Restructure crawling and auth related modules

PFERD/auth/authenticator.py

@@ -0,0 +1,81 @@
+from abc import ABC, abstractmethod
+from typing import Tuple
+
+from ..config import Config, Section
+
+
+class AuthLoadException(Exception):
+    pass
+
+
+class AuthException(Exception):
+    pass
+
+
+class AuthSection(Section):
+    pass
+
+
+class Authenticator(ABC):
+    def __init__(
+            self,
+            name: str,
+            section: AuthSection,
+            config: Config,
+    ) -> None:
+        """
+        Initialize an authenticator from its name and its section in the config
+        file.
+
+        If you are writing your own constructor for your own authenticator,
+        make sure to call this constructor first (via super().__init__).
+
+        May throw an AuthLoadException.
+        """
+
+        self.name = name
+
+    @abstractmethod
+    async def credentials(self) -> Tuple[str, str]:
+        pass
+
+    async def username(self) -> str:
+        username, _ = await self.credentials()
+        return username
+
+    async def password(self) -> str:
+        _, password = await self.credentials()
+        return password
+
+    def invalidate_credentials(self) -> None:
+        """
+        Tell the authenticator that some or all of its credentials are invalid.
+
+        Authenticators should overwrite this function if they have a way to
+        deal with this issue that is likely to result in valid credentials
+        (e. g. prompting the user).
+        """
+
+        raise AuthException("Invalid credentials")
+
+    def invalidate_username(self) -> None:
+        """
+        Tell the authenticator that specifically its username is invalid.
+
+        Authenticators should overwrite this function if they have a way to
+        deal with this issue that is likely to result in valid credentials
+        (e. g. prompting the user).
+        """
+
+        raise AuthException("Invalid username")
+
+    def invalidate_password(self) -> None:
+        """
+        Tell the authenticator that specifically its password is invalid.
+
+        Authenticators should overwrite this function if they have a way to
+        deal with this issue that is likely to result in valid credentials
+        (e. g. prompting the user).
+        """
+
+        raise AuthException("Invalid password")