#!/usr/bin/env python3
# Copyright (c) 2013 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.


"""Top-level presubmit script for Skia.

See http://dev.chromium.org/developers/how-tos/depottools/presubmit-scripts
for more details about the presubmit API built into gcl.
"""

import difflib
import os
import re
import subprocess
import sys


RELEASE_NOTES_DIR = 'relnotes'
RELEASE_NOTES_FILE_NAME = 'RELEASE_NOTES.md'
RELEASE_NOTES_README = '//relnotes/README.md'

GOLD_TRYBOT_URL = 'https://gold.skia.org/search?issue='

SERVICE_ACCOUNT_SUFFIX = [
    '@%s.iam.gserviceaccount.com' % project for project in [
        'skia-buildbots.google.com', 'skia-swarming-bots', 'skia-public',
        'skia-corp.google.com', 'chops-service-accounts']]

USE_PYTHON3 = True

def np(path):
  """normalize path
     This takes in a os-dependent path and returns it using forward slashes only.
  """
  return os.path.normpath(path).replace(os.sep, '/')

def _CheckChangeHasEol(input_api, output_api, source_file_filter=None):
  """Checks that files end with at least one \n (LF)."""
  eof_files = []
  for f in input_api.AffectedSourceFiles(source_file_filter):
    contents = input_api.ReadFile(f, 'rb')
    # Check that the file ends in at least one newline character.
    if len(contents) > 1 and contents[-1:] != '\n':
      eof_files.append(f.LocalPath())

  if eof_files:
    return [output_api.PresubmitPromptWarning(
      'These files should end in a newline character:',
      items=eof_files)]
  return []


def _JsonChecks(input_api, output_api):
  """Run checks on any modified json files."""
  failing_files = []
  for affected_file in input_api.AffectedFiles(None):
    affected_file_path = affected_file.LocalPath()
    is_json = affected_file_path.endswith('.json')
    is_metadata = (np(affected_file_path).startswith('site/') and
                   np(affected_file_path).endswith('/METADATA'))
    if is_json or is_metadata:
      try:
        input_api.json.load(open(affected_file_path, 'r'))
      except ValueError as ve:
        failing_files.append(f'{affected_file_path}\t\t{ve}')

  results = []
  if failing_files:
    results.append(
        output_api.PresubmitError(
            'The following files contain invalid json:\n%s\n' %
                '\n'.join(failing_files)))
  return results


def _IfDefChecks(input_api, output_api):
  """Ensures if/ifdef are not before includes. See skbug/3362 for details."""
  comment_block_start_pattern = re.compile('^\s*\/\*.*$')
  comment_block_middle_pattern = re.compile('^\s+\*.*')
  comment_block_end_pattern = re.compile('^\s+\*\/.*$')
  single_line_comment_pattern = re.compile('^\s*//.*$')
  def is_comment(line):
    return (comment_block_start_pattern.match(line) or
            comment_block_middle_pattern.match(line) or
            comment_block_end_pattern.match(line) or
            single_line_comment_pattern.match(line))

  empty_line_pattern = re.compile('^\s*$')
  def is_empty_line(line):
    return empty_line_pattern.match(line)

  failing_files = []
  for affected_file in input_api.AffectedSourceFiles(None):
    affected_file_path = affected_file.LocalPath()
    if affected_file_path.endswith('.cpp') or affected_file_path.endswith('.h'):
      f = open(affected_file_path)
      for line in f:
        if is_comment(line) or is_empty_line(line):
          continue
        # The below will be the first real line after comments and newlines.
        if line.startswith('#if 0 '):
          pass
        elif line.startswith('#if ') or line.startswith('#ifdef '):
          failing_files.append(affected_file_path)
        break

  results = []
  if failing_files:
    results.append(
        output_api.PresubmitError(
            'The following files have #if or #ifdef before includes:\n%s\n\n'
            'See skbug.com/40034487 for why this should be fixed.' %
                '\n'.join(failing_files)))
  return results


