[recipes.py] move autoroll arg parsing to its module

recipe_engine/autoroll.py

 # Copyright 2016 The LUCI Authors. All rights reserved.
 # Use of this source code is governed under the Apache License, Version 2.0
 # that can be found in the LICENSE file.
 
 from __future__ import print_function
 
 import copy
 import json
 import logging
 import os
@@ skipping 249 matching lines @@
     'roll_details': roll_details,
     'picked_roll_details': picked_roll_details,
     'rejected_candidates_count': len(rejected_candidates),
   }
   if verbose_json:
     ret['rejected_candidate_specs'] = [
       package_io.dump_obj(c.package_pb) for c in rejected_candidates]
   return ret
 
 
-def main(args, repo_root, config_file):
+def add_subparser(parser):
+  autoroll_p = parser.add_parser(
+      'autoroll',
+      help='Roll dependencies of a recipe package forward (implies fetch)')
+  autoroll_p.add_argument(
+      '--output-json',
+      type=os.path.abspath,
+      help='A json file to output information about the roll to.')
+  autoroll_p.add_argument(
+      '--verbose-json',
+      action='store_true',
+      help=('Emit even more data in the output-json file. '
+            'Requires --output-json.'))
+
+  def postprocess_func(parser, args):
+    if args.verbose_json and not args.output_json:
+      parser.error('--verbose-json passed without --output-json')
+
+  autoroll_p.set_defaults(
+    command='autoroll', func=main, postprocess_func=postprocess_func)
+
+
+def main(_package_deps, args):
+  config_file = args.package
+  repo_root = package.InfraRepoConfig().from_recipes_cfg(config_file.path)
+
   package_pb = config_file.read()
 
   context = package.PackageContext.from_package_pb(
     repo_root, package_pb, allow_fetch=not args.no_fetch)
   package_spec = package.PackageSpec.from_package_pb(context, package_pb)
   for repo_spec in package_spec.deps.values():
     repo_spec.fetch()
 
   repo_cfg_block = extract_repo_cfg_block(context)
 
   results = {}
   try:
     results = test_rolls(
       repo_cfg_block, config_file, context, package_spec, args.verbose_json)
   finally:
     if not results.get('success'):
       # Restore initial state. Since we could be running simulation tests
       # on other revisions, re-run them now as well.
       write_spec_to_disk(context, repo_cfg_block, config_file, package_pb)
       run_simulation_test(repo_root, package_spec.recipes_path, ['train'])
 
   if args.output_json:
     with open(args.output_json, 'w') as f:
       json.dump(results, f, sort_keys=True, indent=2)
 
   return 0