# -*- coding: utf-8 -*-
# Copyright 2016 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.

"""Bootstrap for cbuildbot.

This script is intended to checkout chromite on the branch specified by -b or
--branch (as normally accepted by cbuildbot), and then invoke cbuildbot. Most
arguments are not parsed, only passed along. If a branch is not specified, this
script will use 'master'.

Among other things, this allows us to invoke build configs that exist on a given
branch, but not on TOT.
"""

from __future__ import print_function

import functools
import os

from chromite.cbuildbot import repository
from chromite.cbuildbot.stages import sync_stages
from chromite.lib import config_lib
from chromite.lib import constants
from chromite.lib import cros_build_lib
from chromite.lib import cros_logging as logging
from chromite.lib import metrics
from chromite.lib import osutils
from chromite.lib import ts_mon_config
from chromite.scripts import cbuildbot


# This number should be incremented when we change the layout of the buildroot
# in a non-backwards compatible way. This wipes all buildroots.
BUILDROOT_BUILDROOT_LAYOUT = 2

# Metrics reported to Monarch.
METRIC_ACTIVE = 'chromeos/chromite/cbuildbot_launch/active'
METRIC_INVOKED = 'chromeos/chromite/cbuildbot_launch/invoked'
METRIC_COMPLETED = 'chromeos/chromite/cbuildbot_launch/completed'
METRIC_PREP = 'chromeos/chromite/cbuildbot_launch/prep_completed'
METRIC_CLEAN = 'chromeos/chromite/cbuildbot_launch/clean_buildroot_durations'
METRIC_INITIAL = 'chromeos/chromite/cbuildbot_launch/initial_checkout_durations'
METRIC_CBUILDBOT = 'chromeos/chromite/cbuildbot_launch/cbuildbot_durations'
METRIC_CLOBBER = 'chromeos/chromite/cbuildbot_launch/clobber'
METRIC_BRANCH_CLEANUP = 'chromeos/chromite/cbuildbot_launch/branch_cleanup'
METRIC_DEPOT_TOOLS = 'chromeos/chromite/cbuildbot_launch/depot_tools_prep'


def StageDecorator(functor):
  """A Decorator that adds buildbot stage tags around a method.

  It uses the method name as the stage name, and assumes failure on a true
  return value, or an exception.
  """
  @functools.wraps(functor)
  def wrapped_functor(*args, **kwargs):
    try:
      logging.PrintBuildbotStepName(functor.__name__)
      result = functor(*args, **kwargs)
    except Exception:
      logging.PrintBuildbotStepFailure()
      raise

    if result:
      logging.PrintBuildbotStepFailure()
    return result

  return wrapped_functor


def field(fields, **kwargs):
  """Helper for inserting more fields into a metrics fields dictionary.

  Args:
    fields: Dictionary of metrics fields.
    kwargs: Each argument is a key/value pair to insert into dict.

  Returns:
    Copy of original dictionary with kwargs set as fields.
  """
  f = fields.copy()
  f.update(kwargs)
  return f


def PrependPath(prepend):
  """Generate path with new directory at the beginning.

  Args:
    prepend: Directory to add at the beginning of the path.

  Returns:
    Extended path as a string.
  """
  return os.pathsep.join([prepend, os.environ.get('PATH', os.defpath)])


def PreParseArguments(argv):
  """Extract the branch name from cbuildbot command line arguments.

  Args:
    argv: The command line arguments to parse.

  Returns:
    Branch as a string ('master' if nothing is specified).
  """
  parser = cbuildbot.CreateParser()
  options = cbuildbot.ParseCommandLine(parser, argv)
  options.Freeze()

  # This option isn't required for cbuildbot, but is for us.
  if not options.buildroot:
    cros_build_lib.Die('--buildroot is a required option.')

  return options


def GetState(root):
  """Fetch the current state of our working directory.

  Will return with a default result if there is no known state.

  Args:
    root: Root of the working directory tree as a string.

  Returns:
    Layout version as an integer (0 for unknown).
    Previous branch as a string ('' for unknown).
  """
  state_file = os.path.join(root, '.cbuildbot_launch_state')

  try:
    state = osutils.ReadFile(state_file)
    buildroot_layout, branchname = state.split()
    buildroot_layout = int(buildroot_layout)
    return buildroot_layout, branchname
  except (IOError, ValueError):
    # If we are unable to either read or parse the state file, we get here.
    return 0, ''


def SetState(branchname, root):
  """Save the current state of our working directory.

  Args:
    branchname: Name of branch we prepped for as a string.
    root: Root of the working directory tree as a string.
  """
  assert branchname
  state_file = os.path.join(root, '.cbuildbot_launch_state')
  new_state = '%d %s' % (BUILDROOT_BUILDROOT_LAYOUT, branchname)
  osutils.WriteFile(state_file, new_state)


@StageDecorator
def CleanBuildRoot(root, repo, metrics_fields):
  """Some kinds of branch transitions break builds.

  This method ensures that cbuildbot's buildroot is a clean checkout on the
  given branch when it starts. If necessary (a branch transition) it will wipe
  assorted state that cannot be safely reused from the previous build.