def _CopyrightChecks(input_api, output_api, source_file_filter=None):
  results = []
  year_pattern = r'\d{4}'
  year_range_pattern = r'%s(-%s)?' % (year_pattern, year_pattern)
  years_pattern = r'%s(,%s)*,?' % (year_range_pattern, year_range_pattern)
  copyright_pattern = (
      r'Copyright (\([cC]\) )?%s \w+' % years_pattern)

  for affected_file in input_api.AffectedSourceFiles(source_file_filter):
    norm_path = np(affected_file.LocalPath())
    if ('third_party/' in norm_path or
        'tests/sksl/' in norm_path or
        'bazel/rbe/' in norm_path or
        'bazel/external/' in norm_path or
        'bazel/exporter/interfaces/mocks/' in norm_path or
        norm_path.endswith('gen.go')):
      continue
    contents = input_api.ReadFile(affected_file, 'rb')
    if not re.search(copyright_pattern, contents):
      results.append(output_api.PresubmitError(
          '%s is missing a correct copyright header.' % affected_file))
    if affected_file.Action() == 'A':
      if 'Google Inc' in contents:
        results.append(output_api.PresubmitError(
            '%s contains "Google Inc" in copyright header. New files should use "Google LLC".' % affected_file))
  return results


def _InfraTests(input_api, output_api):
  """Run the infra tests."""
  results = []
  if not any(f.LocalPath().startswith('infra')
             for f in input_api.AffectedFiles()):
    return results

  cmd = ['python3', os.path.join('infra', 'bots', 'infra_tests.py')]
  try:
    subprocess.check_output(cmd)
  except subprocess.CalledProcessError as e:
    results.append(output_api.PresubmitError(
        '`%s` failed:\n%s' % (' '.join(cmd), e.output)))
  return results


def _CheckGNFormatted(input_api, output_api):
  """Make sure any .gn files we're changing have been formatted."""
  files = []
  for f in input_api.AffectedFiles(include_deletes=False):
    if (f.LocalPath().endswith('.gn') or
        f.LocalPath().endswith('.gni')):
      files.append(f)
  if not files:
    return []

  cmd = ['python3', os.path.join('bin', 'fetch-gn')]
  try:
    subprocess.check_output(cmd)
  except subprocess.CalledProcessError as e:
    return [output_api.PresubmitError(
        '`%s` failed:\n%s' % (' '.join(cmd), e.output))]

  results = []
  for f in files:
    gn = 'gn.exe' if 'win32' in sys.platform else 'gn'
    gn = os.path.join(input_api.PresubmitLocalPath(), 'bin', gn)
    cmd = [gn, 'format', '--dry-run', f.LocalPath()]
    try:
      subprocess.check_output(cmd)
    except subprocess.CalledProcessError:
      fix = 'bin/gn format ' + f.LocalPath()
      results.append(output_api.PresubmitError(
          '`%s` failed, try\n\t%s' % (' '.join(cmd), fix)))
  return results


def _CheckGitConflictMarkers(input_api, output_api):
  pattern = input_api.re.compile('^(?:<<<<<<<|>>>>>>>) |^=======$')
  results = []
  for f in input_api.AffectedFiles():
    for line_num, line in f.ChangedContents():
      if f.LocalPath().endswith('.md'):
        # First-level headers in markdown look a lot like version control
        # conflict markers. http://daringfireball.net/projects/markdown/basics
        continue
      if pattern.match(line):
        results.append(
            output_api.PresubmitError(
                'Git conflict markers found in %s:%d %s' % (
                    f.LocalPath(), line_num, line)))
  return results


def _CheckIncludesFormatted(input_api, output_api):
  """Make sure #includes in files we're changing have been formatted."""
  files = [str(f) for f in input_api.AffectedFiles() if f.Action() != 'D']
  cmd = ['python3',
         'tools/rewrite_includes.py',
         '--dry-run'] + files
  if 0 != subprocess.call(cmd):
    return [output_api.PresubmitError('`%s` failed' % ' '.join(cmd))]
  return []


