# coding: utf-8

from cpython cimport *

cdef extern from "Python.h":
    ctypedef struct PyObject
    cdef int PyObject_AsReadBuffer(object o, const void** buff, Py_ssize_t* buf_len) except -1
    object PyMemoryView_GetContiguous(object obj, int buffertype, char order)

from libc.stdlib cimport *
from libc.string cimport *
from libc.limits cimport *
ctypedef unsigned long long uint64_t

from .exceptions import (
    BufferFull,
    OutOfData,
    ExtraData,
    FormatError,
    StackError,
)
from ._ext_type import ExtType
from .util import ensure_bytes


cdef extern from "unpack.h":
    ctypedef struct msgpack_user:
        bint use_list
        bint raw
        bint has_pairs_hook # call object_hook with k-v pairs
        bint strict_map_key
        PyObject* object_hook
        PyObject* list_hook
        PyObject* ext_hook
        char *encoding
        char *unicode_errors
        Py_ssize_t max_str_len
        Py_ssize_t max_bin_len
        Py_ssize_t max_array_len
        Py_ssize_t max_map_len
        Py_ssize_t max_ext_len

    ctypedef struct unpack_context:
        msgpack_user user
        PyObject* obj
        Py_ssize_t count

    ctypedef int (*execute_fn)(unpack_context* ctx, const char* data,
                               Py_ssize_t len, Py_ssize_t* off) except? -1
    execute_fn unpack_construct
    execute_fn unpack_skip
    execute_fn read_array_header
    execute_fn read_map_header
    void unpack_init(unpack_context* ctx)
    object unpack_data(unpack_context* ctx)
    void unpack_clear(unpack_context* ctx)

cdef inline init_ctx(unpack_context *ctx,
                     object object_hook, object object_pairs_hook,
                     object list_hook, object ext_hook,
                     bint use_list, bint raw, bint strict_map_key,
                     const char* encoding, const char* unicode_errors,
                     Py_ssize_t max_str_len, Py_ssize_t max_bin_len,
                     Py_ssize_t max_array_len, Py_ssize_t max_map_len,
                     Py_ssize_t max_ext_len):
    unpack_init(ctx)
    ctx.user.use_list = use_list
    ctx.user.raw = raw
    ctx.user.strict_map_key = strict_map_key
    ctx.user.object_hook = ctx.user.list_hook = <PyObject*>NULL
    ctx.user.max_str_len = max_str_len
    ctx.user.max_bin_len = max_bin_len
    ctx.user.max_array_len = max_array_len
    ctx.user.max_map_len = max_map_len
    ctx.user.max_ext_len = max_ext_len

    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 object_hook is not None:
        if not PyCallable_Check(object_hook):
            raise TypeError("object_hook must be a callable.")
        ctx.user.object_hook = <PyObject*>object_hook

    if object_pairs_hook is None:
        ctx.user.has_pairs_hook = False
    else:
        if not PyCallable_Check(object_pairs_hook):
            raise TypeError("object_pairs_hook must be a callable.")
        ctx.user.object_hook = <PyObject*>object_pairs_hook
        ctx.user.has_pairs_hook = True

    if list_hook is not None:
        if not PyCallable_Check(list_hook):
            raise TypeError("list_hook must be a callable.")
        ctx.user.list_hook = <PyObject*>list_hook

    if ext_hook is not None:
        if not PyCallable_Check(ext_hook):
            raise TypeError("ext_hook must be a callable.")
        ctx.user.ext_hook = <PyObject*>ext_hook

    ctx.user.encoding = encoding
    ctx.user.unicode_errors = unicode_errors

def default_read_extended_type(typecode, data):
    raise NotImplementedError("Cannot decode extended type with typecode=%d" % typecode)

