Only try compat parsing after regular parsing fails (#2269)

esphome/__main__.py

@@ -483,75 +483,9 @@ def parse_args(argv):
         metavar=("key", "value"),
     )
 
-    # Keep backward compatibility with the old command line format of
-    # esphome <config> <command>.
-    #
-    # Unfortunately this can't be done by adding another configuration argument to the
-    # main config parser, as argparse is greedy when parsing arguments, so in regular
-    # usage it'll eat the command as the configuration argument and error out out
-    # because it can't parse the configuration as a command.
-    #
-    # Instead, construct an ad-hoc parser for the old format that doesn't actually
-    # process the arguments, but parses them enough to let us figure out if the old
-    # format is used. In that case, swap the command and configuration in the arguments
-    # and continue on with the normal parser (after raising a deprecation warning).
-    #
-    # Disable argparse's built-in help option and add it manually to prevent this
-    # parser from printing the help messagefor the old format when invoked with -h.
-    compat_parser = argparse.ArgumentParser(parents=[options_parser], add_help=False)
-    compat_parser.add_argument("-h", "--help")
-    compat_parser.add_argument("configuration", nargs="*")
-    compat_parser.add_argument(
-        "command",
-        choices=[
-            "config",
-            "compile",
-            "upload",
-            "logs",
-            "run",
-            "clean-mqtt",
-            "wizard",
-            "mqtt-fingerprint",
-            "version",
-            "clean",
-            "dashboard",
-            "vscode",
-            "update-all",
-        ],
-    )
-
-    # on Python 3.9+ we can simply set exit_on_error=False in the constructor
-    def _raise(x):
-        raise argparse.ArgumentError(None, x)
-
-    compat_parser.error = _raise
-
-    deprecated_argv_suggestion = None
-
-    if ["dashboard", "config"] == argv[1:3] or ["version"] == argv[1:2]:
-        # this is most likely meant in new-style arg format. do not try compat parsing
-        pass
-    else:
-        try:
-            result, unparsed = compat_parser.parse_known_args(argv[1:])
-            last_option = len(argv) - len(unparsed) - 1 - len(result.configuration)
-            unparsed = [
-                "--device" if arg in ("--upload-port", "--serial-port") else arg
-                for arg in unparsed
-            ]
-            argv = (
-                argv[0:last_option] + [result.command] + result.configuration + unparsed
-            )
-            deprecated_argv_suggestion = argv
-        except argparse.ArgumentError:
-            # This is not an old-style command line, so we don't have to do anything.
-            pass
-
-    # And continue on with regular parsing
     parser = argparse.ArgumentParser(
         description=f"ESPHome v{const.__version__}", parents=[options_parser]
     )
-    parser.set_defaults(deprecated_argv_suggestion=deprecated_argv_suggestion)
 
     mqtt_options = argparse.ArgumentParser(add_help=False)
     mqtt_options.add_argument("--topic", help="Manually set the MQTT topic.")
@@ -701,7 +635,83 @@ def parse_args(argv):
         "configuration", help="Your YAML configuration file directories.", nargs="+"
     )
 
-    return parser.parse_args(argv[1:])
+    # Keep backward compatibility with the old command line format of
+    # esphome <config> <command>.
+    #
+    # Unfortunately this can't be done by adding another configuration argument to the
+    # main config parser, as argparse is greedy when parsing arguments, so in regular
+    # usage it'll eat the command as the configuration argument and error out out
+    # because it can't parse the configuration as a command.
+    #
+    # Instead, if parsing using the current format fails, construct an ad-hoc parser
+    # that doesn't actually process the arguments, but parses them enough to let us
+    # figure out if the old format is used. In that case, swap the command and
+    # configuration in the arguments and retry with the normal parser (and raise
+    # a deprecation warning).
+    arguments = argv[1:]
+
+    # On Python 3.9+ we can simply set exit_on_error=False in the constructor
+    def _raise(x):
+        raise argparse.ArgumentError(None, x)
+
+    # First, try new-style parsing, but don't exit in case of failure
+    try:
+        # duplicate parser so that we can use the original one to raise errors later on
+        current_parser = argparse.ArgumentParser(add_help=False, parents=[parser])
+        current_parser.set_defaults(deprecated_argv_suggestion=None)
+        current_parser.error = _raise
+        return current_parser.parse_args(arguments)
+    except argparse.ArgumentError:
+        pass
+
+    # Second, try compat parsing and rearrange the command-line if it succeeds
+    # Disable argparse's built-in help option and add it manually to prevent this
+    # parser from printing the help messagefor the old format when invoked with -h.
+    compat_parser = argparse.ArgumentParser(parents=[options_parser], add_help=False)
+    compat_parser.add_argument("-h", "--help", action="store_true")
+    compat_parser.add_argument("configuration", nargs="*")
+    compat_parser.add_argument(
+        "command",
+        choices=[
+            "config",
+            "compile",
+            "upload",
+            "logs",
+            "run",
+            "clean-mqtt",
+            "wizard",
+            "mqtt-fingerprint",
+            "version",
+            "clean",
+            "dashboard",
+            "vscode",
+            "update-all",
+        ],
+    )
+
+    try:
+        compat_parser.error = _raise
+        result, unparsed = compat_parser.parse_known_args(argv[1:])
+        last_option = len(arguments) - len(unparsed) - 1 - len(result.configuration)
+        unparsed = [
+            "--device" if arg in ("--upload-port", "--serial-port") else arg
+            for arg in unparsed
+        ]
+        arguments = (
+            arguments[0:last_option]
+            + [result.command]
+            + result.configuration
+            + unparsed
+        )
+        deprecated_argv_suggestion = arguments
+    except argparse.ArgumentError:
+        # old-style parsing failed, don't suggest any argument
+        deprecated_argv_suggestion = None
+
+    # Finally, run the new-style parser again with the possibly swapped arguments,
+    # and let it error out if the command is unparsable.
+    parser.set_defaults(deprecated_argv_suggestion=deprecated_argv_suggestion)
+    return parser.parse_args(arguments)
 
 
 def run_esphome(argv):
@@ -715,7 +725,7 @@ def run_esphome(argv):
             "and will be removed in the future. "
         )
         _LOGGER.warning("Please instead use:")
-        _LOGGER.warning("   esphome %s", " ".join(args.deprecated_argv_suggestion[1:]))
+        _LOGGER.warning("   esphome %s", " ".join(args.deprecated_argv_suggestion))
 
     if sys.version_info < (3, 7, 0):
         _LOGGER.error(