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

"""Install Debian sysroots for building chromium.
"""

# The sysroot is needed to ensure that binaries that get built will run on
# the oldest stable version of Debian that we currently support.
# This script can be run manually but is more often run as part of gclient
# hooks. When run from hooks this script is a no-op on non-linux platforms.

# The sysroot image could be constructed from scratch based on the current state
# of the Debian archive but for consistency we use a pre-built root image (we
# don't want upstream changes to Debian to effect the chromium build until we
# choose to pull them in). The images will normally need to be rebuilt every
# time chrome's build dependencies are changed but should also be updated
# periodically to include upstream security fixes from Debian.

# This script looks at sysroots.json next to it to find the name of a .tar.xz
# to download and the location to extract it to. The extracted sysroot could for
# example be in build/linux/debian_bullseye_amd64-sysroot/.


import hashlib
import json
import optparse
import os
import shutil
import subprocess
import sys
from urllib.request import urlopen

SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
SRC_DIR = os.path.dirname(os.path.dirname(os.path.dirname(SCRIPT_DIR)))

VALID_ARCHS = ('amd64', 'i386', 'armhf', 'arm64', 'armel', 'mipsel', 'mips64el')

ARCH_TRANSLATIONS = {
    'x64': 'amd64',
    'x86': 'i386',
    'arm': 'armhf',
    'mips': 'mipsel',
    'mips64': 'mips64el',
}

DEFAULT_SYSROOTS_PATH = os.path.join(os.path.relpath(SCRIPT_DIR, SRC_DIR),
                                     'sysroots.json')
DEFAULT_TARGET_PLATFORM = 'bullseye'


class Error(Exception):
  pass


def GetSha1(filename):
  sha1 = hashlib.sha1()
  with open(filename, 'rb') as f:
    while True:
      # Read in 1mb chunks, so it doesn't all have to be loaded into memory.
      chunk = f.read(1024*1024)
      if not chunk:
        break
      sha1.update(chunk)
  return sha1.hexdigest()


def main(args):
  parser = optparse.OptionParser('usage: %prog [OPTIONS]', description=__doc__)
  parser.add_option('--sysroots-json-path',
                    help='The location of sysroots.json file')
  parser.add_option('--arch',
                    help='Sysroot architecture: %s' % ', '.join(VALID_ARCHS))
  parser.add_option('--all', action='store_true',
                    help='Install all sysroot images (useful when updating the'
                         ' images)')
  parser.add_option('--print-key',
                    help='Print the hash of the sysroot for the given arch.')
  options, _ = parser.parse_args(args)

  if options.sysroots_json_path:
    sysroots_json_path = options.sysroots_json_path
  else:
    sysroots_json_path = DEFAULT_SYSROOTS_PATH

  if options.print_key:
    arch = options.print_key
    print(
        GetSysrootDict(sysroots_json_path, DEFAULT_TARGET_PLATFORM,
                       ARCH_TRANSLATIONS.get(arch, arch))['Key'])
    return 0
  if options.arch:
    InstallSysroot(sysroots_json_path, DEFAULT_TARGET_PLATFORM,
                   ARCH_TRANSLATIONS.get(options.arch, options.arch))
  elif options.all:
    for arch in VALID_ARCHS:
      InstallSysroot(sysroots_json_path, DEFAULT_TARGET_PLATFORM, arch)
  else:
    print('You much specify one of the options.')
    return 1

  return 0


def GetSysrootDict(sysroots_json_path, target_platform, target_arch):
  if target_arch not in VALID_ARCHS:
    raise Error('Unknown architecture: %s' % target_arch)

  sysroots_file = os.path.join(SRC_DIR, sysroots_json_path)
  sysroots = json.load(open(sysroots_file))
  sysroot_key = '%s_%s' % (target_platform, target_arch)
  if sysroot_key not in sysroots:
    raise Error('No sysroot for: %s %s' % (target_platform, target_arch))
  return sysroots[sysroot_key]


def InstallSysroot(sysroots_json_path, target_platform, target_arch):
  sysroot_dict = GetSysrootDict(sysroots_json_path, target_platform,
                                target_arch)
  tarball_filename = sysroot_dict['Tarball']
  tarball_sha1sum = sysroot_dict['Sha1Sum']
  url_prefix = sysroot_dict['URL']
  # TODO(thestig) Consider putting this elsewhere to avoid having to recreate
  # it on every build.
  linux_dir = os.path.dirname(SCRIPT_DIR)
  sysroot = os.path.join(linux_dir, sysroot_dict['SysrootDir'])

  url = '%s/%s/%s' % (url_prefix, tarball_sha1sum, tarball_filename)

  stamp = os.path.join(sysroot, '.stamp')
  if os.path.exists(stamp):
    with open(stamp) as s:
      if s.read() == url:
        return

  print('Installing Debian %s %s root image: %s' % \
      (target_platform, target_arch, sysroot))
  if os.path.isdir(sysroot):
    shutil.rmtree(sysroot)
  os.mkdir(sysroot)
  tarball = os.path.join(sysroot, tarball_filename)
  print('Downloading %s' % url)
  sys.stdout.flush()
  sys.stderr.flush()
  for _ in range(3):
    try:
      response = urlopen(url)
      with open(tarball, "wb") as f:
        f.write(response.read())
      break
    except Exception:  # Ignore exceptions.
      pass
  else:
    raise Error('Failed to download %s' % url)
  sha1sum = GetSha1(tarball)
  if sha1sum != tarball_sha1sum:
    raise Error('Tarball sha1sum is wrong.'
                'Expected %s, actual: %s' % (tarball_sha1sum, sha1sum))
  subprocess.check_call(['tar', 'mxf', tarball, '-C', sysroot])
  os.remove(tarball)

  with open(stamp, 'w') as s:
    s.write(url)


if __name__ == '__main__':
  try:
    sys.exit(main(sys.argv[1:]))
  except Error as e:
    sys.stderr.write(str(e) + '\n')
    sys.exit(1)