#!/usr/bin/env python3
# Copyright 2020 Google LLC.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#        http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
################################################################################
"""Check code for common issues before submitting."""

import argparse
import os
import subprocess
import sys
import unittest
import yaml

_SRC_ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))


def _is_project_file(actual_path, expected_filename):
  """Returns True if actual_path's name is |expected_filename| and is a file
  that exists and is in in projects/."""
  if os.path.basename(actual_path) != expected_filename:
    return False

  if os.path.basename(os.path.dirname(
      os.path.dirname(actual_path))) != 'projects':
    return False

  return os.path.exists(actual_path)


# TODO: Check for -fsanitize=fuzzer in files as well.


def _check_one_lib_fuzzing_engine(build_sh_file):
  """Returns False if |build_sh_file| contains -lFuzzingEngine.
  This is deprecated behavior. $LIB_FUZZING_ENGINE should be used instead
  so that -fsanitize=fuzzer is used."""
  if not _is_project_file(build_sh_file, 'build.sh'):
    return True

  with open(build_sh_file) as build_sh:
    build_sh_lines = build_sh.readlines()
  for line_num, line in enumerate(build_sh_lines):
    uncommented_code = line.split('#')[0]
    if '-lFuzzingEngine' in uncommented_code:
      print(
          'Error: build.sh contains deprecated "-lFuzzingEngine" on line: {0}. '
          'Please use "$LIB_FUZZING_ENGINE" instead.'.format(line_num))
      return False
  return True


def check_lib_fuzzing_engine(paths):
  """Call _check_one_lib_fuzzing_engine on each path in |paths|. Return True if
  the result of every call is True."""
  return all([_check_one_lib_fuzzing_engine(path) for path in paths])


class ProjectYamlChecker:
  """Checks for a project.yaml file."""

  # Sections in a project.yaml and the constant values that they are allowed
  # to have.
  SECTIONS_AND_CONSTANTS = {
      'sanitizers': {'address', 'none', 'memory', 'undefined', 'dataflow'},
      'architectures': {'i386', 'x86_64'},
      'fuzzing_engines': {'afl', 'libfuzzer', 'honggfuzz', 'dataflow', 'none'},
  }

  # Note: this list must be updated when we allow new sections.
  VALID_SECTION_NAMES = [
      'architectures',
      'auto_ccs',
      'blackbox',
      'builds_per_day',
      'coverage_extra_args',
      'disabled',
      'fuzzing_engines',
      'help_url',
      'homepage',
      'language',
      'labels',  # For internal use only, hard to lint as it uses fuzzer names.
      'main_repo',
      'primary_contact',
      'run_tests',
      'sanitizers',
      'selective_unpack',
      'vendor_ccs',
      'view_restrictions',
  ]

  LANGUAGES_SUPPORTED = [
      'c',
      'c++',
      'go',
      'jvm',
      'python',
      'rust',
      'swift',
  ]

  # Note that some projects like boost only have auto-ccs. However, forgetting
  # primary contact is probably a mistake.
  REQUIRED_SECTIONS = ['primary_contact', 'main_repo']

  def __init__(self, filename):
    self.filename = filename
    with open(filename) as file_handle:
      self.data = yaml.safe_load(file_handle)

    self.success = True

  def do_checks(self):
    """Do all project.yaml checks. Return True if they pass."""
    if self.is_disabled():
      return True

    checks = [
        self.check_project_yaml_constants,
        self.check_required_sections,
        self.check_valid_section_names,
        self.check_valid_emails,
        self.check_valid_language,
        self.check_dataflow,
    ]
    for check_function in checks:
      check_function()
    return self.success

  def is_disabled(self):
    """Is this project disabled."""
    return self.data.get('disabled', False)

  def error(self, message):
    """Print an error message and set self.success to False."""
    self.success = False
    print('Error in {filename}: {message}'.format(filename=self.filename,
                                                  message=message))

  def check_dataflow(self):
    """Checks that if "dataflow" is specified in "fuzzing_engines", it is also
    specified in "sanitizers", and that if specified in "sanitizers", it is also
    specified in "fuzzing_engines"."""
    engines = self.data.get('fuzzing_engines', [])
    dfsan_engines = 'dataflow' in engines
    sanitizers = self.data.get('sanitizers', [])
    dfsan_sanitizers = 'dataflow' in sanitizers

    if dfsan_engines and not dfsan_sanitizers:
      self.error('"dataflow" only specified in "fuzzing_engines" must also be '
                 'specified in "sanitizers" or in neither.')
      return

    if dfsan_sanitizers and not dfsan_engines:
      self.error('"dataflow" only specified in "sanitizers" must also be '
                 'specified in "fuzzing_engines" or in neither.')
      return

