#!/usr/bin/env python2.7
#
# Copyright 2007 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#




"""Stubs for File service."""


import base64
import datetime
import hashlib
import os
import random
import string
import StringIO
import tempfile
import time

from google.appengine.api import apiproxy_stub
from google.appengine.api import datastore
from google.appengine.api import datastore_errors
from google.appengine.api import blobstore as api_blobstore
from google.appengine.api.blobstore import blobstore_stub
from google.appengine.api.files import blobstore as files_blobstore
from google.appengine.api.files import file as files
from google.appengine.api.files import file_service_pb
from google.appengine.api.files import gs
from google.appengine.ext import blobstore
from google.appengine.runtime import apiproxy_errors


MAX_REQUEST_SIZE = 32 << 20
GS_INFO_KIND = blobstore_stub._GS_INFO_KIND


_now_function = datetime.datetime.now


def _to_seconds(datetime_obj):
  return int(time.mktime(datetime_obj.timetuple()))


def _random_string(length):
  """Generate a random string of given length."""
  return ''.join(
      random.choice(string.letters + string.digits) for _ in range(length))


def raise_error(error_code, error_detail=''):
  """Raise application error helper method."""
  raise apiproxy_errors.ApplicationError(error_code, error_detail=error_detail)


_BLOBSTORE_DIRECTORY = files_blobstore._BLOBSTORE_DIRECTORY
_GS_PREFIX = gs._GS_PREFIX
_GS_UPLOAD_PREFIX = _GS_PREFIX + 'writable:'



class _GoogleStorageUpload(tuple):
  """Stores information about a writable Google Storage file."""
  buf = property(lambda self: self[0])
  content_type = property(lambda self: self[1])
  key = property(lambda self: self[2])


class GoogleStorage(object):
  """Virtual google storage to be used by file api."""



  def _Upload(self, buf, content_type, key):
    return _GoogleStorageUpload([buf, content_type, key])

  def __init__(self, blob_storage):
    """Constructor.

    Args:
      blob_storage:
          apphosting.api.blobstore.blobstore_stub.BlobStorage instance.
    """
    self.blob_storage = blob_storage
    self.uploads = {}
    self.finalized = set()
    self.sequence_keys = {}

  def has_upload(self, filename):
    """Checks if there is an upload at this filename."""
    return filename in self.uploads

  def finalize(self, filename):
    """Marks file as finalized."""
    upload = self.uploads[filename]
    self.finalized.add(filename)
    upload.buf.seek(0)
    self.blob_storage.StoreBlob(self.get_blob_key(upload.key), upload.buf)
    del self.sequence_keys[filename]


    encoded_key = blobstore.create_gs_key(upload.key)
    file_info = datastore.Entity(GS_INFO_KIND,
                                 name=encoded_key,
                                 namespace='')
    file_info['creation'] = _now_function()
    file_info['filename'] = upload.key
    file_info['size'] = upload.buf.len
    file_info['content_type'] = upload.content_type
    file_info['storage_key'] = self.get_blob_key(upload.key)
    datastore.Put(file_info)

  @staticmethod
  def get_blob_key(key):
    """Converts a Google Storage key into a base64 encoded blob key/filename."""
    return base64.urlsafe_b64encode(key)

  def is_finalized(self, filename):
    """Checks if file is already finalized."""
    assert filename in self.uploads
    return filename in self.finalized

  def start_upload(self, request):
    """Starts a new upload based on the specified CreateRequest."""

