#!/usr/bin/env vpython3
# Copyright 2020 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Script for updating the active milestones for the chromium project.

To activate a new chromium branch, run the following from the root of
the repo (where MM is the milestone number and BBBB is the branch
number):
```
scripts/chromium/milestones.py activate --milestone MM --branch BBBB
./main.star
```

To deactivate a chromium branch, run the following from the root of the
repo (where MM is the milestone number):
```
scripts/chromium/milestones.py deactivate --milestone MM
./main.star
```

Usage:
  milestones.py activate --milestone XX --branch YYYY
  milestones.py deactivate --milestone XX
"""

import argparse
import itertools
import json
import os
import re
import sys

INFRA_CONFIG_DIR = os.path.abspath(os.path.join(__file__, '..', '..'))


def parse_args(args=None, *, parser_type=None):
  parser_type = parser_type or argparse.ArgumentParser
  parser = parser_type(
    description='Update the active milestones for the chromium project'
  )
  parser.set_defaults(func=None)
  parser.add_argument(
    '--milestones-json',
    help='Path to the milestones.json file',
    default=os.path.join(INFRA_CONFIG_DIR, 'milestones.json'),
  )

  subparsers = parser.add_subparsers()

  activate_parser = subparsers.add_parser(
    'activate', help='Add an additional active milestone'
  )
  activate_parser.set_defaults(func=activate_cmd)
  activate_parser.add_argument(
    '--milestone',
    required=True,
    help=(
      'The milestone identifier '
      '(e.g. the milestone number for standard release channel)'
    ),
  )
  activate_parser.add_argument(
    '--branch',
    required=True,
    help='The branch name, must correspond to a ref in refs/branch-heads',
  )

  deactivate_parser = subparsers.add_parser(
    'deactivate', help='Remove an active milestone'
  )
  deactivate_parser.set_defaults(func=deactivate_cmd)
  deactivate_parser.add_argument(
    '--milestone',
    required=True,
    help=(
      'The milestone identifier '
      '(e.g. the milestone number for standard release channel)'
    ),
  )

  args = parser.parse_args(args)
  if args.func is None:
    parser.error('no sub-command specified')
  return args


class MilestonesException(Exception):
  pass


_NUMBER_RE = re.compile('([0-9]+)')


def numeric_sort_key(s):
  # The capture group in the regex means that the numeric portions are returned,
  # odd indices will be the numeric portions of the string (the 0th or last
  # element will be empty if the string starts or ends with a number,
  # respectively)
  pieces = _NUMBER_RE.split(s)
  return [
    (int(x), x) if is_numeric else x
    for x, is_numeric in zip(pieces, itertools.cycle([False, True]))
  ]


def add_milestone(milestones, milestone, branch):
  if milestone in milestones:
    raise MilestonesException(
      f'there is already an active milestone with id {milestone!r}: '
      f'{milestones[milestone]}'
    )

  milestones[milestone] = {
    'name': f'm{milestone}',
    'project': f'chromium-m{milestone}',
    'ref': f'refs/branch-heads/{branch}',
  }

  milestones = {
    k: milestones[k] for k in sorted(milestones, key=numeric_sort_key)
  }

  return json.dumps(milestones, indent=4) + '\n'


def activate_cmd(args):
  with open(args.milestones_json) as f:
    milestones = json.load(f)

  milestones = add_milestone(milestones, args.milestone, args.branch)

  with open(args.milestones_json, 'w') as f:
    f.write(milestones)


def remove_milestone(milestones, milestone):
  if milestone not in milestones:
    raise MilestonesException(
      f'{milestone!r} does not refer to an active milestone: '
      f'{list(milestones.keys())}'
    )

  del milestones[milestone]

  milestones = {
    k: milestones[k] for k in sorted(milestones, key=numeric_sort_key)
  }

  return json.dumps(milestones, indent=4) + '\n'


def deactivate_cmd(args):
  with open(args.milestones_json) as f:
    milestones = json.load(f)

  milestones = remove_milestone(milestones, args.milestone)

  with open(args.milestones_json, 'w') as f:
    f.write(milestones)


def main():
  args = parse_args()
  try:
    args.func(args)
  except MilestonesException as e:
    print(str(e), file=sys.stderr)
    sys.exit(1)


if __name__ == '__main__':
  main()