update: generator templates to delegate to api_core helpers

Author: hebaalazzeh

packages/gapic-generator/gapic/templates/%namespace/%name_%version/%sub/services/%service/client.py.j2

@@ -145,37 +145,8 @@ class {{ service.client_name }}(metaclass={{ service.client_name }}Meta):
 
     @staticmethod
     def _get_default_mtls_endpoint(api_endpoint) -> Optional[str]:
-        """Converts api endpoint to mTLS endpoint.
-
-        Convert "*.sandbox.googleapis.com" and "*.googleapis.com" to
-        "*.mtls.sandbox.googleapis.com" and "*.mtls.googleapis.com" respectively.
-        Args:
-            api_endpoint (Optional[str]): the api endpoint to convert.
-        Returns:
-            Optional[str]: converted mTLS api endpoint.
-        """
-        if not api_endpoint:
-            return api_endpoint
-
-        mtls_endpoint_re = re.compile(
-            r"(?P<name>[^.]+)(?P<mtls>\.mtls)?(?P<sandbox>\.sandbox)?(?P<googledomain>\.googleapis\.com)?"
-        )
-
-        m = mtls_endpoint_re.match(api_endpoint)
-        if m is None:
-            # Could not parse api_endpoint; return as-is.
-            return api_endpoint
-
-        name, mtls, sandbox, googledomain = m.groups()
-        if mtls or not googledomain:
-            return api_endpoint
-
-        if sandbox:
-            return api_endpoint.replace(
-                "sandbox.googleapis.com", "mtls.sandbox.googleapis.com"
-            )
-
-        return api_endpoint.replace(".googleapis.com", ".mtls.googleapis.com")
+        """Converts api endpoint to mTLS endpoint."""
+        return gapic_v1.client_helpers._get_default_mtls_endpoint(api_endpoint)
 
     # Note: DEFAULT_ENDPOINT is deprecated. Use _DEFAULT_ENDPOINT_TEMPLATE instead.
     DEFAULT_ENDPOINT = {% if service.host %}"{{ service.host }}"{% else %}None{% endif %}
@@ -190,29 +161,8 @@ class {{ service.client_name }}(metaclass={{ service.client_name }}Meta):
 
     @staticmethod
     def _use_client_cert_effective():
-        """Returns whether client certificate should be used for mTLS if the 
-        google-auth version supports should_use_client_cert automatic mTLS enablement.
-
-        Alternatively, read from the GOOGLE_API_USE_CLIENT_CERTIFICATE env var.
-
-        Returns:
-            bool: whether client certificate should be used for mTLS
-        Raises:
-            ValueError: (If using a version of google-auth without should_use_client_cert and
-	    GOOGLE_API_USE_CLIENT_CERTIFICATE is set to an unexpected value.)
-        """
-        # check if google-auth version supports should_use_client_cert for automatic mTLS enablement
-        if hasattr(mtls, "should_use_client_cert"):  # pragma: NO COVER
-            return mtls.should_use_client_cert()
-        else: # pragma: NO COVER
-            # if unsupported, fallback to reading from env var
-            use_client_cert_str = os.getenv("GOOGLE_API_USE_CLIENT_CERTIFICATE", "false").lower()
-            if use_client_cert_str not in ("true", "false"):
-                raise ValueError(
-                    "Environment variable `GOOGLE_API_USE_CLIENT_CERTIFICATE` must be"
-                    " either `true` or `false`"
-                )
-            return use_client_cert_str == "true"
+        """Returns whether client certificate should be used for mTLS."""
+        return gapic_v1.client_helpers._use_client_cert_effective()
 
     @classmethod
     def from_service_account_info(cls, info: dict, *args, **kwargs):
@@ -393,29 +343,16 @@ class {{ service.client_name }}(metaclass={{ service.client_name }}Meta):
 
     @staticmethod
     def _get_api_endpoint(api_override, client_cert_source, universe_domain, use_mtls_endpoint) -> str:
-        """Return the API endpoint used by the client.
-
-        Args:
-            api_override (str): The API endpoint override. If specified, this is always
-                the return value of this function and the other arguments are not used.
-            client_cert_source (bytes): The client certificate source used by the client.
-            universe_domain (str): The universe domain used by the client.
-            use_mtls_endpoint (str): How to use the mTLS endpoint, which depends also on the other parameters.
-                Possible values are "always", "auto", or "never".
-
-        Returns:
-            str: The API endpoint to be used by the client.
-        """
-        if api_override is not None:
-            api_endpoint = api_override
-        elif use_mtls_endpoint == "always" or (use_mtls_endpoint == "auto" and client_cert_source):
-            _default_universe = {{ service.client_name }}._DEFAULT_UNIVERSE
-            if universe_domain != _default_universe:
-                raise MutualTLSChannelError(f"mTLS is not supported in any universe other than {_default_universe}.")
-            api_endpoint = {{ service.client_name }}.DEFAULT_MTLS_ENDPOINT
-        else:
-            api_endpoint = {{ service.client_name }}._DEFAULT_ENDPOINT_TEMPLATE.format(UNIVERSE_DOMAIN=universe_domain)
-        return api_endpoint
+        """Return the API endpoint used by the client."""
+        return gapic_v1.client_helpers._get_api_endpoint(
+            api_override,
+            client_cert_source,
+            universe_domain,
+            use_mtls_endpoint,
+            {{ service.client_name }}._DEFAULT_UNIVERSE,
+            {{ service.client_name }}.DEFAULT_MTLS_ENDPOINT,
+            {{ service.client_name }}._DEFAULT_ENDPOINT_TEMPLATE,
+        )
 
     @staticmethod
     def _get_universe_domain(client_universe_domain: Optional[str], universe_domain_env: Optional[str]) -> str: