#!/usr/bin/python3 -B
# Copyright 2018 Google LLC. All Rights Reserved. This file and proprietary
# source code may only be used and distributed under the Widevine Master
# License Agreement.
"""Generates build files and builds the CDM source release."""

# Lint as: python2, python3
from __future__ import print_function

import argparse
import math
import os
import subprocess
import sys

# pylint: disable=C6204
# Absolute path to Widevine CDM project repository.
CDM_TOP_PATH = os.path.abspath(os.path.dirname(__file__))

# If gyp has been installed locally in third_party, this will find it.
# Irrelevant if gyp has been installed globally.
sys.path.insert(1, os.path.join(CDM_TOP_PATH, 'third_party'))
import gyp
# pylint: enable=C6204

PLATFORMS_DIR_PATH = os.path.join(CDM_TOP_PATH, 'platforms')
OEMCRYPTO_FUZZTEST_DIR_PATH = os.path.join(CDM_TOP_PATH, 'oemcrypto', 'test',
                                           'fuzz_tests')

# Exit status for script if failure arises.
EXIT_FAILURE = 1


def LoadFields(path):
  """Loads variables from an external python script.

  Attempts to load the specified python fields from the source file
  specified at the given |path|.

  Args:
    path: The path (absolute to relative) to the source file containing module
      to be loaded.

  Returns:
    The fields dictionary if it is successfully loaded.  Otherwise
    returns None
  """
  fields = {}
  with open(path) as f:
    exec(f.read(), fields, fields)  # pylint: disable=W0122
  return fields


def IsNinjaInstalled():
  """Determine if ninja is installed."""
  try:
    if hasattr(subprocess, 'DEVNULL'):
      # Provides better compatibility for Windows, not available in Python 2.x
      dev_null = subprocess.DEVNULL
    else:
      dev_null = open(os.devnull, 'w')
    subprocess.check_call(['ninja', '--version'],
                          stdout=dev_null,
                          stderr=dev_null)
    return True
  except subprocess.CalledProcessError:
    # Error code returned, probably not the ninja we're looking for.
    return False
  except OSError:
    # No such command found.
    return False


def PlatformExists(platform, print_details=False):
  """Determine if specified platform exists.

  Args:
    platform: Name of the platform (ex. "x86-64")
    print_details: An optional flag to enable printing of the reason the
      platform was determined to not exist.  Does not print anything if the
      platform is valid.

  Returns:
    True if the there exists configuration files for the specified |platform|,
    False otherwise.
  """
  target_path = os.path.join(PLATFORMS_DIR_PATH, platform)
  platform_gypi_path = os.path.join(target_path, 'settings.gypi')
  platform_environment_path = os.path.join(target_path, 'environment.py')

  def vprint(msg):
    if print_details:
      print(msg, file=sys.stderr)

  if not os.path.isdir(target_path):
    vprint(' Target path does not exist: platform = {}'.format(platform))
    return False

  if not os.path.isfile(platform_gypi_path):
    vprint(' Target platform is missing settings.gypi file: settings_path = {}'
           .format(platform_gypi_path))
    return False
  if not os.path.isfile(platform_environment_path):
    vprint(
        ' Target platform is missing environment.py file: env_path = {}'.format(
            platform_environment_path))
    return False
  return True


def RetrieveListOfPlatforms():
  """Retrieves a list of names of the support platform.

  Returns:
    A list of strings containing the name of the platform
  """
  if not os.path.isdir(PLATFORMS_DIR_PATH):
    print(
        'Cannot find platforms directory: expected_path = {}'.format(
            PLATFORMS_DIR_PATH),
        file=sys.stderr)
    return []
  return sorted(filter(PlatformExists, os.listdir(PLATFORMS_DIR_PATH)))


def VerboseSubprocess(args):
  """Print sub-process command and execute."""
  print(' Running: ' + ' '.join(args))
  return subprocess.call(args)


def RunMake(unused_output_path, build_config, job_limit, verbose):
  """Run Make as build system."""
  os.environ['BUILDTYPE'] = build_config

  if job_limit is not None:
    if math.isinf(job_limit):
      job_args = ['-j']
    else:
      job_args = ['-j', str(job_limit)]
  else:
    job_args = []

  if verbose:
    job_args.append('-v')
  job_args.extend(['all', 'widevine_ce_cdm_shared'])
  return VerboseSubprocess(['make', '-C', CDM_TOP_PATH] + job_args)


def RunNinja(output_path, build_config, job_limit, verbose):
  """Run Ninja as build system."""
  build_path = os.path.join(output_path, build_config)

  if job_limit is not None:
    if math.isinf(job_limit):
      print('Ninja cannot run an infinite number of jobs', file=sys.stderr)
      print('Running at most 1000 jobs')
      job_limit = 1000
    job_args = ['-j', str(job_limit)]
  else:
    job_args = []

  if verbose:
    job_args += ['-v']
  job_args += ['all', 'widevine_ce_cdm_shared']
  return VerboseSubprocess(['ninja', '-C', build_path] + job_args)


# Map from generator name to generator invocation function.
BUILDERS = {
    'make': RunMake,
    'ninja': RunNinja,
}


def GetBuilder(generator):
  return BUILDERS.get(generator)


def ImportPlatform(platform, gyp_args, build_fuzz_tests):
  """Handles platform-specific setup for the named platform.

  Computes platform-specific paths, sets gyp arguments for platform-specific
  gypis and output paths, imports a platform-specific module, and exports
  platform-specific environment variables.