  def check_project_yaml_constants(self):
    """Check that certain sections only have certain constant values."""
    for section, allowed_constants in self.SECTIONS_AND_CONSTANTS.items():
      if section not in self.data:
        continue
      actual_constants = self.data[section]
      for constant in actual_constants:
        if isinstance(constant, str):
          if constant not in allowed_constants:
            self.error(('{constant} (in {section} section) is not a valid '
                        'constant ({allowed_constants}).').format(
                            constant=constant,
                            section=section,
                            allowed_constants=', '.join(allowed_constants)))
        elif isinstance(constant, dict):
          # The only alternative value allowed is the experimental flag, i.e.
          # `constant == {'memory': {'experimental': True}}`. Do not check the
          # experimental flag, but assert that the sanitizer is a valid one.
          if (len(constant.keys()) > 1 or
              list(constant.keys())[0] not in allowed_constants):
            self.error('Not allowed value in the project.yaml: ' +
                       str(constant))
        else:
          self.error('Not allowed value in the project.yaml: ' + str(constant))

  def check_valid_section_names(self):
    """Check that only valid sections are included."""
    for name in self.data:
      if name not in self.VALID_SECTION_NAMES:
        self.error('{name} is not a valid section name ({valid_names})'.format(
            name=name, valid_names=self.VALID_SECTION_NAMES))

  def check_required_sections(self):
    """Check that all required sections are present."""
    for section in self.REQUIRED_SECTIONS:
      if section not in self.data:
        self.error(section + ' section is missing.')

  def check_valid_emails(self):
    """Check that emails are valid looking."""
    # Get email addresses.
    email_addresses = []
    primary_contact = self.data.get('primary_contact')
    if primary_contact:
      email_addresses.append(primary_contact)
    auto_ccs = self.data.get('auto_ccs')
    if auto_ccs:
      email_addresses.extend(auto_ccs)

    # Check that email addresses seem normal.
    for email_address in email_addresses:
      if '@' not in email_address or '.' not in email_address:
        self.error(email_address + ' is an invalid email address.')

  def check_valid_language(self):
    """Check that the language is specified and valid."""
    language = self.data.get('language')
    if not language:
      self.error('Missing "language" attribute in project.yaml.')
    elif language not in self.LANGUAGES_SUPPORTED:
      self.error(
          '"language: {language}" is not supported ({supported}).'.format(
              language=language, supported=self.LANGUAGES_SUPPORTED))


def _check_one_project_yaml(project_yaml_filename):
  """Do checks on the project.yaml file."""
  if not _is_project_file(project_yaml_filename, 'project.yaml'):
    return True

  checker = ProjectYamlChecker(project_yaml_filename)
  return checker.do_checks()


def check_project_yaml(paths):
  """Call _check_one_project_yaml on each path in |paths|. Return True if
  the result of every call is True."""
  return all([_check_one_project_yaml(path) for path in paths])


def do_checks(changed_files):
  """Run all presubmit checks return False if any fails."""
  checks = [
      check_license, yapf, lint, check_project_yaml, check_lib_fuzzing_engine
  ]
  # Use a list comprehension here and in other cases where we use all() so that
  # we don't quit early on failure. This is more user-friendly since the more
  # errors we spit out at once, the less frequently the less check-fix-check
  # cycles they need to do.
  return all([check(changed_files) for check in checks])


_CHECK_LICENSE_FILENAMES = ['Dockerfile']
_CHECK_LICENSE_EXTENSIONS = [
    '.bash',
    '.c',
    '.cc',
    '.cpp',
    '.css',
    '.h',
    '.htm',
    '.html',
    '.js',
    '.proto',
    '.py',
    '.sh',
]

_LICENSE_STRING = 'http://www.apache.org/licenses/LICENSE-2.0'


def check_license(paths):
  """Validate license header."""
  if not paths:
    return True

  success = True
  for path in paths:
    filename = os.path.basename(path)
    extension = os.path.splitext(path)[1]
    if (filename not in _CHECK_LICENSE_FILENAMES and
        extension not in _CHECK_LICENSE_EXTENSIONS):
      continue

    with open(path) as file_handle:
      if _LICENSE_STRING not in file_handle.read():
        print('Missing license header in file %s.' % str(path))
        success = False

  return success


def bool_to_returncode(success):
  """Return 0 if |success|. Otherwise return 1."""
  if success:
    print('Success.')
    return 0

  print('Failed.')
  return 1


def is_nonfuzzer_python(path):
  """Returns True if |path| ends in .py."""
  return os.path.splitext(path)[1] == '.py' and '/projects/' not in path


def lint(_=None):
  """Run python's linter on infra. Return False if it fails linting."""

