#!/usr/bin/python

# Copyright (c) 2009-2012 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.

"""A CherryPy-based webserver to host images and build packages."""

import json
import logging
import optparse
import os
import re
import sys
import subprocess
import tempfile
import threading
import types

import cherrypy

import autoupdate
import common_util
import downloader
import log_util


# Module-local log function.
def _Log(message, *args, **kwargs):
  return log_util.LogWithTag('DEVSERVER', message, *args, **kwargs)


CACHED_ENTRIES = 12

# Sets up global to share between classes.
global updater
updater = None


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


class LockDict(object):
  """A dictionary of locks.

  This class provides a thread-safe store of threading.Lock objects, which can
  be used to regulate access to any set of hashable resources.  Usage:

    foo_lock_dict = LockDict()
    ...
    with foo_lock_dict.lock('bar'):
      # Critical section for 'bar'
  """
  def __init__(self):
    self._lock = self._new_lock()
    self._dict = {}

  def _new_lock(self):
    return threading.Lock()

  def lock(self, key):
    with self._lock:
      lock = self._dict.get(key)
      if not lock:
        lock = self._new_lock()
        self._dict[key] = lock
      return lock


def _LeadingWhiteSpaceCount(string):
  """Count the amount of leading whitespace in a string.

  Args:
    string: The string to count leading whitespace in.
  Returns:
    number of white space chars before characters start.
  """
  matched = re.match('^\s+', string)
  if matched:
    return len(matched.group())

  return 0


def _PrintDocStringAsHTML(func):
  """Make a functions docstring somewhat HTML style.

  Args:
    func: The function to return the docstring from.
  Returns:
    A string that is somewhat formated for a web browser.
  """
  # TODO(scottz): Make this parse Args/Returns in a prettier way.
  # Arguments could be bolded and indented etc.
  html_doc = []
  for line in func.__doc__.splitlines():
    leading_space = _LeadingWhiteSpaceCount(line)
    if leading_space > 0:
      line = '&nbsp;' * leading_space + line

    html_doc.append('<BR>%s' % line)

  return '\n'.join(html_doc)


def _GetConfig(options):
  """Returns the configuration for the devserver."""
  base_config = { 'global':
                  { 'server.log_request_headers': True,
                    'server.protocol_version': 'HTTP/1.1',
                    'server.socket_host': '::',
                    'server.socket_port': int(options.port),
                    'response.timeout': 6000,
                    'request.show_tracebacks': True,
                    'server.socket_timeout': 60,
                    'tools.staticdir.root':
                      os.path.dirname(os.path.abspath(sys.argv[0])),
                  },
                  '/api':
                  {
                    # Gets rid of cherrypy parsing post file for args.
                    'request.process_request_body': False,
                  },
                  '/build':
                  {
                    'response.timeout': 100000,
                  },
                  '/update':
                  {
                    # Gets rid of cherrypy parsing post file for args.
                    'request.process_request_body': False,
                    'response.timeout': 10000,
                  },
                  # Sets up the static dir for file hosting.
                  '/static':
                  { 'tools.staticdir.dir': 'static',
                    'tools.staticdir.on': True,
                    'response.timeout': 10000,
                  },
                }
  if options.production:
    base_config['global'].update({'server.thread_pool': 75})

  return base_config


def _PrepareToServeUpdatesOnly(image_dir, static_dir):
  """Sets up symlink to image_dir for serving purposes."""
  assert os.path.exists(image_dir), '%s must exist.' % image_dir
  # If  we're  serving  out  of  an archived  build  dir  (e.g.  a
  # buildbot), prepare this webserver's magic 'static/' dir with a
  # link to the build archive.
  _Log('Preparing autoupdate for "serve updates only" mode.')
  if os.path.lexists('%s/archive' % static_dir):
    if image_dir != os.readlink('%s/archive' % static_dir):
      _Log('removing stale symlink to %s' % image_dir)
      os.unlink('%s/archive' % static_dir)
      os.symlink(image_dir, '%s/archive' % static_dir)

  else:
    os.symlink(image_dir, '%s/archive' % static_dir)

  _Log('archive dir: %s ready to be used to serve images.' % image_dir)


def _GetRecursiveMemberObject(root, member_list):
  """Returns an object corresponding to a nested member list.

