#!/usr/bin/env python
# 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.

"""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.

import hashlib
import json
import platform
import optparse
import os
import re
import shutil
import subprocess
import sys
import urllib2

SCRIPT_DIR = os.path.dirname(os.path.abspath(__file__))
sys.path.append(os.path.dirname(os.path.dirname(SCRIPT_DIR)))
import detect_host_arch
import gyp_chromium
import gyp_environment


URL_PREFIX = 'https://commondatastorage.googleapis.com'
URL_PATH = 'chrome-linux-sysroot/toolchain'

VALID_ARCHS = ('arm', 'arm64', 'i386', 'amd64', 'mips', 'mips64el')


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 DetectHostArch():
  # Figure out host arch using build/detect_host_arch.py and
  # set target_arch to host arch
  detected_host_arch = detect_host_arch.HostArch()
  if detected_host_arch == 'x64':
    return 'amd64'
  if detected_host_arch == 'ia32':
    return 'i386'
  if detected_host_arch == 'arm':
    return 'arm'
  if detected_host_arch == 'arm64':
    return 'arm64'
  if detected_host_arch == 'mips':
    return 'mips'
  if detected_host_arch == 'mips64':
    return 'mips64el'
  if detected_host_arch == 'ppc':
    return 'ppc'
  if detected_host_arch == 's390':
    return 's390'

  raise Error('Unrecognized host arch: %s' % detected_host_arch)


def DetectTargetArch():
  """Attempt for determine target architecture.

  This works by looking for target_arch in GYP_DEFINES.
  """
  # TODO(agrieve): Make this script not depend on GYP_DEFINES so that it works
  #     with GN as well.
  gyp_environment.SetEnvironment()
  supplemental_includes = gyp_chromium.GetSupplementalFiles()
  gyp_defines = gyp_chromium.GetGypVars(supplemental_includes)
  target_arch = gyp_defines.get('target_arch')
  if target_arch == 'x64':
    return 'amd64'
  if target_arch == 'ia32':
    return 'i386'
  if target_arch == 'arm':
    return 'arm'
  if target_arch == 'arm64':
    return 'arm64'
  if target_arch == 'mipsel':
    return 'mips'
  if target_arch == 'mips64el':
    return 'mips64el'

  return None


def InstallDefaultSysroots(host_arch):
  """Install the default set of sysroot images.

  This includes at least the sysroot for host architecture, and the 32-bit
  sysroot for building the v8 snapshot image.  It can also include the cross
  compile sysroot for ARM/MIPS if cross compiling environment can be detected.

  Another reason we're installing this by default is so that developers can
  compile and run on our supported platforms without having to worry about
  flipping things back and forth and whether the sysroots have been downloaded
  or not.
  """
  InstallDefaultSysrootForArch(host_arch)

  if host_arch == 'amd64':
    InstallDefaultSysrootForArch('i386')

  # If we can detect a non-standard target_arch such as ARM or MIPS,
  # then install the sysroot too.  Don't attempt to install arm64
  # since this is currently and android-only architecture.
  target_arch = DetectTargetArch()
  if target_arch and target_arch not in (host_arch, 'i386'):
    InstallDefaultSysrootForArch(target_arch)


def main(args):
  parser = optparse.OptionParser('usage: %prog [OPTIONS]', description=__doc__)
  parser.add_option('--running-as-hook', action='store_true',
                    default=False, help='Used when running from gclient hooks.'
                                        ' Installs default sysroot images.')
  parser.add_option('--arch', type='choice', choices=VALID_ARCHS,
                    help='Sysroot architecture: %s' % ', '.join(VALID_ARCHS))
  parser.add_option('--all', action='store_true',
                    help='Install all sysroot images (useful when updating the'
                         ' images)')
  options, _ = parser.parse_args(args)
  if options.running_as_hook and not sys.platform.startswith('linux'):
    return 0

  if options.running_as_hook:
    host_arch = DetectHostArch()
    # PPC/s390 don't use sysroot, see http://crbug.com/646169
    if host_arch in ['ppc','s390']:
      return 0
    InstallDefaultSysroots(host_arch)
  elif options.arch:
    InstallDefaultSysrootForArch(options.arch)
  elif options.all:
    for arch in VALID_ARCHS:
      InstallDefaultSysrootForArch(arch)
  else:
    print 'You much specify either --arch, --all or --running-as-hook'
    return 1

  return 0


def InstallDefaultSysrootForArch(target_arch):
  if target_arch not in VALID_ARCHS:
    raise Error('Unknown architecture: %s' % target_arch)
  InstallSysroot('Stretch', target_arch)


def InstallSysroot(target_platform, target_arch):
  # The sysroot directory should match the one specified in
  # build/config/sysroot.gni.
  # TODO(thestig) Consider putting this elsewhere to avoid having to recreate
  # it on every build.
  linux_dir = os.path.dirname(SCRIPT_DIR)

  sysroots_file = os.path.join(SCRIPT_DIR, 'sysroots.json')
  sysroots = json.load(open(sysroots_file))
  sysroot_key = '%s_%s' % (target_platform.lower(), target_arch)
  if sysroot_key not in sysroots:
    raise Error('No sysroot for: %s %s' % (target_platform, target_arch))
  sysroot_dict = sysroots[sysroot_key]
  revision = sysroot_dict['Revision']
  tarball_filename = sysroot_dict['Tarball']
  tarball_sha1sum = sysroot_dict['Sha1Sum']
  sysroot = os.path.join(linux_dir, sysroot_dict['SysrootDir'])

  url = '%s/%s/%s/%s' % (URL_PREFIX, URL_PATH, revision, 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 = urllib2.urlopen(url)
      with open(tarball, "wb") as f:
        f.write(response.read())
      break
    except:
      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', 'xf', 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)