#!/usr/bin/env python
# -*- coding:utf-8 -*-
#
# Copyright (C) 2008 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Repo launcher.

This is a standalone tool that people may copy to anywhere in their system.
It is used to get an initial repo client checkout, and after that it runs the
copy of repo in the checkout.
"""

from __future__ import print_function

import datetime
import os
import platform
import shlex
import subprocess
import sys


# Keep basic logic in sync with repo_trace.py.
class Trace(object):
  """Trace helper logic."""

  REPO_TRACE = 'REPO_TRACE'

  def __init__(self):
    self.set(os.environ.get(self.REPO_TRACE) == '1')

  def set(self, value):
    self.enabled = bool(value)

  def print(self, *args, **kwargs):
    if self.enabled:
      print(*args, **kwargs)


trace = Trace()


def exec_command(cmd):
  """Execute |cmd| or return None on failure."""
  trace.print(':', ' '.join(cmd))
  try:
    if platform.system() == 'Windows':
      ret = subprocess.call(cmd)
      sys.exit(ret)
    else:
      os.execvp(cmd[0], cmd)
  except Exception:
    pass


def check_python_version():
  """Make sure the active Python version is recent enough."""
  def reexec(prog):
    exec_command([prog] + sys.argv)

  MIN_PYTHON_VERSION = (3, 6)

  ver = sys.version_info
  major = ver.major
  minor = ver.minor

  # Abort on very old Python 2 versions.
  if (major, minor) < (2, 7):
    print('repo: error: Your Python version is too old. '
          'Please use Python {}.{} or newer instead.'.format(
              *MIN_PYTHON_VERSION), file=sys.stderr)
    sys.exit(1)

  # Try to re-exec the version specific Python 3 if needed.
  if (major, minor) < MIN_PYTHON_VERSION:
    # Python makes releases ~once a year, so try our min version +10 to help
    # bridge the gap.  This is the fallback anyways so perf isn't critical.
    min_major, min_minor = MIN_PYTHON_VERSION
    for inc in range(0, 10):
      reexec('python{}.{}'.format(min_major, min_minor + inc))

    # Try the generic Python 3 wrapper, but only if it's new enough.  We don't
    # want to go from (still supported) Python 2.7 to (unsupported) Python 3.5.
    try:
      proc = subprocess.Popen(
          ['python3', '-c', 'import sys; '
           'print(sys.version_info.major, sys.version_info.minor)'],
          stdout=subprocess.PIPE, stderr=subprocess.PIPE)
      (output, _) = proc.communicate()
      python3_ver = tuple(int(x) for x in output.decode('utf-8').split())
    except (OSError, subprocess.CalledProcessError):
      python3_ver = None

    # The python3 version looks like it's new enough, so give it a try.
    if python3_ver and python3_ver >= MIN_PYTHON_VERSION:
      reexec('python3')

    # We're still here, so diagnose things for the user.
    if major < 3:
      print('repo: warning: Python 2 is no longer supported; '
            'Please upgrade to Python {}.{}+.'.format(*MIN_PYTHON_VERSION),
            file=sys.stderr)
    else:
      print('repo: error: Python 3 version is too old; '
            'Please use Python {}.{} or newer.'.format(*MIN_PYTHON_VERSION),
            file=sys.stderr)
      sys.exit(1)


if __name__ == '__main__':
  check_python_version()


# repo default configuration
#
REPO_URL = os.environ.get('REPO_URL', None)
if not REPO_URL:
  REPO_URL = 'https://gerrit.googlesource.com/git-repo'
REPO_REV = os.environ.get('REPO_REV')
if not REPO_REV:
  REPO_REV = 'stable'

# increment this whenever we make important changes to this script
VERSION = (2, 4)

# increment this if the MAINTAINER_KEYS block is modified
KEYRING_VERSION = (2, 3)

# Each individual key entry is created by using:
# gpg --armor --export keyid
MAINTAINER_KEYS = """

     Repo Maintainer <repo@android.kernel.org>
-----BEGIN PGP PUBLIC KEY BLOCK-----

mQGiBEj3ugERBACrLJh/ZPyVSKeClMuznFIrsQ+hpNnmJGw1a9GXKYKk8qHPhAZf
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cZ7aFsJF4PtcDrfdejyAxbtsSHI=
=82Tj
-----END PGP PUBLIC KEY BLOCK-----
"""

