feat: Add generic OAuth provider (Chainlit#1784)

Signed-off-by: Adam Tao <tcx4c70@gmail.com>

Author: tcx4c70

backend/chainlit/oauth_providers.py

@@ -730,6 +730,72 @@ async def get_user_info(self, token: str):
             return (kc_user, user)
 
 
+class GenericOAuthProvider(OAuthProvider):
+    env = [
+        "OAUTH_GENERIC_CLIENT_ID",
+        "OAUTH_GENERIC_CLIENT_SECRET",
+        "OAUTH_GENERIC_AUTH_URL",
+        "OAUTH_GENERIC_TOKEN_URL",
+        "OAUTH_GENERIC_USER_INFO_URL",
+        "OAUTH_GENERIC_SCOPES",
+    ]
+    id = os.environ.get("OAUTH_GENERIC_NAME", "generic")
+
+    def __init__(self):
+        self.client_id = os.environ.get("OAUTH_GENERIC_CLIENT_ID")
+        self.client_secret = os.environ.get("OAUTH_GENERIC_CLIENT_SECRET")
+        self.authorize_url = os.environ.get("OAUTH_GENERIC_AUTH_URL")
+        self.token_url = os.environ.get("OAUTH_GENERIC_TOKEN_URL")
+        self.user_info_url = os.environ.get("OAUTH_GENERIC_USER_INFO_URL")
+        self.scopes = os.environ.get("OAUTH_GENERIC_SCOPES")
+        self.user_identifier = os.environ.get("OAUTH_GENERIC_USER_IDENTIFIER", "email")
+
+        self.authorize_params = {
+            "scope": self.scopes,
+            "response_type": "code",
+        }
+
+        if prompt := self.get_prompt():
+            self.authorize_params["prompt"] = prompt
+
+    async def get_token(self, code: str, url: str):
+        payload = {
+            "client_id": self.client_id,
+            "client_secret": self.client_secret,
+            "code": code,
+            "grant_type": "authorization_code",
+            "redirect_uri": url,
+        }
+        async with httpx.AsyncClient() as client:
+            response = await client.post(self.token_url, data=payload)
+            response.raise_for_status()
+            json = response.json()
+            token = json.get("access_token")
+            if not token:
+                raise httpx.HTTPStatusError(
+                    "Failed to get the access token",
+                    request=response.request,
+                    response=response,
+                )
+            return token
+
+    async def get_user_info(self, token: str):
+        async with httpx.AsyncClient() as client:
+            response = await client.get(
+                self.user_info_url,
+                headers={"Authorization": f"Bearer {token}"},
+            )
+            response.raise_for_status()
+            server_user = response.json()
+            user = User(
+                identifier=server_user.get(self.user_identifier),
+                metadata={
+                    "provider": self.id,
+                },
+            )
+            return (server_user, user)
+
+
 providers = [
     GithubOAuthProvider(),
     GoogleOAuthProvider(),
@@ -741,6 +807,7 @@ async def get_user_info(self, token: str):
     AWSCognitoOAuthProvider(),
     GitlabOAuthProvider(),
     KeycloakOAuthProvider(),
+    GenericOAuthProvider(),
 ]