class _WarningsAsErrors():
  def __init__(self, output_api):
    self.output_api = output_api
    self.old_warning = None
  def __enter__(self):
    self.old_warning = self.output_api.PresubmitPromptWarning
    self.output_api.PresubmitPromptWarning = self.output_api.PresubmitError
    return self.output_api
  def __exit__(self, ex_type, ex_value, ex_traceback):
    self.output_api.PresubmitPromptWarning = self.old_warning


def _RegenerateAllExamplesCPP(input_api, output_api):
  """Regenerates all_examples.cpp if an example was added or deleted."""
  if not any(np(f.LocalPath()).startswith('docs/examples/')
             for f in input_api.AffectedFiles()):
    return []
  command_str =  os.path.join('tools', 'fiddle', 'make_all_examples_cpp.py')
  cmd = ['python3', command_str, '--print-diff']
  proc = subprocess.run(cmd, capture_output=True)
  if proc.returncode != 0:
    return [output_api.PresubmitError('`%s` failed' % ' '.join(cmd))]

  results = []
  diff_output = proc.stdout.decode('utf-8').strip()
  if diff_output:
    results += [output_api.PresubmitError(
        'Diffs found after running "%s":\n\n%s\n'
        'Please commit or discard the above changes.' % (
            command_str,
            diff_output,
        )
    )]
  return results


def _CheckIncludeForOutsideDeps(input_api, output_api):
  """The include directory should consist of only public APIs.

     This check makes sure we don't have anything in the include directory
     depend on outside folders. If we had include/core/SkDonut.h depend on
     src/core/SkPastry.h, then clients would have transitive access to the
     private SkPastry class and any symbols in there, even if they don't
     directly include src/core/SkPastry.h (which can be detected/blocked
     with build systems like GN or Bazel). By keeping include/ self-contained,
     we keep a tighter grip on our public API and make Skia easier to distribute
     (one can ship a .a/.so and a single directory of .h files).
  """
  banned_includes = [
    input_api.re.compile(r'#\s*include\s+("src/.*)'),
    input_api.re.compile(r'#\s*include\s+("tools/.*)'),
  ]
  file_filter = lambda x: (np(x.LocalPath()).startswith('include/'))
  errors = []
  for affected_file in input_api.AffectedSourceFiles(file_filter):
    affected_filepath = affected_file.LocalPath()
    for (line_num, line) in affected_file.ChangedContents():
      for re in banned_includes:
        match = re.search(line)
        if match:
          errors.append(('%s:%s: include/* should only depend on other things in include/*. ' +
                        'Please remove #include of %s, perhaps making it a forward-declare.') % (
                affected_filepath, line_num, match.group(1)))

  if errors:
    return [output_api.PresubmitError('\n'.join(errors))]
  return []


def _CheckExamplesForPrivateAPIs(input_api, output_api):
  """We only want our checked-in examples (aka fiddles) to show public API."""
  banned_includes = [
    input_api.re.compile(r'#\s*include\s+("src/.*)'),
    input_api.re.compile(r'#\s*include\s+("include/private/.*)'),
  ]
  file_filter = lambda x: (np(x.LocalPath()).startswith('docs/examples/'))
  errors = []
  for affected_file in input_api.AffectedSourceFiles(file_filter):
    affected_filepath = affected_file.LocalPath()
    for (line_num, line) in affected_file.ChangedContents():
      for re in banned_includes:
        match = re.search(line)
        if match:
          errors.append('%s:%s: Fiddles should not use private/internal API like %s.' % (
                affected_filepath, line_num, match.group(1)))

  if errors:
    return [output_api.PresubmitError('\n'.join(errors))]
  return []