GIT = 'git'                      # our git command
# NB: The version of git that the repo launcher requires may be much older than
# the version of git that the main repo source tree requires.  Keeping this at
# an older version also makes it easier for users to upgrade/rollback as needed.
#
# git-1.7 is in (EOL) Ubuntu Precise.
MIN_GIT_VERSION = (1, 7, 2)      # minimum supported git version
repodir = '.repo'                # name of repo's private directory
S_repo = 'repo'                  # special repo repository
S_manifests = 'manifests'        # special manifest repository
REPO_MAIN = S_repo + '/main.py'  # main script
GITC_CONFIG_FILE = '/gitc/.config'
GITC_FS_ROOT_DIR = '/gitc/manifest-rw/'


import collections
import errno
import optparse
import re
import shutil
import stat

if sys.version_info[0] == 3:
  import urllib.request
  import urllib.error
else:
  import imp
  import urllib2
  urllib = imp.new_module('urllib')
  urllib.request = urllib2
  urllib.error = urllib2


home_dot_repo = os.path.expanduser('~/.repoconfig')
gpg_dir = os.path.join(home_dot_repo, 'gnupg')

extra_args = []


def GetParser(gitc_init=False):
  """Setup the CLI parser."""
  if gitc_init:
    usage = 'repo gitc-init -u url -c client [options]'
  else:
    usage = 'repo init -u url [options]'

  parser = optparse.OptionParser(usage=usage)

  # Logging.
  group = parser.add_option_group('Logging options')
  group.add_option('-v', '--verbose',
                   dest='output_mode', action='store_true',
                   help='show all output')
  group.add_option('-q', '--quiet',
                   dest='output_mode', action='store_false',
                   help='only show errors')

  # Manifest.
  group = parser.add_option_group('Manifest options')
  group.add_option('-u', '--manifest-url',
                   help='manifest repository location', metavar='URL')
  group.add_option('-b', '--manifest-branch',
                   help='manifest branch or revision', metavar='REVISION')
  group.add_option('-m', '--manifest-name',
                   help='initial manifest file', metavar='NAME.xml')
  cbr_opts = ['--current-branch']
  # The gitc-init subcommand allocates -c itself, but a lot of init users
  # want -c, so try to satisfy both as best we can.
  if not gitc_init:
    cbr_opts += ['-c']
  group.add_option(*cbr_opts,
                   dest='current_branch_only', action='store_true',
                   help='fetch only current manifest branch from server')
  group.add_option('--mirror', action='store_true',
                   help='create a replica of the remote repositories '
                        'rather than a client working directory')
  group.add_option('--reference',
                   help='location of mirror directory', metavar='DIR')
  group.add_option('--dissociate', action='store_true',
                   help='dissociate from reference mirrors after clone')
  group.add_option('--depth', type='int', default=None,
                   help='create a shallow clone with given depth; '
                        'see git clone')
  group.add_option('--partial-clone', action='store_true',
                   help='perform partial clone (https://git-scm.com/'
                        'docs/gitrepository-layout#_code_partialclone_code)')
  group.add_option('--clone-filter', action='store', default='blob:none',
                   help='filter for use with --partial-clone '
                        '[default: %default]')
  group.add_option('--worktree', action='store_true',
                   help=optparse.SUPPRESS_HELP)
  group.add_option('--archive', action='store_true',
                   help='checkout an archive instead of a git repository for '
                        'each project. See git archive.')
  group.add_option('--submodules', action='store_true',
                   help='sync any submodules associated with the manifest repo')
  group.add_option('-g', '--groups', default='default',
                   help='restrict manifest projects to ones with specified '
                        'group(s) [default|all|G1,G2,G3|G4,-G5,-G6]',
                   metavar='GROUP')
  group.add_option('-p', '--platform', default='auto',
                   help='restrict manifest projects to ones with a specified '
                        'platform group [auto|all|none|linux|darwin|...]',
                   metavar='PLATFORM')
  group.add_option('--no-clone-bundle',
                   dest='clone_bundle', default=True, action='store_false',
                   help='disable use of /clone.bundle on HTTP/HTTPS')
  group.add_option('--no-tags',
                   dest='tags', default=True, action='store_false',
                   help="don't fetch tags in the manifest")