  Args:
    root: the root object to search
    member_list: list of nested members to search
  Returns:
    An object corresponding to the member name list; None otherwise.
  """
  for member in member_list:
    next_root = root.__class__.__dict__.get(member)
    if not next_root:
      return None
    root = next_root
  return root


def _IsExposed(name):
  """Returns True iff |name| has an `exposed' attribute and it is set."""
  return hasattr(name, 'exposed') and name.exposed


def _GetExposedMethod(root, nested_member, ignored=[]):
  """Returns a CherryPy-exposed method, if such exists.

  Args:
    root: the root object for searching
    nested_member: a slash-joined path to the nested member
    ignored: method paths to be ignored
  Returns:
    A function object corresponding to the path defined by |member_list| from
    the |root| object, if the function is exposed and not ignored; None
    otherwise.
  """
  method = (nested_member not in ignored and
            _GetRecursiveMemberObject(root, nested_member.split('/')))
  if (method and type(method) == types.FunctionType and _IsExposed(method)):
    return method


def _FindExposedMethods(root, prefix, unlisted=[]):
  """Finds exposed CherryPy methods.

  Args:
    root: the root object for searching
    prefix: slash-joined chain of members leading to current object
    unlisted: URLs to be excluded regardless of their exposed status
  Returns:
    List of exposed URLs that are not unlisted.
  """
  method_list = []
  for member in sorted(root.__class__.__dict__.keys()):
    prefixed_member = prefix + '/' + member if prefix else member
    if prefixed_member in unlisted:
      continue
    member_obj = root.__class__.__dict__[member]
    if _IsExposed(member_obj):
      if type(member_obj) == types.FunctionType:
        method_list.append(prefixed_member)
      else:
        method_list += _FindExposedMethods(
            member_obj, prefixed_member, unlisted)
  return method_list


class ApiRoot(object):
  """RESTful API for Dev Server information."""
  exposed = True

  @cherrypy.expose
  def hostinfo(self, ip):
    """Returns a JSON dictionary containing information about the given ip.

    Not all information may be known at the time the request is made. The
    possible keys are:

        last_event_type: int
            Last update event type received.

        last_event_status: int
            Last update event status received.

        last_known_version: string
            Last known version recieved for update ping.

        forced_update_label: string
            Update label to force next update ping to use. Set by setnextupdate.

    See the OmahaEvent class in update_engine/omaha_request_action.h for status
    code definitions. If the ip does not exist an empty string is returned."""
    return updater.HandleHostInfoPing(ip)

  @cherrypy.expose
  def hostlog(self, ip):
    """Returns a JSON object containing a log of events pertaining to a
    particular host, or all hosts. Log events contain a timestamp and any
    subset of the attributes listed for the hostinfo method."""
    return updater.HandleHostLogPing(ip)

  @cherrypy.expose
  def setnextupdate(self, ip):
    """Allows the response to the next update ping from a host to be set.

    Takes the IP of the host and an update label as normally provided to the
    /update command."""
    body_length = int(cherrypy.request.headers['Content-Length'])
    label = cherrypy.request.rfile.read(body_length)

    if label:
      label = label.strip()
      if label:
        return updater.HandleSetUpdatePing(ip, label)
    raise cherrypy.HTTPError(400, 'No label provided.')


  @cherrypy.expose
  def fileinfo(self, *path_args):
    """Returns information about a given staged file.

    Args:
      path_args: path to the file inside the server's static staging directory
    Returns:
      A JSON encoded dictionary with information about the said file, which may
      contain the following keys/values:
        size:   the file size in bytes (int)
        sha1:   a base64 encoded SHA1 hash (string)
        sha256: a base64 encoded SHA256 hash (string)
    """
    file_path = os.path.join(updater.static_dir, *path_args)
    if not os.path.exists(file_path):
      raise DevServerError('file not found: %s' % file_path)
    try:
      file_size = os.path.getsize(file_path)
      file_sha1 = common_util.GetFileSha1(file_path)
      file_sha256 = common_util.GetFileSha256(file_path)
    except os.error, e:
      raise DevServerError('failed to get info for file %s: %s' %
                           (file_path, str(e)))
    return json.dumps(
        {'size': file_size, 'sha1': file_sha1, 'sha256': file_sha256})

class DevServerRoot(object):
  """The Root Class for the Dev Server.