cdef inline int get_data_from_buffer(object obj,
                                     Py_buffer *view,
                                     char **buf,
                                     Py_ssize_t *buffer_len,
                                     int *new_protocol) except 0:
    cdef object contiguous
    cdef Py_buffer tmp
    if PyObject_CheckBuffer(obj):
        new_protocol[0] = 1
        if PyObject_GetBuffer(obj, view, PyBUF_FULL_RO) == -1:
            raise
        if view.itemsize != 1:
            PyBuffer_Release(view)
            raise BufferError("cannot unpack from multi-byte object")
        if PyBuffer_IsContiguous(view, b'A') == 0:
            PyBuffer_Release(view)
            # create a contiguous copy and get buffer
            contiguous = PyMemoryView_GetContiguous(obj, PyBUF_READ, b'C')
            PyObject_GetBuffer(contiguous, view, PyBUF_SIMPLE)
            # view must hold the only reference to contiguous,
            # so memory is freed when view is released
            Py_DECREF(contiguous)
        buffer_len[0] = view.len
        buf[0] = <char*> view.buf
        return 1
    else:
        new_protocol[0] = 0
        if PyObject_AsReadBuffer(obj, <const void**> buf, buffer_len) == -1:
            raise BufferError("could not get memoryview")
        PyErr_WarnEx(RuntimeWarning,
                     "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),
                     1)
        return 1

cdef Py_ssize_t MAX_LENGTH = 2**32 -1

def unpackb(object packed, object object_hook=None, object list_hook=None,
            bint use_list=True, bint raw=True, bint strict_map_key=False,
            encoding=None, unicode_errors=None,
            object_pairs_hook=None, ext_hook=ExtType,
            Py_ssize_t max_str_len=MAX_LENGTH,
            Py_ssize_t max_bin_len=MAX_LENGTH,
            Py_ssize_t max_array_len=MAX_LENGTH,
            Py_ssize_t max_map_len=MAX_LENGTH,
            Py_ssize_t max_ext_len=MAX_LENGTH):
    """
    Unpack packed_bytes to object. Returns an unpacked object.

    Raises ``ExtraData`` when *packed* contains extra bytes.
    Raises ``ValueError`` when *packed* is incomplete.
    Raises ``FormatError`` when *packed* is not valid msgpack.
    Raises ``StackError`` when *packed* contains too nested.
    Other exceptions can be raised during unpacking.

    See :class:`Unpacker` for options.
    """
    cdef unpack_context ctx
    cdef Py_ssize_t off = 0
    cdef int ret

    cdef Py_buffer view
    cdef char* buf = NULL
    cdef Py_ssize_t buf_len
    cdef const char* cenc = NULL
    cdef const char* cerr = NULL
    cdef int new_protocol = 0

    if encoding is not None:
        encoding = ensure_bytes(encoding)
        cenc = encoding

    if unicode_errors is not None:
        unicode_errors = ensure_bytes(unicode_errors)
        cerr = unicode_errors

    get_data_from_buffer(packed, &view, &buf, &buf_len, &new_protocol)
    try:
        init_ctx(&ctx, object_hook, object_pairs_hook, list_hook, ext_hook,
                 use_list, raw, strict_map_key, cenc, cerr,
                 max_str_len, max_bin_len, max_array_len, max_map_len, max_ext_len)
        ret = unpack_construct(&ctx, buf, buf_len, &off)
    finally:
        if new_protocol:
            PyBuffer_Release(&view);

    if ret == 1:
        obj = unpack_data(&ctx)
        if off < buf_len:
            raise ExtraData(obj, PyBytes_FromStringAndSize(buf+off, buf_len-off))
        return obj
    unpack_clear(&ctx)
    if ret == 0:
        raise ValueError("Unpack failed: incomplete input")
    elif ret == -2:
        raise FormatError
    elif ret == -3:
        raise StackError
    raise ValueError("Unpack failed: error = %d" % (ret,))


def unpack(object stream, **kwargs):
    data = stream.read()
    return unpackb(data, **kwargs)


cdef 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(1024**2, 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 bool strict_map_key:
        If true, only str or bytes are accepted for map (dict) keys.
        It's False by default for backward-compatibility.
        But it will be True from msgpack 1.0.

