Add airtable connector auth flow routes

surfsense_backend/app/schemas/airtable_auth_credentials.py

@@ -0,0 +1,51 @@
+from datetime import UTC, datetime
+
+from pydantic import BaseModel
+
+
+class AirtableAuthCredentialsBase(BaseModel):
+    access_token: str
+    refresh_token: str | None = None
+    token_type: str = "Bearer"
+    expires_in: int | None = None
+    expires_at: datetime | None = None
+    scope: str | None = None
+
+    @property
+    def is_expired(self) -> bool:
+        """Check if the credentials have expired."""
+        if self.expires_at is None:
+            return False
+        return self.expires_at <= datetime.now(UTC)
+
+    @property
+    def is_refreshable(self) -> bool:
+        """Check if the credentials can be refreshed."""
+        return self.refresh_token is not None
+
+    def to_dict(self) -> dict:
+        """Convert credentials to dictionary for storage."""
+        return {
+            "access_token": self.access_token,
+            "refresh_token": self.refresh_token,
+            "token_type": self.token_type,
+            "expires_in": self.expires_in,
+            "expires_at": self.expires_at.isoformat() if self.expires_at else None,
+            "scope": self.scope,
+        }
+
+    @classmethod
+    def from_dict(cls, data: dict) -> "AirtableAuthCredentialsBase":
+        """Create credentials from dictionary."""
+        expires_at = None
+        if data.get("expires_at"):
+            expires_at = datetime.fromisoformat(data["expires_at"])
+
+        return cls(
+            access_token=data["access_token"],
+            refresh_token=data.get("refresh_token"),
+            token_type=data.get("token_type", "Bearer"),
+            expires_in=data.get("expires_in"),
+            expires_at=expires_at,
+            scope=data.get("scope"),
+        )