  # Tool.
  group = parser.add_option_group('repo Version options')
  group.add_option('--repo-url', metavar='URL',
                   help='repo repository location ($REPO_URL)')
  group.add_option('--repo-branch', metavar='REVISION',
                   help='repo branch or revision ($REPO_REV)')
  group.add_option('--no-repo-verify',
                   dest='repo_verify', default=True, action='store_false',
                   help='do not verify repo source code')

  # Other.
  group = parser.add_option_group('Other options')
  group.add_option('--config-name',
                   action='store_true', default=False,
                   help='Always prompt for name/e-mail')

  # gitc-init specific settings.
  if gitc_init:
    group = parser.add_option_group('GITC options')
    group.add_option('-f', '--manifest-file',
                     help='Optional manifest file to use for this GITC client.')
    group.add_option('-c', '--gitc-client',
                     help='Name of the gitc_client instance to create or modify.')

  return parser


# This is a poor replacement for subprocess.run until we require Python 3.6+.
RunResult = collections.namedtuple(
    'RunResult', ('returncode', 'stdout', 'stderr'))


class RunError(Exception):
  """Error when running a command failed."""


def run_command(cmd, **kwargs):
  """Run |cmd| and return its output."""
  check = kwargs.pop('check', False)
  if kwargs.pop('capture_output', False):
    kwargs.setdefault('stdout', subprocess.PIPE)
    kwargs.setdefault('stderr', subprocess.PIPE)
  cmd_input = kwargs.pop('input', None)

  def decode(output):
    """Decode |output| to text."""
    if output is None:
      return output
    try:
      return output.decode('utf-8')
    except UnicodeError:
      print('repo: warning: Invalid UTF-8 output:\ncmd: %r\n%r' % (cmd, output),
            file=sys.stderr)
      # TODO(vapier): Once we require Python 3, use 'backslashreplace'.
      return output.decode('utf-8', 'replace')

  # Run & package the results.
  proc = subprocess.Popen(cmd, **kwargs)
  (stdout, stderr) = proc.communicate(input=cmd_input)
  dbg = ': ' + ' '.join(cmd)
  if cmd_input is not None:
    dbg += ' 0<|'
  if stdout == subprocess.PIPE:
    dbg += ' 1>|'
  if stderr == subprocess.PIPE:
    dbg += ' 2>|'
  elif stderr == subprocess.STDOUT:
    dbg += ' 2>&1'
  trace.print(dbg)
  ret = RunResult(proc.returncode, decode(stdout), decode(stderr))

  # If things failed, print useful debugging output.
  if check and ret.returncode:
    print('repo: error: "%s" failed with exit status %s' %
          (cmd[0], ret.returncode), file=sys.stderr)
    print('  cwd: %s\n  cmd: %r' %
          (kwargs.get('cwd', os.getcwd()), cmd), file=sys.stderr)

    def _print_output(name, output):
      if output:
        print('  %s:\n  >> %s' % (name, '\n  >> '.join(output.splitlines())),
              file=sys.stderr)

    _print_output('stdout', ret.stdout)
    _print_output('stderr', ret.stderr)
    raise RunError(ret)

  return ret


_gitc_manifest_dir = None


def get_gitc_manifest_dir():
  global _gitc_manifest_dir
  if _gitc_manifest_dir is None:
    _gitc_manifest_dir = ''
    try:
      with open(GITC_CONFIG_FILE, 'r') as gitc_config:
        for line in gitc_config:
          match = re.match('gitc_dir=(?P<gitc_manifest_dir>.*)', line)
          if match:
            _gitc_manifest_dir = match.group('gitc_manifest_dir')
    except IOError:
      pass
  return _gitc_manifest_dir


def gitc_parse_clientdir(gitc_fs_path):
  """Parse a path in the GITC FS and return its client name.

  @param gitc_fs_path: A subdirectory path within the GITC_FS_ROOT_DIR.