    mime_type = None
    gs_filename = request.filename()
    ignored_parameters = [
        gs._CACHE_CONTROL_PARAMETER,
        gs._CANNED_ACL_PARAMETER,
        gs._CONTENT_DISPOSITION_PARAMETER,
        gs._CONTENT_ENCODING_PARAMETER,
        ]

    for param in request.parameters_list():
      name = param.name()
      if name == gs._MIME_TYPE_PARAMETER:
        mime_type = param.value()
      elif (name in ignored_parameters or
            name.startswith(gs._USER_METADATA_PREFIX)):
        pass
      else:
        raise_error(file_service_pb.FileServiceErrors.INVALID_PARAMETER)

    if not mime_type:
      raise_error(file_service_pb.FileServiceErrors.INVALID_PARAMETER)
    elif not gs_filename:
      raise_error(file_service_pb.FileServiceErrors.INVALID_PARAMETER)

    random_str = ''.join(
        random.choice(string.ascii_uppercase + string.digits)
        for _ in range(64))
    writable_name = '%s%s' % (
        _GS_UPLOAD_PREFIX, base64.urlsafe_b64encode(random_str))
    self.uploads[writable_name] = self._Upload(
        StringIO.StringIO(), mime_type, gs_filename)
    self.sequence_keys[writable_name] = None


    datastore.Delete(
        datastore.Key.from_path(GS_INFO_KIND,
                                blobstore.create_gs_key(gs_filename),
                                namespace=''))
    return writable_name

  def append(self, filename, data, sequence_key):
    """Appends data to the upload filename."""
    assert not self.is_finalized(filename)
    if sequence_key:
      current_sequence_key = self.sequence_keys[filename]
      if current_sequence_key and current_sequence_key >= sequence_key:
        raise_error(file_service_pb.FileServiceErrors.SEQUENCE_KEY_OUT_OF_ORDER,
                    error_detail=current_sequence_key)
      self.sequence_keys[filename] = sequence_key
    self.uploads[filename].buf.write(data)

  def stat(self, filename):
    """
    Returns:
      file info for a finalized file with given filename
    """
    blob_key = blobstore.create_gs_key(filename)
    try:
      return datastore.Get(
          datastore.Key.from_path(GS_INFO_KIND, blob_key, namespace=''))
    except datastore_errors.EntityNotFoundError:
      raise raise_error(file_service_pb.FileServiceErrors.EXISTENCE_ERROR,
                        filename)

  def get_reader(self, filename):
    try:
      return self.blob_storage.OpenBlob(self.get_blob_key(filename))
    except IOError:
      return None

  def listdir(self, request, response):
    """listdir.

    Args:
      request: ListDir RPC request.
      response: ListDir RPC response.

    Returns:
      A list of fully qualified filenames under a certain path sorted by in
      char order.
    """
    path = request.path()
    prefix = request.prefix() if request.has_prefix() else ''

    q = datastore.Query(GS_INFO_KIND, namespace='')
    fully_qualified_name = '/'.join([path, prefix])
    if request.has_marker():
      q['filename >'] = '/'.join([path, request.marker()])
    else:
      q['filename >='] = fully_qualified_name

    if request.has_max_keys():
      max_keys = request.max_keys()
    else:
      max_keys = 2**31-1
    for gs_file_info in q.Get(max_keys):
      filename = gs_file_info['filename']
      if filename.startswith(fully_qualified_name):
        response.add_filenames(filename)
      else:
        break


class GoogleStorageFile(object):
  """File object for '/gs/' files."""





  def __init__(self, open_request, file_storage):
    self.filename = open_request.filename()
    self.file_storage = file_storage
    self.open_mode = open_request.open_mode()

    content_type = open_request.content_type()

    if self.is_appending:

      if not self.filename.startswith(_GS_UPLOAD_PREFIX):
        raise_error(file_service_pb.FileServiceErrors.INVALID_FILE_NAME)
      elif not self.file_storage.has_upload(self.filename):
        raise_error(file_service_pb.FileServiceErrors.EXISTENCE_ERROR)
      elif self.file_storage.is_finalized(self.filename):
        raise_error(file_service_pb.FileServiceErrors.FINALIZATION_ERROR,
                    'File is already finalized')
    else:

      if not self.filename.startswith(_GS_PREFIX):
        raise_error(file_service_pb.FileServiceErrors.INVALID_FILE_NAME)
      elif self.filename.startswith(_GS_UPLOAD_PREFIX):

        raise_error(file_service_pb.FileServiceErrors.INVALID_FILE_NAME)
      else:
        self.buf = self.file_storage.get_reader(self.filename)
        if not self.buf:
          raise_error(file_service_pb.FileServiceErrors.EXISTENCE_ERROR)

    if content_type != file_service_pb.FileContentType.RAW:
      raise_error(file_service_pb.FileServiceErrors.WRONG_CONTENT_TYPE)

