feat: create OTP class based on SMTP SSL

module/data/__init__.py

@@ -3,5 +3,6 @@
     REPORT,
     HELP,
     HELP_CMD_TEXT,
-    START_CMD_TEXT
+    START_CMD_TEXT,
+    MAIL_TEMPLATE
 )

module/data/constants.py

@@ -6,3 +6,11 @@
 
 REPORT = "Segnalazioni Rappresentanti 📬"
 HELP = "Help ❔"
+
+MAIL_TEMPLATE = (
+    "Ciao!\n\n"
+    "Se stai ricevendo questo messaggio vuol dire che ti stai registrando a FinderUniCT-Bot. "
+    "Se non sei stato tu, ignora semplicemente questo messaggio.\n"
+    "Il tuo codice OTP e': {otp}\n\n"
+    "Il team di FinderUniCT-Bot!"
+)

module/otp.py

@@ -0,0 +1,95 @@
+"""
+    OTP module.
+"""
+import os
+import random
+import smtplib
+from email.mime.text import MIMEText
+
+from module.data import MAIL_TEMPLATE
+
+#: Define the following in settings.yaml
+HOST = 'HOST'
+USER = "USER"
+PASSWORD = "PASSWORD"
+
+class OTPException(Exception):
+    pass
+
+class OTPConnectionFailed(OTPException):
+    pass
+
+class OTPLoginFailed(OTPException):
+    pass
+
+class OTPNotAuthenticated(OTPException):
+    pass
+
+class OTPCodeNotSent(OTPException):
+    pass
+
+class OTPSender:
+    """
+        OTP sender class.
+
+        Attributes:
+            authenticated (bool): True if the user is authenticated, False otherwise.
+
+        Methods:
+            login() -> None: 
+                Logs in to the SMTP server. Modifies the authenticated attribute.
+            send(to: str) -> str | None:
+                Sends a randomly generated OTP to the specified email address.
+                Returns the OTP sent to the specified email address.
+    """
+    def __init__(self):
+        try:
+            self.__server = smtplib.SMTP_SSL(HOST, smtplib.SMTP_SSL_PORT)
+        except Exception as e:
+            raise OTPConnectionFailed('Connection failed.') from e
+
+        self.authenticated = False
+        self.login()
+
+    def login(self) -> None:
+        """
+            Logs in to the SMTP server.
+
+            Returns:
+                None: check self.authenticated for login status.
+        """
+        if self.authenticated:
+            return
+
+        try:
+            self.__server.login(USER, PASSWORD)
+            self.authenticated = True
+        except Exception as e:
+            raise OTPLoginFailed('Login failed.') from e
+
+    def send(self, to: str) -> str:
+        """
+            Sends a randomly generated OTP to the specified email address.
+
+            Args:
+                to (str): The email address of the recipient.
+
+            Returns:
+                str: The OTP sent to the specified email address.
+        """
+        if not self.authenticated:
+            raise OTPNotAuthenticated('Not authenticated.')
+
+        random.seed(os.urandom(64))
+        otp = str(random.randint(100000, 999999))
+
+        message = MIMEText(MAIL_TEMPLATE.format(otp=otp))
+        message['From'] = USER
+        message['To'] = to
+        message['Subject'] = "FinderUniCT-Bot - Codice OTP"
+
+        try:
+            self.__server.send_message(message)
+            return otp
+        except Exception as e:
+            raise OTPCodeNotSent('OTP code not sent.') from e