  @returns: The GITC client name
  """
  if gitc_fs_path == GITC_FS_ROOT_DIR:
    return None
  if not gitc_fs_path.startswith(GITC_FS_ROOT_DIR):
    manifest_dir = get_gitc_manifest_dir()
    if manifest_dir == '':
      return None
    if manifest_dir[-1] != '/':
      manifest_dir += '/'
    if gitc_fs_path == manifest_dir:
      return None
    if not gitc_fs_path.startswith(manifest_dir):
      return None
    return gitc_fs_path.split(manifest_dir)[1].split('/')[0]
  return gitc_fs_path.split(GITC_FS_ROOT_DIR)[1].split('/')[0]


class CloneFailure(Exception):

  """Indicate the remote clone of repo itself failed.
  """


def _Init(args, gitc_init=False):
  """Installs repo by cloning it over the network.
  """
  parser = GetParser(gitc_init=gitc_init)
  opt, args = parser.parse_args(args)
  if args:
    parser.print_usage()
    sys.exit(1)
  opt.quiet = opt.output_mode is False
  opt.verbose = opt.output_mode is True

  url = opt.repo_url
  if not url:
    url = REPO_URL
    extra_args.append('--repo-url=%s' % url)

  branch = opt.repo_branch
  if not branch:
    branch = REPO_REV
    extra_args.append('--repo-branch=%s' % branch)

  if branch.startswith('refs/heads/'):
    branch = branch[len('refs/heads/'):]
  if branch.startswith('refs/'):
    print("fatal: invalid branch name '%s'" % branch, file=sys.stderr)
    raise CloneFailure()

  try:
    if gitc_init:
      gitc_manifest_dir = get_gitc_manifest_dir()
      if not gitc_manifest_dir:
        print('fatal: GITC filesystem is not available. Exiting...',
              file=sys.stderr)
        sys.exit(1)
      gitc_client = opt.gitc_client
      if not gitc_client:
        gitc_client = gitc_parse_clientdir(os.getcwd())
      if not gitc_client:
        print('fatal: GITC client (-c) is required.', file=sys.stderr)
        sys.exit(1)
      client_dir = os.path.join(gitc_manifest_dir, gitc_client)
      if not os.path.exists(client_dir):
        os.makedirs(client_dir)
      os.chdir(client_dir)
      if os.path.exists(repodir):
        # This GITC Client has already initialized repo so continue.
        return

    os.mkdir(repodir)
  except OSError as e:
    if e.errno != errno.EEXIST:
      print('fatal: cannot make %s directory: %s'
            % (repodir, e.strerror), file=sys.stderr)
      # Don't raise CloneFailure; that would delete the
      # name. Instead exit immediately.
      #
      sys.exit(1)

  _CheckGitVersion()
  try:
    if not opt.repo_verify:
      do_verify = False
    else:
      if NeedSetupGnuPG():
        do_verify = SetupGnuPG(opt.quiet)
      else:
        do_verify = True

    if not opt.quiet:
      print('Downloading Repo source from', url)
    dst = os.path.abspath(os.path.join(repodir, S_repo))
    _Clone(url, dst, opt.clone_bundle, opt.quiet, opt.verbose)

    if do_verify:
      rev = _Verify(dst, branch, opt.quiet)
    else:
      rev = 'refs/remotes/origin/%s^0' % branch

    _Checkout(dst, branch, rev, opt.quiet)

    if not os.path.isfile(os.path.join(dst, 'repo')):
      print("warning: '%s' does not look like a git-repo repository, is "
            "REPO_URL set correctly?" % url, file=sys.stderr)

  except CloneFailure:
    if opt.quiet:
      print('fatal: repo init failed; run without --quiet to see why',
            file=sys.stderr)
    raise


def run_git(*args, **kwargs):
  """Run git and return execution details."""
  kwargs.setdefault('capture_output', True)
  kwargs.setdefault('check', True)
  try:
    return run_command([GIT] + list(args), **kwargs)
  except OSError as e:
    print(file=sys.stderr)
    print('repo: error: "%s" is not available' % GIT, file=sys.stderr)
    print('repo: error: %s' % e, file=sys.stderr)
    print(file=sys.stderr)
    print('Please make sure %s is installed and in your path.' % GIT,
          file=sys.stderr)
    sys.exit(1)
  except RunError:
    raise CloneFailure()


