1 files changed, 77 insertions, 65 deletions

diff --git a/src/mailman/bin/mailman.py b/src/mailman/bin/mailman.py
index 62066175e..e012237f3 100644
--- a/src/mailman/bin/mailman.py
+++ b/src/mailman/bin/mailman.py
@@ -17,81 +17,93 @@
 
 """The 'mailman' command dispatcher."""
 
-import os
-import argparse
+import click
 
-from functools import cmp_to_key
+from contextlib import ExitStack
+from mailman.config import config
 from mailman.core.i18n import _
 from mailman.core.initialize import initialize
 from mailman.database.transaction import transaction
 from mailman.interfaces.command import ICLISubCommand
-from mailman.utilities.modules import find_components
+from mailman.utilities.modules import add_components
 from mailman.version import MAILMAN_VERSION_FULL
 from public import public
 
 
-# --help should display the subcommands by alphabetical order, except that
-# 'mailman help' should be first.
-def _help_sorter(command, other):
-    """Sorting helper."""
-    if command.name == 'help':
-        return -1
-    elif other.name == 'help':
-        return 1
-    elif command.name < other.name:
-        return -1
-    elif command.name == other.name:
-        return 0
-    else:
-        assert command.name > other.name
-        return 1
+class Subcommands(click.MultiCommand):
+    # Handle dynamic listing and loading of `mailman` subcommands.
+    def __init__(self, *args, **kws):
+        super().__init__(*args, **kws)
+        self._commands = {}
+        # Look at all modules in the mailman.bin package and if they are
+        # prepared to add a subcommand, let them do so.  I'm still undecided as
+        # to whether this should be pluggable or not.  If so, then we'll
+        # probably have to partially parse the arguments now, then initialize
+        # the system, then find the plugins.  Punt on this for now.
+        add_components('mailman.commands', ICLISubCommand, self._commands)
 
+    def list_commands(self, ctx):
+        return sorted(self._commands)               # pragma: nocover
 
+    def get_command(self, ctx, name):
+        try:
+            return self._commands[name].command
+        except KeyError as error:
+            # Returning None here signals click to report usage information
+            # and a "No such command" error message.
+            return None
+
+    # This is here to hook command parsing into the Mailman database
+    # transaction system.  If the subcommand succeeds, the transaction is
+    # committed, otherwise it's aborted.
+    def invoke(self, ctx):
+        with ExitStack() as resources:
+            # If given a bogus subcommand, the database won't have been
+            # initialized so there's no transaction to commit.
+            if config.db is not None:
+                resources.enter_context(transaction())
+            return super().invoke(ctx)
+
+    # https://github.com/pallets/click/issues/834
+    #
+    # Note that this only handles the case for the `mailman --help` output.
+    # To handle `mailman <subcommand> --help` we create a custom click.Command
+    # subclass and override this method there too.  See
+    # src/mailman/utilities/options.py
+    def format_options(self, ctx, formatter):
+        """Writes all the options into the formatter if they exist."""
+        opts = []
+        for param in self.get_params(ctx):
+            rv = param.get_help_record(ctx)
+            if rv is not None:
+                part_a, part_b = rv
+                opts.append((part_a, part_b.replace('\n', ' ')))
+        if opts:
+            with formatter.section('Options'):
+                formatter.write_dl(opts)
+
+
+@click.group(
+    cls=Subcommands,
+    context_settings=dict(help_option_names=['-h', '--help']))
+@click.pass_context
+@click.option(
+    '-C', '--config', 'config_file',
+    envvar='MAILMAN_CONFIG_FILE',
+    type=click.Path(exists=True, dir_okay=False, resolve_path=True),
+    help=_("""\
+    Configuration file to use.  If not given, the environment variable
+    MAILMAN_CONFIG_FILE is consulted and used if set.  If neither are given, a
+    default configuration file is loaded."""))
+@click.version_option(MAILMAN_VERSION_FULL, message='%(version)s')
 @public
-def main():
-    """The `mailman` command dispatcher."""
-    # Create the basic parser and add all globally common options.
-    parser = argparse.ArgumentParser(
-        description=_("""\
-        The GNU Mailman mailing list management system
-        Copyright 1998-2017 by the Free Software Foundation, Inc.
-        http://www.list.org
-        """),
-        formatter_class=argparse.RawDescriptionHelpFormatter)
-    parser.add_argument(
-        '-v', '--version',
-        action='version', version=MAILMAN_VERSION_FULL,
-        help=_('Print this version string and exit'))
-    parser.add_argument(
-        '-C', '--config',
-        help=_("""\
-        Configuration file to use.  If not given, the environment variable
-        MAILMAN_CONFIG_FILE is consulted and used if set.  If neither are
-        given, a default configuration file is loaded."""))
-    # Look at all modules in the mailman.bin package and if they are prepared
-    # to add a subcommand, let them do so.  I'm still undecided as to whether
-    # this should be pluggable or not.  If so, then we'll probably have to
-    # partially parse the arguments now, then initialize the system, then find
-    # the plugins.  Punt on this for now.
-    subparser = parser.add_subparsers(title='Commands')
-    subcommands = []
-    for command in find_components('mailman.commands', ICLISubCommand):
-        subcommands.append(command)
-    subcommands.sort(key=cmp_to_key(_help_sorter))
-    for command in subcommands:
-        command_parser = subparser.add_parser(
-            command.name, help=_(command.__doc__))
-        command.add(parser, command_parser)
-        command_parser.set_defaults(func=command.process)
-    args = parser.parse_args()
-    if len(args.__dict__) <= 1:
-        # No arguments or subcommands were given.
-        parser.print_help()
-        parser.exit()
+def main(ctx, config_file):
+    # XXX https://github.com/pallets/click/issues/303
+    """\
+    The GNU Mailman mailing list management system
+    Copyright 1998-2017 by the Free Software Foundation, Inc.
+    http://www.list.org
+    """
     # Initialize the system.  Honor the -C flag if given.
-    config_path = (None if args.config is None
-                   else os.path.abspath(os.path.expanduser(args.config)))
-    initialize(config_path)
-    # Perform the subcommand option.
-    with transaction():
-        args.func(args)
+    initialize(config_file)
+    # click handles dispatching to the subcommand via the Subcommands class.