def _CheckGeneratedBazelBUILDFiles(input_api, output_api):
  if 'win32' in sys.platform:
    # TODO(skbug.com/40043154): Remove when Bazel builds work on Windows.
    # Note: `make` is not installed on Windows by default.
    return []
  if 'darwin' in sys.platform:
    # This takes too long on Mac with default settings. Probably due to sandboxing.
    return []
  files = []
  for affected_file in input_api.AffectedFiles(include_deletes=True):
    affected_file_path = affected_file.LocalPath()
    if (affected_file_path.endswith('.go') or
          affected_file_path.endswith('BUILD.bazel')):
      files.append(affected_file)
  if not files:
    return []
  return _RunCommandAndCheckDiff(
      output_api, ['make', '-C', 'bazel', 'generate_go'], files
  )


def _CheckBazelBUILDFiles(input_api, output_api):
  """Makes sure our BUILD.bazel files are compatible with G3."""
  results = []
  for affected_file in input_api.AffectedFiles(include_deletes=False):
    affected_file_path = affected_file.LocalPath()
    norm_path = np(affected_file_path)
    is_bazel = affected_file_path.endswith('BUILD.bazel')
    # This list lines up with the one in autoroller_lib.py (see G3).
    excluded_paths = ["infra/", "bazel/rbe/", "bazel/external/", "bazel/common_config_settings/",
                      "modules/canvaskit/go/", "experimental/", "bazel/platform", "third_party/",
                      "tests/", "resources/", "bazel/deps_parser/", "bazel/exporter_tool/",
                      "tools/ganesh/gl/interface/", "bazel/utils/", "include/config/",
                      "bench/", "example/external_client/"]
    is_excluded = any(norm_path.startswith(n) for n in excluded_paths)
    if is_bazel and not is_excluded:
      with open(affected_file_path, 'r') as file:
        contents = file.read()
        if 'licenses(["notice"])' not in contents:
          results.append(output_api.PresubmitError(
            ('%s needs to have\nlicenses(["notice"])\nimmediately after ' +
             'the load() calls to comply with G3 policies.') % affected_file_path
          ))
        if 'cc_library(' in contents and '"skia_cc_library"' not in contents:
          results.append(output_api.PresubmitError(
            ('%s needs to load skia_cc_library from skia_rules.bzl instead of using the ' +
             'native one. This allows us to build differently for G3.\n' +
             'Add "skia_cc_library" to load("//bazel:skia_rules.bzl", ...)')
            % affected_file_path
          ))
        if 'default_applicable_licenses' not in contents:
          # See https://opensource.google/documentation/reference/thirdparty/new_license_rules
          results.append(output_api.PresubmitError(
            ('%s needs to have\npackage(default_applicable_licenses = ["//:license"])\n'+
             'to comply with G3 policies') % affected_file_path
          ))
  return results


def _RunCommandAndCheckDiff(output_api, command, files_to_check):
  """Run an arbitrary command. Fail if it produces any diffs on the given files."""
  prev_contents = {}
  for file in files_to_check:
    # NewContents just reads the file.
    prev_contents[file] = file.NewContents()

  command_str = ' '.join(command)
  results = []

  try:
    subprocess.check_output(
        command,
        stderr=subprocess.STDOUT, encoding='utf-8')
  except subprocess.CalledProcessError as e:
    results += [output_api.PresubmitError(
        'Command "%s" returned non-zero exit code %d. Output: \n\n%s' % (
            command_str,
            e.returncode,
            e.output,
        )
    )]

  # Compare the new content to the previous content.
  diffs = []
  for file, prev_content in prev_contents.items():
    new_content = file.NewContents(flush_cache=True)
    if new_content != prev_content:
      path = file.LocalPath()
      diff = difflib.unified_diff(prev_content, new_content, path, path, lineterm='')
      diffs.append('\n'.join(diff))

  if diffs:
    results += [output_api.PresubmitError(
        'Diffs found after running "%s":\n\n%s\n\n'
        'Please commit or discard the above changes.' % (
            command_str,
            '\n'.join(diffs),
        )
    )]

  return results


def _CheckGNIGenerated(input_api, output_api):
  """Ensures that the generated *.gni files are current.