# The git version info broken down into components for easy analysis.
# Similar to Python's sys.version_info.
GitVersion = collections.namedtuple(
    'GitVersion', ('major', 'minor', 'micro', 'full'))


def ParseGitVersion(ver_str=None):
  if ver_str is None:
    # Load the version ourselves.
    ver_str = run_git('--version').stdout

  if not ver_str.startswith('git version '):
    return None

  full_version = ver_str[len('git version '):].strip()
  num_ver_str = full_version.split('-')[0]
  to_tuple = []
  for num_str in num_ver_str.split('.')[:3]:
    if num_str.isdigit():
      to_tuple.append(int(num_str))
    else:
      to_tuple.append(0)
  to_tuple.append(full_version)
  return GitVersion(*to_tuple)


def _CheckGitVersion():
  ver_act = ParseGitVersion()
  if ver_act is None:
    print('fatal: unable to detect git version', file=sys.stderr)
    raise CloneFailure()

  if ver_act < MIN_GIT_VERSION:
    need = '.'.join(map(str, MIN_GIT_VERSION))
    print('fatal: git %s or later required' % need, file=sys.stderr)
    raise CloneFailure()


def SetGitTrace2ParentSid(env=None):
  """Set up GIT_TRACE2_PARENT_SID for git tracing."""
  # We roughly follow the format git itself uses in trace2/tr2_sid.c.
  # (1) Be unique (2) be valid filename (3) be fixed length.
  #
  # Since we always export this variable, we try to avoid more expensive calls.
  # e.g. We don't attempt hostname lookups or hashing the results.
  if env is None:
    env = os.environ

  KEY = 'GIT_TRACE2_PARENT_SID'

  now = datetime.datetime.utcnow()
  value = 'repo-%s-P%08x' % (now.strftime('%Y%m%dT%H%M%SZ'), os.getpid())

  # If it's already set, then append ourselves.
  if KEY in env:
    value = env[KEY] + '/' + value

  _setenv(KEY, value, env=env)


def _setenv(key, value, env=None):
  """Set |key| in the OS environment |env| to |value|."""
  if env is None:
    env = os.environ
  # Environment handling across systems is messy.
  try:
    env[key] = value
  except UnicodeEncodeError:
    env[key] = value.encode()


def NeedSetupGnuPG():
  if not os.path.isdir(home_dot_repo):
    return True

  kv = os.path.join(home_dot_repo, 'keyring-version')
  if not os.path.exists(kv):
    return True

  kv = open(kv).read()
  if not kv:
    return True

  kv = tuple(map(int, kv.split('.')))
  if kv < KEYRING_VERSION:
    return True
  return False


def SetupGnuPG(quiet):
  try:
    os.mkdir(home_dot_repo)
  except OSError as e:
    if e.errno != errno.EEXIST:
      print('fatal: cannot make %s directory: %s'
            % (home_dot_repo, e.strerror), file=sys.stderr)
      sys.exit(1)

  try:
    os.mkdir(gpg_dir, stat.S_IRWXU)
  except OSError as e:
    if e.errno != errno.EEXIST:
      print('fatal: cannot make %s directory: %s' % (gpg_dir, e.strerror),
            file=sys.stderr)
      sys.exit(1)

  if not quiet:
    print('repo: Updating release signing keys to keyset ver %s' %
          ('.'.join(str(x) for x in KEYRING_VERSION),))
  # NB: We use --homedir (and cwd below) because some environments (Windows) do
  # not correctly handle full native paths.  We avoid the issue by changing to
  # the right dir with cwd=gpg_dir before executing gpg, and then telling gpg to
  # use the cwd (.) as its homedir which leaves the path resolution logic to it.
  cmd = ['gpg', '--homedir', '.', '--import']
  try:
    # gpg can be pretty chatty.  Always capture the output and if something goes
    # wrong, the builtin check failure will dump stdout & stderr for debugging.
    run_command(cmd, stdin=subprocess.PIPE, capture_output=True,
                cwd=gpg_dir, check=True,
                input=MAINTAINER_KEYS.encode('utf-8'))
  except OSError:
    if not quiet:
      print('warning: gpg (GnuPG) is not available.', file=sys.stderr)
      print('warning: Installing it is strongly encouraged.', file=sys.stderr)
      print(file=sys.stderr)
    return False