  Args:
    root: Root directory owned by cbuildbot_launch.
    repo: repository.RepoRepository instance.
    metrics_fields: Dictionary of fields to include in metrics.
  """
  old_buildroot_layout, old_branch = GetState(root)

  if old_buildroot_layout != BUILDROOT_BUILDROOT_LAYOUT:
    logging.PrintBuildbotStepText('Unknown layout: Wiping buildroot.')
    metrics.Counter(METRIC_CLOBBER).increment(
        field(metrics_fields, reason='layout_change'))
    chroot_dir = os.path.join(root, 'chroot')
    if os.path.exists(chroot_dir) or os.path.exists(chroot_dir + '.img'):
      cros_build_lib.CleanupChrootMount(chroot_dir, delete_image=True)
    osutils.RmDir(root, ignore_missing=True, sudo=True)
  else:
    if old_branch != repo.branch:
      logging.PrintBuildbotStepText('Branch change: Cleaning buildroot.')
      logging.info('Unmatched branch: %s -> %s', old_branch, repo.branch)
      metrics.Counter(METRIC_BRANCH_CLEANUP).increment(
          field(metrics_fields, old_branch=old_branch))

      logging.info('Remove Chroot.')
      chroot_dir = os.path.join(repo.directory, 'chroot')
      if os.path.exists(chroot_dir) or os.path.exists(chroot_dir + '.img'):
        cros_build_lib.CleanupChrootMount(chroot_dir, delete_image=True)
      osutils.RmDir(chroot_dir, ignore_missing=True, sudo=True)

      logging.info('Remove Chrome checkout.')
      osutils.RmDir(os.path.join(repo.directory, '.cache', 'distfiles'),
                    ignore_missing=True, sudo=True)

    try:
      # If there is any failure doing the cleanup, wipe everything.
      repo.BuildRootGitCleanup(prune_all=True)
    except Exception:
      logging.info('Checkout cleanup failed, wiping buildroot:', exc_info=True)
      metrics.Counter(METRIC_CLOBBER).increment(
          field(metrics_fields, reason='repo_cleanup_failure'))
      repository.ClearBuildRoot(repo.directory)

  # Ensure buildroot exists. Save the state we are prepped for.
  osutils.SafeMakedirs(repo.directory)
  SetState(repo.branch, root)


@StageDecorator
def InitialCheckout(repo):
  """Preliminary ChromeOS checkout.

  Perform a complete checkout of ChromeOS on the specified branch. This does NOT
  match what the build needs, but ensures the buildroot both has a 'hot'
  checkout, and is close enough that the branched cbuildbot can successfully get
  the right checkout.

  This checks out full ChromeOS, even if a ChromiumOS build is going to be
  performed. This is because we have no knowledge of the build config to be
  used.

  Args:
    repo: repository.RepoRepository instance.
  """
  logging.PrintBuildbotStepText('Branch: %s' % repo.branch)
  logging.info('Bootstrap script starting initial sync on branch: %s',
               repo.branch)
  repo.Sync(detach=True)


@StageDecorator
def DepotToolsEnsureBootstrap(depot_tools_path):
  """Start cbuildbot in specified directory with all arguments.

  Args:
    buildroot: Directory to be passed to cbuildbot with --buildroot.
    depot_tools_path: Directory for depot_tools to be used by cbuildbot.
    argv: Command line options passed to cbuildbot_launch.

  Returns:
    Return code of cbuildbot as an integer.
  """
  ensure_bootstrap_script = os.path.join(depot_tools_path, 'ensure_bootstrap')
  if os.path.exists(ensure_bootstrap_script):
    extra_env = {'PATH': PrependPath(depot_tools_path)}
    cros_build_lib.RunCommand(
        [ensure_bootstrap_script], extra_env=extra_env, cwd=depot_tools_path)
  else:
    # This is normal when checking out branches older than this script.
    logging.warn('ensure_bootstrap not found, skipping: %s',
                 ensure_bootstrap_script)


@StageDecorator
def RunCbuildbot(buildroot, depot_tools_path, argv):
  """Start cbuildbot in specified directory with all arguments.

  Args:
    buildroot: Directory to be passed to cbuildbot with --buildroot.
    depot_tools_path: Directory for depot_tools to be used by cbuildbot.
    argv: Command line options passed to cbuildbot_launch.

  Returns:
    Return code of cbuildbot as an integer.
  """
  logging.info('Bootstrap cbuildbot in: %s', buildroot)

  # Fixup buildroot parameter.
  argv = argv[:]
  for i in xrange(len(argv)):
    if argv[i] in ('-r', '--buildroot'):
      argv[i+1] = buildroot

  # This filters out command line arguments not supported by older versions
  # of cbuildbot.
  parser = cbuildbot.CreateParser()
  options = cbuildbot.ParseCommandLine(parser, argv)
  cbuildbot_path = os.path.join(buildroot, 'chromite', 'bin', 'cbuildbot')
  cmd = sync_stages.BootstrapStage.FilterArgsForTargetCbuildbot(
      buildroot, cbuildbot_path, options)

  # We want cbuildbot to use branched depot_tools scripts from our manifest,
  # so that depot_tools is branched to match cbuildbot.
  logging.info('Adding depot_tools into PATH: %s', depot_tools_path)
  extra_env = {'PATH': PrependPath(depot_tools_path)}

  result = cros_build_lib.RunCommand(
      cmd, extra_env=extra_env, error_code_ok=True, cwd=buildroot)
  return result.returncode


def _InstallSystemCrcmodIfNeeded():
  """Install Crcmod binary extension if needed.

