PasswordGenerator

import random

def getLength():
#This function prompts the user to enter the desired password length, 
#checks if the input is a positive integer, and returns the length value.
    while True:
        try:
            length = int(input("\nPlease enter the length of your password: "))
            if length <= 0:
                print("The length must be a positive integer number. Please try again.")
                continue
            break
        except ValueError:
            print("The length must be a positive integer number.")
    return length

def getComplexity():
#This function prompts the user to choose a complexity level for the password,
#displays a description of each level, checks if the input is a number between 1 and 5, 
#and returns the complexity value.
    print("\nPlease choose the complexity level of your password, according to the following description:")
    print("Level 1: very low: contains only digits")
    print("Level 2: low: contains digits and some letters")
    print("Level 3: moderate: contains digits and letters approximately equally")
    print("Level 4: strong: contains digits, letters and some special characters")
    print("Level 5: very strong: contains digits, letters and special characters approximately equally")
    while True:
        try:
            complexity = int(input("\nPlease enter the complexity level (1-5): "))
            if complexity not in range(1,6):
                print("The complexity must be an integer between 1 to 5.")
                continue
            break
        except ValueError:
            print("The complexity must be an integer between 1 to 5.")
    return complexity

def passwordSegments(length, complexity):
#This function takes in the desired password length and complexity level,
#determines the number of characters from each segment that the password should contain,
#and returns a list of these segment counts.
    segments = [0,0,0] #segments[0] = digits, segments[1] = letters, segments[2] = special chars
    if complexity == 1:
        segments[0], segments[1], segments[2] = length, 0, 0
    elif complexity == 2:
        segments[0], segments[1], segments[2] = int(length*0.8), length-int(length*0.8), 0
    elif complexity == 3:
        segments[0], segments[1], segments[2] = int(length*0.5), length-int(length*0.5), 0
    elif complexity == 4:
        segments[0], segments[1], segments[2] = int(length*0.4), int(length*0.4), length-int(length*0.4)-int(length*0.4)
    else:
        segments[0], segments[1], segments[2] = int(length*(1/3)), int(length*(1/3)), length-int(length*(1/3))-int(length*(1/3))
    return segments

def getSpecialChars(complexity):
#This function prompts the user to choose whether to use default special characters
#or to enter their own special characters. If the user chooses to enter their own characters,
#the function checks that the input contains only special characters and returns the special characters string.
    specialChars = "!@#$%^&*()-_+=/.,<>:;'{}\|~`" #built in chars.
    if complexity > 3:
    #if complexity <= 3 it means that the password will contain only digits and letters!
        while True:
            choice = input("Do you want to use the default special characters? (y/n): ")
            while True:
                if choice.lower() == "n":
                    specialChars = input("Enter your special characters: ")
                    temp = ''
                    for i in range(len(specialChars)): #removes digits and letters. keeps only special chars.
                        if specialChars[i].isalnum() == False:
                            temp += specialChars[i]
                    specialChars = ''.join(temp)
                    if len(specialChars) < 1:
                        print("You must enter at least one special character.")
                    else:
                        return specialChars
                elif choice.lower() != "y":
                    print("Enter n or y only.")
                    break
                else:
                    return specialChars

def generatePassword(length, complexity):
#The function takes in length and complexity given by the user and generates a password.
#Firstly creates the segments of the characters that can be in the password.
#After that randomlly picks from each segment and builds the password.
    newPassword = []
    segmentsCount = passwordSegments(length, complexity) #a counter list for the amount of chars from each segment.
    segments = ["0123456789", "AaBbCcDdEeFfGgHhIiJjKkLlMmNnOoPpQqRrSsTtUuVvWwXxYyZz"]
    segments.append(getSpecialChars(complexity))
    for i in range(length): #builds the password
        pickSegment = random.randint(0,2)
        while segmentsCount[pickSegment] == 0:
            pickSegment = random.randint(0,2)
        newPassword.append(random.choice(segments[pickSegment]))
        segmentsCount[pickSegment] -= 1
    newPassword = ''.join(newPassword)
    return newPassword

def startAgain():
#a function for letting the user to start again the program.
    choice = input("\nStart again? (y/n): ")
    choice = choice.lower()
    if choice == 'y':
        main()
    elif choice == 'n':
        return
    else:
        print("Type y or n only please.")
        startAgain()
    
def main():
    print("Hello!")
    length = getLength()
    complexity = getComplexity()
    while length < complexity:
        print("Password length cannot be less than complexity level. Please try again.")
        length = getLength()
        complexity = getComplexity()
    password = generatePassword(length, complexity)
    print(".\n.\n.\n.\n.\nYour password is: ", password)
    startAgain()
    
main()