  with open(os.path.join(home_dot_repo, 'keyring-version'), 'w') as fd:
    fd.write('.'.join(map(str, KEYRING_VERSION)) + '\n')
  return True


def _SetConfig(cwd, name, value):
  """Set a git configuration option to the specified value.
  """
  run_git('config', name, value, cwd=cwd)


def _GetRepoConfig(name):
  """Read a repo configuration option."""
  config = os.path.join(home_dot_repo, 'config')
  if not os.path.exists(config):
    return None

  cmd = ['config', '--file', config, '--get', name]
  ret = run_git(*cmd, check=False)
  if ret.returncode == 0:
    return ret.stdout
  elif ret.returncode == 1:
    return None
  else:
    print('repo: error: git %s failed:\n%s' % (' '.join(cmd), ret.stderr),
          file=sys.stderr)
    raise RunError()


def _InitHttp():
  handlers = []

  mgr = urllib.request.HTTPPasswordMgrWithDefaultRealm()
  try:
    import netrc
    n = netrc.netrc()
    for host in n.hosts:
      p = n.hosts[host]
      mgr.add_password(p[1], 'http://%s/' % host, p[0], p[2])
      mgr.add_password(p[1], 'https://%s/' % host, p[0], p[2])
  except Exception:
    pass
  handlers.append(urllib.request.HTTPBasicAuthHandler(mgr))
  handlers.append(urllib.request.HTTPDigestAuthHandler(mgr))

  if 'http_proxy' in os.environ:
    url = os.environ['http_proxy']
    handlers.append(urllib.request.ProxyHandler({'http': url, 'https': url}))
  if 'REPO_CURL_VERBOSE' in os.environ:
    handlers.append(urllib.request.HTTPHandler(debuglevel=1))
    handlers.append(urllib.request.HTTPSHandler(debuglevel=1))
  urllib.request.install_opener(urllib.request.build_opener(*handlers))


def _Fetch(url, cwd, src, quiet, verbose):
  cmd = ['fetch']
  if quiet:
    cmd.append('--quiet')
    err = subprocess.PIPE
  else:
    err = None
  cmd.append(src)
  cmd.append('+refs/heads/*:refs/remotes/origin/*')
  cmd.append('+refs/tags/*:refs/tags/*')
  run_git(*cmd, stderr=err, cwd=cwd)


def _DownloadBundle(url, cwd, quiet, verbose):
  if not url.endswith('/'):
    url += '/'
  url += 'clone.bundle'

  ret = run_git('config', '--get-regexp', 'url.*.insteadof', cwd=cwd,
                check=False)
  for line in ret.stdout.splitlines():
    m = re.compile(r'^url\.(.*)\.insteadof (.*)$').match(line)
    if m:
      new_url = m.group(1)
      old_url = m.group(2)
      if url.startswith(old_url):
        url = new_url + url[len(old_url):]
        break

  if not url.startswith('http:') and not url.startswith('https:'):
    return False

  dest = open(os.path.join(cwd, '.git', 'clone.bundle'), 'w+b')
  try:
    try:
      r = urllib.request.urlopen(url)
    except urllib.error.HTTPError as e:
      if e.code in [401, 403, 404, 501]:
        return False
      print('fatal: Cannot get %s' % url, file=sys.stderr)
      print('fatal: HTTP error %s' % e.code, file=sys.stderr)
      raise CloneFailure()
    except urllib.error.URLError as e:
      print('fatal: Cannot get %s' % url, file=sys.stderr)
      print('fatal: error %s' % e.reason, file=sys.stderr)
      raise CloneFailure()
    try:
      if verbose:
        print('Downloading clone bundle %s' % url, file=sys.stderr)
      while True:
        buf = r.read(8192)
        if not buf:
          return True
        dest.write(buf)
    finally:
      r.close()
  finally:
    dest.close()


def _ImportBundle(cwd):
  path = os.path.join(cwd, '.git', 'clone.bundle')
  try:
    _Fetch(cwd, cwd, path, True, False)
  finally:
    os.remove(path)


def _Clone(url, cwd, clone_bundle, quiet, verbose):
  """Clones a git repository to a new subdirectory of repodir
  """
  if verbose:
    print('Cloning git repository', url)

  try:
    os.mkdir(cwd)
  except OSError as e:
    print('fatal: cannot make %s directory: %s' % (cwd, e.strerror),
          file=sys.stderr)
    raise CloneFailure()

  run_git('init', '--quiet', cwd=cwd)