  CherryPy works as follows:
    For each method in this class, cherrpy interprets root/path
    as a call to an instance of DevServerRoot->method_name.  For example,
    a call to http://myhost/build will call build.  CherryPy automatically
    parses http args and places them as keyword arguments in each method.
    For paths http://myhost/update/dir1/dir2, you can use *args so that
    cherrypy uses the update method and puts the extra paths in args.
  """
  # Method names that should not be listed on the index page.
  _UNLISTED_METHODS = ['index', 'doc']

  api = ApiRoot()

  def __init__(self):
    self._builder = None
    self._download_lock_dict = LockDict()
    self._downloader_dict = {}

  @cherrypy.expose
  def build(self, board, pkg, **kwargs):
    """Builds the package specified."""
    import builder
    if self._builder is None:
      self._builder = builder.Builder()
    return self._builder.Build(board, pkg, kwargs)

  @staticmethod
  def _canonicalize_archive_url(archive_url):
    """Canonicalizes archive_url strings.

    Raises:
      DevserverError: if archive_url is not set.
    """
    if archive_url:
      return archive_url.rstrip('/')
    else:
      raise DevServerError("Must specify an archive_url in the request")

  @cherrypy.expose
  def download(self, **kwargs):
    """Downloads and archives full/delta payloads from Google Storage.

    This methods downloads artifacts. It may download artifacts in the
    background in which case a caller should call wait_for_status to get
    the status of the background artifact downloads. They should use the same
    args passed to download.

    Args:
      archive_url: Google Storage URL for the build.

    Example URL:
      http://myhost/download?archive_url=gs://chromeos-image-archive/
      x86-generic/R17-1208.0.0-a1-b338
    """
    archive_url = self._canonicalize_archive_url(kwargs.get('archive_url'))

    # Guarantees that no two downloads for the same url can run this code
    # at the same time.
    with self._download_lock_dict.lock(archive_url):
      try:
        # If we are currently downloading, return. Note, due to the above lock
        # we know that the foreground artifacts must have finished downloading
        # and returned Success if this downloader instance exists.
        if (self._downloader_dict.get(archive_url) or
            downloader.Downloader.BuildStaged(archive_url, updater.static_dir)):
          _Log('Build %s has already been processed.' % archive_url)
          return 'Success'

        downloader_instance = downloader.Downloader(updater.static_dir)
        self._downloader_dict[archive_url] = downloader_instance
        return downloader_instance.Download(archive_url, background=True)

      except:
        # On any exception, reset the state of the downloader_dict.
        self._downloader_dict[archive_url] = None
        raise

  @cherrypy.expose
  def wait_for_status(self, **kwargs):
    """Waits for background artifacts to be downloaded from Google Storage.

    Args:
      archive_url: Google Storage URL for the build.

    Example URL:
      http://myhost/wait_for_status?archive_url=gs://chromeos-image-archive/
      x86-generic/R17-1208.0.0-a1-b338
    """
    archive_url = self._canonicalize_archive_url(kwargs.get('archive_url'))
    downloader_instance = self._downloader_dict.get(archive_url)
    if downloader_instance:
      status = downloader_instance.GetStatusOfBackgroundDownloads()
      self._downloader_dict[archive_url] = None
      return status
    else:
      # We may have previously downloaded but removed the downloader instance
      # from the cache.
      if downloader.Downloader.BuildStaged(archive_url, updater.static_dir):
        logging.info('%s not found in downloader cache but previously staged.',
                     archive_url)
        return 'Success'
      else:
        raise DevServerError('No download for the given archive_url found.')

  @cherrypy.expose
  def stage_debug(self, **kwargs):
    """Downloads and stages debug symbol payloads from Google Storage.

