#!/usr/bin/env python3
# Copyright 2017 The Chromium Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Tool for finding the cause of binary size bloat.

See //tools/binary_size/README.md for example usage.

Note: this tool will perform gclient sync/git checkout on your local repo.
"""

import argparse
import atexit
import collections
from contextlib import contextmanager
import json
import logging
import os
import re
import shutil
import subprocess
import sys


_COMMIT_COUNT_WARN_THRESHOLD = 15
_ALLOWED_CONSECUTIVE_FAILURES = 2
_SRC_ROOT = os.path.abspath(
    os.path.join(os.path.dirname(__file__), os.pardir, os.pardir))
_DEFAULT_ARCHIVE_DIR = os.path.join(_SRC_ROOT, 'out', 'binary-size-results')
_DEFAULT_OUT_DIR = os.path.join(_SRC_ROOT, 'out', 'binary-size-build')
_SUPERSIZE_PATH = os.path.join(_SRC_ROOT, 'tools', 'binary_size', 'supersize')
_RESOURCE_SIZES_PATH = os.path.join(
    _SRC_ROOT, 'build', 'android', 'resource_sizes.py')
_AUTONINJA_PATH = shutil.which('autoninja')
_GN_PATH = shutil.which('gn')
_LLVM_TOOLS_DIR = os.path.join(_SRC_ROOT, 'third_party', 'llvm-build',
                               'Release+Asserts', 'bin')
_CLANG_UPDATE_PATH = os.path.join(_SRC_ROOT, 'tools', 'clang', 'scripts',
                                  'update.py')


_DiffResult = collections.namedtuple('DiffResult', ['name', 'value', 'units'])


class BaseDiff:
  """Base class capturing binary size diffs."""
  def __init__(self, name):
    self.name = name
    self.banner = '\n' + '*' * 30 + name + '*' * 30

  def AppendResults(self, logfiles):
    """Print and write diff results to an open |logfile|."""
    full, short = logfiles
    _WriteToFile(full, self.banner)
    _WriteToFile(short, self.banner)

    for s in self.Summary():
      _WriteToFile(short, s)
    _WriteToFile(short, '')

    for s in self.DetailedResults():
      full.write(s + '\n')

  @property
  def summary_stat(self):
    """Returns a tuple of (name, value, units) for the most important metric."""
    raise NotImplementedError()

  def Summary(self):
    """A short description that summarizes the source of binary size bloat."""
    raise NotImplementedError()

  def DetailedResults(self):
    """An iterable description of the cause of binary size bloat."""
    raise NotImplementedError()

  def ProduceDiff(self, before_dir, after_dir):
    """Prepare a binary size diff with ready to print results."""
    raise NotImplementedError()

  def RunDiff(self, logfiles, before_dir, after_dir):
    logging.info('Creating: %s', self.name)
    self.ProduceDiff(before_dir, after_dir)
    self.AppendResults(logfiles)


class NativeDiff(BaseDiff):
  # E.g.: Section Sizes (Total=1.2 kb (1222 bytes)):
  _RE_SUMMARY_STAT = re.compile(
      r'Section Sizes \(Total=(?P<value>-?[0-9\.]+) ?(?P<units>\w+)')
  _SUMMARY_STAT_NAME = 'Native Library Delta'

  def __init__(self, size_name):
    self._size_name = size_name
    self._diff = []
    super().__init__('Native Diff')

  @property
  def summary_stat(self):
    m = NativeDiff._RE_SUMMARY_STAT.search(self._diff)
    if m:
      return _DiffResult(
          NativeDiff._SUMMARY_STAT_NAME, m.group('value'), m.group('units'))
    raise Exception('Could not extract total from:\n' + self._diff)

  def DetailedResults(self):
    return self._diff.splitlines()

  def Summary(self):
    return self.DetailedResults()[:100]

  def ProduceDiff(self, before_dir, after_dir):
    before_size = os.path.join(before_dir, self._size_name)
    after_size = os.path.join(after_dir, self._size_name)
    cmd = [_SUPERSIZE_PATH, 'diff', before_size, after_size]
    self._diff = _RunCmd(cmd)[0].replace('{', '{{').replace('}', '}}')


class ResourceSizesDiff(BaseDiff):
  # Ordered by output appearance.
  _SUMMARY_SECTIONS = (
      'Specifics', 'InstallSize', 'InstallBreakdown', 'Dex')
  # Sections where it makes sense to sum subsections into a section total.
  _AGGREGATE_SECTIONS = (
      'InstallBreakdown', 'Breakdown', 'MainLibInfo', 'Uncompressed')

  def __init__(self, filename='results-chart.json', include_sections=None):
    self._diff = None  # Set by |ProduceDiff()|
    self._filename = filename
    self._include_sections = include_sections
    super().__init__('Resource Sizes Diff')