  _InitHttp()
  _SetConfig(cwd, 'remote.origin.url', url)
  _SetConfig(cwd,
             'remote.origin.fetch',
             '+refs/heads/*:refs/remotes/origin/*')
  if clone_bundle and _DownloadBundle(url, cwd, quiet, verbose):
    _ImportBundle(cwd)
  _Fetch(url, cwd, 'origin', quiet, verbose)


def _Verify(cwd, branch, quiet):
  """Verify the branch has been signed by a tag.
  """
  try:
    ret = run_git('describe', 'origin/%s' % branch, cwd=cwd)
    cur = ret.stdout.strip()
  except CloneFailure:
    print("fatal: branch '%s' has not been signed" % branch, file=sys.stderr)
    raise

  m = re.compile(r'^(.*)-[0-9]{1,}-g[0-9a-f]{1,}$').match(cur)
  if m:
    cur = m.group(1)
    if not quiet:
      print(file=sys.stderr)
      print("info: Ignoring branch '%s'; using tagged release '%s'"
            % (branch, cur), file=sys.stderr)
      print(file=sys.stderr)

  env = os.environ.copy()
  _setenv('GNUPGHOME', gpg_dir, env)
  run_git('tag', '-v', cur, cwd=cwd, env=env)
  return '%s^0' % cur


def _Checkout(cwd, branch, rev, quiet):
  """Checkout an upstream branch into the repository and track it.
  """
  run_git('update-ref', 'refs/heads/default', rev, cwd=cwd)

  _SetConfig(cwd, 'branch.default.remote', 'origin')
  _SetConfig(cwd, 'branch.default.merge', 'refs/heads/%s' % branch)

  run_git('symbolic-ref', 'HEAD', 'refs/heads/default', cwd=cwd)

  cmd = ['read-tree', '--reset', '-u']
  if not quiet:
    cmd.append('-v')
  cmd.append('HEAD')
  run_git(*cmd, cwd=cwd)


def _FindRepo():
  """Look for a repo installation, starting at the current directory.
  """
  curdir = os.getcwd()
  repo = None

  olddir = None
  while curdir != '/' \
          and curdir != olddir \
          and not repo:
    repo = os.path.join(curdir, repodir, REPO_MAIN)
    if not os.path.isfile(repo):
      repo = None
      olddir = curdir
      curdir = os.path.dirname(curdir)
  return (repo, os.path.join(curdir, repodir))


class _Options(object):
  help = False
  version = False


def _ExpandAlias(name):
  """Look up user registered aliases."""
  # We don't resolve aliases for existing subcommands.  This matches git.
  if name in {'gitc-init', 'help', 'init'}:
    return name, []

  alias = _GetRepoConfig('alias.%s' % (name,))
  if alias is None:
    return name, []

  args = alias.strip().split(' ', 1)
  name = args[0]
  if len(args) == 2:
    args = shlex.split(args[1])
  else:
    args = []
  return name, args


def _ParseArguments(args):
  cmd = None
  opt = _Options()
  arg = []

  for i in range(len(args)):
    a = args[i]
    if a == '-h' or a == '--help':
      opt.help = True
    elif a == '--version':
      opt.version = True
    elif a == '--trace':
      trace.set(True)
    elif not a.startswith('-'):
      cmd = a
      arg = args[i + 1:]
      break
  return cmd, opt, arg


def _Usage():
  gitc_usage = ""
  if get_gitc_manifest_dir():
    gitc_usage = "  gitc-init Initialize a GITC Client.\n"

  print(
      """usage: repo COMMAND [ARGS]

repo is not yet installed.  Use "repo init" to install it here.

