# First course work for Udemy "Become a Professional Python Programmer" training

import statistics

CorrectUsername = "Admin"
CorrectPassword = "999"
studentDict = {}


def add_student():
    name_to_add = str(input('Student name: '))
    grade_to_add = int(input('Grade: '))
    if name_to_add not in studentDict:
        studentDict[name_to_add] = []
        studentDict[name_to_add].append(grade_to_add)
    else:
        studentDict[name_to_add].append(grade_to_add)
    print(studentDict)


def remove_student():
    name_to_remove = str(input('Student name: '))
    if name_to_remove in studentDict:
        del studentDict[name_to_remove]
    print(studentDict)


def average_grade():
    name_avg = str(input('Student name: '))
    if name_avg in studentDict:
        print('\nAverage grade: ', statistics.mean(studentDict[name_avg]))


def authorization():
    loop = True
    while loop:
        username = input('Please, enter your username: ')
        if username == CorrectUsername:
            password = input('Please enter your password: ')
            if password == CorrectPassword:
                print('Logged in successfully as ' + username)
                loop = False
            else:
                print('Password incorrect!')
        else:
            print('Username incorrect!')


def menu():
    trigger = True
    while trigger:
        print("""
        [1] - Enter Grades\n
        [2] - Remove Student\n
        [3] - Student Average Grades\n
        [4] - Exit\n
        What would you like to do today? (Enter a number: )
        """)
        answer = input('What would you like to do? ')
        if answer == '1':
            add_student()
        elif answer == '2':
            remove_student()
        elif answer == '3':
            average_grade()
        elif answer == '4':
            trigger = False
        else:
            print('You enter non-valid value, please try again!')

authorization()
menu()