  @property
  def summary_stat(self):
    items = []
    for section_name, results in self._diff.items():
      for subsection_name, value, units in results:
        if 'normalized' in subsection_name:
          items.append([section_name, subsection_name, value, units])
    if len(items) > 1:  # Handle Trichrome.
      items = [item for item in items if 'Combined_normalized' in item[1]]
    if len(items) == 1:
      [section_name, subsection_name, value, units] = items[0]
      full_name = '{} {}'.format(section_name, subsection_name)
      return _DiffResult(full_name, value, units)
    raise Exception('Could not find canonical "normalized" in: %r' % self._diff)

  def CombinedSizeChangeForSection(self, section):
    for subsection_name, value, _ in self._diff[section]:
      if 'Combined' in subsection_name:
        return value
    raise Exception('Could not find "Combined" in: ' +
                    repr(self._diff[section]))

  def DetailedResults(self):
    return self._ResultLines()

  def Summary(self):
    footer_lines = [
        '',
        'For an explanation of these metrics, see:',
        ('https://chromium.googlesource.com/chromium/src/+/main/docs/speed/'
         'binary_size/metrics.md#Metrics-for-Android')]
    return self._ResultLines(
        include_sections=ResourceSizesDiff._SUMMARY_SECTIONS) + footer_lines

  def ProduceDiff(self, before_dir, after_dir):
    before = self._LoadResults(before_dir)
    after = self._LoadResults(after_dir)
    self._diff = collections.defaultdict(list)
    for section, section_dict in after.items():
      if self._include_sections and section not in self._include_sections:
        continue
      for subsection, v in section_dict.items():
        # Ignore entries when resource_sizes.py chartjson format has changed.
        if (section not in before or
            subsection not in before[section] or
            v['units'] != before[section][subsection]['units']):
          logging.warning(
              'Found differing dict structures for resource_sizes.py, '
              'skipping %s %s', section, subsection)
        else:
          self._diff[section].append(_DiffResult(
              subsection,
              v['value'] - before[section][subsection]['value'],
              v['units']))

  def _ResultLines(self, include_sections=None):
    """Generates diff lines for the specified sections (defaults to all)."""
    section_lines = collections.defaultdict(list)
    for section_name, section_results in self._diff.items():
      if not include_sections or section_name in include_sections:
        subsection_lines = []
        section_sum = 0
        units = ''
        for name, value, units in section_results:
          # Omit subsections with no changes for summaries.
          if value == 0 and include_sections:
            continue
          section_sum += value
          subsection_lines.append('{:>+14,} {} {}'.format(value, units, name))
        section_header = section_name
        if section_name in ResourceSizesDiff._AGGREGATE_SECTIONS:
          section_header += ' ({:+,} {})'.format(section_sum, units)
        section_header += ':'
        # Omit sections with empty subsections.
        if subsection_lines:
          section_lines[section_name].append(section_header)
          section_lines[section_name].extend(subsection_lines)
    if not section_lines:
      return ['Empty ' + self.name]
    ret = []
    for k in include_sections or sorted(section_lines):
      ret.extend(section_lines[k])
    return ret

  def _LoadResults(self, archive_dir):
    chartjson_file = os.path.join(archive_dir, self._filename)
    with open(chartjson_file) as f:
      chartjson = json.load(f)
    charts = chartjson['charts']
    # Older versions of resource_sizes.py prefixed the apk onto section names.
    ret = {}
    for section, section_dict in charts.items():
      section_no_target = re.sub(r'^.*_', '', section)
      ret[section_no_target] = section_dict
    return ret


class _BuildHelper:
  """Helper class for generating and building targets."""
  def __init__(self, args):
    self.clean = args.clean
    self.enable_chrome_android_internal = args.enable_chrome_android_internal
    self.extra_gn_args_str = args.gn_args
    self.apply_patch = args.extra_rev
    self.output_directory = args.output_directory
    self.target = args.target
    self.target_os = args.target_os
    self.use_reclient = args.use_reclient
    self.apk_name_override = args.custom_apk_name
    self.main_lib_path_override = args.custom_main_lib_path
    self._SetDefaults()
    self.is_bundle = 'minimal' in self.target

  def _MaybeAddGoogleSuffix(self, path):
    if self.IsTrichrome() and '_google' in self.target:
      return path.replace('.', 'Google.', 1)
    return path

  @property
  def abs_apk_paths(self):
    return [os.path.join(self.output_directory, x) for x in self.apk_paths]

  @property
  def abs_mapping_paths(self):
    def to_mapping_path(p):
      return p.replace('.minimal.apks', '.aab') + '.mapping'

    return [to_mapping_path(x) for x in self.abs_apk_paths]