  Args:
    platform: The name of the platform.
    gyp_args: An array of gyp arguments to which this function will append.
    build_fuzz_tests: True when we are building OEMCrypto fuzz tests.

  Returns:
    The path to the root of the build output.
  """

  print(' Target Platform: ' + platform)
  assert PlatformExists(platform)

  target_path = os.path.join(PLATFORMS_DIR_PATH, platform)
  platform_gypi_path = os.path.join(target_path, 'settings.gypi')
  platform_environment_path = os.path.join(target_path, 'environment.py')
  output_path = os.path.join(CDM_TOP_PATH, 'out', platform)

  gyp_args.append('--include=' + platform_gypi_path)
  if build_fuzz_tests:
    fuzzer_settings_path = os.path.join(OEMCRYPTO_FUZZTEST_DIR_PATH,
                                        'platforms/x86-64')
    fuzzer_settings_gypi_path = os.path.join(fuzzer_settings_path,
                                             'fuzzer_settings.gypi')
    gyp_args.append('--include=' + fuzzer_settings_gypi_path)
  gyp_args.append('-Goutput_dir=' + output_path)

  platform_environment_path = os.path.join(target_path, 'environment.py')
  target = LoadFields(platform_environment_path)

  if 'export_variables' in target:
    for variable, value in target['export_variables'].items():
      if not os.environ.get(variable):
        os.environ[variable] = value
        print(' set {} to {}'.format(variable, value))

  return output_path


def main(args):
  if IsNinjaInstalled():
    print('ninja is installed - use ninja for default generator')
    default_generator = 'ninja'
  else:
    print('ninja is not installed - use make for default generator')
    default_generator = 'make'

  parser = argparse.ArgumentParser()
  parser.add_argument(
      'platform',
      help=('The platform to target. To add a new platform, create a new '
            'platform directory with "environment.py" and "settings.gypi" '
            'files under platforms/.'),
      choices=RetrieveListOfPlatforms())

  build_config_group = parser.add_mutually_exclusive_group(required=True)
  build_config_group.add_argument(
      '-d',
      '--debug',
      dest='build_config',
      action='store_const',
      const='debug',
      help='Build a debug build. This is shorthand for "--config debug".')
  build_config_group.add_argument(
      '-r',
      '--release',
      dest='build_config',
      action='store_const',
      const='release',
      help='Build a release build. This is shorthand for "--config release".')
  build_config_group.add_argument(
      '-c',
      '--config',
      dest='build_config',
      help=('Select a build configuration to use. Any configuration defined in '
            'the chosen platform\'s "settings.gypi" file may be used.'))

  parser.add_argument(
      '-g',
      '--generator',
      default=default_generator,
      help='Which build system to use. Defaults to {}.'.format(
          default_generator),
      choices=BUILDERS.keys())
  parser.add_argument(
      '-j',
      '--jobs',
      nargs='?',
      const=float('inf'),
      type=int,
      help=('When building, run up to this many jobs in parallel. The default '
            'is the default for your chosen generator. If this flag is '
            'specified without a value, jobs will spawn without limit.'))
  parser.add_argument(
      '-D',
      '--define',
      action='append',
      default=[],
      help=('Pass variable definitions to GYP. (May be specified multiple '
            'times.)'))
  parser.add_argument(
      '-e',
      '--extra_gyp',
      action='append',
      default=[],
      help=('External GYP file that is processed after the standard GYP files. '
            '(May be specified multiple times.)'))
  parser.add_argument(
      '-ft',
      '--fuzz_tests',
      action='store_true',
      help='Set this flag if you want to build fuzz tests.')
  parser.add_argument(
      '-v',
      '--verbose',
      action='store_true',
      help=('Print verbose build output, including verbose output from the '
            'generator.'))

  options = parser.parse_args(args)

  if not PlatformExists(options.platform, print_details=True):
    platforms = RetrieveListOfPlatforms()
    if platforms:
      print(' Available platforms: ' + ', '.join(platforms), file=sys.stderr)
    return EXIT_FAILURE

  gyp_args = [
      '--format=' + options.generator,
      '--depth=' + CDM_TOP_PATH,
  ]
  if options.fuzz_tests:
    gyp_args.append(
        os.path.join(OEMCRYPTO_FUZZTEST_DIR_PATH, 'oemcrypto_fuzztests.gyp'))
  else:
    gyp_args.append(os.path.join(CDM_TOP_PATH, 'cdm', 'cdm_unittests.gyp'))

  for var in options.extra_gyp:
    gyp_args.append(var)

  for var in options.define:
    gyp_args.append('-D' + var)

  output_path = ImportPlatform(options.platform, gyp_args, options.fuzz_tests)

  print(' Running: {}'.format(' '.join(['gyp'] + gyp_args)))
  retval = gyp.main(gyp_args)
  if retval != 0:
    return retval

  # The gyp argument --build=xyz only works on newer versions of gyp and
  # ignores the generator flag output_dir (as of 2014-05-28 with ninja).
  # So instead of using --build, we simply invoke the build system ourselves.
  builder = GetBuilder(options.generator)
  if builder is None:
    print(' Cannot automatically build with this generator', file=sys.stderr)
    print(' Please start the build manually', file=sys.stderr)
    return EXIT_FAILURE
  return builder(output_path, options.build_config, options.jobs,
                 options.verbose)


if __name__ == '__main__':
  sys.exit(main(sys.argv[1:]))