  @property
  def is_appending(self):
    """Checks if the file is opened for appending or reading."""
    return self.open_mode == file_service_pb.OpenRequest.APPEND

  def stat(self, request, response):
    """Fill response with file stat.

    Current implementation only fills length, finalized, filename, and content
    type. File must be opened in read mode before stat is called.
    """
    file_info = self.file_storage.stat(self.filename)
    file_stat = response.add_stat()
    file_stat.set_filename(file_info['filename'])
    file_stat.set_finalized(True)
    file_stat.set_length(file_info['size'])
    file_stat.set_ctime(_to_seconds(file_info['creation']))
    file_stat.set_mtime(_to_seconds(file_info['creation']))
    file_stat.set_content_type(file_service_pb.FileContentType.RAW)
    response.set_more_files_found(False)

  def read(self, request, response):
    """Copies up to max_bytes starting at pos into response from filename."""
    if self.is_appending:
      raise_error(file_service_pb.FileServiceErrors.WRONG_OPEN_MODE)
    self.buf.seek(request.pos())
    data = self.buf.read(request.max_bytes())
    response.set_data(data)

  def append(self, request, response):
    """Appends data to filename."""
    if not self.is_appending:
      raise_error(file_service_pb.FileServiceErrors.WRONG_OPEN_MODE)
    self.file_storage.append(
        self.filename, request.data(), request.sequence_key())

  def finalize(self):
    """Finalize a file.

    Copies temp file data to permanent location for reading.
    """
    if not self.is_appending:
      raise_error(file_service_pb.FileServiceErrors.WRONG_OPEN_MODE)
    elif self.file_storage.is_finalized(self.filename):
      raise_error(
          file_service_pb.FileServiceErrors.FINALIZATION_ERROR,
          'File is already finalized')
    self.file_storage.finalize(self.filename)


class BlobstoreStorage(object):
  """Virtual file storage to be used by file api.

  Abstracts away all aspects of logical and physical file organization of the
  API.
  """

  def __init__(self, blob_storage):
    """Constructor.

    Args:
      blob_storage: An instance of
      apphosting.api.blobstore.blobstore_stub.BlobStorage to use for blob
      integration.
    """
    self.blob_keys = {}
    self.blobstore_files = set()
    self.finalized_files = set()
    self.created_files = set()
    self.data_files = {}
    self.sequence_keys = {}
    self.blob_storage = blob_storage



    self.blob_content_types = {}


    self.blob_file_names = {}

  def finalize(self, filename):
    """Marks file as finalized."""
    if self.is_finalized(filename):
      raise_error(file_service_pb.FileServiceErrors.FINALIZATION_ERROR,
                  'File is already finalized')
    self.finalized_files.add(filename)

  def is_finalized(self, filename):
    """Checks if file is already finalized."""
    return filename in self.finalized_files

  def get_blob_key(self, ticket):
    """Gets blob key for blob creation ticket."""
    return self.blob_keys.get(ticket)

  def register_blob_key(self, ticket, blob_key):
    """Register blob key for a ticket."""
    self.blob_keys[ticket] = blob_key

  def has_blobstore_file(self, filename):
    """Checks if blobstore file was already created."""
    return filename in self.blobstore_files

  def add_blobstore_file(self, request):
    """Registers a created blob store file."""

