Exercise-16-Password-Generator.py

'''
Exercise 16: Password Generator

Write a password generator in Python. Be creative with how
you generate passwords - strong passwords have a mix of lowercase
letters, uppercase letters, numbers, and symbols. The passwords
should be random, generating a new password every time the user
asks for a new password. Include your run-time code in a main method.

Extra:

Ask the user how strong they want their password to be. For weak
passwords, pick a word or two from a list.

'''

# Solution
def generate_passwords(level):
    """
    Generate password of specific level.
    
    Arguments:
    level -- password security level. 8 characters for low, 12 for
    middle, and 16 for high. In each pattern, the password is a
    mix of lowercase letters, uppercase letters, numbers, and symbols.
    
    Returns:
    password -- a password string.
    """
    import string
    import random
    
    level_dict = {'low':8, 'middle':12, 'high':16}
    
    segment = [0, 0, 0, 0]
    for x in range(level_dict[level]):
        r = random.randint(0,3)
        segment[r] += 1
    
    lower_letter = random.choices(string.ascii_lowercase, k=segment[0])
    upper_letter = random.choices(string.ascii_uppercase, k=segment[1])
    digits = random.choices(string.digits, k=segment[2])
    symbols = random.choices('!@#$%^&*()_+', k=segment[3])
    
    password = lower_letter + upper_letter + digits + symbols
    random.shuffle(password)
    
    return ''.join(password)

def check_level_input(string, level):
    """
    Check the input string is a level or not.
    
    Arguments:
    string -- input string.
    level -- correct level string.
    
    Returns:
    True/False -- if the input is correct level, return True, else return false.
    """
    if string.lower() == level or string.lower() == level.lower()[0]:
        return True
    else:
        return False
    
def main():
    while True:
        level = input('Choose your password security level: [low/middle/high]')
        if level.lower() == 'exit':
            break
        elif check_level_input(level, 'low'):
            print(generate_passwords('low'))
        elif check_level_input(level, 'middle'):
            print(generate_passwords('middle'))
        elif check_level_input(level, 'high'):
            print(generate_passwords('high'))
        else:
            print('Input error.')
        
if __name__ == "__main__":
    main()

# Test Part
# Choose your password security level: [low/middle/high]low
# #*ug38Gu
# Choose your password security level: [low/middle/high]mi
# Input error.
# Choose your password security level: [low/middle/high]middle
# N*(&wB_If1#R
# Choose your password security level: [low/middle/high]high
# _)6oC03@y%BJj)u9
# Choose your password security level: [low/middle/high]high
# jEby&f8$^59z9l%K
# Choose your password security level: [low/middle/high]exit