    :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 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: 1024*1024)

    :param int max_bin_len:
        Limits max length of bin. (default: 1024*1024)

    :param int max_array_len:
        Limits max length of array. (default: 128*1024)

    :param int max_map_len:
        Limits max length of map. (default: 32*1024)

    :param int max_ext_len:
        Limits max length of map. (default: 1024*1024)

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

    :param str unicode_errors:
        Error handler used for decoding str type.  (default: `'strict'`)


    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)

    Raises ``ExtraData`` when *packed* contains extra bytes.
    Raises ``OutOfData`` when *packed* is incomplete.
    Raises ``FormatError`` when *packed* is not valid msgpack.
    Raises ``StackError`` when *packed* contains too nested.
    Other exceptions can be raised during unpacking.
    """
    cdef unpack_context ctx
    cdef char* buf
    cdef Py_ssize_t buf_size, buf_head, buf_tail
    cdef object file_like
    cdef object file_like_read
    cdef Py_ssize_t read_size
    # To maintain refcnt.
    cdef object object_hook, object_pairs_hook, list_hook, ext_hook
    cdef object encoding, unicode_errors
    cdef Py_ssize_t max_buffer_size
    cdef uint64_t stream_offset

    def __cinit__(self):
        self.buf = NULL

    def __dealloc__(self):
        PyMem_Free(self.buf)
        self.buf = NULL

    def __init__(self, file_like=None, Py_ssize_t read_size=0,
                 bint use_list=True, bint raw=True, bint strict_map_key=False,
                 object object_hook=None, object object_pairs_hook=None, object list_hook=None,
                 encoding=None, unicode_errors=None, Py_ssize_t max_buffer_size=0,
                 object ext_hook=ExtType,
                 Py_ssize_t max_str_len=1024*1024,
                 Py_ssize_t max_bin_len=1024*1024,
                 Py_ssize_t max_array_len=128*1024,
                 Py_ssize_t max_map_len=32*1024,
                 Py_ssize_t max_ext_len=1024*1024):
        cdef const char *cenc=NULL,
        cdef const char *cerr=NULL

        self.object_hook = object_hook
        self.object_pairs_hook = object_pairs_hook
        self.list_hook = list_hook
        self.ext_hook = ext_hook

        self.file_like = file_like
        if file_like:
            self.file_like_read = file_like.read
            if not PyCallable_Check(self.file_like_read):
                raise TypeError("`file_like.read` must be a callable.")
        if not max_buffer_size:
            max_buffer_size = INT_MAX
        if read_size > max_buffer_size:
            raise ValueError("read_size should be less or equal to max_buffer_size")
        if not read_size:
            read_size = min(max_buffer_size, 1024**2)
        self.max_buffer_size = max_buffer_size
        self.read_size = read_size
        self.buf = <char*>PyMem_Malloc(read_size)
        if self.buf == NULL:
            raise MemoryError("Unable to allocate internal buffer.")
        self.buf_size = read_size
        self.buf_head = 0
        self.buf_tail = 0
        self.stream_offset = 0

        if encoding is not None:
            encoding = ensure_bytes(encoding)
            self.encoding = encoding
            cenc = encoding

        if unicode_errors is not None:
            unicode_errors = ensure_bytes(unicode_errors)
            self.unicode_errors = unicode_errors
            cerr = unicode_errors

        init_ctx(&self.ctx, object_hook, object_pairs_hook, list_hook,
                 ext_hook, use_list, raw, strict_map_key, cenc, cerr,
                 max_str_len, max_bin_len, max_array_len,
                 max_map_len, max_ext_len)

    def feed(self, object next_bytes):
        """Append `next_bytes` to internal buffer."""
        cdef Py_buffer pybuff
        cdef int new_protocol = 0
        cdef char* buf
        cdef Py_ssize_t buf_len

        if self.file_like is not None:
            raise AssertionError(
                    "unpacker.feed() is not be able to use with `file_like`.")

