# Copyright (c) 2012 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.

"""Helper class for interacting with the Dev Server."""

import cherrypy
import distutils.version
import errno
import os
import random
import shutil
import time

import downloadable_artifact
import gsutil_util

AU_BASE = 'au'
NTON_DIR_SUFFIX = '_nton'
MTON_DIR_SUFFIX = '_mton'
DEV_BUILD_PREFIX = 'dev'


class DevServerUtilError(Exception):
  """Exception classes used by this module."""
  pass


def ParsePayloadList(payload_list):
  """Parse and return the full/delta payload URLs.

  Args:
    payload_list: A list of Google Storage URLs.

  Returns:
    Tuple of 3 payloads URLs: (full, nton, mton).

  Raises:
    DevServerUtilError: If payloads missing or invalid.
  """
  full_payload_url = None
  mton_payload_url = None
  nton_payload_url = None
  for payload in payload_list:
    if '_full_' in payload:
      full_payload_url = payload
    elif '_delta_' in payload:
      # e.g. chromeos_{from_version}_{to_version}_x86-generic_delta_dev.bin
      from_version, to_version = payload.rsplit('/', 1)[1].split('_')[1:3]
      if from_version == to_version:
        nton_payload_url = payload
      else:
        mton_payload_url = payload

  if not full_payload_url:
    raise DevServerUtilError(
        'Full payload is missing or has unexpected name format.', payload_list)

  return full_payload_url, nton_payload_url, mton_payload_url


def GatherArtifactDownloads(main_staging_dir, archive_url, build, build_dir):
  """Generates artifacts that we mean to download and install for autotest.

  This method generates the list of artifacts we will need for autotest. These
  artifacts are instances of downloadable_artifact.DownloadableArtifact.

  Note, these artifacts can be downloaded asynchronously iff
  !artifact.Synchronous().
  """
  cmd = 'gsutil ls %s/*.bin' % archive_url
  msg = 'Failed to get a list of payloads.'
  payload_list = gsutil_util.GSUtilRun(cmd, msg).splitlines()

  # First we gather the urls/paths for the update payloads.
  full_url, nton_url, mton_url = ParsePayloadList(payload_list)

  full_payload = os.path.join(build_dir, downloadable_artifact.ROOT_UPDATE)

  artifacts = []
  artifacts.append(downloadable_artifact.DownloadableArtifact(full_url,
      main_staging_dir, full_payload, synchronous=True))

  if nton_url:
    nton_payload = os.path.join(build_dir, AU_BASE, build + NTON_DIR_SUFFIX,
                                downloadable_artifact.ROOT_UPDATE)
    artifacts.append(downloadable_artifact.AUTestPayload(nton_url,
      main_staging_dir, nton_payload))

  if mton_url:
    mton_payload = os.path.join(build_dir, AU_BASE, build + MTON_DIR_SUFFIX,
                                downloadable_artifact.ROOT_UPDATE)
    artifacts.append(downloadable_artifact.AUTestPayload(
        mton_url, main_staging_dir, mton_payload))

  # Next we gather the miscellaneous payloads.
  stateful_url = archive_url + '/' + downloadable_artifact.STATEFUL_UPDATE
  autotest_url = archive_url + '/' + downloadable_artifact.AUTOTEST_PACKAGE
  test_suites_url = (archive_url + '/' +
                     downloadable_artifact.TEST_SUITES_PACKAGE)

  stateful_payload = os.path.join(build_dir,
                                  downloadable_artifact.STATEFUL_UPDATE)

  artifacts.append(downloadable_artifact.DownloadableArtifact(
      stateful_url, main_staging_dir, stateful_payload, synchronous=True))
  artifacts.append(downloadable_artifact.AutotestTarball(
      autotest_url, main_staging_dir, build_dir))
  artifacts.append(downloadable_artifact.Tarball(
      test_suites_url, main_staging_dir, build_dir, synchronous=True))
  return artifacts


def GatherSymbolArtifactDownloads(temp_download_dir, archive_url, staging_dir,
                                  timeout=600, delay=10):
  """Generates debug symbol artifacts that we mean to download and stage.

  This method generates the list of artifacts we will need to
  symbolicate crash dumps that occur during autotest runs.  These
  artifacts are instances of downloadable_artifact.DownloadableArtifact.

  This will poll google storage until the debug symbol artifact becomes
  available, or until the 10 minute timeout is up.

