#   Copyright (c) 2022 PaddlePaddle Authors. All Rights Reserved.
#
# 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.

import numpy as np

import paddle.fluid as fluid
from paddle import _legacy_C_ops
from paddle.fluid.layer_helper import LayerHelper
from paddle.fluid.layers import utils
from paddle.fluid.param_attr import ParamAttr
from paddle.nn import Layer
from paddle.nn import initializer as I

__all__ = ['resnet_basic_block', 'ResNetBasicBlock']


def resnet_basic_block(
    x,
    filter1,
    scale1,
    bias1,
    mean1,
    var1,
    filter2,
    scale2,
    bias2,
    mean2,
    var2,
    filter3,
    scale3,
    bias3,
    mean3,
    var3,
    stride1,
    stride2,
    stride3,
    padding1,
    padding2,
    padding3,
    dilation1,
    dilation2,
    dilation3,
    groups,
    momentum,
    eps,
    data_format,
    has_shortcut,
    use_global_stats=None,
    training=False,
    trainable_statistics=False,
    find_conv_max=True,
):

    if fluid.framework._non_static_mode():
        attrs = (
            'stride1',
            stride1,
            'stride2',
            stride2,
            'stride3',
            stride3,
            'padding1',
            padding1,
            'padding2',
            padding2,
            'padding3',
            padding3,
            'dilation1',
            dilation1,
            'dilation2',
            dilation2,
            'dilation3',
            dilation3,
            'group',
            groups,
            'momentum',
            momentum,
            'epsilon',
            eps,
            'data_format',
            data_format,
            'has_shortcut',
            has_shortcut,
            'use_global_stats',
            use_global_stats,
            "trainable_statistics",
            trainable_statistics,
            'is_test',
            not training,
            'act_type',
            "relu",
            'find_conv_input_max',
            find_conv_max,
        )

        (
            out,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
            _,
        ) = _legacy_C_ops.resnet_basic_block(
            x,
            filter1,
            scale1,
            bias1,
            mean1,
            var1,
            filter2,
            scale2,
            bias2,
            mean2,
            var2,
            filter3,
            scale3,
            bias3,
            mean3,
            var3,
            mean1,
            var1,
            mean2,
            var2,
            mean3,
            var3,
            *attrs
        )
        return out
    helper = LayerHelper('resnet_basic_block', **locals())
    bn_param_dtype = fluid.core.VarDesc.VarType.FP32
    max_dtype = fluid.core.VarDesc.VarType.FP32

    out = helper.create_variable_for_type_inference(
        dtype=x.dtype, stop_gradient=True
    )
    conv1 = helper.create_variable_for_type_inference(
        dtype=x.dtype, stop_gradient=True
    )
    saved_mean1 = helper.create_variable_for_type_inference(
        dtype=bn_param_dtype, stop_gradient=True
    )
    saved_invstd1 = helper.create_variable_for_type_inference(
        dtype=bn_param_dtype, stop_gradient=True
    )
    running_mean1 = (
        helper.create_variable_for_type_inference(
            dtype=bn_param_dtype, stop_gradient=True
        )
        if mean1 is None
        else mean1
    )
    running_var1 = (
        helper.create_variable_for_type_inference(
            dtype=bn_param_dtype, stop_gradient=True
        )
        if var1 is None
        else var1
    )
    conv2 = helper.create_variable_for_type_inference(
        dtype=x.dtype, stop_gradient=True
    )
    conv2_input = helper.create_variable_for_type_inference(
        dtype=x.dtype, stop_gradient=True
    )
    saved_mean2 = helper.create_variable_for_type_inference(
        dtype=bn_param_dtype, stop_gradient=True
    )
    saved_invstd2 = helper.create_variable_for_type_inference(
        dtype=bn_param_dtype, stop_gradient=True
    )
    running_mean2 = (
        helper.create_variable_for_type_inference(
            dtype=bn_param_dtype, stop_gradient=True
        )
        if mean2 is None
        else mean2
    )
    running_var2 = (
        helper.create_variable_for_type_inference(
            dtype=bn_param_dtype, stop_gradient=True
        )
        if var2 is None
        else var2
    )
    conv3 = helper.create_variable_for_type_inference(
        dtype=x.dtype, stop_gradient=True
    )
    saved_mean3 = helper.create_variable_for_type_inference(
        dtype=bn_param_dtype, stop_gradient=True
    )
    saved_invstd3 = helper.create_variable_for_type_inference(
        dtype=bn_param_dtype, stop_gradient=True
    )
    running_mean3 = (
        helper.create_variable_for_type_inference(
            dtype=bn_param_dtype, stop_gradient=True
        )
        if mean3 is None
        else mean3
    )
    running_var3 = (
        helper.create_variable_for_type_inference(
            dtype=bn_param_dtype, stop_gradient=True
        )
        if var3 is None
        else var3
    )
    conv1_input_max = helper.create_variable_for_type_inference(
        dtype=max_dtype, stop_gradient=True
    )
    conv1_filter_max = helper.create_variable_for_type_inference(
        dtype=max_dtype, stop_gradient=True
    )
    conv2_input_max = helper.create_variable_for_type_inference(
        dtype=max_dtype, stop_gradient=True
    )
    conv2_filter_max = helper.create_variable_for_type_inference(
        dtype=max_dtype, stop_gradient=True
    )
    conv3_input_max = helper.create_variable_for_type_inference(
        dtype=max_dtype, stop_gradient=True
    )
    conv3_filter_max = helper.create_variable_for_type_inference(
        dtype=max_dtype, stop_gradient=True
    )