  The Bazel project files are authoritative and some *.gni files are
  generated from them using the exporter_tool. This check ensures they
  are still current.
  """
  if 'win32' in sys.platform:
    # TODO(skbug.com/40043154): Remove when Bazel builds work on Windows.
    # Note: `make` is not installed on Windows by default.
    return [
        output_api.PresubmitNotifyResult(
            'Skipping Bazel=>GNI export check on Windows (unsupported platform).'
        )
    ]
  if 'darwin' in sys.platform:
    # This takes too long on Mac with default settings. Probably due to sandboxing.
    return []
  files = []
  for affected_file in input_api.AffectedFiles(include_deletes=True):
    affected_file_path = affected_file.LocalPath()
    if affected_file_path.endswith('BUILD.bazel') or affected_file_path.endswith('.gni'):
      files.append(affected_file)
  # Generate GNI files and verify no changes.
  if not files:
    # No Bazel build files changed.
    return []
  return _RunCommandAndCheckDiff(
      output_api, ['make', '-C', 'bazel', 'generate_gni'], files
  )


def _CheckBuildifier(input_api, output_api):
  """Runs Buildifier and fails on linting errors, or if it produces any diffs.

  This check only runs if the affected files include any WORKSPACE, BUILD,
  BUILD.bazel or *.bzl files.
  """
  files = []
  # Please keep the below exclude patterns in sync with those in the //:buildifier rule definition.
  for affected_file in input_api.AffectedFiles(include_deletes=False):
    affected_file_path = affected_file.LocalPath()
    norm_path = np(affected_file.LocalPath())
    if norm_path.endswith('BUILD.bazel') or norm_path.endswith('.bzl'):
      if not norm_path.endswith('public.bzl') and \
        not "bazel/rbe/gce_linux/" in norm_path and \
        not norm_path.startswith("third_party/externals/") and \
        not "node_modules/" in norm_path:  # Skip generated files.
        files.append(affected_file)
  if not files:
    return []
  try:
    subprocess.check_output(
        ['buildifier', '--version'],
        stderr=subprocess.STDOUT)
  except:
    return [output_api.PresubmitNotifyResult(
      'Skipping buildifier check because it is not on PATH. \n' +
      'You can download it from https://github.com/bazelbuild/buildtools/releases')]

  return _RunCommandAndCheckDiff(
    # Please keep the below arguments in sync with those in the //:buildifier rule definition.
    output_api, [
      'buildifier',
      '--mode=fix',
      '--lint=fix',
      '--warnings',
      ','.join([
        '-native-android',
        '-native-cc',
        '-native-py',
      ])
    ] + [f.LocalPath() for f in files], files)


def _CheckBannedAPIs(input_api, output_api):
  """Check source code for functions, packages, and symbols that should not be used."""

  # A list of tuples of a regex to match an API and a suggested replacement for
  # that API. There is an optional third parameter for files which *can* use this
  # API without warning.
  banned_replacements = [
    (r'std::stof\(', 'std::strtof(), which does not throw'),
    (r'std::stod\(', 'std::strtod(), which does not throw'),
    (r'std::stold\(', 'std::strtold(), which does not throw'),
    # go/cstyle#Disallowed_Stdlib
    (r'std::barrier', ''),
    (r'std::condition_variable', ''),
    (r'std::counting_semaphore', ''),
    (r'std::future', ''),
    (r'std::jthread', ''),
    (r'std::latch', ''),
    (r'std::mutex', 'SkMutex'),
    (r'std::shared_mutex', 'SkSharedMutex'),
    (r'std::stop_token', ''),
    (r'std::thread', '', ['^tests/', 'SkExecutor']),

    # We used to have separate symbols for this, but coalesced them to make the
    # Bazel build easier.
    (r'GR_TEST_UTILS', 'GPU_TEST_UTILS'),
    (r'GRAPHITE_TEST_UTILS', 'GPU_TEST_UTILS'),