  @property
  def abs_extra_paths(self):
    def to_extra_paths(p):
      aab_path = p.replace('.minimal.apks', '.aab')
      return [aab_path + '.unused_resources', aab_path + '.R.txt']

    return [p for x in self.abs_apk_paths for p in to_extra_paths(x)]

  @property
  def apk_name(self):
    if self.apk_name_override:
      return self.apk_name_override
    # my_great_apk -> MyGreat.apk
    apk_name = ''.join(s.title() for s in self.target.split('_')[:-1]) + '.apk'
    if self.is_bundle:
      # trichrome_32_minimal_apks -> Trichrome32Minimal.apk
      #                           -> Trichrome32.minimal.apks
      apk_name = apk_name.replace('Minimal.apk', '.minimal.apks')
    return apk_name.replace('Webview', 'WebView')

  @property
  def supersize_input(self):
    if self.IsTrichrome():
      return self._MaybeAddGoogleSuffix(
          os.path.join(self.output_directory, 'apks', 'Trichrome.ssargs'))
    return self.abs_apk_paths[0]

  @property
  def apk_paths(self):
    if self.IsTrichrome():
      ret = [
          os.path.join('apks', 'TrichromeChrome.minimal.apks'),
          os.path.join('apks', 'TrichromeWebView.minimal.apks'),
          os.path.join('apks', 'TrichromeLibrary.apk'),
      ]
      return [self._MaybeAddGoogleSuffix(x) for x in ret]

    return [os.path.join('apks', self.apk_name)]

  @property
  def main_lib_path(self):
    # TODO(agrieve): Could maybe extract from .apk or GN?
    if self.main_lib_path_override:
      return self.main_lib_path_override
    if self.IsLinux():
      return 'chrome'
    if 'monochrome' in self.target or 'trichrome' in self.target:
      ret = 'lib.unstripped/libmonochrome.so'
    elif 'webview' in self.target:
      ret = 'lib.unstripped/libwebviewchromium.so'
    else:
      ret = 'lib.unstripped/libchrome.so'
    return ret

  @property
  def abs_main_lib_path(self):
    return os.path.join(self.output_directory, self.main_lib_path)

  @property
  def map_file_path(self):
    return self.main_lib_path + '.map.gz'

  @property
  def size_name(self):
    if self.IsLinux():
      return os.path.basename(self.main_lib_path) + '.size'
    return self.apk_name + '.size'

  def _SetDefaults(self):
    has_internal = os.path.exists(os.path.join(_SRC_ROOT, 'internal'))
    if has_internal:
      self.extra_gn_args_str = (
          'is_chrome_branded=true ' + self.extra_gn_args_str)
    else:
      self.extra_gn_args_str = (
          'ffmpeg_branding="Chrome" proprietary_codecs=true' +
          self.extra_gn_args_str)
    if self.IsLinux():
      self.extra_gn_args_str = (
          'is_cfi=false generate_linker_map=true ' + self.extra_gn_args_str)
    self.extra_gn_args_str = ' ' + self.extra_gn_args_str.strip()

    if not self.target:
      if self.IsLinux():
        self.target = 'chrome'
      elif self.enable_chrome_android_internal:
        self.target = 'trichrome_google_32_minimal_apks'
      else:
        self.target = 'trichrome_32_minimal_apks'

  def _GenGnCmd(self):
    gn_args = 'is_official_build=true'
    gn_args += ' android_channel="stable"'
    # Variables often become unused when experimenting with macros to reduce
    # size, so don't fail on warnings.
    gn_args += ' treat_warnings_as_errors=false'
    # Speed things up a bit by skipping lint & errorprone.
    gn_args += ' disable_android_lint=true'
    # Down from default of 2 to speed up compile and use less disk.
    # Compiles need at least symbol_level=1 for pak allowlist to work.
    gn_args += ' symbol_level=1'
    gn_args += ' use_errorprone_java_compiler=false'
    gn_args += ' use_remoteexec=%s' % str(self.use_reclient).lower()
    gn_args += ' target_os="%s"' % self.target_os
    if self.IsAndroid():
      gn_args += (' enable_chrome_android_internal=%s' %
                  str(self.enable_chrome_android_internal).lower())
    gn_args += self.extra_gn_args_str
    return [_GN_PATH, 'gen', self.output_directory, '--args=%s' % gn_args]

  def _GenNinjaCmd(self):
    cmd = [_AUTONINJA_PATH, '-C', self.output_directory]
    cmd += [self.target]
    return cmd

