#!/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 Jessie,
# the oldest supported linux distribution. 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 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:
                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)