The most commonly used repo commands are:

  init      Install repo in the current working directory
""" + gitc_usage +
      """  help      Display detailed help on a command

For access to the full online help, install repo ("repo init").
""")
  sys.exit(0)


def _Help(args):
  if args:
    if args[0] in {'init', 'gitc-init'}:
      parser = GetParser(gitc_init=args[0] == 'gitc-init')
      parser.print_help()
      sys.exit(0)
    else:
      print("error: '%s' is not a bootstrap command.\n"
            '        For access to online help, install repo ("repo init").'
            % args[0], file=sys.stderr)
  else:
    _Usage()
  sys.exit(1)


def _Version():
  """Show version information."""
  print('<repo not installed>')
  print('repo launcher version %s' % ('.'.join(str(x) for x in VERSION),))
  print('       (from %s)' % (__file__,))
  print('git %s' % (ParseGitVersion().full,))
  print('Python %s' % sys.version)
  sys.exit(0)


def _NotInstalled():
  print('error: repo is not installed.  Use "repo init" to install it here.',
        file=sys.stderr)
  sys.exit(1)


def _NoCommands(cmd):
  print("""error: command '%s' requires repo to be installed first.
        Use "repo init" to install it here.""" % cmd, file=sys.stderr)
  sys.exit(1)


def _RunSelf(wrapper_path):
  my_dir = os.path.dirname(wrapper_path)
  my_main = os.path.join(my_dir, 'main.py')
  my_git = os.path.join(my_dir, '.git')

  if os.path.isfile(my_main) and os.path.isdir(my_git):
    for name in ['git_config.py',
                 'project.py',
                 'subcmds']:
      if not os.path.exists(os.path.join(my_dir, name)):
        return None, None
    return my_main, my_git
  return None, None


def _SetDefaultsTo(gitdir):
  global REPO_URL
  global REPO_REV

  REPO_URL = gitdir
  try:
    ret = run_git('--git-dir=%s' % gitdir, 'symbolic-ref', 'HEAD')
    REPO_REV = ret.stdout.strip()
  except CloneFailure:
    print('fatal: %s has no current branch' % gitdir, file=sys.stderr)
    sys.exit(1)


def main(orig_args):
  cmd, opt, args = _ParseArguments(orig_args)

  # We run this early as we run some git commands ourselves.
  SetGitTrace2ParentSid()

  repo_main, rel_repo_dir = None, None
  # Don't use the local repo copy, make sure to switch to the gitc client first.
  if cmd != 'gitc-init':
    repo_main, rel_repo_dir = _FindRepo()

  wrapper_path = os.path.abspath(__file__)
  my_main, my_git = _RunSelf(wrapper_path)

  cwd = os.getcwd()
  if get_gitc_manifest_dir() and cwd.startswith(get_gitc_manifest_dir()):
    print('error: repo cannot be used in the GITC local manifest directory.'
          '\nIf you want to work on this GITC client please rerun this '
          'command from the corresponding client under /gitc/',
          file=sys.stderr)
    sys.exit(1)
  if not repo_main:
    # Only expand aliases here since we'll be parsing the CLI ourselves.
    # If we had repo_main, alias expansion would happen in main.py.
    cmd, alias_args = _ExpandAlias(cmd)
    args = alias_args + args

    if opt.help:
      _Usage()
    if cmd == 'help':
      _Help(args)
    if opt.version or cmd == 'version':
      _Version()
    if not cmd:
      _NotInstalled()
    if cmd == 'init' or cmd == 'gitc-init':
      if my_git:
        _SetDefaultsTo(my_git)
      try:
        _Init(args, gitc_init=(cmd == 'gitc-init'))
      except CloneFailure:
        path = os.path.join(repodir, S_repo)
        print("fatal: cloning the git-repo repository failed, will remove "
              "'%s' " % path, file=sys.stderr)
        shutil.rmtree(path, ignore_errors=True)
        sys.exit(1)
      repo_main, rel_repo_dir = _FindRepo()
    else:
      _NoCommands(cmd)

  if my_main:
    repo_main = my_main

  ver_str = '.'.join(map(str, VERSION))
  me = [sys.executable, repo_main,
        '--repo-dir=%s' % rel_repo_dir,
        '--wrapper-version=%s' % ver_str,
        '--wrapper-path=%s' % wrapper_path,
        '--']
  me.extend(orig_args)
  me.extend(extra_args)
  exec_command(me)
  print("fatal: unable to start %s" % repo_main, file=sys.stderr)
  sys.exit(148)


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