  def Run(self):
    """Run GN gen/ninja build and return the process returncode."""
    logging.info('Building %s within %s (this might take a while).',
                 self.target, os.path.relpath(self.output_directory))
    if self.clean:
      _RunCmd([_GN_PATH, 'clean', self.output_directory], cwd=_SRC_ROOT)
    retcode = _RunCmd(self._GenGnCmd(),
                      cwd=_SRC_ROOT,
                      verbose=True,
                      exit_on_failure=False)[1]
    if retcode:
      return retcode
    return _RunCmd(self._GenNinjaCmd(),
                   cwd=_SRC_ROOT,
                   verbose=True,
                   exit_on_failure=False)[1]

  def IsAndroid(self):
    return self.target_os == 'android'

  def IsTrichrome(self):
    return 'trichrome' in self.target

  def IsLinux(self):
    return self.target_os == 'linux'


class _BuildArchive:
  """Class for managing a directory with build results and build metadata."""

  def __init__(self, rev, base_archive_dir, build, subrepo, save_unstripped,
               supersize_archive_args):
    self.build = build
    self.dir = os.path.join(base_archive_dir, rev)
    metadata_path = os.path.join(self.dir, 'metadata.txt')
    self.rev = rev
    self.metadata = _Metadata([self], build, metadata_path, subrepo)
    self._save_unstripped = save_unstripped
    self._supersize_archive_args = supersize_archive_args

  def ArchiveBuildResults(self):
    """Save build artifacts necessary for diffing."""
    logging.info('Saving build results to: %s', self.dir)
    _EnsureDirsExist(self.dir)
    if self.build.IsAndroid():
      for path in self.build.abs_apk_paths:
        self._ArchiveFile(path)
      for path in self.build.abs_mapping_paths:
        # Some apks have no .mapping files.
        self._ArchiveFile(path, missing_ok=True)
      for path in self.build.abs_extra_paths:
        # These are useful for debugging but not necessary.
        self._ArchiveFile(path, missing_ok=True)
      self._ArchiveResourceSizes()
    self._ArchiveSizeFile()
    if self._save_unstripped:
      self._ArchiveFile(self.build.abs_main_lib_path)
    self.metadata.Write()
    assert self.Exists()

  def Exists(self):
    ret = self.metadata.Exists() and os.path.exists(self.archived_size_path)
    if self._save_unstripped:
      ret = ret and os.path.exists(self.archived_unstripped_path)
    return ret

  @property
  def archived_unstripped_path(self):
    return os.path.join(self.dir, os.path.basename(self.build.main_lib_path))

  @property
  def archived_size_path(self):
    return os.path.join(self.dir, self.build.size_name)

  def _ArchiveResourceSizes(self):
    cmd = [
        _RESOURCE_SIZES_PATH, '--output-dir', self.dir, '--chartjson',
        '--chromium-output-dir', self.build.output_directory
    ]
    if self.build.IsTrichrome():
      get_apk = lambda t: next(x for x in self.build.abs_apk_paths if t in x)
      cmd += ['--trichrome-chrome', get_apk('Chrome')]
      cmd += ['--trichrome-webview', get_apk('WebView')]
      cmd += ['--trichrome-library', get_apk('Library')]
      cmd += [self.build.apk_name]
    else:
      cmd += [self.build.abs_apk_paths[0]]
    _RunCmd(cmd)

  def _ArchiveFile(self, filename, missing_ok=False):
    if not os.path.exists(filename):
      if missing_ok:
        return
      _Die('missing expected file: %s', filename)
    shutil.copy(filename, self.dir)

  def _ArchiveSizeFile(self):
    supersize_cmd = [_SUPERSIZE_PATH, 'archive', self.archived_size_path]
    if self.build.IsAndroid():
      supersize_cmd += ['-f', self.build.supersize_input]
      if os.path.exists(self.build.abs_main_lib_path):
        supersize_cmd += ['--aux-elf-file', self.build.abs_main_lib_path]
    else:
      supersize_cmd += ['--elf-file', self.build.abs_main_lib_path]
    supersize_cmd += ['--output-directory', self.build.output_directory]
    if self._supersize_archive_args:
      supersize_cmd.extend(self._supersize_archive_args.split())
    logging.info('Creating .size file')
    _RunCmd(supersize_cmd)


class _DiffArchiveManager:
  """Class for maintaining BuildArchives and their related diff artifacts."""

