# Copyright 2012 Pinterest.com
#
# 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.

from functools import partial
import logging
from io import BytesIO
import six
from six.moves import cPickle as pickle

try:
    long_type = long  # noqa
except NameError:
    long_type = None


FLAG_BYTES = 0
FLAG_PICKLE = 1 << 0
FLAG_INTEGER = 1 << 1
FLAG_LONG = 1 << 2
FLAG_COMPRESSED = 1 << 3  # unused, to main compatibility with python-memcached
FLAG_TEXT = 1 << 4

# Pickle protocol version (highest available to runtime)
# Warning with `0`: If somewhere in your value lies a slotted object,
# ie defines `__slots__`, even if you do not include it in your pickleable
# state via `__getstate__`, python will complain with something like:
#   TypeError: a class that defines __slots__ without defining __getstate__
#   cannot be pickled
DEFAULT_PICKLE_VERSION = pickle.HIGHEST_PROTOCOL


def _python_memcache_serializer(key, value, pickle_version=None):
    flags = 0
    value_type = type(value)

    # Check against exact types so that subclasses of native types will be
    # restored as their native type
    if value_type is bytes:
        pass

    elif value_type is six.text_type:
        flags |= FLAG_TEXT
        value = value.encode('utf8')

    elif value_type is int:
        flags |= FLAG_INTEGER
        value = "%d" % value

    elif six.PY2 and value_type is long_type:
        flags |= FLAG_LONG
        value = "%d" % value

    else:
        flags |= FLAG_PICKLE
        output = BytesIO()
        pickler = pickle.Pickler(output, pickle_version)
        pickler.dump(value)
        value = output.getvalue()

    return value, flags


def get_python_memcache_serializer(pickle_version=DEFAULT_PICKLE_VERSION):
    """Return a serializer using a specific pickle version"""
    return partial(_python_memcache_serializer, pickle_version=pickle_version)


python_memcache_serializer = get_python_memcache_serializer()


def python_memcache_deserializer(key, value, flags):
    if flags == 0:
        return value

    elif flags & FLAG_TEXT:
        return value.decode('utf8')

    elif flags & FLAG_INTEGER:
        return int(value)

    elif flags & FLAG_LONG:
        if six.PY3:
            return int(value)
        else:
            return long_type(value)

    elif flags & FLAG_PICKLE:
        try:
            buf = BytesIO(value)
            unpickler = pickle.Unpickler(buf)
            return unpickler.load()
        except Exception:
            logging.info('Pickle error', exc_info=True)
            return None

    return value
