Handle instances with a default port of 443

Closes #162

spectacles/cli.py

@@ -350,8 +350,7 @@ def _build_base_subparser() -> argparse.ArgumentParser:
         type=int,
         action=EnvVarAction,
         env_var="LOOKER_PORT",
-        default=19999,
-        help="The port of your Looker instance’s API. The default is port 19999.",
+        help="The port of your Looker instance’s API. The default is port 443 (HTTPS) for GCP-hosted instances and 19999 for legacy instances.",
     )
     base_subparser.add_argument(
         "--api-version",

spectacles/client.py

@@ -48,7 +48,7 @@ def __init__(
         base_url: str,
         client_id: str,
         client_secret: str,
-        port: int = 19999,
+        port: Optional[int] = None,
         api_version: float = 3.1,
     ):
         supported_api_versions = [3.1]
@@ -64,7 +64,17 @@ def __init__(
             )
 
         self.base_url: str = base_url.rstrip("/")
-        self.api_url: str = f"{self.base_url}:{port}/api/{api_version}/"
+        if port is None and self.base_url.endswith("cloud.looker.com"):
+            # GCP-hosted instance, so use default port of 443 with HTTPS
+            if not self.base_url.startswith("https"):
+                raise SpectaclesException(
+                    name="invalid-base-url",
+                    title="Looker instance base URL is not valid.",
+                    detail="The URL must be an HTTPS URL.",
+                )
+            self.api_url: str = f"{self.base_url}/api/{api_version}/"
+        else:
+            self.api_url = f"{self.base_url}:{port or 19999}/api/{api_version}/"
         self.client_id: str = client_id
         self.client_secret: str = client_secret
         self.api_version: float = api_version