  def __init__(self, revs, archive_dir, diffs, build, subrepo, save_unstripped,
               supersize_archive_args, share):
    self.archive_dir = archive_dir
    self.build = build
    self.build_archives = [
        _BuildArchive(rev, archive_dir, build, subrepo, save_unstripped,
                      supersize_archive_args) for rev in revs
    ]
    self.diffs = diffs
    self.subrepo = subrepo
    self.share = share
    self._summary_stats = []

  def MaybeDiff(self, before_id, after_id):
    """Perform diffs given two build archives."""
    before = self.build_archives[before_id]
    after = self.build_archives[after_id]
    diff_path, short_diff_path = self._DiffFilePaths(before, after)
    if not self._CanDiff(before, after):
      logging.info(
          'Skipping diff for %s due to missing build archives.', diff_path)
      return

    metadata_path = self._DiffMetadataPath(before, after)
    metadata = _Metadata(
        [before, after], self.build, metadata_path, self.subrepo)
    if metadata.Exists():
      logging.info(
          'Skipping diff for %s and %s. Matching diff already exists: %s',
          before.rev, after.rev, diff_path)
    else:
      with open(diff_path, 'w') as diff_file, \
           open(short_diff_path, 'w') as summary_file:
        for d in self.diffs:
          d.RunDiff((diff_file, summary_file), before.dir, after.dir)
      metadata.Write()
      self._AddDiffSummaryStat(before, after)
    if os.path.exists(short_diff_path):
      _PrintFile(short_diff_path)
    logging.info('See detailed diff results here: %s',
                 os.path.relpath(diff_path))

  def GenerateHtmlReport(self, before_id, after_id, is_internal=False):
    """Generate HTML report given two build archives."""
    before = self.build_archives[before_id]
    after = self.build_archives[after_id]
    diff_path = self._DiffDir(before, after)
    if not self._CanDiff(before, after):
      logging.info(
          'Skipping HTML report for %s due to missing build archives.',
          diff_path)
      return

    report_path = os.path.join(diff_path, 'diff.sizediff')

    supersize_cmd = [
        _SUPERSIZE_PATH, 'save_diff', before.archived_size_path,
        after.archived_size_path, report_path
    ]

    logging.info('Creating .sizediff')
    _RunCmd(supersize_cmd)
    gsutil_cmd = ['gsutil.py', 'cp']
    if is_internal:
      oneoffs_dir = 'private-oneoffs'
    else:
      oneoffs_dir = 'oneoffs'
      gsutil_cmd += ['-a', 'public-read']
    unique_name = '{}_{}.sizediff'.format(before.rev, after.rev)
    local = os.path.relpath(report_path)
    gsutil_cmd += [local, f'gs://chrome-supersize/{oneoffs_dir}/{unique_name}']

    if self.share:
      msg = 'Automatically uploaded, '
      _RunCmd(gsutil_cmd)
    else:
      msg = (f'Saved locally to {local}. To view, upload to '
             'https://chrome-supersize.firebaseapp.com/viewer.html.\n'
             'To share, run:\n'
             f'> {" ".join(gsutil_cmd)}\n\n'
             'Then ')
    msg = '\n=====================\n' + msg + (
        'view it at https://chrome-supersize.firebaseapp.com/viewer.html'
        '?load_url=https://storage.googleapis.com/chrome-supersize/'
        f'{oneoffs_dir}/{unique_name}'
        '\n=====================\n')
    logging.info(msg)

  def Summarize(self):
    path = os.path.join(self.archive_dir, 'last_diff_summary.txt')
    if self._summary_stats:
      with open(path, 'w') as f:
        stats = sorted(
            self._summary_stats, key=lambda x: x[0].value, reverse=True)
        _WriteToFile(f, '\nDiff Summary')
        for s, before, after in stats:
          _WriteToFile(f, '{:>+10} {} {} for range: {}..{}',
                               s.value, s.units, s.name, before, after)

    # Print cached file if all builds were cached.
    num_archives = len(self.build_archives)
    if os.path.exists(path) and num_archives > 1:
      _PrintFile(path)
    if num_archives <= 2:
      if not all(a.Exists() for a in self.build_archives):
        return
      size2 = ''
      if num_archives == 2:
        size2 = os.path.relpath(self.build_archives[-1].archived_size_path)
      logging.info('Enter supersize console via: %s console %s %s',
                   os.path.relpath(_SUPERSIZE_PATH),
                   os.path.relpath(self.build_archives[0].archived_size_path),
                   size2)


  def _AddDiffSummaryStat(self, before, after):
    stat = None
    if self.build.IsAndroid():
      summary_diff_type = ResourceSizesDiff
    else:
      summary_diff_type = NativeDiff
    for d in self.diffs:
      if isinstance(d, summary_diff_type):
        stat = d.summary_stat
    if stat:
      self._summary_stats.append((stat, before.rev, after.rev))

  def _CanDiff(self, before, after):
    return before.Exists() and after.Exists()

  def _DiffFilePaths(self, before, after):
    ret = os.path.join(self._DiffDir(before, after), 'diff_results')
    return ret + '.txt', ret + '.short.txt'