  @param temp_download_dir: the tempdir into which we're downloading artifacts
                            prior to staging them.
  @param archive_url: the google storage url of the bucket where the debug
                      symbols for the desired build are stored.
  @param staging_dir: the dir into which to stage the symbols

  @return an iterable of one DebugTarball pointing to the right debug symbols.
          This is an iterable so that it's similar to GatherArtifactDownloads.
          Also, it's possible that someday we might have more than one.
  """
  symbol_url = archive_url + '/' + downloadable_artifact.DEBUG_SYMBOLS
  cmd = 'gsutil ls %s' % symbol_url
  msg = 'Debug symbols for %s not archived.' % archive_url

  deadline = time.time() + timeout
  while time.time() < deadline:
    to_delay = delay + random.choice([-1, 1]) * random.random() * .5 * delay
    try:
      gsutil_util.GSUtilRun(cmd, msg)
      break
    except gsutil_util.GSUtilError as e:
      cherrypy.log('%s, Retrying in %f seconds...' % (e, to_delay),
                   'SYMBOL_DOWNLOAD')
      time.sleep(to_delay)
  else:
    # On the last try, run and allow exceptions to escape.
    gsutil_util.GSUtilRun(cmd, msg)

  return [downloadable_artifact.DebugTarball(symbol_url, temp_download_dir,
                                             staging_dir)]


def PrepareBuildDirectory(build_dir):
  """Preliminary staging of installation directory for build.

  Args:
    build_dir: Directory to install build components into.
  """
  if not os.path.isdir(build_dir):
    os.path.makedirs(build_dir)

  # Create blank chromiumos_test_image.bin. Otherwise the Dev Server will
  # try to rebuild it unnecessarily.
  test_image = os.path.join(build_dir, downloadable_artifact.TEST_IMAGE)
  open(test_image, 'a').close()


def SafeSandboxAccess(static_dir, path):
  """Verify that the path is in static_dir.

  Args:
    static_dir: Directory where builds are served from.
    path: Path to verify.

  Returns:
    True if path is in static_dir, False otherwise
  """
  static_dir = os.path.realpath(static_dir)
  path = os.path.realpath(path)
  return (path.startswith(static_dir) and path != static_dir)


def AcquireLock(static_dir, tag):
  """Acquires a lock for a given tag.

  Creates a directory for the specified tag, telling other
  components the resource/task represented by the tag is unavailable.

  Args:
    static_dir: Directory where builds are served from.
    tag: Unique resource/task identifier. Use '/' for nested tags.

  Returns:
    Path to the created directory or None if creation failed.

  Raises:
    DevServerUtilError: If lock can't be acquired.
  """
  build_dir = os.path.join(static_dir, tag)
  if not SafeSandboxAccess(static_dir, build_dir):
    raise DevServerUtilError('Invalid tag "%s".' % tag)

  try:
    os.makedirs(build_dir)
  except OSError, e:
    if e.errno == errno.EEXIST:
      raise DevServerUtilError(str(e))
    else:
      raise

  return build_dir


def ReleaseLock(static_dir, tag):
  """Releases the lock for a given tag. Removes lock directory content.

  Args:
    static_dir: Directory where builds are served from.
    tag: Unique resource/task identifier. Use '/' for nested tags.

  Raises:
    DevServerUtilError: If lock can't be released.
  """
  build_dir = os.path.join(static_dir, tag)
  if not SafeSandboxAccess(static_dir, build_dir):
    raise DevServerUtilError('Invaid tag "%s".' % tag)

  shutil.rmtree(build_dir)


def FindMatchingBoards(static_dir, board):
  """Returns a list of boards given a partial board name.

  Args:
    static_dir: Directory where builds are served from.
    board: Partial board name for this build; e.g. x86-generic.

  Returns:
    Returns a list of boards given a partial board.
  """
  return [brd for brd in os.listdir(static_dir) if board in brd]


def FindMatchingBuilds(static_dir, board, build):
  """Returns a list of matching builds given a board and partial build.

  Args:
    static_dir: Directory where builds are served from.
    board: Partial board name for this build; e.g. x86-generic-release.
    build: Partial build string to look for; e.g. R17-1234.

  Returns:
    Returns a list of (board, build) tuples given a partial board and build.
  """
  matches = []
  for brd in FindMatchingBoards(static_dir, board):
    a = [(brd, bld) for bld in
         os.listdir(os.path.join(static_dir, brd)) if build in bld]
    matches.extend(a)
  return matches


def GetLatestBuildVersion(static_dir, target, milestone=None):
  """Retrieves the latest build version for a given board.

  Args:
    static_dir: Directory where builds are served from.
    target: The build target, typically a combination of the board and the
        type of build e.g. x86-mario-release.
    milestone: For latest build set to None, for builds only in a specific
        milestone set to a str of format Rxx (e.g. R16). Default: None.

  Returns:
    If latest found, a full build string is returned e.g. R17-1234.0.0-a1-b983.
    If no latest is found for some reason or another a '' string is returned.