    inputs = {
        'X': x,
        'Filter1': filter1,
        'Scale1': scale1,
        'Bias1': bias1,
        'Mean1': mean1,
        'Var1': var1,
        'Filter2': filter2,
        'Scale2': scale2,
        'Bias2': bias2,
        'Mean2': mean2,
        'Var2': var2,
        'Filter3': filter3,
        'Scale3': scale3,
        'Bias3': bias3,
        'Mean3': mean3,
        'Var3': var3,
    }

    attrs = {
        'stride1': stride1,
        'stride2': stride2,
        'stride3': stride3,
        'padding1': padding1,
        'padding2': padding2,
        'padding3': padding3,
        'dilation1': dilation1,
        'dilation2': dilation2,
        'dilation3': dilation3,
        'group': groups,
        'momentum': momentum,
        'epsilon': eps,
        'data_format': data_format,
        'has_shortcut': has_shortcut,
        'use_global_stats': use_global_stats,
        "trainable_statistics": trainable_statistics,
        'is_test': not training,
        'act_type': "relu",
        'find_conv_input_max': find_conv_max,
    }

    outputs = {
        'Y': out,
        'Conv1': conv1,
        'SavedMean1': saved_mean1,
        'SavedInvstd1': saved_invstd1,
        'Mean1Out': running_mean1,
        'Var1Out': running_var1,
        'Conv2': conv2,
        'SavedMean2': saved_mean2,
        'SavedInvstd2': saved_invstd2,
        'Mean2Out': running_mean2,
        'Var2Out': running_var2,
        'Conv2Input': conv2_input,
        'Conv3': conv3,
        'SavedMean3': saved_mean3,
        'SavedInvstd3': saved_invstd3,
        'Mean3Out': running_mean3,
        'Var3Out': running_var3,
        'MaxInput1': conv1_input_max,
        'MaxFilter1': conv1_filter_max,
        'MaxInput2': conv2_input_max,
        'MaxFilter2': conv2_filter_max,
        'MaxInput3': conv3_input_max,
        'MaxFilter3': conv3_filter_max,
    }
    helper.append_op(
        type='resnet_basic_block', inputs=inputs, outputs=outputs, attrs=attrs
    )
    return out


class ResNetBasicBlock(Layer):
    r"""

    ResNetBasicBlock is designed for optimize the performence of the basic unit of ssd resnet block.
    If has_shortcut = True, it can calculate 3 Conv2D, 3 BatchNorm and 2 ReLU in one time.
    If has_shortcut = False, it can calculate 2 Conv2D, 2 BatchNorm and 2 ReLU in one time. In this
    case the shape of output is same with input.