  def _DiffMetadataPath(self, before, after):
    return os.path.join(self._DiffDir(before, after), 'metadata.txt')

  def _DiffDir(self, before, after):
    archive_range = '%s..%s' % (before.rev, after.rev)
    diff_path = os.path.join(self.archive_dir, 'diffs', archive_range)
    _EnsureDirsExist(diff_path)
    return diff_path


class _Metadata:

  def __init__(self, archives, build, path, subrepo):
    self.data = {
      'revs': [a.rev for a in archives],
      'apply_patch': build.apply_patch,
      'archive_dirs': [a.dir for a in archives],
      'target': build.target,
      'target_os': build.target_os,
      'subrepo': subrepo,
      'path': path,
      'gn_args': {
        'extra_gn_args_str': build.extra_gn_args_str,
        'enable_chrome_android_internal': build.enable_chrome_android_internal,
      }
    }

  def Exists(self):
    path = self.data['path']
    if os.path.exists(path):
      with open(path, 'r') as f:
        return self.data == json.load(f)
    return False

  def Write(self):
    with open(self.data['path'], 'w') as f:
      json.dump(self.data, f)


def _EnsureDirsExist(path):
  if not os.path.exists(path):
    os.makedirs(path)


def _RunCmd(cmd, cwd=None, verbose=False, exit_on_failure=True):
  """Convenience function for running commands.

  Args:
    cmd: the command to run.
    verbose: if this is True, then the stdout and stderr of the process will be
        printed. If it's false, the stdout will be returned.
    exit_on_failure: die if an error occurs when this is True.

  Returns:
    Tuple of (process stdout, process returncode).
  """
  assert not (verbose and exit_on_failure)
  cmd_str = ' '.join(c for c in cmd)
  logging.debug('Running: %s', cmd_str)
  proc_stdout = proc_stderr = subprocess.PIPE
  if verbose:
    proc_stdout, proc_stderr = sys.stdout, subprocess.STDOUT

  # pylint: disable=unexpected-keyword-arg
  proc = subprocess.Popen(cmd,
                          cwd=cwd,
                          stdout=proc_stdout,
                          stderr=proc_stderr,
                          encoding='utf-8')
  stdout, stderr = proc.communicate()

  if proc.returncode and exit_on_failure:
    _Die('command failed: %s\nstderr:\n%s', cmd_str, stderr)

  stdout = stdout.strip() if stdout else ''
  return stdout, proc.returncode


def _GitCmd(args, subrepo):
  return _RunCmd(['git', '-C', subrepo] + args)[0]


def _GclientSyncCmd(rev, subrepo):
  cwd = os.getcwd()
  os.chdir(subrepo)
  _, retcode = _RunCmd(['gclient', 'sync', '-r', 'src@' + rev],
                       verbose=True, exit_on_failure=False)
  os.chdir(cwd)
  return retcode


def _SyncAndBuild(archive, build, subrepo, no_gclient, extra_rev):
  """Sync, build and return non 0 if any commands failed."""
  # Simply do a checkout if subrepo is used.
  if _CurrentGitHash(subrepo) == archive.rev:
    if subrepo != _SRC_ROOT:
      logging.info('Skipping git checkout since already at desired rev')
    else:
      logging.info('Skipping gclient sync since already at desired rev')
  elif subrepo != _SRC_ROOT or no_gclient:
    _GitCmd(['checkout',  archive.rev], subrepo)
  else:
    # Move to a detached state since gclient sync doesn't work with local
    # commits on a branch.
    _GitCmd(['checkout', '--detach'], subrepo)
    logging.info('Syncing to %s', archive.rev)
    ret = _GclientSyncCmd(archive.rev, subrepo)
    if ret:
      return ret
  with _ApplyPatch(extra_rev, subrepo):
    return build.Run()


@contextmanager
def _ApplyPatch(rev, subrepo):
  if not rev:
    yield
  else:
    restore_func = _GenRestoreFunc(subrepo)
    try:
      _GitCmd(['cherry-pick', rev, '--strategy-option', 'theirs'], subrepo)
      yield
    finally:
      restore_func()


def _GenerateRevList(rev, reference_rev, all_in_range, subrepo, step):
  """Normalize and optionally generate a list of commits in the given range.