  If the build host has python-crcmod installed without the binary extension,
  that breaks some versions of gsutil. In that case, this function installs
  a new copy of the module with the extension.

  Newer branches workaround this in gs.py, and hopefully future versions of
  gsutil will work around this in gsutil, however, older branches will always
  have this problem.

  So... this method will always be required unless/until we chose to solve this
  through configuration management of hosts.

  http://crbug.com/763438 covers this in detail.
  """
  try:
    import crcmod
    # If crcmod exists on the system, but doesn't have the binary extension,
    # gsutil behaves badly. Override the system module with one that contains
    # the binary extension. This depends on /usr/local/lib overridding /usr/lib.
    if not (getattr(crcmod, 'crcmod', None) and
            getattr(crcmod.crcmod, '_usingExtension', None)):
      logging.warn('FORCING CRCMOD INSTALL to workaround crbug.com/763438.')
      cmd = ['pip', 'install', '--ignore-installed', 'crcmod']
      result = cros_build_lib.SudoRunCommand(
          cmd, error_code_ok=True, mute_output=True)
      logging.warn('CRCMOD INSTALL RETURNED :%d', result.returncode)
  except ImportError:
    # If crcmod doesn't exist on the system, gs.py will properly use its
    # version in the cache.
    pass


def ConfigureGlobalEnvironment():
  """Setup process wide environmental changes."""
  # Set umask to 022 so files created by buildbot are readable.
  os.umask(0o22)

  # These variables can interfere with LANG / locale behavior.
  unwanted_local_vars = [
      'LC_ALL', 'LC_CTYPE', 'LC_COLLATE', 'LC_TIME', 'LC_NUMERIC',
      'LC_MONETARY', 'LC_MESSAGES', 'LC_PAPER', 'LC_NAME', 'LC_ADDRESS',
      'LC_TELEPHONE', 'LC_MEASUREMENT', 'LC_IDENTIFICATION',
  ]
  for v in unwanted_local_vars:
    os.environ.pop(v, None)

  # This variable is required for repo sync's to work in all cases.
  os.environ['LANG'] = 'en_US.UTF-8'

  _InstallSystemCrcmodIfNeeded()


def _main(argv):
  """main method of script.

  Args:
    argv: All command line arguments to pass as list of strings.

  Returns:
    Return code of cbuildbot as an integer.
  """
  options = PreParseArguments(argv)

  branchname = options.branch or 'master'
  root = options.buildroot
  buildroot = os.path.join(root, 'repository')
  depot_tools_path = os.path.join(buildroot, constants.DEPOT_TOOLS_SUBPATH)

  metrics_fields = {
      'branch_name': branchname,
      'build_config': options.build_config_name,
      'tryjob': options.remote_trybot,
  }

  # Does the entire build pass or fail.
  with metrics.Presence(METRIC_ACTIVE, metrics_fields), \
       metrics.SuccessCounter(METRIC_COMPLETED, metrics_fields) as s_fields:

    # Preliminary set, mostly command line parsing.
    with metrics.SuccessCounter(METRIC_INVOKED, metrics_fields):
      if options.enable_buildbot_tags:
        logging.EnableBuildbotMarkers()
      ConfigureGlobalEnvironment()

    # Prepare the buildroot with source for the build.
    with metrics.SuccessCounter(METRIC_PREP, metrics_fields):
      site_config = config_lib.GetConfig()
      manifest_url = site_config.params['MANIFEST_INT_URL']
      repo = repository.RepoRepository(manifest_url, buildroot,
                                       branch=branchname,
                                       git_cache_dir=options.git_cache_dir)

      # Clean up the buildroot to a safe state.
      with metrics.SecondsTimer(METRIC_CLEAN, fields=metrics_fields):
        CleanBuildRoot(root, repo, metrics_fields)

      # Get a checkout close enough to the branch that cbuildbot can handle it.
      with metrics.SecondsTimer(METRIC_INITIAL, fields=metrics_fields):
        InitialCheckout(repo)

      # Get a checkout close enough to the branch that cbuildbot can handle it.
      with metrics.SecondsTimer(METRIC_DEPOT_TOOLS, fields=metrics_fields):
        DepotToolsEnsureBootstrap(depot_tools_path)

    # Run cbuildbot inside the full ChromeOS checkout, on the specified branch.
    with metrics.SecondsTimer(METRIC_CBUILDBOT, fields=metrics_fields):
      result = RunCbuildbot(buildroot, depot_tools_path, argv)
      s_fields['success'] = (result == 0)
      return result


def main(argv):
  # Enable Monarch metrics gathering.
  with ts_mon_config.SetupTsMonGlobalState('cbuildbot_launch', indirect=True):
    return _main(argv)