Refactor SSO authentication to support multiple providers and enhance error handling

auth/providers/base.py

@@ -0,0 +1,35 @@
+from abc import ABC, abstractmethod
+import requests
+
+
+class SSOProvider(ABC):
+    """Base class for SSO authentication providers."""
+
+    # Override these in subclasses
+    name: str = "base"
+    domain: str = ""
+
+    def __init__(self, username: str, password: str):
+        self.username = username
+        self.password = password
+        self.session: requests.Session = None
+        self.redirect_response: requests.Response = None
+        self.saml_response_html: str = None
+
+    def set_session(self, session: requests.Session):
+        """Set the shared session from AnnySession."""
+        self.session = session
+
+    def set_redirect_response(self, response: requests.Response):
+        """Set the redirect response from Anny SSO initiation."""
+        self.redirect_response = response
+
+    @abstractmethod
+    def authenticate(self) -> str:
+        """
+        Perform institution-specific authentication.
+
+        Returns:
+            The HTML containing the SAML response, or raises an exception on failure.
+        """
+        pass