        get_data_from_buffer(next_bytes, &pybuff, &buf, &buf_len, &new_protocol)
        try:
            self.append_buffer(buf, buf_len)
        finally:
            if new_protocol:
                PyBuffer_Release(&pybuff)

    cdef append_buffer(self, void* _buf, Py_ssize_t _buf_len):
        cdef:
            char* buf = self.buf
            char* new_buf
            Py_ssize_t head = self.buf_head
            Py_ssize_t tail = self.buf_tail
            Py_ssize_t buf_size = self.buf_size
            Py_ssize_t new_size

        if tail + _buf_len > buf_size:
            if ((tail - head) + _buf_len) <= buf_size:
                # move to front.
                memmove(buf, buf + head, tail - head)
                tail -= head
                head = 0
            else:
                # expand buffer.
                new_size = (tail-head) + _buf_len
                if new_size > self.max_buffer_size:
                    raise BufferFull
                new_size = min(new_size*2, self.max_buffer_size)
                new_buf = <char*>PyMem_Malloc(new_size)
                if new_buf == NULL:
                    # self.buf still holds old buffer and will be freed during
                    # obj destruction
                    raise MemoryError("Unable to enlarge internal buffer.")
                memcpy(new_buf, buf + head, tail - head)
                PyMem_Free(buf)

                buf = new_buf
                buf_size = new_size
                tail -= head
                head = 0

        memcpy(buf + tail, <char*>(_buf), _buf_len)
        self.buf = buf
        self.buf_head = head
        self.buf_size = buf_size
        self.buf_tail = tail + _buf_len

    cdef read_from_file(self):
        next_bytes = self.file_like_read(
                min(self.read_size,
                    self.max_buffer_size - (self.buf_tail - self.buf_head)
                    ))
        if next_bytes:
            self.append_buffer(PyBytes_AsString(next_bytes), PyBytes_Size(next_bytes))
        else:
            self.file_like = None

    cdef object _unpack(self, execute_fn execute, bint iter=0):
        cdef int ret
        cdef object obj
        cdef Py_ssize_t prev_head

        if self.buf_head >= self.buf_tail and self.file_like is not None:
            self.read_from_file()

        while 1:
            prev_head = self.buf_head
            if prev_head >= self.buf_tail:
                if iter:
                    raise StopIteration("No more data to unpack.")
                else:
                    raise OutOfData("No more data to unpack.")

            ret = execute(&self.ctx, self.buf, self.buf_tail, &self.buf_head)
            self.stream_offset += self.buf_head - prev_head

            if ret == 1:
                obj = unpack_data(&self.ctx)
                unpack_init(&self.ctx)
                return obj
            elif ret == 0:
                if self.file_like is not None:
                    self.read_from_file()
                    continue
                if iter:
                    raise StopIteration("No more data to unpack.")
                else:
                    raise OutOfData("No more data to unpack.")
            elif ret == -2:
                raise FormatError
            elif ret == -3:
                raise StackError
            else:
                raise ValueError("Unpack failed: error = %d" % (ret,))

    def read_bytes(self, Py_ssize_t nbytes):
        """Read a specified number of raw bytes from the stream"""
        cdef Py_ssize_t nread
        nread = min(self.buf_tail - self.buf_head, nbytes)
        ret = PyBytes_FromStringAndSize(self.buf + self.buf_head, nread)
        self.buf_head += nread
        if len(ret) < nbytes and self.file_like is not None:
            ret += self.file_like.read(nbytes - len(ret))
        return ret

    def unpack(self):
        """Unpack one object

        Raises `OutOfData` when there are no more bytes to unpack.
        """
        return self._unpack(unpack_construct)

    def skip(self):
        """Read and ignore one object, returning None

        Raises `OutOfData` when there are no more bytes to unpack.
        """
        return self._unpack(unpack_skip)

    def read_array_header(self):
        """assuming the next object is an array, return its size n, such that
        the next n unpack() calls will iterate over its contents.

        Raises `OutOfData` when there are no more bytes to unpack.
        """
        return self._unpack(read_array_header)

    def read_map_header(self):
        """assuming the next object is a map, return its size n, such that the
        next n * 2 unpack() calls will iterate over its key-value pairs.

        Raises `OutOfData` when there are no more bytes to unpack.
        """
        return self._unpack(read_map_header)

    def tell(self):
        return self.stream_offset

    def __iter__(self):
        return self

    def __next__(self):
        return self._unpack(unpack_construct, 1)

    # for debug.
    #def _buf(self):
    #    return PyString_FromStringAndSize(self.buf, self.buf_tail)

    #def _off(self):
    #    return self.buf_head