    This methods downloads the debug symbol build artifact synchronously,
    and then stages it for use by symbolicate_dump/.

    Args:
      archive_url: Google Storage URL for the build.

    Example URL:
      http://myhost/stage_debug?archive_url=gs://chromeos-image-archive/
      x86-generic/R17-1208.0.0-a1-b338
    """
    archive_url = self._canonicalize_archive_url(kwargs.get('archive_url'))
    return downloader.SymbolDownloader(updater.static_dir).Download(archive_url)

  @cherrypy.expose
  def symbolicate_dump(self, minidump):
    """Symbolicates a minidump using pre-downloaded symbols, returns it.

    Callers will need to POST to this URL with a body of MIME-type
    "multipart/form-data".
    The body should include a single argument, 'minidump', containing the
    binary-formatted minidump to symbolicate.

    It is up to the caller to ensure that the symbols they want are currently
    staged.

    Args:
      minidump: The binary minidump file to symbolicate.
    """
    to_return = ''
    with tempfile.NamedTemporaryFile() as local:
      while True:
        data = minidump.file.read(8192)
        if not data:
          break
        local.write(data)
      local.flush()
      stackwalk = subprocess.Popen(['minidump_stackwalk',
                                    local.name,
                                    updater.static_dir + '/debug/breakpad'],
                                   stdout=subprocess.PIPE,
                                   stderr=subprocess.PIPE)
      to_return, error_text = stackwalk.communicate()
      if stackwalk.returncode != 0:
        raise DevServerError("Can't generate stack trace: %s (rc=%d)" % (
            error_text, stackwalk.returncode))

    return to_return

  @cherrypy.expose
  def latestbuild(self, **params):
    """Return a string representing the latest build for a given target.

    Args:
      target: The build target, typically a combination of the board and the
          type of build e.g. x86-mario-release.
      milestone: The milestone to filter builds on. E.g. R16. Optional, if not
          provided the latest RXX build will be returned.
    Returns:
      A string representation of the latest build if one exists, i.e.
          R19-1993.0.0-a1-b1480.
      An empty string if no latest could be found.
    """
    if not params:
      return _PrintDocStringAsHTML(self.latestbuild)

    if 'target' not in params:
      raise cherrypy.HTTPError('500 Internal Server Error',
                               'Error: target= is required!')
    try:
      return common_util.GetLatestBuildVersion(
          updater.static_dir, params['target'],
          milestone=params.get('milestone'))
    except common_util.CommonUtilError as errmsg:
      raise cherrypy.HTTPError('500 Internal Server Error', str(errmsg))

  @cherrypy.expose
  def controlfiles(self, **params):
    """Return a control file or a list of all known control files.

    Example URL:
      To List all control files:
      http://dev-server/controlfiles?board=x86-alex-release&build=R18-1514.0.0
      To return the contents of a path:
      http://dev-server/controlfiles?board=x86-alex-release&build=R18-1514.0.0&control_path=client/sleeptest/control

    Args:
      build: The build i.e. x86-alex-release/R18-1514.0.0-a1-b1450.
      control_path: If you want the contents of a control file set this
        to the path. E.g. client/site_tests/sleeptest/control
        Optional, if not provided return a list of control files is returned.
    Returns:
      Contents of a control file if control_path is provided.
      A list of control files if no control_path is provided.
    """
    if not params:
      return _PrintDocStringAsHTML(self.controlfiles)

    if 'build' not in params:
      raise cherrypy.HTTPError('500 Internal Server Error',
                               'Error: build= is required!')

    if 'control_path' not in params:
      return common_util.GetControlFileList(
          updater.static_dir, params['build'])
    else:
      return common_util.GetControlFile(
          updater.static_dir, params['build'], params['control_path'])

  @cherrypy.expose
  def stage_images(self, **kwargs):
    """Downloads and stages a Chrome OS image from Google Storage.

    This method downloads a zipped archive from a specified GS location, then
    extracts and stages the specified list of images and stages them under
    static/images/BOARD/BUILD/. Download is synchronous.

