#!/usr/bin/env python

# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Build packages on a host machine, then install them on the local target.

Contacts a devserver (trunk/src/platform/dev/devserver.py) and
requests that it build a package, then performs a binary install of
that package on the local machine.
"""

import optparse
import os
import shutil
import subprocess
import sys
import urllib
import urllib2

LSB_RELEASE_PATH = '/etc/lsb-release'
STATEFUL_LSB_RELEASE_PATH = '/mnt/stateful_partition/etc/lsb-release'


class GMergeParsingException(Exception):
  """A fatal exception raised when an expected variable is not parsed."""


class GMerger(object):
  """emerges a package from the devserver."""
  def __init__(self, devserver_url, board):
    self.devserver_url = devserver_url
    self.board_name = board

  @staticmethod
  def RemountOrChangeRoot(environ):
    """Remount the root filesystem rw; install into /usr/local if this fails.

    Args:
      environ: The environment dictionary.
    """
    rc = subprocess.call(['mount', '-o', 'remount,rw', '/'])
    if rc == 0:
      return
    try:
      answer = raw_input(
          'Could not mount / as writable.  Install into /usr/local? (Y/n)')
    except EOFError:
      # Received if stdin is piped through /dev/null.
      answer = None

    if answer and answer[0] not in 'Yy':
      sys.exit('Better safe than sorry.')

    environ['ROOT'] = '/usr/local'

  def ParseLsbRelease(self, lsb_release_lines):
    """Parses LSB release and set out internal variables accordingly

    Args:
      lsb_release_lines: a list of key=val lines e.g. the output of opening
                         /etc/lsb-release and using readlines().
    """
    lsb_release = dict((k, v) for k, _, v in [line.rstrip().partition('=')
                                          for line in lsb_release_lines])

    parsing_msg = ('%(variable)s not set. Please set by using a command line '
                   'option or overriding in ' + STATEFUL_LSB_RELEASE_PATH)
    if not self.devserver_url:
      self.devserver_url = lsb_release['CHROMEOS_DEVSERVER']
      if not self.devserver_url:
        raise GMergeParsingException(parsing_msg % dict(
            variable='CHROMEOS_DEVSERVER'))

    if not self.board_name:
      self.board_name = lsb_release['CHROMEOS_RELEASE_BOARD']
      if not self.board_name:
        raise GMergeParsingException(parsing_msg % dict(
            variable='CHROMEOS_RELEASE_BOARD'))

  def SetupPortageEnvironment(self, environ, include_masked_files):
    """Setup portage to use stateful partition and fetch from dev server.

    Args:
      environ: The environment dictionary to setup.
      include_masked_files: If true, include masked files in package
        (e.g. debug symbols).
    """
    binhost_prefix = '%s/static/pkgroot/%s' % (self.devserver_url,
                                               self.board_name)
    binhost = '%s/packages' % binhost_prefix
    if not include_masked_files:
      binhost += ' %s/gmerge-packages' % binhost_prefix

    environ.update({
        'PORTDIR': '/usr/local/portage',
        'PKGDIR': '/usr/local/portage',
        'DISTDIR': '/usr/local/portage/distfiles',
        'PORTAGE_BINHOST': binhost,
        'PORTAGE_TMPDIR': '/tmp',
        'CONFIG_PROTECT': '-*',
        'FEATURES': '-sandbox -usersandbox',
        'ACCEPT_KEYWORDS': 'arm x86 amd64 ~arm ~x86 ~amd64',
        'ROOT': os.environ.get('ROOT', '/'),
        'PORTAGE_CONFIGROOT': '/usr/local'
        })

  def RequestPackageBuild(self, package_name, deep, accept_stable, usepkg):
    """Contacts devserver to request a build.