    # This form of multi line string can unintentionally cause Skia to ship with
    # extraneous spaces and newlines in its SkSL (or generated) code, which slightly
    # increases code size and parse time. Instead, use normal quotes and C++'s
    # auto-concatenation
    #    "this string"
    #       "and this"
    #    "string will be joined without extra spaces"
    (r'R"\(', 'implied string concatenation',
       ['^bench/',
        '^docs/',
        '^gm/',
        '^modules/skottie/tests/',
        '^src/sksl/lex/Main.cpp',
        '^tests/',
        '^tools/']
     ),

    # Our Bazel rules have special copies of our cc_library rules with GPU_TEST_UTILS
    # set. If GPU_TEST_UTILS is used outside of those files in Skia proper, the build
    # will break/crash in mysterious ways (because files may get compiled in multiple
    # conflicting ways as a result of the define being inconsistently set).
    (r'GPU_TEST_UTILS', 'use only in GPU code and tests',
      ['^include/core/SkTypes.h',
       '^include/gpu/',
       '^include/private/gpu/',
       '^src/gpu/ganesh',
       '^src/gpu/graphite',
       '^tests/',
       '^tools/']
     ),
  ]

  # These defines are either there or not, and using them with just an #if is a
  # subtle, frustrating bug.
  existence_defines = ['SK_GANESH', 'SK_GRAPHITE', 'SK_GL', 'SK_VULKAN', 'SK_DAWN', 'SK_METAL',
                       'SK_DIRECT3D', 'SK_DEBUG', 'GPU_TEST_UTILS']
  for d in existence_defines:
    banned_replacements.append(('#if {}'.format(d),
                                '#if defined({})'.format(d)))
  compiled_replacements = []
  for rep in banned_replacements:
    exceptions = []
    if len(rep) == 3:
      (re, replacement, exceptions) = rep
    else:
      (re, replacement) = rep

    compiled_re = input_api.re.compile(re)
    compiled_exceptions = [input_api.re.compile(exc) for exc in exceptions]
    compiled_replacements.append(
        (compiled_re, replacement, compiled_exceptions))

  errors = []
  file_filter = lambda x: (x.LocalPath().endswith('.h') or
                           x.LocalPath().endswith('.cpp') or
                           x.LocalPath().endswith('.cc') or
                           x.LocalPath().endswith('.m') or
                           x.LocalPath().endswith('.mm'))
  for affected_file in input_api.AffectedSourceFiles(file_filter):
    affected_filepath = affected_file.LocalPath()
    for (line_num, line) in affected_file.ChangedContents():
      for (re, replacement, exceptions) in compiled_replacements:
        match = re.search(line)
        if match:
          norm_path = np(affected_filepath)
          for exc in exceptions:
            if exc.search(norm_path):
              break
          else:
            errors.append('%s:%s: Instead of %s, please use %s.' % (
                affected_filepath, line_num, match.group(), replacement))

  if errors:
    return [output_api.PresubmitError('\n'.join(errors))]

  return []


def _CheckDEPS(input_api, output_api):
  """If DEPS was modified, run the deps_parser to update bazel/deps.json"""
  files = []
  for affected_file in input_api.AffectedFiles(include_deletes=False):
    affected_file_path = affected_file.LocalPath()
    if affected_file_path.endswith('DEPS') or affected_file_path.endswith('deps.json'):
      files.append(affected_file)
  if not files:
    return []
  try:
    subprocess.check_output(
        ['bazelisk', '--version'],
        stderr=subprocess.STDOUT)
  except:
    return [output_api.PresubmitNotifyResult(
      'Skipping DEPS check because bazelisk is not on PATH. \n' +
      'You can download it from https://github.com/bazelbuild/bazelisk/releases/tag/v1.14.0')]

  return _RunCommandAndCheckDiff(
      output_api, ['bazelisk', 'run', '//bazel/deps_parser'], files
  )


