Create unit3_ex3.4.py

Author: lironmiz

Diff for: unit3_ex3.4.py

@@ -0,0 +1,171 @@
+# exercise 3.4 from unit 3
+'''
+Ido maintains a baking blog online for food lovers. Every surfer who wants to connect to the blog is obliged to choose a username and password as follows.
+
+Username:
+
+Must consist of the following legal characters: English letters, numbers and an underscore.
+It must be between 3 and 16 characters long.
+The password:
+
+Must consist of at least 8 characters, and up to a maximum of 40 characters in length.
+Must contain at least one of the following mandatory characters: one uppercase English letter, one lowercase English letter,
+ one number and one special sign such as an exclamation mark (to perform the task you can use string.punctuation).
+You must help Ido write a code that checks whether the username and password entered by surfers meet the conditions.
+
+Write a function called check_input defined as follows:
+
+def check_input(username, password):
+
+The function accepts two parameters of type string: username and password. The function prints "OK" to the screen if the username and
+ password are correct (that is, meet the conditions presented earlier).
+
+If the username or password (or both) do not meet the defined conditions we would like to throw a detailed exception describing what
+ went wrong. For this purpose, fulfill the following exceptions:
+
+Exception named UsernameContainsIllegalCharacter - describes a username that contains illegal characters.
+Exception named UsernameTooShort - describes a username consisting of less than 3 characters.
+Exception named UsernameTooLong - describes a username consisting of more than 16 characters.
+An exception named PasswordMissingCharacter - describes a password that does not contain at least one of the mandatory characters.
+Exception named PasswordTooShort - describes a password consisting of less than 8 characters.
+Exception named PasswordTooLong - describes a password consisting of more than 40 characters.
+Please note: each exception is implemented in a separate class that inherits from the Exception superclass.
+
+We have updated the code of the check_input function so that in a situation where it receives as input an invalid username or password,
+ an appropriate exception will be thrown.
+
+If everything is correct, the function will print OK as usual.
+
+For your convenience, we have compiled for you inputs with which you can test the code you wrote.
+
+check_input("1", "2")
+check_input("0123456789ABCDEFG", "2")
+check_input("A_a1.", "12345678")
+check_input("A_1", "2")
+check_input("A_1", "ThisIsAQuiteLongPasswordAndHonestlyUnnecessary")
+check_input("A_1", "abcdefghijklmnop")
+check_input("A_1", "ABCDEFGHIJLKMNOP")
+check_input("A_1", "ABCDEFGhijklmnop")
+check_input("A_1", "4BCD3F6h1jk1mn0p")
+check_input("A_1", "4BCD3F6.1jk1mn0p")
+All inputs except the last one are incorrect. Make sure that for each of the inputs one exception is thrown that describes
+ the problem with it. The order of priority of the thrown exception is determined according to the order of the clauses in the question.
+
+Write a main main function that receives the user's username and password for the blog. Incorporate in the main function block a call
+ to the check_input function to check whether the input meets the conditions.
+
+If the input is not correct, ensure that a detailed message describing the problem with the input is printed to the user. Then ask
+ for more input until you get proper input.
+
+Below is a sample run:
+
+To view an accessible code snippet
+check_input("1", "2")
+check_input("0123456789ABCDEFG", "2")
+check_input("A_a1.", "12345678")
+check_input("A_1", "2")
+check_input("A_1", "ThisIsAQuiteLongPasswordAndHonestlyUnnecessary")
+check_input("A_1", "abcdefghijklmnop")
+check_input("A_1", "ABCDEFGHIJLKMNOP")
+check_input("A_1", "ABCDEFGhijklmnop")
+check_input("A_1", "4BCD3F6h1jk1mn0p")
+check_input("A_1", "4BCD3F6.1jk1mn0p")
+
+Improved the UsernameContainsIllegalCharacter and PasswordMissingCharacter exceptions to contain a more accurate description of the problem.
+
+So far the UsernameContainsIllegalCharacter exception class has printed a generic message:
+
+The username contains an illegal character
+
+Now, add a description of the illegal character and its position in the string to the UsernameContainsIllegalCharacter class.
+
+Below is a sample run:
+
+To view an accessible code snippet
+check_input("A_a1.", "12345678")
+So far the PasswordMissingCharacter exception class has printed a generic message:
+
+The password is missing a character
+
+Now, create 4 subclasses that inherit from the PasswordMissingCharacter class, where each class will describe a missing character in the password.
+
+Note, the classes must extend the use of the __str__ method of the superclass, so that when printing it will only add in parentheses additional
+ detail about the missing character. That is, it must use the method of the superclass and add to it.
+
+Here are additions for certain characters:
+
+check_input("A_1", "abcdefghijklmnop")
+check_input("A_1", "ABCDEFGHIJLKMNOP")
+check_input("A_1", "ABCDEFGhijklmnop")
+check_input("A_1", "4BCD3F6h1jk1mn0p")
+The password is missing a character (Uppercase)
+The password is missing a character (Lowercase)
+The password is missing a character (Digit)
+The password is missing a character (Special)
+'''
+
+import string
+
+
+class UsernameContainsIllegalCharacter(Exception):
+    def __init__(self, username, illegal_char, index):
+        self.username = username
+        self.illegal_char = illegal_char
+        self.index = index
+
+    def __str__(self):
+        return f"The username '{self.username}' contains the illegal character '{self.illegal_char}' at index {self.index}."
+class UsernameTooShort(Exception):
+    def __str__(self):
+        return "Username is too short. It must be at least 3 characters long."
+
+class UsernameTooLong(Exception):
+    def __str__(self):
+        return "Username is too long. It must be at most 16 characters long."
+
+
+class PasswordMissingCharacter(Exception):
+    def __init__(self, password, missing_char):
+        self.password = password
+        self.missing_char = missing_char
+
+    def __str__(self):
+        return f"The password '{self.password}' is missing the required character '{self.missing_char}'."
+class PasswordTooShort(Exception):
+    def __str__(self):
+        return "Password is too short. It must be at least 8 characters long."
+
+class PasswordTooLong(Exception):
+    def __str__(self):
+        return "Password is too long. It must be at most 40 characters long."
+
+def check_input(username, password):
+    if any(c.isalpha() for c in username):
+        raise UsernameContainsIllegalCharacter(username, c, username.index(c))
+
+    if not any(c.isdigit() for c in password):
+        raise PasswordMissingCharacter(password, 'a digit')
+    elif len(username) < 3:
+        raise UsernameTooShort
+    elif len(username) > 16:
+        raise UsernameTooLong
+    elif not any(c.isupper() for c in password) or not any(c.islower() for c in password) or not any(c.isdigit() for c in password) or not any(c in string.punctuation for c in password):
+        raise PasswordMissingCharacter
+    elif len(password) < 8:
+        raise PasswordTooShort
+    elif len(password) > 40:
+        raise PasswordTooLong
+    else:
+        print("OK")
+
+def main():
+    while True:
+        username = input("Enter a username: ")
+        password = input("Enter a password: ")
+        try:
+            check_input(username, password)
+            break
+        except Exception as e:
+            print(e)
+
+main()