  Raises:
    DevServerUtilError: If for some reason the latest build cannot be
        deteremined, this could be due to the dir not existing or no builds
        being present after filtering on milestone.
  """
  target_path = os.path.join(static_dir, target)
  if not os.path.isdir(target_path):
    raise DevServerUtilError('Cannot find path %s' % target_path)

  builds = [distutils.version.LooseVersion(build) for build in
            os.listdir(target_path)]

  if milestone and builds:
    # Check if milestone Rxx is in the string representation of the build.
    builds = filter(lambda x: milestone.upper() in str(x), builds)

  if not builds:
    raise DevServerUtilError('Could not determine build for %s' % target)

  return str(max(builds))


def CloneBuild(static_dir, board, build, tag, force=False):
  """Clone an official build into the developer sandbox.

  Developer sandbox directory must already exist.

  Args:
    static_dir: Directory where builds are served from.
    board: Fully qualified board name; e.g. x86-generic-release.
    build: Fully qualified build string; e.g. R17-1234.0.0-a1-b983.
    tag: Unique resource/task identifier. Use '/' for nested tags.
    force: Force re-creation of build_dir even if it already exists.

  Returns:
    The path to the new build.
  """
  # Create the developer build directory.
  dev_static_dir = os.path.join(static_dir, DEV_BUILD_PREFIX)
  dev_build_dir = os.path.join(dev_static_dir, tag)
  official_build_dir = os.path.join(static_dir, board, build)
  cherrypy.log('Cloning %s -> %s' % (official_build_dir, dev_build_dir),
               'DEVSERVER_UTIL')
  dev_build_exists = False
  try:
    AcquireLock(dev_static_dir, tag)
  except DevServerUtilError:
    dev_build_exists = True
    if force:
      dev_build_exists = False
      ReleaseLock(dev_static_dir, tag)
      AcquireLock(dev_static_dir, tag)

  # Make a copy of the official build, only take necessary files.
  if not dev_build_exists:
    copy_list = [downloadable_artifact.TEST_IMAGE,
                 downloadable_artifact.ROOT_UPDATE,
                 downloadable_artifact.STATEFUL_UPDATE]
    for f in copy_list:
      shutil.copy(os.path.join(official_build_dir, f), dev_build_dir)

  return dev_build_dir


def GetControlFile(static_dir, build, control_path):
  """Attempts to pull the requested control file from the Dev Server.

  Args:
    static_dir: Directory where builds are served from.
    build: Fully qualified build string; e.g. R17-1234.0.0-a1-b983.
    control_path: Path to control file on Dev Server relative to Autotest root.

  Raises:
    DevServerUtilError: If lock can't be acquired.

  Returns:
    Content of the requested control file.
  """
  # Be forgiving if the user passes in the control_path with a leading /
  control_path = control_path.lstrip('/')
  control_path = os.path.join(static_dir, build, 'autotest',
                              control_path)
  if not SafeSandboxAccess(static_dir, control_path):
    raise DevServerUtilError('Invaid control file "%s".' % control_path)

  if not os.path.exists(control_path):
    # TODO(scottz): Come up with some sort of error mechanism.
    # crosbug.com/25040
    return 'Unknown control path %s' % control_path

  with open(control_path, 'r') as control_file:
    return control_file.read()


def GetControlFileList(static_dir, build):
  """List all control|control. files in the specified board/build path.

  Args:
    static_dir: Directory where builds are served from.
    build: Fully qualified build string; e.g. R17-1234.0.0-a1-b983.

  Raises:
    DevServerUtilError: If path is outside of sandbox.

  Returns:
    String of each file separated by a newline.
  """
  autotest_dir = os.path.join(static_dir, build, 'autotest/')
  if not SafeSandboxAccess(static_dir, autotest_dir):
    raise DevServerUtilError('Autotest dir not in sandbox "%s".' % autotest_dir)

  control_files = set()
  if not os.path.exists(autotest_dir):
    # TODO(scottz): Come up with some sort of error mechanism.
    # crosbug.com/25040
    return 'Unknown build path %s' % autotest_dir

  for entry in os.walk(autotest_dir):
    dir_path, _, files = entry
    for file_entry in files:
      if file_entry.startswith('control.') or file_entry == 'control':
        control_files.add(os.path.join(dir_path,
                                       file_entry).replace(autotest_dir, ''))

  return '\n'.join(control_files)


def ListAutoupdateTargets(static_dir, board, build):
  """Returns a list of autoupdate test targets for the given board, build.

  Args:
    static_dir: Directory where builds are served from.
    board: Fully qualified board name; e.g. x86-generic-release.
    build: Fully qualified build string; e.g. R17-1234.0.0-a1-b983.

  Returns:
    List of autoupdate test targets; e.g. ['0.14.747.0-r2bf8859c-b2927_nton']
  """
  return os.listdir(os.path.join(static_dir, board, build, AU_BASE))