# 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 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'


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 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.')

  if len(options.build_targets) != 1:
    cros_build_lib.Die('Exactly one build target required, got: %s',
                       ', '.join(options.build_targets) or 'None')

  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'))
    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.')
      osutils.RmDir(os.path.join(repo.directory, 'chroot'),
                    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 RunCbuildbot(buildroot, argv):
  """Start cbuildbot in specified directory with all arguments.

  Args:
    buildroot: Directory to be passed to cbuildbot with --buildroot.
    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)

  # Actually run cbuildbot with the fixed up command line options.
  result = cros_build_lib.RunCommand(cmd, error_code_ok=True, cwd=buildroot)
  return result.returncode


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'


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')
  build_config = options.build_targets[0]

  metrics_fields = {
      'branch_name': branchname,
      'build_config': build_config,
      '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):
      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 the branched cbuildbot can handle it.
      with metrics.SecondsTimer(METRIC_INITIAL, fields=metrics_fields):
        InitialCheckout(repo)

    # Run cbuildbot inside the full ChromeOS checkout, on the specified branch.
    with metrics.SecondsTimer(METRIC_CBUILDBOT, fields=metrics_fields):
      result = RunCbuildbot(buildroot, 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)