Split out main cli module into lazily loaded submodules (#1039)

kasa/cli/lazygroup.py

@@ -0,0 +1,70 @@
+"""Module for lazily instantiating sub modules.
+
+Taken from the click help files.
+"""
+
+import importlib
+
+import asyncclick as click
+
+
+class LazyGroup(click.Group):
+    """Lazy group class."""
+
+    def __init__(self, *args, lazy_subcommands=None, **kwargs):
+        super().__init__(*args, **kwargs)
+        # lazy_subcommands is a map of the form:
+        #
+        #   {command-name} -> {module-name}.{command-object-name}
+        #
+        self.lazy_subcommands = lazy_subcommands or {}
+
+    def list_commands(self, ctx):
+        """List click commands."""
+        base = super().list_commands(ctx)
+        lazy = list(self.lazy_subcommands.keys())
+        return lazy + base
+
+    def get_command(self, ctx, cmd_name):
+        """Get click command."""
+        if cmd_name in self.lazy_subcommands:
+            return self._lazy_load(cmd_name)
+        return super().get_command(ctx, cmd_name)
+
+    def format_commands(self, ctx, formatter):
+        """Format the top level help output."""
+        sections = {}
+        for cmd, parent in self.lazy_subcommands.items():
+            sections.setdefault(parent, [])
+            cmd_obj = self.get_command(ctx, cmd)
+            help = cmd_obj.get_short_help_str()
+            sections[parent].append((cmd, help))
+        for section in sections:
+            if section:
+                header = (
+                    f"Common {section} commands (also available "
+                    f"under the `{section}` subcommand)"
+                )
+            else:
+                header = "Subcommands"
+            with formatter.section(header):
+                formatter.write_dl(sections[section])
+
+    def _lazy_load(self, cmd_name):
+        # lazily loading a command, first get the module name and attribute name
+        if not (import_path := self.lazy_subcommands[cmd_name]):
+            import_path = f".{cmd_name}.{cmd_name}"
+        else:
+            import_path = f".{import_path}.{cmd_name}"
+        modname, cmd_object_name = import_path.rsplit(".", 1)
+        # do the import
+        mod = importlib.import_module(modname, package=__package__)
+        # get the Command object from that module
+        cmd_object = getattr(mod, cmd_object_name)
+        # check the result to make debugging easier
+        if not isinstance(cmd_object, click.BaseCommand):
+            raise ValueError(
+                f"Lazy loading of {cmd_name} failed by returning "
+                "a non-command object"
+            )
+        return cmd_object