import csv
import pandas as pd
from pandas import DataFrame

from PyQt6 import uic, QtWidgets
from PyQt6.QtGui import QWindow
from PyQt6.QtWidgets import QDialog, QApplication

class TitanicCounts(QWindow):
    """
    The main application window.
    """
    
    def __init__(self):
        """
        Load the UI and initialize its components.
        """
        super().__init__()
                
        self._passenger_df = pd.read_csv('TitanicSurvival.csv')
        self.ui = uic.loadUi('titanic_counts.ui')
        
        self._initialize_class_menu()
        self.ui.count_text.setText('')
        
        # Connect the event handler to the menu.
        self.ui.class_menu.currentIndexChanged.connect(
                                        self._update_count)
        
        self.ui.show();
        
    def _initialize_class_menu(self):
        """
        Initialize the passenger class menu.
        """
        self.ui.class_menu.addItem('[select passenger class]', '')
        self.ui.class_menu.addItem('All passengers', 'all')
        self.ui.class_menu.addItem('1st class passengers', '1st')
        self.ui.class_menu.addItem('2nd class passengers', '2nd')
        self.ui.class_menu.addItem('3rd class passengers', '3rd')
        
    def _update_count(self):
        klass = self.ui.class_menu.currentData()
        
        # Determine which passenger class.
        if klass == '':
            self.ui.count_text.setText('')
            return
        elif klass == 'all':
            df = self._passenger_df
        else:
            df = self._passenger_df[
                    self._passenger_df.passengerClass == klass
            ]
               
        row_count = len(df.index)
        self.ui.count_text.setText(f'{row_count:,d}')