"""Fallback pure Python implementation of msgpack"""

import sys
import struct
import warnings

if sys.version_info[0] == 3:
    PY3 = True
    int_types = int
    Unicode = str
    xrange = range
    def dict_iteritems(d):
        return d.items()
else:
    PY3 = False
    int_types = (int, long)
    Unicode = unicode
    def dict_iteritems(d):
        return d.iteritems()


if hasattr(sys, 'pypy_version_info'):
    # cStringIO is slow on PyPy, StringIO is faster.  However: PyPy's own
    # StringBuilder is fastest.
    from __pypy__ import newlist_hint
    try:
        from __pypy__.builders import BytesBuilder as StringBuilder
    except ImportError:
        from __pypy__.builders import StringBuilder
    USING_STRINGBUILDER = True
    class StringIO(object):
        def __init__(self, s=b''):
            if s:
                self.builder = StringBuilder(len(s))
                self.builder.append(s)
            else:
                self.builder = StringBuilder()
        def write(self, s):
            if isinstance(s, memoryview):
                s = s.tobytes()
            elif isinstance(s, bytearray):
                s = bytes(s)
            self.builder.append(s)
        def getvalue(self):
            return self.builder.build()
else:
    USING_STRINGBUILDER = False
    from io import BytesIO as StringIO
    newlist_hint = lambda size: []


from msgpack.exceptions import (
    BufferFull,
    OutOfData,
    UnpackValueError,
    PackValueError,
    PackOverflowError,
    ExtraData)

from msgpack import ExtType


EX_SKIP                 = 0
EX_CONSTRUCT            = 1
EX_READ_ARRAY_HEADER    = 2
EX_READ_MAP_HEADER      = 3

TYPE_IMMEDIATE          = 0
TYPE_ARRAY              = 1
TYPE_MAP                = 2
TYPE_RAW                = 3
TYPE_BIN                = 4
TYPE_EXT                = 5

DEFAULT_RECURSE_LIMIT = 511


def _check_type_strict(obj, t, type=type, tuple=tuple):
    if type(t) is tuple:
        return type(obj) in t
    else:
        return type(obj) is t


def _get_data_from_buffer(obj):
    try:
        view = memoryview(obj)
    except TypeError:
        # try to use legacy buffer protocol if 2.7, otherwise re-raise
        if not PY3:
            view = memoryview(buffer(obj))
            warnings.warn("using old buffer interface to unpack %s; "
                          "this leads to unpacking errors if slicing is used and "
                          "will be removed in a future version" % type(obj),
                          RuntimeWarning)
        else:
            raise
    if view.itemsize != 1:
        raise ValueError("cannot unpack from multi-byte object")
    return view


def unpack(stream, **kwargs):
    warnings.warn(
        "Direct calling implementation's unpack() is deprecated, Use msgpack.unpack() or unpackb() instead.",
        PendingDeprecationWarning)
    data = stream.read()
    return unpackb(data, **kwargs)


def unpackb(packed, **kwargs):
    """
    Unpack an object from `packed`.

    Raises `ExtraData` when `packed` contains extra bytes.
    See :class:`Unpacker` for options.
    """
    unpacker = Unpacker(None, **kwargs)
    unpacker.feed(packed)
    try:
        ret = unpacker._unpack()
    except OutOfData:
        raise UnpackValueError("Data is not enough.")
    if unpacker._got_extradata():
        raise ExtraData(ret, unpacker._get_extradata())
    return ret


class Unpacker(object):
    """Streaming unpacker.

    arguments:

    :param file_like:
        File-like object having `.read(n)` method.
        If specified, unpacker reads serialized data from it and :meth:`feed()` is not usable.

    :param int read_size:
        Used as `file_like.read(read_size)`. (default: `min(16*1024, max_buffer_size)`)

    :param bool use_list:
        If true, unpack msgpack array to Python list.
        Otherwise, unpack to Python tuple. (default: True)

    :param bool raw:
        If true, unpack msgpack raw to Python bytes (default).
        Otherwise, unpack to Python str (or unicode on Python 2) by decoding
        with UTF-8 encoding (recommended).
        Currently, the default is true, but it will be changed to false in
        near future.  So you must specify it explicitly for keeping backward
        compatibility.

        *encoding* option which is deprecated overrides this option.

    :param callable object_hook:
        When specified, it should be callable.
        Unpacker calls it with a dict argument after unpacking msgpack map.
        (See also simplejson)

    :param callable object_pairs_hook:
        When specified, it should be callable.
        Unpacker calls it with a list of key-value pairs after unpacking msgpack map.
        (See also simplejson)

    :param str encoding:
        Encoding used for decoding msgpack raw.
        If it is None (default), msgpack raw is deserialized to Python bytes.

    :param str unicode_errors:
        (deprecated) Used for decoding msgpack raw with *encoding*.
        (default: `'strict'`)

    :param int max_buffer_size:
        Limits size of data waiting unpacked.  0 means system's INT_MAX (default).
        Raises `BufferFull` exception when it is insufficient.
        You should set this parameter when unpacking data from untrusted source.