    mime_type = None
    blob_filename = ''
    for param in request.parameters_list():
      name = param.name()
      if name == files_blobstore._MIME_TYPE_PARAMETER:
        mime_type = param.value()
      elif name == files_blobstore._BLOBINFO_UPLOADED_FILENAME_PARAMETER:
        blob_filename = param.value()
      else:
        raise_error(file_service_pb.FileServiceErrors.INVALID_PARAMETER)
    if mime_type is None:
      raise_error(file_service_pb.FileServiceErrors.INVALID_PARAMETER)

    random_str = ''.join(
        random.choice(string.ascii_uppercase + string.digits)
        for _ in range(64))
    filename = (_BLOBSTORE_DIRECTORY +
                files._CREATION_HANDLE_PREFIX +
                base64.urlsafe_b64encode(random_str))
    self.blobstore_files.add(filename)
    self.blob_content_types[filename] = mime_type
    self.blob_file_names[filename] = blob_filename
    return filename

  def get_sequence_key(self, filename):
    """Get sequence key for a file."""
    return self.sequence_keys.get(filename, '')

  def set_sequence_key(self, filename, sequence_key):
    """Set sequence key for a file."""
    self.sequence_keys[filename] = sequence_key

  def stat(self, filename):
    """
    Returns:
      file info for a finalized file with given filename."""
    blob_key = files_blobstore.get_blob_key(filename)
    file_info = datastore.Get(
        datastore.Key.from_path(api_blobstore.BLOB_INFO_KIND, str(blob_key),
            namespace=''))
    if file_info == None:
      raise raise_error(
          file_service_pb.FileServiceErrors.EXISTENCE_ERROR_MEATADATA_NOT_FOUND,
          filename)
    return file_info

  def save_blob(self, filename, blob_key):
    """Save filename temp data to a blobstore under given key."""
    f = self._get_data_file(filename)
    f.seek(0)
    self.blob_storage.StoreBlob(blob_key, f)
    f.seek(0, os.SEEK_END)
    size = f.tell()
    f.close()
    del self.data_files[filename]
    return size

  def _get_data_file(self, filename):
    """Get a temp data file for a file."""
    if not filename in self.data_files:
      f = tempfile.TemporaryFile()
      self.data_files[filename] = f
      return f
    return self.data_files[filename]

  def get_md5_from_blob(self, blobkey):
    """Get md5 hexdigest of the blobfile with blobkey."""
    try:
      f = self.blob_storage.OpenBlob(blobkey)
      file_md5 = hashlib.md5()
      file_md5.update(f.read())
      return file_md5.hexdigest()
    finally:
      f.close()

  def append(self, filename, data):
    """Append data to file."""
    self._get_data_file(filename).write(data)

  def get_content_type(self, filename):
    return self.blob_content_types[filename]

  def get_blob_file_name(self, filename):
    return self.blob_file_names[filename]


class BlobstoreFile(object):
  """File object for generic /blobstore/ file."""

  def __init__(self, open_request, file_storage):
    """Constructor.

    Args:
      open_request: An instance of open file request.
      file_storage: An instance of BlobstoreStorage.
    """
    self.filename = open_request.filename()
    self.file_storage = file_storage
    self.blob_reader = None
    self.content_type = None
    self.mime_content_type = None

    open_mode = open_request.open_mode()
    content_type = open_request.content_type()

    if not self.filename.startswith(_BLOBSTORE_DIRECTORY):
      if not self.file_storage.has_blobstore_file(self.filename):
        raise_error(file_service_pb.FileServiceErrors.INVALID_FILE_NAME)

    self.ticket = self.filename[len(_BLOBSTORE_DIRECTORY):]

    if open_mode == file_service_pb.OpenRequest.APPEND:
      if not self.file_storage.has_blobstore_file(self.filename):
        raise_error(file_service_pb.FileServiceErrors.EXISTENCE_ERROR)