    Args:
      package_name: The name of the package to build.
      deep: Update package and all dependencies.
      accept_stable: Allow non-workon packages.
      usepkg: Use currently built binary packages on server.
    """
    def GeneratePackageRequest():
      """Build the POST string that conveys our options to the devserver."""
      post_data = {'board': self.board_name,
                 'deep': deep or '',
                 'pkg': package_name,
                 'features': os.environ.get('FEATURES'),
                 'use': os.environ.get('USE'),
                 'accept_stable': accept_stable or '',
                 'usepkg': usepkg or '',
                }
      post_data = dict([(key, value) for (key, value) in post_data.iteritems()
                      if value is not None])
      return urllib.urlencode(post_data)

    print 'Sending build request to', self.devserver_url
    try:
      result = urllib2.urlopen(
          self.devserver_url + '/build',
          data=GeneratePackageRequest())
      print result.read()
      result.close()

    except urllib2.HTTPError, e:
      # The exception includes the content, which is the error mesage
      sys.exit(e.read())
    except urllib2.URLError, e:
      sys.exit('Could not reach devserver. Reason: %s' % e.reason)

  @staticmethod
  def EmergePackage(package_name, deep, extra):
    """Emerges the package from the binhost.

    Args:
      package_name: The name of the package to build.
      deep: Update package and all dependencies.
      extra: Extra arguments to emerge.
    """
    # In case the version is the same as the one that's installed, don't re-use
    # it.
    print 'Emerging ', package_name
    shutil.rmtree('/usr/local/portage', ignore_errors=True)
    shutil.rmtree('/var/cache/edb/binhost', ignore_errors=True)

    emerge_args = ['emerge', '--getbinpkgonly', '--usepkgonly', '--verbose']
    if deep:
      emerge_args.extend(['--update', '--deep'])

    if extra:
      emerge_args.extend(extra.split())

    emerge_args.append(package_name)
    subprocess.check_call(emerge_args)


def main():
  parser = optparse.OptionParser(usage='usage: %prog [options] package_name')
  parser.add_option('--accept_stable',
                    action='store_true', default=False,
                    help=('Build even if a cros_workon package is not '
                          'using the live package'))
  parser.add_option('-b', '--board', default=None,
                    help='Specify a different board to use when building.')
  parser.add_option('-d', '--devserver_url', default=None,
                    help='Specify a different devserver(binhost) url to use'
                    'to build and download packages.')
  parser.add_option('--include_masked_files',
                    action='store_true',
                    default=False, help=('Include masked files in package '
                                         '(e.g. debug symbols)'))
  parser.add_option('-n', '--usepkg',
                    action='store_true', default=False,
                    help='Use currently built binary packages on server.')
  parser.add_option('-D', '--deep',
                    action='store_true', default=False,
                    help='Update package and all dependencies '
                         '(requires --usepkg).')
  parser.add_option('-x', '--extra', default='',
                    help='Extra arguments to pass to emerge command.')

  options, remaining_arguments = parser.parse_args()
  if len(remaining_arguments) != 1:
    parser.print_help()
    sys.exit('Need exactly one package name')


  # TODO(davidjames): Should we allow --deep without --usepkg? Not sure what
  # the desired behavior should be in this case, so disabling the combo for
  # now.
  if options.deep and not options.usepkg:
    sys.exit('If using --deep, --usepkg must also be enabled.')

  package_name = remaining_arguments[0]

  subprocess.check_call(['mount', '-o', 'remount,exec', '/tmp'])
  try:
    etc_lsb_release_lines = open(LSB_RELEASE_PATH).readlines()
    # Allow overrides from the stateful partition.
    if os.path.exists(STATEFUL_LSB_RELEASE_PATH):
      etc_lsb_release_lines += open(STATEFUL_LSB_RELEASE_PATH).readlines()
      print 'Stateful lsb release file found', STATEFUL_LSB_RELEASE_PATH

    merger = GMerger(options.devserver_url, options.board)
    merger.ParseLsbRelease(etc_lsb_release_lines)
    merger.RequestPackageBuild(package_name, options.deep,
                               options.accept_stable, options.usepkg)

    merger.SetupPortageEnvironment(os.environ, options.include_masked_files)
    merger.RemountOrChangeRoot(os.environ)
    merger.EmergePackage(package_name, options.deep, options.extra)
  finally:
    subprocess.call(['mount', '-o', 'remount,noexec', '/tmp'])


if __name__ == '__main__':
  main()