  Returns:
    A list of revisions ordered from oldest to newest.
  """
  rev_seq = '%s^..%s' % (reference_rev, rev)
  stdout = _GitCmd(['rev-list', rev_seq], subrepo)
  all_revs = stdout.splitlines()[::-1]
  if all_in_range or len(all_revs) < 2 or step:
    revs = all_revs
    if step:
      revs = revs[::step]
  else:
    revs = [all_revs[0], all_revs[-1]]
  num_revs = len(revs)
  if num_revs >= _COMMIT_COUNT_WARN_THRESHOLD:
    _VerifyUserAccepts(
        'You\'ve provided a commit range that contains %d commits.' % num_revs)
  logging.info('Processing %d commits', num_revs)
  return revs


def _ValidateRevs(rev, reference_rev, subrepo, extra_rev):
  def git_fatal(args, message):
    devnull = open(os.devnull, 'wb')
    retcode = subprocess.call(
        ['git', '-C', subrepo] + args, stdout=devnull, stderr=subprocess.STDOUT)
    if retcode:
      _Die(message)

  no_obj_message = ('%s either doesn\'t exist or your local repo is out of '
                    'date, try "git fetch origin master"')
  git_fatal(['cat-file', '-e', rev], no_obj_message % rev)
  git_fatal(['cat-file', '-e', reference_rev], no_obj_message % reference_rev)
  if extra_rev:
    git_fatal(['cat-file', '-e', extra_rev], no_obj_message % extra_rev)
  git_fatal(['merge-base', '--is-ancestor', reference_rev, rev],
            f'reference-rev ({reference_rev}) is not an ancestor of '
            f'rev ({rev})')


def _VerifyUserAccepts(message):
  print(message + ' Do you want to proceed? [y/n]')
  if input('> ').lower() != 'y':
    sys.exit()


def _EnsureDirectoryClean(subrepo):
  logging.info('Checking source directory')
  stdout = _GitCmd(['status', '--porcelain'], subrepo)
  # Ignore untracked files.
  if stdout and stdout[:2] != '??':
    logging.error('Failure: please ensure working directory is clean.')
    sys.exit()


def _Die(s, *args):
  logging.error('Failure: ' + s, *args)
  sys.exit(1)


def _WriteToFile(logfile, s, *args, **kwargs):
  if isinstance(s, str):
    data = s.format(*args, **kwargs) + '\n'
  else:
    data = '\n'.join(s) + '\n'
  logfile.write(data)


def _PrintFile(path):
  with open(path) as f:
    sys.stdout.write(f.read())


def _CurrentGitHash(subrepo):
  return _GitCmd(['rev-parse', 'HEAD'], subrepo)


def _GenRestoreFunc(subrepo):
  branch = _GitCmd(['rev-parse', '--abbrev-ref', 'HEAD'], subrepo)
  # Happens when the repo didn't start on a named branch.
  if branch == 'HEAD':
    branch = _GitCmd(['rev-parse', 'HEAD'], subrepo)
  def _RestoreFunc():
    logging.warning('Restoring original git checkout')
    _GitCmd(['checkout', branch], subrepo)
  return _RestoreFunc


def _SetRestoreFunc(subrepo):
  atexit.register(_GenRestoreFunc(subrepo))


def main():
  parser = argparse.ArgumentParser(
      description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter)
  parser.add_argument('rev',
                      help='Find binary size bloat for this commit.')
  parser.add_argument('--archive-directory',
                      default=_DEFAULT_ARCHIVE_DIR,
                      help='Where results are stored.')
  parser.add_argument('--reference-rev',
                      help='Older rev to diff against. If not supplied, '
                           'the previous commit to rev will be used.')
  parser.add_argument('--all',
                      action='store_true',
                      help='Build/download all revs from --reference-rev to '
                           'rev and diff the contiguous revisions.')
  parser.add_argument('--single',
                      action='store_true',
                      help='Sets --reference-rev=rev.')
  parser.add_argument('--unstripped',
                      action='store_true',
                      help='Save the unstripped native library when archiving.')
  parser.add_argument(
      '--subrepo',
      help='Specify a subrepo directory to use. Implies '
      '--no-gclient. All git commands will be executed '
      'from the subrepo directory.')
  parser.add_argument('--no-gclient',
                      action='store_true',
                      help='Do not perform gclient sync steps.')
  parser.add_argument('--apply-patch', dest='extra_rev',
                      help='A local commit to cherry-pick before each build. '
                           'This can leave your repo in a broken state if '
                           'the cherry-pick fails.')
  parser.add_argument('--step', type=int,
                      help='Assumes --all and only builds/downloads every '
                           '--step\'th revision.')
  parser.add_argument('-v',
                      '--verbose',
                      action='store_true',
                      help='Show commands executed, extra debugging output'
                           ', and Ninja/GN output.')
  parser.add_argument('--supersize-archive-args',
                      help='Args to pass through to the supersize archive '
                      'command (e.g. --java-only, --no-output-directory, etc).')
  parser.add_argument('--share',
                      action='store_true',
                      help='Automatically upload using gsutil.py.')

