import cStringIO as StringIO
import hashlib

from collections import defaultdict
from uuid import uuid4

from storage.basestorage import BaseStorageV2

_GLOBAL_FAKE_STORAGE_MAP = defaultdict(StringIO.StringIO)

class FakeStorage(BaseStorageV2):
  def __init__(self, context):
    super(FakeStorage, self).__init__()
    self._fake_storage_map = (defaultdict(StringIO.StringIO)
                              if context == 'local' else _GLOBAL_FAKE_STORAGE_MAP)

  def _init_path(self, path=None, create=False):
    return path

  def get_direct_download_url(self, path, request_ip=None, expires_in=60, requires_cors=False, head=False):
    try:
      if self.get_content('supports_direct_download') == 'true':
        return 'http://somefakeurl?goes=here'
    except:
      pass

    return None

  def get_content(self, path):
    if not path in self._fake_storage_map:
      raise IOError('Fake file %s not found. Exist: %s' % (path, self._fake_storage_map.keys()))

    self._fake_storage_map.get(path).seek(0)
    return self._fake_storage_map.get(path).read()

  def put_content(self, path, content):
    self._fake_storage_map.pop(path, None)
    self._fake_storage_map[path].write(content)

  def stream_read(self, path):
    io_obj = self._fake_storage_map[path]
    io_obj.seek(0)
    while True:
      buf = io_obj.read(self.buffer_size)
      if not buf:
        break
      yield buf

  def stream_read_file(self, path):
    return StringIO.StringIO(self.get_content(path))

  def stream_write(self, path, fp, content_type=None, content_encoding=None):
    out_fp = self._fake_storage_map[path]
    out_fp.seek(0)
    self.stream_write_to_fp(fp, out_fp)

  def remove(self, path):
    self._fake_storage_map.pop(path, None)

  def exists(self, path):
    if self._fake_storage_map.get('all_files_exist', None):
      return True
    return path in self._fake_storage_map

  def get_checksum(self, path):
    return hashlib.sha256(self._fake_storage_map[path].read()).hexdigest()[:7]

  def initiate_chunked_upload(self):
    new_uuid = str(uuid4())
    self._fake_storage_map[new_uuid].seek(0)
    return new_uuid, {}

  def stream_upload_chunk(self, uuid, offset, length, in_fp, _, content_type=None):
    upload_storage = self._fake_storage_map[uuid]
    try:
      return self.stream_write_to_fp(in_fp, upload_storage, length), {}, None
    except IOError as ex:
      return 0, {}, ex

  def complete_chunked_upload(self, uuid, final_path, _):
    self._fake_storage_map[final_path] = self._fake_storage_map[uuid]
    self._fake_storage_map.pop(uuid, None)

  def cancel_chunked_upload(self, uuid, _):
    self._fake_storage_map.pop(uuid, None)

  def copy_to(self, destination, path):
    if self.exists('break_copying'):
      raise IOError('Broken!')

    if self.exists('fake_copying'):
      return

    if self.exists('except_copying'):
      raise Exception("I'm an exception!")

    content = self.get_content(path)
    destination.put_content(path, content)