    Args:
      archive_url: Google Storage URL for the build.
      image_types: comma-separated list of images to download, may include
                   'test', 'recovery', and 'base'

    Example URL:
      http://myhost/stage_images?archive_url=gs://chromeos-image-archive/
      x86-generic/R17-1208.0.0-a1-b338&image_types=test,base
    """
    # TODO(garnold) This needs to turn into an async operation, to avoid
    # unnecessary failure of concurrent secondary requests (chromium-os:34661).
    archive_url = self._canonicalize_archive_url(kwargs.get('archive_url'))
    image_types = kwargs.get('image_types').split(',')
    return (downloader.ImagesDownloader(
        updater.static_dir).Download(archive_url, image_types))

  @cherrypy.expose
  def index(self):
    """Presents a welcome message and documentation links."""
    method_dict = DevServerRoot.__dict__
    return ('Welcome to the Dev Server!<br>\n'
            '<br>\n'
            'Here are the available methods, click for documentation:<br>\n'
            '<br>\n'
            '%s' %
            '<br>\n'.join(
                [('<a href=doc/%s>%s</a>' % (name, name))
                 for name in _FindExposedMethods(
                     self, '', unlisted=self._UNLISTED_METHODS)]))

  @cherrypy.expose
  def doc(self, *args):
    """Shows the documentation for available methods / URLs.

    Example:
      http://myhost/doc/update
    """
    name = '/'.join(args)
    method = _GetExposedMethod(self, name)
    if not method:
      raise DevServerError("No exposed method named `%s'" % name)
    if not method.__doc__:
      raise DevServerError("No documentation for exposed method `%s'" % name)
    return '<pre>\n%s</pre>' % method.__doc__

  @cherrypy.expose
  def update(self, *args):
    """Handles an update check from a Chrome OS client.

    The HTTP request should contain the standard Omaha-style XML blob. The URL
    line may contain an additional intermediate path to the update payload.

    Example:
      http://myhost/update/optional/path/to/payload
    """
    label = '/'.join(args)
    body_length = int(cherrypy.request.headers.get('Content-Length', 0))
    data = cherrypy.request.rfile.read(body_length)
    return updater.HandleUpdatePing(data, label)


def main():
  usage = 'usage: %prog [options]'
  parser = optparse.OptionParser(usage=usage)
  parser.add_option('--archive_dir', dest='archive_dir',
                    help='serve archived builds only.')
  parser.add_option('--board', dest='board',
                    help='When pre-generating update, board for latest image.')
  parser.add_option('--clear_cache', action='store_true', default=False,
                    help='Clear out all cached updates and exit')
  parser.add_option('--critical_update', dest='critical_update',
                    action='store_true', default=False,
                    help='Present update payload as critical')
  parser.add_option('--data_dir', dest='data_dir',
                    help='Writable directory where static lives',
                    default=os.path.dirname(os.path.abspath(sys.argv[0])))
  parser.add_option('--exit', action='store_true', default=False,
                    help='Don\'t start the server (still pregenerate or clear'
                         'cache).')
  parser.add_option('--factory_config', dest='factory_config',
                    help='Config file for serving images from factory floor.')
  parser.add_option('--for_vm', dest='vm', default=False, action='store_true',
                    help='Update is for a vm image.')
  parser.add_option('--image', dest='image',
                    help='Force update using this image.')
  parser.add_option('--logfile', dest='logfile',
                    help='Log output to this file instead of stdout.')
  parser.add_option('-p', '--pregenerate_update', action='store_true',
                    default=False, help='Pre-generate update payload.')
  parser.add_option('--payload', dest='payload',
                    help='Use update payload from specified directory.')
  parser.add_option('--port', default=8080,
                    help='Port for the dev server to use (default: 8080).')
  parser.add_option('--private_key', default=None,
                    help='Path to the private key in pem format.')
  parser.add_option('--production', action='store_true', default=False,
                    help='Have the devserver use production values.')
  parser.add_option('--proxy_port', default=None,
                    help='Port to have the client connect to (testing support)')
  parser.add_option('--remote_payload', action='store_true', default=False,
                    help='Payload is being served from a remote machine.')
  parser.add_option('--src_image', default='',
                    help='Image on remote machine for generating delta update.')
  parser.add_option('-t', action='store_true', dest='test_image')
  parser.add_option('-u', '--urlbase', dest='urlbase',
                    help='base URL, other than devserver, for update images.')
  parser.add_option('--validate_factory_config', action="store_true",
                    dest='validate_factory_config',
                    help='Validate factory config file, then exit.')
  (options, _) = parser.parse_args()

