Improve command line util

Author: staadecker

switch_model/__main__.py

@@ -17,6 +17,11 @@ def version():
         print(f"Switch Git branch: {branch}")
     return 0
 
+def help_text():
+    print(
+        f"Must specifiy one of the following commands: {list(cmds.keys())}.\nE.g. Run 'switch solve' or 'switch get_inputs'.")
+
+
 def get_module_runner(module):
     def runner():
         importlib.import_module(module).main()
@@ -29,18 +34,20 @@ def runner():
     "test": get_module_runner("switch_model.test"),
     "upgrade": get_module_runner("switch_model.upgrade"),
     "get_inputs": get_module_runner("switch_model.wecc.get_inputs"),
-    "version": version,
     "drop": get_module_runner("switch_model.tools.drop"),
     "new": get_module_runner("switch_model.tools.new"),
     "graph": get_module_runner("switch_model.tools.graph.cli_graph"),
     "compare": get_module_runner("switch_model.tools.graph.cli_compare"),
     "db": get_module_runner("switch_model.wecc.__main__"),
+    "help": help_text
 }
 
 
 def main():
     parser = argparse.ArgumentParser(add_help=False)
-    parser.add_argument("subcommand", choices=cmds.keys(), help="The possible switch subcommands")
+    parser.add_argument("--version", default=False, action="store_true", help="Get version info")
+    parser.add_argument("subcommand", choices=cmds.keys(), help="The possible switch subcommands", nargs="?",
+                        default="help")
 
     # If users run a script from the command line, the location of the script
     # gets added to the start of sys.path; if they call a module from the
@@ -53,9 +60,13 @@ def main():
 
     args, remaining_args = parser.parse_known_args()
 
+    if args.version:
+        return version()
+
     # adjust the argument list to make it look like someone ran "python -m <module>" directly
-    sys.argv[0] += " " + sys.argv[1]
-    del sys.argv[1]
+    if len(sys.argv) > 1:
+        sys.argv[0] += " " + sys.argv[1]
+        del sys.argv[1]
     cmds[args.subcommand]()