  build_group = parser.add_argument_group('build arguments')
  build_group.add_argument('--no-reclient',
                           action='store_false',
                           dest='use_reclient',
                           default=True,
                           help='Do not use reclient when building with ninja.')
  build_group.add_argument('--clean',
                           action='store_true',
                           help='Do a clean build for each revision.')
  build_group.add_argument('--gn-args',
                           default='',
                           help='Extra GN args to set.')
  build_group.add_argument('--target-os',
                           default='android',
                           choices=['android', 'linux'],
                           help='target_os gn arg. Default: android.')
  build_group.add_argument('--output-directory',
                           default=_DEFAULT_OUT_DIR,
                           help='ninja output directory. '
                                'Default: %s.' % _DEFAULT_OUT_DIR)
  build_group.add_argument('--enable-chrome-android-internal',
                           action='store_true',
                           help='Allow downstream targets to be built.')
  build_group.add_argument('--target',
                           help='GN target to build. Linux default: chrome. '
                           'Android default: trichrome_32_minimal_apks or '
                           'trichrome_google_32_minimal_apks (depending on '
                           '--enable-chrome-android-internal).')
  build_group.add_argument('--custom-apk-name',
                           help='The apk name by default is derived from the '
                           'target name, but occasionally targets set a custom '
                           'apk name in GN. In those cases use this flag to '
                           'specify the actual apk name (e.g. '
                           '--custom-apk-name=ChromiumNetTestSupport.apk for '
                           'net_test_support_apk).')
  build_group.add_argument('--custom-main-lib-path',
                           help='The main lib path by default is derived from '
                           'the target name. Set this if your target has its '
                           'own main lib path (e.g. '
                           '--custom-main-lib-path=lib.unstripped/'
                           'libnet_java_test_native_support.so for '
                           'net_test_support_apk).')
  if len(sys.argv) == 1:
    parser.print_help()
    return 1

  args = parser.parse_args()
  log_level = logging.DEBUG if args.verbose else logging.INFO
  logging.basicConfig(level=log_level,
                      format='%(levelname).1s %(relativeCreated)6d %(message)s')
  if args.target and args.target.endswith('_bundle'):
    parser.error('Bundle targets must use _minimal_apks variants')

  if _GN_PATH is None:
    parser.error('Could not find "gn" on your PATH')
  if _AUTONINJA_PATH is None:
    parser.error('Could not find "autoninja" on your PATH')

  build = _BuildHelper(args)
  subrepo = args.subrepo or _SRC_ROOT
  _EnsureDirectoryClean(subrepo)
  _SetRestoreFunc(subrepo)

  if build.IsLinux():
    _VerifyUserAccepts('Linux diffs have known deficiencies (crbug/717550).')

  # llvm-objdump always exists for android checkouts, which run it as DEPS hook,
  # but not for linux.
  if not os.path.exists(os.path.join(_LLVM_TOOLS_DIR, 'llvm-objdump')):
    _RunCmd([_CLANG_UPDATE_PATH, '--package=objdump'])

  reference_rev = args.reference_rev or args.rev + '^'
  if args.single:
    reference_rev = args.rev
  _ValidateRevs(args.rev, reference_rev, subrepo, args.extra_rev)
  revs = _GenerateRevList(args.rev, reference_rev, args.all, subrepo, args.step)

  diffs = [NativeDiff(build.size_name)]
  if build.IsAndroid():
    diffs += [ResourceSizesDiff()]
  diff_mngr = _DiffArchiveManager(revs, args.archive_directory, diffs, build,
                                  subrepo, args.unstripped,
                                  args.supersize_archive_args, args.share)
  consecutive_failures = 0
  i = 0
  for i, archive in enumerate(diff_mngr.build_archives):
    if archive.Exists():
      logging.info('Found matching metadata for %s, skipping build step.',
                   archive.rev)
    else:
      build_failure = _SyncAndBuild(archive, build, subrepo, args.no_gclient,
                                    args.extra_rev)
      if build_failure:
        logging.info(
            'Build failed for %s, diffs using this rev will be skipped.',
            archive.rev)
        consecutive_failures += 1
        if len(diff_mngr.build_archives) <= 2:
          _Die('Stopping due to build failure.')
        elif consecutive_failures > _ALLOWED_CONSECUTIVE_FAILURES:
          _Die('%d builds failed in a row, last failure was %s.',
               consecutive_failures, archive.rev)
      else:
        archive.ArchiveBuildResults()
        consecutive_failures = 0

    if i != 0:
      diff_mngr.MaybeDiff(i - 1, i)

  diff_mngr.GenerateHtmlReport(0,
                               i,
                               is_internal=args.enable_chrome_android_internal)
  diff_mngr.Summarize()

  return 0


if __name__ == '__main__':
  sys.exit(main())