  devserver_dir = os.path.dirname(os.path.abspath(sys.argv[0]))
  root_dir = os.path.realpath('%s/../..' % devserver_dir)
  serve_only = False

  static_dir = os.path.realpath('%s/static' % options.data_dir)
  os.system('mkdir -p %s' % static_dir)

  if options.archive_dir:
  # TODO(zbehan) Remove legacy support:
  #  archive_dir is the directory where static/archive will point.
  #  If this is an absolute path, all is fine. If someone calls this
  #  using a relative path, that is relative to src/platform/dev/.
  #  That use case is unmaintainable, but since applications use it
  #  with =./static, instead of a boolean flag, we'll make this relative
  #  to devserver_dir  to keep these unbroken. For now.
    archive_dir = options.archive_dir
    if not os.path.isabs(archive_dir):
      archive_dir = os.path.realpath(os.path.join(devserver_dir, archive_dir))
    _PrepareToServeUpdatesOnly(archive_dir, static_dir)
    static_dir = os.path.realpath(archive_dir)
    serve_only = True

  cache_dir = os.path.join(static_dir, 'cache')
  _Log('Using cache directory %s' % cache_dir)

  if os.path.exists(cache_dir):
    if options.clear_cache:
      # Clear the cache and exit on error.
      cmd = 'rm -rf %s/*' % cache_dir
      if os.system(cmd) != 0:
        _Log('Failed to clear the cache with %s' % cmd)
        sys.exit(1)

    else:
      # Clear all but the last N cached updates
      cmd = ('cd %s; ls -tr | head --lines=-%d | xargs rm -rf' %
             (cache_dir, CACHED_ENTRIES))
      if os.system(cmd) != 0:
        _Log('Failed to clean up old delta cache files with %s' % cmd)
        sys.exit(1)
  else:
    os.makedirs(cache_dir)

  _Log('Data dir is %s' % options.data_dir)
  _Log('Source root is %s' % root_dir)
  _Log('Serving from %s' % static_dir)

  global updater
  updater = autoupdate.Autoupdate(
      root_dir=root_dir,
      static_dir=static_dir,
      serve_only=serve_only,
      urlbase=options.urlbase,
      test_image=options.test_image,
      factory_config_path=options.factory_config,
      forced_image=options.image,
      payload_path=options.payload,
      proxy_port=options.proxy_port,
      src_image=options.src_image,
      vm=options.vm,
      board=options.board,
      copy_to_static_root=not options.exit,
      private_key=options.private_key,
      critical_update=options.critical_update,
      remote_payload=options.remote_payload,
  )

  # Sanity-check for use of validate_factory_config.
  if not options.factory_config and options.validate_factory_config:
    parser.error('You need a factory_config to validate.')

  if options.factory_config:
    updater.ImportFactoryConfigFile(options.factory_config,
                                     options.validate_factory_config)
    # We don't run the dev server with this option.
    if options.validate_factory_config:
      sys.exit(0)
  elif options.pregenerate_update:
    if not updater.PreGenerateUpdate():
      sys.exit(1)

  # If the command line requested after setup, it's time to do it.
  if not options.exit:
    # Handle options that must be set globally in cherrypy.
    if options.production:
      cherrypy.config.update({'environment': 'production'})
    if not options.logfile:
      cherrypy.config.update({'log.screen': True})
    else:
      cherrypy.config.update({'log.error_file': options.logfile,
                              'log.access_file': options.logfile})

    cherrypy.quickstart(DevServerRoot(), config=_GetConfig(options))


if __name__ == '__main__':
  main()