      if self.file_storage.is_finalized(self.filename):
        raise_error(file_service_pb.FileServiceErrors.FINALIZATION_ERROR,
                    'File is already finalized')

      self.mime_content_type = self.file_storage.get_content_type(self.filename)
      self.blob_file_name = self.file_storage.get_blob_file_name(self.filename)
    else:
      if self.ticket.startswith(files._CREATION_HANDLE_PREFIX):
        blobkey = self.file_storage.get_blob_key(self.ticket)
        if not blobkey:
          raise_error(file_service_pb.FileServiceErrors.FINALIZATION_ERROR,
                      'Blobkey not found.')
      else:
        blobkey = self.ticket

      blob_info = blobstore.BlobInfo.get(blobkey)

      if not blob_info:
        raise_error(file_service_pb.FileServiceErrors.FINALIZATION_ERROR,
                    'Blobinfo not found.')

      self.blob_reader = blobstore.BlobReader(blob_info)
      self.mime_content_type = blob_info.content_type

    if content_type != file_service_pb.FileContentType.RAW:
      raise_error(file_service_pb.FileServiceErrors.WRONG_CONTENT_TYPE)

  @property
  def is_appending(self):
    """Checks if the file is opened for appending or reading."""
    return self.blob_reader == None

  def stat(self, request, response):
    """Fill response with file stat.

    Current implementation only fills length, finalized, filename, and content
    type. File must be opened in read mode before stat is called.
    """
    file_info = self.file_storage.stat(self.filename)
    file_stat = response.add_stat()
    file_stat.set_filename(self.filename)
    file_stat.set_finalized(True)
    file_stat.set_length(file_info['size'])
    file_stat.set_ctime(_to_seconds(file_info['creation']))
    file_stat.set_mtime(_to_seconds(file_info['creation']))
    file_stat.set_content_type(file_service_pb.FileContentType.RAW)
    response.set_more_files_found(False)

  def read(self, request, response):
    """Read data from file

    Args:
      request: An instance of file_service_pb.ReadRequest.
      response: An instance of file_service_pb.ReadResponse.
    """
    if self.is_appending:
      raise_error(file_service_pb.FileServiceErrors.WRONG_OPEN_MODE)
    self.blob_reader.seek(request.pos())
    response.set_data(self.blob_reader.read(request.max_bytes()))

  def append(self, request, response):
    """Append data to file.

    Args:
      request: An instance of file_service_pb.AppendRequest.
      response: An instance of file_service_pb.AppendResponse.
    """
    sequence_key = request.sequence_key()

    if sequence_key:
      current_sequence_key = self.file_storage.get_sequence_key(self.filename)
      if current_sequence_key and current_sequence_key >= sequence_key:
        raise_error(file_service_pb.FileServiceErrors.SEQUENCE_KEY_OUT_OF_ORDER,
                    error_detail=current_sequence_key)
      self.file_storage.set_sequence_key(self.filename, sequence_key)
    self.file_storage.append(self.filename, request.data())

  def finalize(self):
    """Finalize a file.

    Copies temp file data to the blobstore.
    """
    self.file_storage.finalize(self.filename)
    blob_key = _random_string(64)
    self.file_storage.register_blob_key(self.ticket, blob_key)

    size = self.file_storage.save_blob(self.filename, blob_key)
    blob_info = datastore.Entity(api_blobstore.BLOB_INFO_KIND,
        name=str(blob_key), namespace='')
    blob_info['content_type'] = self.mime_content_type
    blob_info['creation'] = _now_function()
    blob_info['filename'] = self.blob_file_name
    blob_info['size'] = size
    blob_info['creation_handle'] = self.ticket
    blob_info['md5_hash'] = self.file_storage.get_md5_from_blob(blob_key)
    datastore.Put(blob_info)

    blob_file = datastore.Entity('__BlobFileIndex__',
                                 name=self.ticket,
                                 namespace='')
    blob_file['blob_key'] = str(blob_key)
    datastore.Put(blob_file)


class FileServiceStub(apiproxy_stub.APIProxyStub):
  """Python stub for file service."""