    Args:
        num_channels (int): The number of input image channel.
        num_filter (int): The number of filter. It is as same as the output image channel.
        filter_size (int|list|tuple): The filter size. If filter_size
            is a tuple, it must contain two integers, (filter_size_height,
            filter_size_width). Otherwise, filter_size_height = filter_size_width =\
            filter_size.
        stride (int, optional): The stride size. It means the stride in convolution.
            If stride is a tuple, it must contain two integers, (stride_height, stride_width).
            Otherwise, stride_height = stride_width = stride. Default: stride = 1.
        act (str, optional): Activation type, if it is set to None, activation is not appended.
            Default: None
        momentum (float, optional): The value used for the moving_mean and
            moving_var computation. This should be a float number or a Tensor with
            shape [1] and data type as float32. The updated formula is:
            :math:`moving\_mean = moving\_mean * momentum + new\_mean * (1. - momentum)`
            :math:`moving\_var = moving\_var * momentum + new\_var * (1. - momentum)`
            Default is 0.9.
        eps (float, optional): A value added to the denominator for
            numerical stability. Default is 1e-5.
        data_format (str, optional): Specify the data format of the input, and the data format of the output
            will be consistent with that of the input. Now is only support `"NCHW"`, the data is stored in
            the order of: `[batch_size, input_channels, input_height, input_width]`.
        has_shortcut (bool, optional): Whether to calculate CONV3 and BN3. Default: False.
        use_global_stats (bool, optional): Whether to use global mean and
            variance. In inference or test mode, set use_global_stats to true
            or is_test to true, and the behavior is equivalent.
            In train mode, when setting use_global_stats True, the global mean
            and variance are also used during train period. Default: False.
        is_test (bool, optional): A flag indicating whether it is in
            test phrase or not. Default: False.
        filter_attr (ParamAttr, optional): The parameter attribute for learnable parameters/weights
            of conv2d. If it is set to None or one attribute of ParamAttr, conv2d
            will create ParamAttr as param_attr. Default: None.
        scale_attr (ParamAttr, optional): The parameter attribute for Parameter `scale`
            of batch_norm. If it is set to None or one attribute of ParamAttr, batch_norm will create ParamAttr
            as param_attr, the name of scale can be set in ParamAttr. If the Initializer of the param_attr is not set,
            the parameter is initialized with Xavier. Default: None.
        bias_attr (ParamAttr, optional): The parameter attribute for the bias of batch_norm.
            If it is set to None or one attribute of ParamAttr, batch_norm
            will create ParamAttr as bias_attr, the name of bias can be set in ParamAttr.
            If the Initializer of the bias_attr is not set, the bias is initialized zero.
            Default: None.
        moving_mean_name (str, optional): The name of moving_mean which store the global Mean. If it
            is set to None, batch_norm will save global mean with a random name, otherwise, batch_norm
            will save global mean with the string. Default: None.
        moving_var_name (str, optional): The name of the moving_variance which store the global Variance.
            If it is set to None, batch_norm will save global variance with a random name, otherwise, batch_norm
            will save global variance with the string. Default: None.
        padding (int, optional): The padding size. It is only spupport padding_height = padding_width = padding.
            Default: padding = 0.
        dilation (int, optional): The dilation size. It means the spacing between the kernel
            points. It is only spupport dilation_height = dilation_width = dilation.
            Default: dilation = 1.
        trainable_statistics (bool, optional): Whether to calculate mean and var in eval mode. In eval mode, when
            setting trainable_statistics True, mean and variance will be calculated by current batch statistics.
            Default: False.
        find_conv_max (bool, optional): Whether to calculate max value of each conv2d. Default: True.


    Returns:
        A Tensor representing the ResNetBasicBlock, whose data type is the same with input.


