"""
Secure code execution tools
Provides timeouts, resource limits and a sandbox environment
"""

import os
import signal
import sys
import threading
import traceback
from contextlib import contextmanager
from typing import Any, Dict, Optional, Tuple

from app.utils.logger import get_logger

logger = get_logger(__name__)


class TimeoutError(Exception):
    """Code execution timeout exception"""

    pass


@contextmanager
def timeout_context(seconds: int):
    """
    Code execution timeout context manager

    Notice:
    - Only works on Unix/Linux systems
    - Only valid in the main thread, non-main threads will be downgraded to unlimited timeout
    - Will downgrade to unlimited timeout on Windows

    Args:
        seconds: timeout (seconds)
    """
    # Check if in main thread
    is_main_thread = threading.current_thread() is threading.main_thread()

    if sys.platform == "win32":
        # signal.alarm is not supported on Windows, only warnings can be logged
        logger.warning("Windows does not support signal-based timeouts; execution time limits may not work")
        yield
        return

    if not is_main_thread:
        # Non-main threads cannot use signal. Warnings are logged but timeouts are not limited.
        # logger.warning(f"Currently running in a non-main thread (thread: {threading.current_thread().name}),"
        #               f"signal timeout is not available, code execution may not limit the time")
        yield
        return

    def timeout_handler(signum, frame):
        raise TimeoutError(f"Code execution timed out after {seconds} seconds")

    try:
        # Set up signal handler
        old_handler = signal.signal(signal.SIGALRM, timeout_handler)
        signal.alarm(seconds)

        try:
            yield
        finally:
            # Restore original signal handler
            signal.alarm(0)
            signal.signal(signal.SIGALRM, old_handler)
    except ValueError as e:
        # If signal setup fails (such as in some environments), log a warning but do not interrupt execution
        logger.warning(f"Failed to set signal timeout: {str(e)}; execution will continue without timeout enforcement")
        yield


def safe_exec_code(
    code: str,
    exec_globals: Dict[str, Any],
    exec_locals: Optional[Dict[str, Any]] = None,
    timeout: int = 30,
    max_memory_mb: Optional[int] = None,
) -> Dict[str, Any]:
    """
    Safe execution of Python code

    Args:
        code: Python code to execute
        exec_globals: dictionary of global variables
        exec_locals: dictionary of local variables (if None, exec_globals is used)
        timeout: timeout (seconds), default 30 seconds
        max_memory_mb: Maximum memory limit (MB), default 500MB

    Returns:
        Execution result dictionary, including:
        - success: bool, whether the execution was successful
        - error: str, error message (if failure)
        - result: Any, execution result (if any)

    Raises:
        TimeoutError: If the code execution times out
    """
    if exec_locals is None:
        exec_locals = exec_globals

    # Set memory limit (if supported)
    if max_memory_mb is None:
        max_memory_mb = 500  # Default 500MB

    try:
        # Note: resource.setrlimit is process level and affects the entire API process.
        # The previous global limit of 500MB could prevent parallel strategies/threads from allocating memory.
        # Only set if SAFE_EXEC_ENABLE_RLIMIT is explicitly turned on.
        if sys.platform != "win32" and os.getenv("SAFE_EXEC_ENABLE_RLIMIT", "false").lower() == "true":
            try:
                import resource

                max_memory_bytes = max_memory_mb * 1024 * 1024
                resource.setrlimit(resource.RLIMIT_AS, (max_memory_bytes, max_memory_bytes))
                logger.debug(f"Memory limit set: {max_memory_mb}MB (SAFE_EXEC_ENABLE_RLIMIT enabled)")
            except (ImportError, ValueError, OSError) as e:
                logger.warning(f"Failed to set memory limit: {str(e)}")
        else:
            logger.debug("No resource memory limit (SAFE_EXEC_ENABLE_RLIMIT disabled or unsupported platform)")

        # On Windows, timeout_context doesn't really limit the time
        # But a warning will be logged
        with timeout_context(timeout):
            exec(code, exec_globals, exec_locals)

        return {"success": True, "error": None, "result": None}

    except MemoryError:
        error_msg = f"Code execution exceeded the memory limit of {max_memory_mb}MB"
        logger.error(f"Code execution out of memory (limit={max_memory_mb}MB)")
        return {"success": False, "error": error_msg, "result": None}
    except TimeoutError as e:
        error_msg = str(e)
        logger.error(f"Code execution timed out (timeout={timeout}s)")
        return {"success": False, "error": error_msg, "result": None}
    except Exception as e:
        error_msg = f"Code execution error: {str(e)}\n{traceback.format_exc()}"
        logger.error(f"Code execution error: {str(e)}")
        logger.error(traceback.format_exc())
        return {"success": False, "error": error_msg, "result": None}


def validate_code_safety(code: str) -> Tuple[bool, Optional[str]]:
    """
    Verify code security (basic check)

    Check your code for dangerous function calls or imports

    Args:
        code: Python code to check

    Returns:
        (is_safe: bool, error_message: Optional[str])
    """
    import ast
    import re

