Improve password generator security and input handling

Password-Generator/password.py

@@ -1,63 +1,80 @@
-import random
+import secrets
+import string
 
-def generatePassword(pwlength):
-
-    alphabet = "abcdefghijklmnopqrstuvwxyz"
-
-    passwords = [] 
-
-    for i in pwlength:
-
-        password = "" 
-        for j in range(i):
-            next_letter_index = random.randrange(len(alphabet))
-            password = password + alphabet[next_letter_index]
-
-        password = replaceWithNumber(password)
-        password = replaceWithUppercaseLetter(password)
-
-        passwords.append(password) 
+def generate_password(length: int = 12, digits: bool = True, symbols: bool = True) -> str:
 
-    return passwords
-
-
-def replaceWithNumber(pword):
-    for i in range(random.randrange(1,3)):
-        replace_index = random.randrange(len(pword)//2)
-        pword = pword[0:replace_index] + str(random.randrange(10)) + pword[replace_index+1:]
-        return pword
-
-
-def replaceWithUppercaseLetter(pword):
-    for i in range(random.randrange(1,3)):
-        replace_index = random.randrange(len(pword)//2,len(pword))
-        pword = pword[0:replace_index] + pword[replace_index].upper() + pword[replace_index+1:]
-        return pword
-
-
-
-def main():
+    min_required = int(digits) + int(symbols)
+    if length < min_required:
+        raise ValueError("Password length too small for selected options")
 
-    numPasswords = int(input("How many passwords do you want to generate? "))
+    pool = string.ascii_letters
+    required_chars = []
 
-    print("Generating " +str(numPasswords)+" passwords")
-
-    passwordLengths = []
-
-    print("Minimum length of password should be 3")
+    if digits:
+        pool += string.digits
+        required_chars.append(secrets.choice(string.digits))
 
-    for i in range(numPasswords):
-        length = int(input("Enter the length of Password #" + str(i+1) + " "))
-        if length<3:
-            length = 3
-        passwordLengths.append(length)
+    if symbols:
+        pool += string.punctuation
+        required_chars.append(secrets.choice(string.punctuation))
 
+    remaining_length = length - len(required_chars)
 
-    Password = generatePassword(passwordLengths)
-
-    for i in range(numPasswords):
-        print ("Password #"+str(i+1)+" = " + Password[i])
-
+    password = required_chars + [secrets.choice(pool) for _ in range(remaining_length)]
+    secrets.SystemRandom().shuffle(password)
+
+    return ''.join(password)
+
+def save(passwords: list) -> None:
+    try:
+        agree: str = input("Do you want to save the passwords to a file? (y/n): ").lower().strip()
+        if agree not in ["y", "yes"]:
+            return
+        else:
+            fileName: str = input("Enter the name of the file (without .txt): ").strip()
+            if not fileName:
+                fileName: str = "passwords"
+        print("\nSaving passwords to file...")
+        with open(fileName + ".txt", "w") as f:
+            for password in passwords:
+                f.write(password + "\n")
+        print("Passwords saved successfully!")
+    except OSError as e:
+        print(f"Error saving passwords: {e}")
 
+def main():
+    try:
+        length: int = int(input("Enter the length of the password: "))
+        count: int = int(input("Enter the number of passwords to generate: "))
+
+        if length < 1 or count < 1:
+            print("Please enter positive integers only.")
+            return
+
+        if length > 128:
+            print("Password length cannot be greater than 128 characters.")
+            return
+
+        if length < 6:
+            print("Password is too short - Generating Passwords of length 6")
+            length = 6
+
+        digits: bool = input("Include digits? (y/n): ").lower().strip() in ["y", "yes"]
+        symbols: bool = input("Include symbols? (y/n): ").lower().strip() in ["y", "yes"]
+
+        print("\nGenerating Secure Passwords...\n")
+        passwords = []
+        for i in range(count):
+            password = generate_password(length, digits=digits, symbols=symbols)
+            passwords.append(password)
+            print(f"Password #{i + 1}: {password}")
+
+        save(passwords)
+
+    except ValueError:
+        print("Please Enter Valid Integers Only")
+    except Exception as e:
+        print(f"An unexpected error occurred: {e}")
 
-main()
+if __name__ == "__main__":
+    main()