main.py

# main.py

import sys
from PyQt5.QtWidgets import QApplication, QMainWindow, QStackedWidget

from windows.login_window import LoginWindow
from windows.new_account_window import NewAccountWindow
from windows.main_window import MainWindow

class MainApp(QMainWindow):
    def __init__(self):
        super(MainApp, self).__init__()

        self.stack = QStackedWidget()
        self.setCentralWidget(self.stack)
        self.init_app_settings()
        self.show_login_window()

    def show_login_window(self):
        self.login_window = LoginWindow(self)
        self.stack.addWidget(self.login_window)
        self.stack.setCurrentWidget(self.login_window)

    def show_new_account_window(self):
        self.new_account_window = NewAccountWindow(self)
        self.stack.addWidget(self.new_account_window)
        self.stack.setCurrentWidget(self.new_account_window)

    def show_main_window(self, username_in):
        self.main_window = MainWindow(self, username_in)
        self.stack.addWidget(self.main_window)
        self.stack.setCurrentWidget(self.main_window)

    def init_app_settings(self):
        title = "Wirtualny trener personalny"
        min_window_width = 1200
        min_window_height = 800

        self.setWindowTitle(title)
        self.setMinimumSize(min_window_width, min_window_height)

    def closeEvent(self, event):
        current_widget = self.stack.currentWidget()
        if isinstance(current_widget, MainWindow):
             current_page = current_widget.stacked_main_window.currentWidget()
             if hasattr(current_page, 'stop_training_if_any'):
                 current_page.stop_training_if_any()

def main():
    app = QApplication(sys.argv)
    main_window = MainApp()
    main_window.show()
    sys.exit(app.exec_())


if __name__ == "__main__":
    main()