    # Dangerous keywords and function names
    dangerous_patterns = [
        # System command execution
        r"\bos\.system\b",
        r"\bos\.popen\b",
        r"\bos\.spawn\b",
        r"\bos\.exec\b",
        r"\bos\.fork\b",
        r"\bsubprocess\b",
        r"\bcommands\b",
        # code execution
        r"\b__import__\s*\(",
        r"\beval\s*\(",
        r"\bexec\s*\(",
        r"\bcompile\s*\(",
        # File operations
        r"\bopen\s*\(",
        r"\bfile\s*\(",
        r"\b__builtins__\b",
        # module import
        r"\bimport\s+os\b",
        r"\bimport\s+sys\b",
        r"\bimport\s+subprocess\b",
        r"\bimport\s+pymysql\b",
        r"\bimport\s+sqlite3\b",
        r"\bimport\s+requests\b",
        r"\bimport\s+urllib\b",
        r"\bimport\s+http\b",
        r"\bimport\s+socket\b",
        r"\bimport\s+ftplib\b",
        r"\bimport\s+telnetlib\b",
        r"\bimport\s+pickle\b",
        r"\bimport\s+cpickle\b",
        r"\bimport\s+marshal\b",
        r"\bimport\s+ctypes\b",
        r"\bimport\s+multiprocessing\b",
        r"\bimport\s+threading\b",
        r"\bimport\s+concurrent\b",
        # Reflection and metaprogramming (possibly used to bypass restrictions)
        r"\bgetattr\s*\(.*__import__",
        r"\bgetattr\s*\(.*eval",
        r"\bgetattr\s*\(.*exec",
        r"\bsetattr\s*\(",
        r"\b__getattribute__\b",
        r"\b__setattr__\b",
        r"\b__dict__\b",
        r"\bglobals\s*\(",
        r"\blocals\s*\(",
        r"\bdir\s*\(",
        r"\btype\s*\(.*\)\s*\(",  # type() may be used to create new types
        r"\b__class__\b",
        r"\b__bases__\b",
        r"\b__subclasses__\b",
        r"\b__mro__\b",
        r"\b__init__\b.*__import__",
        r"\b__new__\b.*__import__",
        # Other dangerous operations
        r"\b__builtins__\s*\[",
        r"\b__builtins__\s*\.",
        r"\b__import__\s*\(",
        r"\bimportlib\b",
        r"\bimp\b",
    ]

    # Check your code for dangerous patterns
    for pattern in dangerous_patterns:
        if re.search(pattern, code):
            return False, f"Dangerous code pattern detected: {pattern}"

    # Try parsing the AST, checking for dangerous nodes
    try:
        tree = ast.parse(code)

        # List of dangerous modules (extended)
        dangerous_modules = [
            "os",
            "sys",
            "subprocess",
            "pymysql",
            "sqlite3",
            "requests",
            "urllib",
            "http",
            "socket",
            "ftplib",
            "telnetlib",
            "pickle",
            "cpickle",
            "marshal",
            "ctypes",
            "multiprocessing",
            "threading",
            "concurrent",
            "importlib",
            "imp",
            "builtins",
        ]

        # List of dangerous functions (extended)
        # Note: hasattr is safe and is only used to check attributes, not to access
        dangerous_functions = [
            "eval",
            "exec",
            "compile",
            "__import__",
            "getattr",
            "setattr",
            "delattr",  # hasattr has been removed, it is safe
            "globals",
            "locals",
            "vars",
            "dir",
            "type",
        ]

        # Check for dangerous function calls
        for node in ast.walk(tree):
            # Check for calls to dangerous functions
            if isinstance(node, ast.Call):
                if isinstance(node.func, ast.Name):
                    func_name = node.func.id
                    if func_name in dangerous_functions:
                        return False, f"Dangerous function call detected: {func_name}()"

                # Check if there are calls to os.system etc.
                if isinstance(node.func, ast.Attribute):
                    if isinstance(node.func.value, ast.Name):
                        if node.func.value.id in dangerous_modules:
                            return False, f"Dangerous module call detected: {node.func.value.id}.{node.func.attr}"

                    # Check if there are bypass methods such as getattr(builtins, '__import__')
                    if isinstance(node.func, ast.Name) and node.func.id == "getattr":
                        # Check the parameters of getattr
                        if len(node.args) >= 2:
                            if isinstance(node.args[0], ast.Name) and node.args[0].id in ["builtins", "__builtins__"]:
                                if isinstance(node.args[1], ast.Constant) and node.args[1].value in dangerous_functions:
                                    return (
                                        False,
                                        f"Detected an attempt to bypass restrictions via getattr: getattr({node.args[0].id}, '{node.args[1].value}')",
                                    )

        # Check the import statement: the use of import is prohibited in user scripts (security dependencies are uniformly injected by the platform)
        for node in ast.walk(tree):
            if isinstance(node, ast.Import):
                return (
                    False,
                    "Import statements are not allowed in scripts. Use the platform-provided objects such as pd and np directly.",
                )

            if isinstance(node, ast.ImportFrom):
                return (
                    False,
                    "Import statements are not allowed in scripts. Use the platform-provided objects such as pd and np directly.",
                )

        # Check if there is an attempt to access __builtins__
        for node in ast.walk(tree):
            if isinstance(node, ast.Attribute):
                if isinstance(node.attr, str) and node.attr.startswith("__") and node.attr.endswith("__"):
                    if node.attr in [
                        "__builtins__",
                        "__import__",
                        "__class__",
                        "__bases__",
                        "__subclasses__",
                        "__mro__",
                    ]:
                        # Check if used in dangerous context
                        if isinstance(node.value, ast.Name) and node.value.id in ["builtins", "__builtins__"]:
                            return False, f"Dangerous attribute access detected: {node.value.id}.{node.attr}"

    except SyntaxError as e:
        return False, f"Code syntax error: {str(e)}"
    except Exception as e:
        # If AST parsing fails, log a warning but allow to continue (possibly incomplete code)
        logger.warning(f"AST parse failed; skipping safety checks: {str(e)}")

    return True, None