    Examples:
        .. code-block:: python

            # required: xpu
            import paddle
            from paddle.incubate.xpu.resnet_block import ResNetBasicBlock

            ch_in = 4
            ch_out = 8
            x = paddle.uniform((2, ch_in, 16, 16), dtype='float32', min=-1., max=1.)
            resnet_basic_block = ResNetBasicBlock(num_channels1=ch_in,
                                                num_filter1=ch_out,
                                                filter1_size=3,
                                                num_channels2=ch_out,
                                                num_filter2=ch_out,
                                                filter2_size=3,
                                                num_channels3=ch_in,
                                                num_filter3=ch_out,
                                                filter3_size=1,
                                                stride1=1,
                                                stride2=1,
                                                stride3=1,
                                                act='relu',
                                                padding1=1,
                                                padding2=1,
                                                padding3=0,
                                                has_shortcut=True)
            out = resnet_basic_block.forward(x)

            print(out.shape) # [2, 8, 16, 16]

    """

    def __init__(
        self,
        num_channels1,
        num_filter1,
        filter1_size,
        num_channels2,
        num_filter2,
        filter2_size,
        num_channels3,
        num_filter3,
        filter3_size,
        stride1=1,
        stride2=1,
        stride3=1,
        act='relu',
        momentum=0.9,
        eps=1e-5,
        data_format='NCHW',
        has_shortcut=False,
        use_global_stats=False,
        is_test=False,
        filter1_attr=None,
        scale1_attr=None,
        bias1_attr=None,
        moving_mean1_name=None,
        moving_var1_name=None,
        filter2_attr=None,
        scale2_attr=None,
        bias2_attr=None,
        moving_mean2_name=None,
        moving_var2_name=None,
        filter3_attr=None,
        scale3_attr=None,
        bias3_attr=None,
        moving_mean3_name=None,
        moving_var3_name=None,
        padding1=0,
        padding2=0,
        padding3=0,
        dilation1=1,
        dilation2=1,
        dilation3=1,
        trainable_statistics=False,
        find_conv_max=True,
    ):
        super().__init__()
        self._stride1 = stride1
        self._stride2 = stride2
        self._kernel1_size = utils.convert_to_list(
            filter1_size, 2, 'filter1_size'
        )
        self._kernel2_size = utils.convert_to_list(
            filter2_size, 2, 'filter2_size'
        )
        self._dilation1 = dilation1
        self._dilation2 = dilation2
        self._padding1 = padding1
        self._padding2 = padding2
        self._groups = 1
        self._momentum = momentum
        self._eps = eps
        self._data_format = data_format
        self._act = act
        self._has_shortcut = has_shortcut
        self._use_global_stats = use_global_stats
        self._is_test = is_test
        self._trainable_statistics = trainable_statistics
        self._find_conv_max = find_conv_max

        if has_shortcut:
            self._kernel3_size = utils.convert_to_list(
                filter3_size, 2, 'filter3_size'
            )
            self._padding3 = padding3
            self._stride3 = stride3
            self._dilation3 = dilation3
        else:
            self._kernel3_size = None
            self._padding3 = 1
            self._stride3 = 1
            self._dilation3 = 1

        # check format
        valid_format = {'NCHW'}
        if data_format not in valid_format:
            raise ValueError(
                "conv_format must be one of {}, but got conv_format={}".format(
                    valid_format, data_format
                )
            )

        def _get_default_param_initializer(channels, kernel_size):
            filter_elem_num = np.prod(kernel_size) * channels
            std = (2.0 / filter_elem_num) ** 0.5
            return I.Normal(0.0, std)

        # init filter
        bn_param_dtype = fluid.core.VarDesc.VarType.FP32
        bn1_param_shape = [1, 1, num_filter1]
        bn2_param_shape = [1, 1, num_filter2]
        filter1_shape = [num_filter1, num_channels1, filter1_size, filter1_size]
        filter2_shape = [num_filter2, num_channels2, filter2_size, filter2_size]

        self.filter_1 = self.create_parameter(
            shape=filter1_shape,
            attr=filter1_attr,
            default_initializer=_get_default_param_initializer(
                num_channels1, self._kernel1_size
            ),
        )
        self.scale_1 = self.create_parameter(
            shape=bn1_param_shape,
            attr=scale1_attr,
            dtype=bn_param_dtype,
            default_initializer=I.Constant(1.0),
        )
        self.bias_1 = self.create_parameter(
            shape=bn1_param_shape,
            attr=bias1_attr,
            dtype=bn_param_dtype,
            is_bias=True,
        )
        self.mean_1 = self.create_parameter(
            attr=ParamAttr(
                name=moving_mean1_name,
                initializer=I.Constant(0.0),
                trainable=False,
            ),
            shape=bn1_param_shape,
            dtype=bn_param_dtype,
        )
        self.mean_1.stop_gradient = True
        self.var_1 = self.create_parameter(
            attr=ParamAttr(
                name=moving_var1_name,
                initializer=I.Constant(1.0),
                trainable=False,
            ),
            shape=bn1_param_shape,
            dtype=bn_param_dtype,
        )
        self.var_1.stop_gradient = True