  def __init__(self, blob_storage):
    """Constructor."""
    super(FileServiceStub, self).__init__('file',
                                          max_request_size=MAX_REQUEST_SIZE)
    self.open_files = {}
    self.file_storage = BlobstoreStorage(blob_storage)
    self.gs_storage = GoogleStorage(blob_storage)

  def _Dynamic_Create(self, request, response):
    filesystem = request.filesystem()

    if request.has_filename() and filesystem != gs._GS_FILESYSTEM:
      raise_error(file_service_pb.FileServiceErrors.FILE_NAME_SPECIFIED)

    if filesystem == files_blobstore._BLOBSTORE_FILESYSTEM:
      response.set_filename(self.file_storage.add_blobstore_file(request))
    elif filesystem == gs._GS_FILESYSTEM:
      response.set_filename(self.gs_storage.start_upload(request))
    else:
      raise_error(file_service_pb.FileServiceErrors.UNSUPPORTED_FILE_SYSTEM)

  def _Dynamic_Open(self, request, response):
    """Handler for Open RPC call."""
    filename = request.filename()

    if request.exclusive_lock() and filename in self.open_files:
      raise_error(file_service_pb.FileServiceErrors.EXCLUSIVE_LOCK_FAILED)

    if filename.startswith(_BLOBSTORE_DIRECTORY):
      self.open_files[filename] = BlobstoreFile(request, self.file_storage)
    elif filename.startswith(_GS_PREFIX):
      self.open_files[filename] = GoogleStorageFile(request, self.gs_storage)
    else:
      raise_error(file_service_pb.FileServiceErrors.INVALID_FILE_NAME)

  def _Dynamic_Close(self, request, response):
    """Handler for Close RPC call."""
    filename = request.filename()
    finalize = request.finalize()

    if not filename in self.open_files:
      raise_error(file_service_pb.FileServiceErrors.FILE_NOT_OPENED)

    if finalize:
      self.open_files[filename].finalize()

    del self.open_files[filename]

  def _Dynamic_Stat(self, request, response):
    """Handler for Stat RPC call."""
    filename = request.filename()

    if not filename in self.open_files:
      raise_error(file_service_pb.FileServiceErrors.FILE_NOT_OPENED)

    file = self.open_files[filename]
    if file.is_appending:
      raise_error(file_service_pb.FileServiceErrors.WRONG_OPEN_MODE)
    file.stat(request, response)

  def _Dynamic_Read(self, request, response):
    """Handler for Read RPC call."""
    filename = request.filename()

    if not filename in self.open_files:
      raise_error(file_service_pb.FileServiceErrors.FILE_NOT_OPENED)

    self.open_files[filename].read(request, response)

  def _Dynamic_Append(self, request, response):
    """Handler for Append RPC call."""
    filename = request.filename()

    if not filename in self.open_files:
      raise_error(file_service_pb.FileServiceErrors.FILE_NOT_OPENED)

    self.open_files[filename].append(request, response)

  def _Dynamic_GetCapabilities(self, request, response):
    """Handler for GetCapabilities RPC call."""
    response.add_filesystem('blobstore')
    response.add_filesystem('gs')
    response.set_shuffle_available(False)

  def _Dynamic_GetDefaultGsBucketName(self, request, response):
    """Handler for GetDefaultGsBucketName RPC call."""
    response.set_default_gs_bucket_name('app_default_bucket')

  def _Dynamic_ListDir(self, request, response):
    """Handler for ListDir RPC call.

    Only for dev app server. See b/6761691.
    """
    path = request.path()
    if not path.startswith(_GS_PREFIX):
      raise_error(file_service_pb.FileServiceErrors.UNSUPPORTED_FILE_SYSTEM)
    self.gs_storage.listdir(request, response)
