'pyNastran'
}

# Blacklist of dangerous operations
DANGEROUS_OPERATIONS = {
    'eval', 'exec', 'compile', '__import__',
    'open',  # File operations should be explicit
    'subprocess', 'os.system', 'os.popen',
    'shutil.rmtree',  # Dangerous file operations
}


def validate_plugin_code(code: str, allow_file_ops: bool = False) -> None:
    """
    Validate plugin code for safety before execution.

    Args:
        code: Python source code to validate
        allow_file_ops: Whether to allow file operations (open, Path.write_text, etc.)

    Raises:
        PluginValidationError: If code contains unsafe operations

    Example:
        >>> code = "def my_hook(context): return {'result': context['x'] * 2}"
        >>> validate_plugin_code(code)  # Passes
        >>>
        >>> code = "import os; os.system('rm -rf /')"
        >>> validate_plugin_code(code)  # Raises PluginValidationError
    """
    try:
        tree = ast.parse(code)
    except SyntaxError as e:
        raise PluginValidationError(f"Syntax error in plugin code: {e}")

    # Check for dangerous imports
    for node in ast.walk(tree):
        if isinstance(node, ast.Import):
            for alias in node.names:
                if alias.name not in SAFE_MODULES:
                    raise PluginValidationError(
                        f"Unsafe import: {alias.name}. "
                        f"Allowed modules: {SAFE_MODULES}"
                    )

        elif isinstance(node, ast.ImportFrom):
            if node.module and node.module not in SAFE_MODULES:
                # Allow submodules of safe modules
                base_module = node.module.split('.')[0]
                if base_module not in SAFE_MODULES:
                    raise PluginValidationError(
                        f"Unsafe import from: {node.module}"
                    )

        # Check for dangerous function calls
        elif isinstance(node, ast.Call):
            if isinstance(node.func, ast.Name):
                if node.func.id in DANGEROUS_OPERATIONS:
                    if node.func.id == 'open' and allow_file_ops:
                        continue  # Allow if explicitly permitted
                    raise PluginValidationError(
                        f"Dangerous operation: {node.func.id}"
                    )

        # Check for attribute access to dangerous methods
        elif isinstance(node, ast.Attribute):
            dangerous_attrs = {'system', 'popen', 'rmtree', 'remove', 'unlink'}
            if node.attr in dangerous_attrs and not allow_file_ops:
                raise PluginValidationError(
                    f"Dangerous attribute access: {node.attr}"
                )

    logger.info("Plugin code validation passed")


def check_hook_function_signature(func_code: str) -> bool:
    """
    Verify that a hook function has the correct signature.

    Expected: def hook_name(context: Dict[str, Any]) -> Optional[Dict[str, Any]]

    Args:
        func_code: Function source code

    Returns:
        True if signature is valid

    Raises:
        PluginValidationError: If signature is invalid
    """
    try:
        tree = ast.parse(func_code)
    except SyntaxError as e:
        raise PluginValidationError(f"Syntax error: {e}")

    # Find function definition
    func_def = None
    for node in ast.walk(tree):
        if isinstance(node, ast.FunctionDef):
            func_def = node
            break

    if func_def is None:
        raise PluginValidationError("No function definition found")

    # Check that it takes exactly one argument (context)
    if len(func_def.args.args) != 1:
        raise PluginValidationError(
            f"Hook function must take exactly 1 argument (context), "
            f"got {len(func_def.args.args)}"
        )

    logger.info(f"Hook function '{func_def.name}' signature is valid")
    return True


def sanitize_plugin_name(name: str) -> str:
    """
    Sanitize a plugin name to be safe for filesystem and imports.

    Args:
        name: Original plugin name

    Returns:
        Sanitized name (lowercase, alphanumeric + underscore only)
    """
    # Remove special characters, keep only alphanumeric and underscore
    sanitized = re.sub(r'[^a-z0-9_]', '_', name.lower())

    # Ensure it doesn't start with a number
    if sanitized[0].isdigit():
        sanitized = f"plugin_{sanitized}"

    return sanitized


def get_imported_modules(code: str) -> Set[str]:
    """
    Extract all imported modules from code.

    Args:
        code: Python source code

    Returns:
        Set of module names
    """
    try:
        tree = ast.parse(code)
    except SyntaxError:
        return set()

    modules = set()
    for node in ast.walk(tree):
        if isinstance(node, ast.Import):
            for alias in node.names:
                modules.add(alias.name)
        elif isinstance(node, ast.ImportFrom):
            if node.module:
                modules.add(node.module)

    return modules


def estimate_complexity(code: str) -> int:
    """
    Estimate the cyclomatic complexity of code.

    Higher values indicate more complex code with more branching.

    Args:
        code: Python source code

    Returns:
        Complexity estimate (1 = simple, 10+ = complex)
    """
    try:
        tree = ast.parse(code)
    except SyntaxError:
        return 0

    complexity = 1  # Base complexity

    for node in ast.walk(tree):
        # Add 1 for each branching statement
        if isinstance(node, (ast.If, ast.While, ast.For, ast.ExceptHandler)):
            complexity += 1
        elif isinstance(node, ast.BoolOp):
            complexity += len(node.values) - 1

    return complexity