from PyQt5 import uic
from PyQt5.QtGui import QWindow
from DATA225utils import make_connection

class TitanicWindow(QWindow):
    """
    The main application window.
    """
    
    def __init__(self):
        """
        Load the UI and initialize its components.
        """
        super().__init__()
        
        # Load the display.
        self.ui = uic.loadUi('titanic_window.ui')
        
        # Initialize the class menu.
        self._initialize_class_menu()
        self.ui.class_menu.currentIndexChanged.connect(self._display_passenger_count)

        # Display the initial count.
        self._display_passenger_count()

        self.ui.show()

    def _initialize_class_menu(self):
        """
        Initialize the class menu with passenger classes.
        """
        for klass in ['1st', '2nd', '3rd']:
            self.ui.class_menu.addItem(klass, klass)
            
    def _display_passenger_count(self):
        """
        Menu item event handler:
        Display the count of passengers of the chosen passenger class.
        """
        klass = self.ui.class_menu.currentData()
                
        # Query the database to get the passenger count
        # of the chosen passenger class.
        conn = make_connection(config_file = 'titanic.ini')
        cursor = conn.cursor()

        sql = ( """
                SELECT COUNT(*)
                FROM passengers
                """
              f"WHERE class = '{klass}'"
              )
        
        cursor.execute(sql)
        count = cursor.fetchone()
        
        cursor.close()
        conn.close()
        
        # Set the count into the text field.
        self.ui.the_count.setText(f'{count[0]}')