#!/usr/bin/env python3

"""Script to do the first step of Abseil roll into chromium.
"""

import argparse
import logging
import os
import re
import subprocess
import tempfile
from datetime import datetime

ABSL_URI = 'https://github.com/abseil/abseil-cpp.git'

def _PullAbseil(abseil_dir, revision):
  logging.info('Updating abseil...')
  args = ['git', 'clone', ABSL_URI]
  if revision:
    args.extend(['--revision', revision])
  subprocess.check_call(args, cwd=abseil_dir)

def _SyncChromium(chromium_dir):
  logging.info('Updating chromium...')
  subprocess.check_call(['git', 'pull', '--rebase'], cwd=chromium_dir)
  subprocess.check_call(['gclient', 'sync'], cwd=chromium_dir)


def _UpdateChromiumReadme(readme_filename, abseil_dir):
  logging.info('Updating ' + readme_filename)

  stdout = subprocess.check_output(['git', 'log', '-n1', '--pretty=short'],
                                   cwd=abseil_dir)
  new_revision = re.search('commit\\s(.{40})', str(stdout)).group(1)

  with open(readme_filename, 'r+') as f:
    content = f.read()
    prefix = 'Revision: '
    pos = content.find(prefix)
    assert(pos > 0)
    pos = pos + len(prefix)
    old_revision = content[pos:pos+40]
    f.seek(pos)
    f.write(new_revision)

  logging.info('Abseil old revision is ' + old_revision)
  logging.info('Abseil new revision is ' + new_revision)
  return old_revision[0:10] + '..' + new_revision[0:10]


def _UpdateAbseilInChromium(abseil_dir, chromium_dir):
 logging.info('Syncing abseil in chromium/src/third_party...')
 exclude = [
   '*BUILD.gn',
   'DIR_METADATA',
   'README.chromium',
   'OWNERS',
   '.clang-format-ignore',
   '.git',
   '.gitignore',
   '*.gni',
   '*clang-format',
   'patches/*',
   'patches',
   'absl_hardening_test.cc',
   'roll_abseil.py',
   'generate_def_files.py',
   '*.def',
 ]
 params = ['rsync', '-aP', abseil_dir, os.path.join(chromium_dir, 'third_party'), '--delete']
 for e in exclude:
   params.append('--exclude={}'.format(e))
 subprocess.check_call(params, cwd=chromium_dir)


def _PatchAbseil(abseil_in_chromium_dir):
  logging.info('Patching abseil...')
  for patch in os.listdir(os.path.join(abseil_in_chromium_dir, 'patches')):
    subprocess.check_call(['patch', '--strip', '1', '-i', os.path.join(abseil_in_chromium_dir, 'patches', patch)])

  os.remove(os.path.join(abseil_in_chromium_dir, 'absl', 'base', 'internal', 'dynamic_annotations.h'))


def _Commit(chromium_dir, hash_diff, should_upload):
  logging.info('Commit...')
  desc="""Roll abseil_revision {0}

Change Log:
https://chromium.googlesource.com/external/github.com/abseil/abseil-cpp/+log/{0}
Full diff:
https://chromium.googlesource.com/external/github.com/abseil/abseil-cpp/+/{0}
Bug: None""".format(hash_diff)

  subprocess.check_call(['git', 'add', 'third_party/abseil-cpp'], cwd=chromium_dir)
  proc = subprocess.run(['git', 'diff', '--staged', '--quiet', 'third_party/abseil-cpp'], cwd=chromium_dir)
  if proc.returncode == 0:
    logging.info('Abseil is up-to-date, nothing to commit!')
    return

  subprocess.check_call(['git', 'commit', '-m', desc], cwd=chromium_dir)

  if should_upload:
    logging.info('Upload...')
    subprocess.check_call(['git', 'cl', 'upload', '-m', desc, '--bypass-hooks'], cwd=chromium_dir)

  logging.info("Next step is manual: Fix BUILD.gn files to match BUILD.bazel changes.")
  logging.info("After that run generate_def_files.py. ")


def _Roll(should_branch, should_pull, should_upload, revision):
  chromium_dir = os.getcwd()
  abseil_in_chromium_dir = os.path.join(chromium_dir, 'third_party', 'abseil-cpp')
  if should_branch:
    branch_name = datetime.today().strftime('rolling-absl-%Y%m%d')
    logging.info('Creating branch ' + branch_name + ' for the roll...')
    subprocess.check_call(['git', 'new-branch', branch_name], cwd=chromium_dir)

  if should_pull:
    _SyncChromium(chromium_dir)

  with tempfile.TemporaryDirectory() as abseil_root:
    _PullAbseil(abseil_root, revision)
    abseil_dir = os.path.join(abseil_root, 'abseil-cpp')
    _UpdateAbseilInChromium(abseil_dir, chromium_dir)
    hash_diff = _UpdateChromiumReadme(os.path.join(abseil_in_chromium_dir, 'README.chromium'),
                                      abseil_dir)

  _PatchAbseil(abseil_in_chromium_dir)
  _Commit(chromium_dir, hash_diff, should_upload)


if __name__ == '__main__':
  logging.getLogger().setLevel(logging.INFO)

  parser = argparse.ArgumentParser()
  parser.add_argument('--no-branch', action='store_true',
                      help='Skip creating a new branch, use the current one.')
  parser.add_argument('--no-pull', action='store_true',
                      help='Skip pulling the latest Chromium revision.')
  parser.add_argument('--no-upload', action='store_true',
                      help='Skip uploading the change.')
  parser.add_argument('--revision', default=None,
                      help='Revision to roll to. The default is the latest.')
  args = parser.parse_args()

  if os.getcwd().endswith('src') and os.path.exists('chrome/browser'):
    _Roll(not args.no_branch, not args.no_pull, not args.no_upload,
          args.revision)
  else:
    logging.error('Run this script from a chromium/src/ directory.')