app_err_handler.py

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"""!
********************************************************************************
@file   app_err_handler.py
@brief  Error handler to catch all unexpected exceptions to prevent application crashes
********************************************************************************
"""
 
# Source: https://timlehr.com/python-exception-hooks-with-qt-message-box/
 
import sys
import traceback
import logging
from typing import Optional, Any, TYPE_CHECKING
from types import TracebackType
 
from Source.version import __title__
from Source.Util.app_data import reset_config_dialog
from Source.Util.gui_toolkit import APPLICATION, SIGNAL, OBJECT, config_window, open_message_box
 
from Source.Model.language import L_CLOSE, L_REPAIR, L_UNEXP_ERROR
 
if TYPE_CHECKING:
    from Source.Controller.main_window import MainWindow
 
log = logging.getLogger(__title__)
 
 
class UncaughtHook(OBJECT):
    """!
    @brief Global exception handler. Overrides system exception hook to catch all unexpected errors.
    """
    exception_caught = SIGNAL(object)
 
    def __init__(self, *args: Any, **kwargs: Any) -> None:
        log.debug("Initializing Exception Handler")
 
        super().__init__(*args, **kwargs)
 
        self.main_window_controller: "MainWindow | None" = None
        self.crash_arrived = False
 
        # this registers the exception_hook() function as hook with the Python interpreter
        sys.excepthook = self.exception_hook
 
        # connect signal to execute the message box function always on main thread
        self.exception_caught.connect(self.show_exception_box)
 
    def show_exception_box(self, s_log_msg: str) -> None:
        """!
        @brief Displays the error message box
        @param s_log_msg : the error message to be displayed in details section
        """
        # check if QApplication instance is available
        self.crash_arrived = True
        if (APPLICATION is not None) and (APPLICATION.instance() is not None):
            b_close = (self.main_window_controller is not None) and self.main_window_controller.test_mode
            l_close_text = L_CLOSE
            if self.main_window_controller:
                text = self.main_window_controller.model.c_language.get_language_text(L_UNEXP_ERROR)
                repair_text = self.main_window_controller.model.c_language.get_language_text(L_REPAIR)
                close_text = self.main_window_controller.model.c_language.get_language_text(l_close_text)
            else:
                text = L_UNEXP_ERROR[0]
                repair_text = L_REPAIR[0]
                close_text = l_close_text[0]
            choice, _ = open_message_box(self.main_window_controller,
                                         "Error", f"{text}\t\t\t\t",
                                         btn_close=close_text,
                                         btn_special=repair_text,
                                         detailed_text=s_log_msg,
                                         execute=not b_close)
            if b_close:
                sys.exit(1)
            if choice:
                reset_config_dialog(self.main_window_controller)
            if self.main_window_controller:
                config_window(self.main_window_controller, show=False)
        else:
            log.error("Can't show Exception Display - No QApplication instance available.")
 
    def exception_hook(self, exc_type: type[BaseException], exc_value: BaseException, exc_traceback: Optional[TracebackType] = None) -> None:
        """!
        @brief Custom exception hook. It is triggered each time an uncaught exception occurs.
        @param exc_type : exception type
        @param exc_value : exception value
        @param exc_traceback : exception traceback
        """
        if issubclass(exc_type, KeyboardInterrupt):
            # ignore keyboard interrupt to support console application
            sys.__excepthook__(exc_type, exc_value, exc_traceback)
        else:
            log_msg = "\n".join([f"{exc_type.__name__}: {exc_value}",
                                 "".join(traceback.format_tb(exc_traceback))])
            log.error(log_msg)
 
            # trigger message box show
            self.exception_caught.emit(log_msg)
 
    def set_main_window_controller(self, main_window_controller: "MainWindow") -> None:
        """!
        @brief Sets the main window controller in order to unblock the UI after a critical exception is caught.
        @param main_window_controller : main window controller
        """
        self.main_window_controller = main_window_controller