def _CommonChecks(input_api, output_api):
  """Presubmit checks common to upload and commit."""
  results = []
  sources = lambda x: (x.LocalPath().endswith('.h') or
                       x.LocalPath().endswith('.py') or
                       x.LocalPath().endswith('.sh') or
                       x.LocalPath().endswith('.m') or
                       x.LocalPath().endswith('.mm') or
                       x.LocalPath().endswith('.go') or
                       x.LocalPath().endswith('.c') or
                       x.LocalPath().endswith('.cc') or
                       x.LocalPath().endswith('.cpp'))
  results.extend(_CheckChangeHasEol(
      input_api, output_api, source_file_filter=sources))
  with _WarningsAsErrors(output_api):
    results.extend(input_api.canned_checks.CheckChangeHasNoCR(
        input_api, output_api, source_file_filter=sources))
    results.extend(input_api.canned_checks.CheckChangeHasNoStrayWhitespace(
        input_api, output_api, source_file_filter=sources))
  results.extend(_JsonChecks(input_api, output_api))
  results.extend(_IfDefChecks(input_api, output_api))
  results.extend(_CopyrightChecks(input_api, output_api, source_file_filter=sources))
  results.extend(_CheckIncludesFormatted(input_api, output_api))
  results.extend(_CheckGNFormatted(input_api, output_api))
  results.extend(_CheckGitConflictMarkers(input_api, output_api))
  results.extend(_RegenerateAllExamplesCPP(input_api, output_api))
  results.extend(_CheckExamplesForPrivateAPIs(input_api, output_api))
  results.extend(_CheckIncludeForOutsideDeps(input_api, output_api))
  results.extend(_CheckBazelBUILDFiles(input_api, output_api))
  results.extend(_CheckBannedAPIs(input_api, output_api))
  return results


def CheckChangeOnUpload(input_api, output_api):
  """Presubmit checks for the change on upload."""
  results = []
  results.extend(_CommonChecks(input_api, output_api))
  # Run on upload, not commit, since the presubmit bot apparently doesn't have
  # coverage or Go installed.
  results.extend(_InfraTests(input_api, output_api))
  results.extend(_CheckTopReleaseNotesChanged(input_api, output_api))
  results.extend(_CheckReleaseNotesForPublicAPI(input_api, output_api))
  # Buildifier might not be on the CI machines.
  results.extend(_CheckBuildifier(input_api, output_api))
  # We don't want this to block the CQ (for now).
  results.extend(_CheckDEPS(input_api, output_api))
  # Bazelisk is not yet included in the Presubmit job.
  results.extend(_CheckGeneratedBazelBUILDFiles(input_api, output_api))
  results.extend(_CheckGNIGenerated(input_api, output_api))
  return results


class CodeReview(object):
  """Abstracts which codereview tool is used for the specified issue."""

  def __init__(self, input_api):
    self._issue = input_api.change.issue
    self._gerrit = input_api.gerrit

  def GetOwnerEmail(self):
    return self._gerrit.GetChangeOwner(self._issue)

  def GetSubject(self):
    return self._gerrit.GetChangeInfo(self._issue)['subject']

  def GetDescription(self):
    return self._gerrit.GetChangeDescription(self._issue)

  def GetReviewers(self):
    code_review_label = (
        self._gerrit.GetChangeInfo(self._issue)['labels']['Code-Review'])
    return [r['email'] for r in code_review_label.get('all', [])]

  def GetApprovers(self):
    approvers = []
    code_review_label = (
        self._gerrit.GetChangeInfo(self._issue)['labels']['Code-Review'])
    for m in code_review_label.get('all', []):
      if m.get("value") == 1:
        approvers.append(m["email"])
    return approvers


def _CheckReleaseNotesForPublicAPI(input_api, output_api):
  """Checks to see if a release notes file is added or edited with public API changes."""
  results = []
  public_api_changed = False
  release_file_changed = False
  for affected_file in input_api.AffectedFiles():
    affected_file_path = affected_file.LocalPath()
    file_path, file_ext = os.path.splitext(affected_file_path)
    # We only care about files that end in .h and are under the top-level
    # include dir, but not include/private.
    if (file_ext == '.h' and
        file_path.split(os.path.sep)[0] == 'include' and
        'private' not in file_path):
      public_api_changed = True
    elif os.path.dirname(file_path) == RELEASE_NOTES_DIR:
      release_file_changed = True