    :param int max_str_len:
        Limits max length of str. (default: 2**31-1)

    :param int max_bin_len:
        Limits max length of bin. (default: 2**31-1)

    :param int max_array_len:
        Limits max length of array. (default: 2**31-1)

    :param int max_map_len:
        Limits max length of map. (default: 2**31-1)


    example of streaming deserialize from file-like object::

        unpacker = Unpacker(file_like, raw=False)
        for o in unpacker:
            process(o)

    example of streaming deserialize from socket::

        unpacker = Unpacker(raw=False)
        while True:
            buf = sock.recv(1024**2)
            if not buf:
                break
            unpacker.feed(buf)
            for o in unpacker:
                process(o)
    """

    def __init__(self, file_like=None, read_size=0, use_list=True, raw=True,
                 object_hook=None, object_pairs_hook=None, list_hook=None,
                 encoding=None, unicode_errors=None, max_buffer_size=0,
                 ext_hook=ExtType,
                 max_str_len=2147483647, # 2**32-1
                 max_bin_len=2147483647,
                 max_array_len=2147483647,
                 max_map_len=2147483647,
                 max_ext_len=2147483647):

        if encoding is not None:
            warnings.warn(
                "encoding is deprecated, Use raw=False instead.",
                PendingDeprecationWarning)

        if unicode_errors is None:
            unicode_errors = 'strict'

        if file_like is None:
            self._feeding = True
        else:
            if not callable(file_like.read):
                raise TypeError("`file_like.read` must be callable")
            self.file_like = file_like
            self._feeding = False

        #: array of bytes fed.
        self._buffer = bytearray()
        #: Which position we currently reads
        self._buff_i = 0

        # When Unpacker is used as an iterable, between the calls to next(),
        # the buffer is not "consumed" completely, for efficiency sake.
        # Instead, it is done sloppily.  To make sure we raise BufferFull at
        # the correct moments, we have to keep track of how sloppy we were.
        # Furthermore, when the buffer is incomplete (that is: in the case
        # we raise an OutOfData) we need to rollback the buffer to the correct
        # state, which _buf_checkpoint records.
        self._buf_checkpoint = 0

        self._max_buffer_size = max_buffer_size or 2**31-1
        if read_size > self._max_buffer_size:
            raise ValueError("read_size must be smaller than max_buffer_size")
        self._read_size = read_size or min(self._max_buffer_size, 16*1024)
        self._raw = bool(raw)
        self._encoding = encoding
        self._unicode_errors = unicode_errors
        self._use_list = use_list
        self._list_hook = list_hook
        self._object_hook = object_hook
        self._object_pairs_hook = object_pairs_hook
        self._ext_hook = ext_hook
        self._max_str_len = max_str_len
        self._max_bin_len = max_bin_len
        self._max_array_len = max_array_len
        self._max_map_len = max_map_len
        self._max_ext_len = max_ext_len
        self._stream_offset = 0

        if list_hook is not None and not callable(list_hook):
            raise TypeError('`list_hook` is not callable')
        if object_hook is not None and not callable(object_hook):
            raise TypeError('`object_hook` is not callable')
        if object_pairs_hook is not None and not callable(object_pairs_hook):
            raise TypeError('`object_pairs_hook` is not callable')
        if object_hook is not None and object_pairs_hook is not None:
            raise TypeError("object_pairs_hook and object_hook are mutually "
                            "exclusive")
        if not callable(ext_hook):
            raise TypeError("`ext_hook` is not callable")

    def feed(self, next_bytes):
        assert self._feeding
        view = _get_data_from_buffer(next_bytes)
        if (len(self._buffer) - self._buff_i + len(view) > self._max_buffer_size):
            raise BufferFull

        # Strip buffer before checkpoint before reading file.
        if self._buf_checkpoint > 0:
            del self._buffer[:self._buf_checkpoint]
            self._buff_i -= self._buf_checkpoint
            self._buf_checkpoint = 0

        self._buffer += view

    def _consume(self):
        """ Gets rid of the used parts of the buffer. """
        self._stream_offset += self._buff_i - self._buf_checkpoint
        self._buf_checkpoint = self._buff_i

    def _got_extradata(self):
        return self._buff_i < len(self._buffer)

    def _get_extradata(self):
        return self._buffer[self._buff_i:]

    def read_bytes(self, n):
        return self._read(n)

    def _read(self, n):
        # (int) -> bytearray
        self._reserve(n)
        i = self._buff_i
        self._buff_i = i+n
        return self._buffer[i:i+n]

    def _reserve(self, n):
        remain_bytes = len(self._buffer) - self._buff_i - n

        # Fast path: buffer has n bytes already
        if remain_bytes >= 0:
            return

        if self._feeding:
            self._buff_i = self._buf_checkpoint
            raise OutOfData

        # Strip buffer before checkpoint before reading file.
        if self._buf_checkpoint > 0:
            del self._buffer[:self._buf_checkpoint]
            self._buff_i -= self._buf_checkpoint
            self._buf_checkpoint = 0

        # Read from file
        remain_bytes = -remain_bytes
        while remain_bytes > 0:
            to_read_bytes = max(self._read_size, remain_bytes)
            read_data = self.file_like.read(to_read_bytes)
            if not read_data:
                break
            assert isinstance(read_data, bytes)
            self._buffer += read_data
            remain_bytes -= len(read_data)

        if len(self._buffer) < n + self._buff_i:
            self._buff_i = 0  # rollback
            raise OutOfData