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# to you 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.

"""Register backend ops in mxnet.ndarray namespace"""
from __future__ import absolute_import
import os as _os
import ctypes
import numpy as _np  # pylint: disable=unused-import

from ._internal import NDArrayBase, _imperative_invoke # pylint: disable=unused-import
from ..ndarray_doc import _build_doc

from ..base import mx_uint, check_call, _LIB, py_str, _init_op_module, _Null # pylint: disable=unused-import


# pylint: disable=too-many-locals
def _generate_ndarray_function_code(handle, name, func_name, signature_only=False):
    """Generate function for ndarray op by handle and function name."""
    real_name = ctypes.c_char_p()
    desc = ctypes.c_char_p()
    num_args = mx_uint()
    arg_names = ctypes.POINTER(ctypes.c_char_p)()
    arg_types = ctypes.POINTER(ctypes.c_char_p)()
    arg_descs = ctypes.POINTER(ctypes.c_char_p)()
    key_var_num_args = ctypes.c_char_p()
    ret_type = ctypes.c_char_p()

    check_call(_LIB.MXSymbolGetAtomicSymbolInfo(
        handle, ctypes.byref(real_name), ctypes.byref(desc),
        ctypes.byref(num_args),
        ctypes.byref(arg_names),
        ctypes.byref(arg_types),
        ctypes.byref(arg_descs),
        ctypes.byref(key_var_num_args),
        ctypes.byref(ret_type)))
    narg = int(num_args.value)
    arg_names = [py_str(arg_names[i]) for i in range(narg)]
    arg_types = [py_str(arg_types[i]) for i in range(narg)]
    key_var_num_args = py_str(key_var_num_args.value)
    ret_type = py_str(ret_type.value) if ret_type.value is not None else ''
    doc_str = _build_doc(name,
                         py_str(desc.value),
                         arg_names,
                         arg_types,
                         [py_str(arg_descs[i]) for i in range(narg)],
                         key_var_num_args,
                         ret_type)

    dtype_name = None
    arr_name = None
    ndsignature = []
    signature = []
    ndarg_names = []
    kwarg_names = []
    for i in range(narg):
        name, atype = arg_names[i], arg_types[i]
        if name == 'dtype':
            dtype_name = name
            signature.append('%s=_Null'%name)
        elif atype.startswith('NDArray') or atype.startswith('Symbol'):
            assert not arr_name, \
                "Op can only have one argument with variable " \
                "size and it must be the last argument."
            if atype.endswith('[]'):
                ndsignature.append('*%s'%name)
                arr_name = name
            else:
                ndsignature.append('%s=None'%name)
                ndarg_names.append(name)
        else:
            signature.append('%s=_Null'%name)
            kwarg_names.append(name)
    signature.append('out=None')
    signature.append('name=None')
    signature.append('**kwargs')
    signature = ndsignature + signature

    code = []
    if arr_name:
        code.append("""
def %s(*%s, **kwargs):"""%(func_name, arr_name))
        if not signature_only:
            code.append("""
    ndargs = []
    for i in {}:
        assert isinstance(i, NDArrayBase), \\
            "Positional arguments must have NDArray type, " \\
            "but got %s"%str(i)
        ndargs.append(i)""".format(arr_name))
            if dtype_name is not None:
                code.append("""
    if '%s' in kwargs:
        kwargs['%s'] = _np.dtype(kwargs['%s']).name"""%(
            dtype_name, dtype_name, dtype_name))
            code.append("""
    _ = kwargs.pop('name', None)
    out = kwargs.pop('out', None)
    keys = list(kwargs.keys())
    vals = list(kwargs.values())""")
    else:
        code.append("""
def %s(%s):"""%(func_name, ', '.join(signature)))
        if not signature_only:
            code.append("""
    ndargs = []
    keys = list(kwargs.keys())
    vals = list(kwargs.values())""")
            # NDArray args
            for name in ndarg_names: # pylint: disable=redefined-argument-from-local
                code.append("""
    if {name} is not None:
        assert isinstance({name}, NDArrayBase), \\
            "Argument {name} must have NDArray type, but got %s"%str({name})
        ndargs.append({name})""".format(name=name))
            # kwargs
            for name in kwarg_names: # pylint: disable=redefined-argument-from-local
                code.append("""
    if %s is not _Null:
        keys.append('%s')
        vals.append(%s)"""%(name, name, name))
            # dtype
            if dtype_name is not None:
                code.append("""
    if %s is not _Null:
        keys.append('%s')
        vals.append(_np.dtype(%s).name)"""%(dtype_name, dtype_name, dtype_name))

    if not signature_only:
        code.append("""
    return _imperative_invoke(%d, ndargs, keys, vals, out)"""%(
        handle.value))
    else:
        code.append("""
    return (0,)""")

    doc_str_lines = _os.linesep+''.join(['    '+s if s.strip() else s
                                         for s in 'r"""{doc_str}"""'.format(doc_str=doc_str)
                                         .splitlines(True)])
    code.insert(1, doc_str_lines)
    return ''.join(code), doc_str


# pylint: disable=too-many-locals, invalid-name
def _make_ndarray_function(handle, name, func_name):
    """Create a NDArray function from the FunctionHandle."""
    code, doc_str = _generate_ndarray_function_code(handle, name, func_name)

    local = {}
    exec(code, None, local)  # pylint: disable=exec-used
    ndarray_function = local[func_name]
    ndarray_function.__name__ = func_name
    ndarray_function.__doc__ = doc_str
    ndarray_function.__module__ = 'mxnet.ndarray'
    return ndarray_function

_init_op_module('mxnet', 'ndarray', _make_ndarray_function)

# Update operator documentation with added float support
# Note that we can only do this after the op module is initialized
# Otherwise the backend operators cannot be found
# pylint: disable=wrong-import-position
from .contrib import adamw_update, mp_adamw_update
from ._internal import _adamw_update, _mp_adamw_update
adamw_update.__doc__ = _adamw_update.__doc__.replace("rescale_grad : NDArray",
                                                     "rescale_grad : NDArray or float")
mp_adamw_update.__doc__ = _mp_adamw_update.__doc__.replace("rescale_grad : NDArray",
                                                           "rescale_grad : NDArray or float")