  command = ['python3', '-m', 'pylint', '-j', '0', 'infra']
  returncode = subprocess.run(command, check=False).returncode
  return returncode == 0


def yapf(paths, validate=True):
  """Do yapf on |path| if it is Python file. Only validates format if
  |validate| otherwise, formats the file. Returns False if validation
  or formatting fails."""
  paths = [path for path in paths if is_nonfuzzer_python(path)]
  if not paths:
    return True

  validate_argument = '-d' if validate else '-i'
  command = ['yapf', validate_argument, '-p']
  command.extend(paths)

  returncode = subprocess.run(command, check=False).returncode
  return returncode == 0


def get_changed_files():
  """Return a list of absolute paths of files changed in this git branch."""
  branch_commit_hash = subprocess.check_output(
      ['git', 'merge-base', 'FETCH_HEAD', 'origin/HEAD']).strip().decode()

  diff_commands = [
      # Return list of modified files in the commits on this branch.
      ['git', 'diff', '--name-only', branch_commit_hash + '..'],
      # Return list of modified files from uncommitted changes.
      ['git', 'diff', '--name-only']
  ]

  changed_files = set()
  for command in diff_commands:
    file_paths = subprocess.check_output(command).decode().splitlines()
    for file_path in file_paths:
      if not os.path.isfile(file_path):
        continue
      changed_files.add(file_path)
  print('Changed files: {changed_files}'.format(
      changed_files=' '.join(changed_files)))
  return [os.path.abspath(f) for f in changed_files]


def run_build_tests():
  """Runs build tests because they can't be run in parallel."""
  suite_list = [
      unittest.TestLoader().discover(os.path.join(_SRC_ROOT, 'infra', 'build'),
                                     pattern='*_test.py'),
  ]
  suite = unittest.TestSuite(suite_list)
  print('Running build tests.')
  result = unittest.TextTestRunner().run(suite)
  return not result.failures and not result.errors


def run_nonbuild_tests(parallel):
  """Run all tests but build tests. Do it in parallel if |parallel|. The reason
  why we exclude build tests is because they use an emulator that prevents them
  from being used in parallel."""
  # We look for all project directories because otherwise pytest won't run tests
  # that are not in valid modules (e.g. "base-images").
  relevant_dirs = set()
  all_files = get_all_files()
  for file_path in all_files:
    directory = os.path.dirname(file_path)
    relevant_dirs.add(directory)

  # Use ignore-glob because ignore doesn't seem to work properly with the way we
  # pass directories to pytest.
  command = [
      'pytest',
      # Test errors with error: "ModuleNotFoundError: No module named 'apt'.
      '--ignore-glob=infra/base-images/base-sanitizer-libs-builder/*',
      '--ignore-glob=infra/build/*',
  ]
  if parallel:
    command.extend(['-n', 'auto'])
  command += list(relevant_dirs)
  print('Running non-build tests.')
  return subprocess.run(command, check=False).returncode == 0


def run_tests(_=None, parallel=False, skip_build_tests=False):
  """Runs all unit tests."""
  nonbuild_success = run_nonbuild_tests(parallel)

  if skip_build_tests:
    print('Skipping build tests as specified.')
    return nonbuild_success

  build_success = run_build_tests()
  return nonbuild_success and build_success


def get_all_files():
  """Returns a list of absolute paths of files in this repo."""
  get_all_files_command = ['git', 'ls-files']
  output = subprocess.check_output(get_all_files_command).decode().splitlines()
  return [os.path.abspath(path) for path in output if os.path.isfile(path)]


def main():
  """Check changes on a branch for common issues before submitting."""
  # Get program arguments.
  parser = argparse.ArgumentParser(description='Presubmit script for oss-fuzz.')
  parser.add_argument('command',
                      choices=['format', 'lint', 'license', 'infra-tests'],
                      nargs='?')
  parser.add_argument('-a',
                      '--all-files',
                      action='store_true',
                      help='Run presubmit check(s) on all files',
                      default=False)
  parser.add_argument('-p',
                      '--parallel',
                      action='store_true',
                      help='Run tests in parallel.',
                      default=False)
  parser.add_argument('-s',
                      '--skip-build-tests',
                      action='store_true',
                      help='Skip build tests which are slow and must run '
                      'sequentially.',
                      default=False)
  args = parser.parse_args()

  if args.all_files:
    relevant_files = get_all_files()
  else:
    relevant_files = get_changed_files()

  os.chdir(_SRC_ROOT)

  # Do one specific check if the user asked for it.
  if args.command == 'format':
    success = yapf(relevant_files, False)
    return bool_to_returncode(success)

  if args.command == 'lint':
    success = lint()
    return bool_to_returncode(success)

  if args.command == 'license':
    success = check_license(relevant_files)
    return bool_to_returncode(success)

  if args.command == 'infra-tests':
    success = run_tests(relevant_files,
                        parallel=args.parallel,
                        skip_build_tests=args.skip_build_tests)
    return bool_to_returncode(success)

  # Do all the checks (but no tests).
  success = do_checks(relevant_files)

  return bool_to_returncode(success)


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