#!/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 will run on Debian Wheezy,
# the oldest supported linux distribution. For ARM64 linux, we have Debian
# Jessie sysroot as Jessie is the first version with ARM64 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 or Debian Wheezy/Jessie but for consistency we currently use a
# pre-built root image. The image will normally need to be rebuilt every time
# chrome's build dependencies are changed.

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


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

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


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'
  elif detected_host_arch == 'ia32':
    return 'i386'
  elif detected_host_arch == 'arm':
    return 'arm'
  elif detected_host_arch == 'arm64':
    return 'arm64'
  elif detected_host_arch == 'mips':
    return 'mips'
  elif detected_host_arch == 'ppc':
    return 'ppc'
  elif detected_host_arch == 's390':
    return 's390'

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


def main(args):
  parser = optparse.OptionParser('usage: %prog [OPTIONS]', description=__doc__)
  parser.add_option('--arch', type='choice', choices=VALID_ARCHS,
                    help='Sysroot architecture: %s' % ', '.join(VALID_ARCHS))
  options, _ = parser.parse_args(args)
  if not sys.platform.startswith('linux'):
    return 0

  if not options.arch:
    print 'You much specify either --arch or --running-as-hook'
    return 1
  InstallDefaultSysrootForArch(options.arch)

  return 0


def InstallDefaultSysrootForArch(target_arch):
  if target_arch == 'amd64':
    InstallSysroot('Jessie', 'amd64')
  elif target_arch == 'arm':
    InstallSysroot('Jessie', 'arm')
  elif target_arch == 'arm64':
    InstallSysroot('Jessie', 'arm64')
  elif target_arch == 'i386':
    InstallSysroot('Jessie', 'i386')
  elif target_arch == 'mips':
    InstallSysroot('Jessie', 'mips')
  else:
    raise Error('Unknown architecture: %s' % target_arch)


def InstallSysroot(target_platform, target_arch):
  # The sysroot directory should match the one specified in build/common.gypi.
  # 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:
        print '%s %s sysroot image already up to date: %s' % \
            (target_platform, target_arch, sysroot)
        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)