        self.filter_2 = self.create_parameter(
            shape=filter2_shape,
            attr=filter2_attr,
            default_initializer=_get_default_param_initializer(
                num_channels2, self._kernel2_size
            ),
        )
        self.scale_2 = self.create_parameter(
            shape=bn2_param_shape,
            attr=scale2_attr,
            dtype=bn_param_dtype,
            default_initializer=I.Constant(1.0),
        )
        self.bias_2 = self.create_parameter(
            shape=bn2_param_shape,
            attr=bias2_attr,
            dtype=bn_param_dtype,
            is_bias=True,
        )
        self.mean_2 = self.create_parameter(
            attr=ParamAttr(
                name=moving_mean2_name,
                initializer=I.Constant(0.0),
                trainable=False,
            ),
            shape=bn2_param_shape,
            dtype=bn_param_dtype,
        )
        self.mean_2.stop_gradient = True
        self.var_2 = self.create_parameter(
            attr=ParamAttr(
                name=moving_var2_name,
                initializer=I.Constant(1.0),
                trainable=False,
            ),
            shape=bn2_param_shape,
            dtype=bn_param_dtype,
        )
        self.var_2.stop_gradient = True

        if has_shortcut:
            bn3_param_shape = [1, 1, num_filter3]
            filter3_shape = [
                num_filter3,
                num_channels3,
                filter3_size,
                filter3_size,
            ]
            self.filter_3 = self.create_parameter(
                shape=filter3_shape,
                attr=filter3_attr,
                default_initializer=_get_default_param_initializer(
                    num_channels3, self._kernel3_size
                ),
            )
            self.scale_3 = self.create_parameter(
                shape=bn3_param_shape,
                attr=scale3_attr,
                dtype=bn_param_dtype,
                default_initializer=I.Constant(1.0),
            )
            self.bias_3 = self.create_parameter(
                shape=bn3_param_shape,
                attr=bias3_attr,
                dtype=bn_param_dtype,
                is_bias=True,
            )
            self.mean_3 = self.create_parameter(
                attr=ParamAttr(
                    name=moving_mean3_name,
                    initializer=I.Constant(0.0),
                    trainable=False,
                ),
                shape=bn3_param_shape,
                dtype=bn_param_dtype,
            )
            self.mean_3.stop_gradient = True
            self.var_3 = self.create_parameter(
                attr=ParamAttr(
                    name=moving_var3_name,
                    initializer=I.Constant(1.0),
                    trainable=False,
                ),
                shape=bn3_param_shape,
                dtype=bn_param_dtype,
            )
            self.var_3.stop_gradient = True
        else:
            self.filter_3 = None
            self.scale_3 = None
            self.bias_3 = None
            self.mean_3 = None
            self.var_3 = None

    def forward(self, x):
        out = resnet_basic_block(
            x,
            self.filter_1,
            self.scale_1,
            self.bias_1,
            self.mean_1,
            self.var_1,
            self.filter_2,
            self.scale_2,
            self.bias_2,
            self.mean_2,
            self.var_2,
            self.filter_3,
            self.scale_3,
            self.bias_3,
            self.mean_3,
            self.var_3,
            self._stride1,
            self._stride2,
            self._stride3,
            self._padding1,
            self._padding2,
            self._padding3,
            self._dilation1,
            self._dilation2,
            self._dilation3,
            self._groups,
            self._momentum,
            self._eps,
            self._data_format,
            self._has_shortcut,
            use_global_stats=self._use_global_stats,
            training=self.training,
            trainable_statistics=self._trainable_statistics,
            find_conv_max=self._find_conv_max,
        )
        return out