  if public_api_changed and not release_file_changed:
    results.append(output_api.PresubmitPromptWarning(
        'If this change affects a client API, please add a new summary '
        'file in the %s directory. More information can be found in '
        '%s.' % (RELEASE_NOTES_DIR, RELEASE_NOTES_README)))
  return results


def _CheckTopReleaseNotesChanged(input_api, output_api):
  """Warns if the top level release notes file was changed.

  The top level file is now auto-edited, and new release notes should
  be added to the RELEASE_NOTES_DIR directory"""
  results = []
  top_relnotes_changed = False
  release_file_changed = False
  for affected_file in input_api.AffectedFiles():
    affected_file_path = affected_file.LocalPath()
    file_path, file_ext = os.path.splitext(affected_file_path)
    if affected_file_path == RELEASE_NOTES_FILE_NAME:
      top_relnotes_changed = True
    elif os.path.dirname(file_path) == RELEASE_NOTES_DIR:
      release_file_changed = True
  # When relnotes_util is run it will modify RELEASE_NOTES_FILE_NAME
  # and delete the individual note files in RELEASE_NOTES_DIR.
  # So, if both paths are modified do not emit a warning.
  if top_relnotes_changed and not release_file_changed:
    results.append(output_api.PresubmitPromptWarning(
        'Do not edit %s directly. %s is automatically edited during the '
        'release process. Release notes should be added as new files in '
        'the %s directory. More information can be found in %s.' % (RELEASE_NOTES_FILE_NAME,
                                                                    RELEASE_NOTES_FILE_NAME,
                                                                    RELEASE_NOTES_DIR,
                                                                    RELEASE_NOTES_README)))
  return results


def PostUploadHook(gerrit, change, output_api):
  """git cl upload will call this hook after the issue is created/modified.

  This hook does the following:
  * Adds a link to preview docs changes if there are any docs changes in the CL.
  * Adds 'No-Try: true' if the CL contains only docs changes.
  """
  if not change.issue:
    return []

  # Skip PostUploadHooks for all auto-commit service account bots. New
  # patchsets (caused due to PostUploadHooks) invalidates the CQ+2 vote from
  # the "--use-commit-queue" flag to "git cl upload".
  for suffix in SERVICE_ACCOUNT_SUFFIX:
    if change.author_email.endswith(suffix):
      return []

  results = []
  at_least_one_docs_change = False
  all_docs_changes = True
  for affected_file in change.AffectedFiles():
    affected_file_path = affected_file.LocalPath()
    file_path, _ = os.path.splitext(affected_file_path)
    if 'site' == file_path.split(os.path.sep)[0]:
      at_least_one_docs_change = True
    else:
      all_docs_changes = False
    if at_least_one_docs_change and not all_docs_changes:
      break

  footers = change.GitFootersFromDescription()
  description_changed = False

  # If the change includes only doc changes then add No-Try: true in the
  # CL's description if it does not exist yet.
  if all_docs_changes and 'true' not in footers.get('No-Try', []):
    description_changed = True
    change.AddDescriptionFooter('No-Try', 'true')
    results.append(
        output_api.PresubmitNotifyResult(
            'This change has only doc changes. Automatically added '
            '\'No-Try: true\' to the CL\'s description'))

  # If the description has changed update it.
  if description_changed:
    gerrit.UpdateDescription(
        change.FullDescriptionText(), change.issue)

  return results


def CheckChangeOnCommit(input_api, output_api):
  """Presubmit checks for the change on commit."""
  results = []
  results.extend(_CommonChecks(input_api, output_api))
  # Checks for the presence of 'DO NOT''SUBMIT' in CL description and in
  # content of files.
  results.extend(
      input_api.canned_checks.CheckDoNotSubmit(input_api, output_api))
  return results