#   Copyright (c) 2018 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 unittest
import numpy as np
import paddle.fluid.core as core
from paddle.fluid.op import Operator
import paddle.fluid as fluid
from op_test import OpTest
from paddle.fluid.framework import grad_var_name


def _reference_testing(x, scale, offset, mean, var, epsilon, data_format):
    x_shape = x.shape
    if len(x_shape) == 2:
        if data_format == "NCHW":
            x = np.reshape(x, (x.shape[0], x.shape[1], 1, 1))
        else:
            x = np.reshape(x, (x.shape[0], 1, 1, x.shape[1]))

    if data_format == "NCHW":
        n, c, h, w = x.shape
        mean_tile = np.reshape(mean, (1, c, 1, 1))
        mean_tile = np.tile(mean_tile, (n, 1, h, w))
        var_tile = np.reshape(var, (1, c, 1, 1))
        var_tile = np.tile(var_tile, (n, 1, h, w))
        normalized = (x - mean_tile) / np.sqrt(var_tile + epsilon)
        scale_tile = np.reshape(scale, (1, c, 1, 1))
        scale_tile = np.tile(scale_tile, (n, 1, h, w))
        offset_tile = np.reshape(offset, (1, c, 1, 1))
        offset_tile = np.reshape(offset_tile, (1, c, 1, 1))
        y = normalized * scale_tile + offset_tile
    elif data_format == "NHWC":
        normalized = (x - mean) / np.sqrt(var + epsilon)
        y = normalized * scale + offset
    else:
        raise ValueError("Unknown data order.")

    if len(x_shape) == 2:
        y = np.reshape(y, x_shape)
    return y


def _reference_training(x, scale, offset, epsilon, data_format):
    x_shape = x.shape

    if data_format == "NCHW":
        n, c, h, w = x.shape
        x_square = x * x
        x_square_sum = np.sum(x_square, (0, 2, 3))
        x_sum = np.sum(x, axis=(0, 2, 3))
        element_count = np.size(x) / int(np.shape(x)[1])
        mean = x_sum / element_count
        var = x_square_sum / element_count - mean * mean
        mean_tile = np.reshape(mean, (1, c, 1, 1))
        mean_tile = np.tile(mean_tile, (n, 1, h, w))
        var_tile = np.reshape(var, (1, c, 1, 1))
        var_tile = np.tile(var_tile, (n, 1, h, w))
        normalized = (x - mean_tile) / np.sqrt(var_tile + epsilon)
        scale_tile = np.reshape(scale, (1, c, 1, 1))
        scale_tile = np.tile(scale_tile, (n, 1, h, w))
        offset_tile = np.reshape(offset, (1, c, 1, 1))
        offset_tile = np.reshape(offset_tile, (1, c, 1, 1))
        y = normalized * scale_tile + offset_tile
        return y, mean, var
    elif data_format == "NHWC":
        x_square = x * x
        x_square_sum = np.sum(x_square, (0, 1, 2))
        x_sum = np.sum(x, axis=(0, 1, 2))
        element_count = np.size(x) / int(np.shape(x)[-1])
        mean = x_sum / element_count
        var = x_square_sum / element_count - mean * mean
        normalized = (x - mean) / np.sqrt(var + epsilon)
        y = normalized * scale + offset
        return y, mean, var
    else:
        raise ValueError("Unknown data order.")


def _reference_grad(x, y_grad, scale, mean, var, epsilon, data_format):
    # Use the following formulas to calculate gradients:
    # grad_scale =
    #   sum(grad_y * (x - mean)) * rsqrt(var + epsilon)
    #
    # grad_offset = sum(output_y)
    #
    # x_grad =
    #   1/N * scale * rsqrt(var + epsilon) * (N * grad_y - sum(grad_y) -
    #   (x - mean) * sum(grad_y * (x - mean)) / (var + epsilon))

    # transfer from (N, C, H, W) to (N, H, W, C) to simplify computation
    if data_format != "NCHW" and data_format != "NHWC":
        raise ValueError("Unknown data order.")

    if data_format == "NCHW":
        x = np.transpose(x, (0, 2, 3, 1))
        y_grad = np.transpose(y_grad, (0, 2, 3, 1))

    x_grad = scale * (y_grad - np.mean(
        y_grad, axis=(0, 1, 2)) - (x - mean) * np.mean(
            y_grad * (x - mean), axis=(0, 1, 2)) /
                      (var + epsilon)) / np.sqrt(var + epsilon)
    grad_scale = np.sum(y_grad * (x - mean) / np.sqrt(var + epsilon),
                        axis=(0, 1, 2))
    grad_offset = np.sum(y_grad, axis=(0, 1, 2))

    # transfer back to N, C, H, W
    if data_format == "NCHW":
        x_grad = np.transpose(x_grad, (0, 3, 1, 2))
        x = np.transpose(x, (0, 3, 1, 2))
        y_grad = np.transpose(y_grad, (0, 3, 1, 2))

    return x_grad, grad_scale, grad_offset


def create_or_get_tensor(scope, var_name, var, place):
    tensor = scope.var(var_name).get_tensor()
    if var is not None:
        assert isinstance(var, np.ndarray)
        tensor.set_lod([[]])
        tensor.set_dims(var.shape)
        tensor.set(var, place)
    return tensor


def set_output_grad(scope, outputs, place, feed_dict=None):
    def __set_tensor__(name, data=None):
        out_tensor = scope.find_var(name).get_tensor()
        grad_tensor = scope.var(grad_var_name(name)).get_tensor()
        out_dtype = out_tensor.dtype()
        if data is None:
            if out_dtype == core.VarDesc.VarType.FP64:
                data = np.ones(out_tensor.shape(), dtype=np.float64)
            elif out_dtype == core.VarDesc.VarType.FP32:
                data = np.ones(out_tensor.shape(), dtype=np.float32)
            else:
                raise ValueError("Not supported data type " + str(out_dtype))
        grad_tensor.set(data, place)

    for output in outputs:
        data = None
        if output in feed_dict:
            data = feed_dict[output]
        __set_tensor__(output, data)


class TestBatchNormOpInference(unittest.TestCase):
    def setUp(self):
        self.dtype = np.float32
        self.use_mkldnn = False
        self.init_kernel_type()

    def __assert_close(self, tensor, np_array, msg, atol=1e-4):
        self.assertTrue(np.allclose(np.array(tensor), np_array, atol=atol), msg)

    def check_with_place(self, place, data_layout, dtype, shape):
        epsilon = 0.00001
        if len(shape) == 2:
            x_shape = shape
            c = x_shape[1]
        else:
            n, h, w, c = shape[0], shape[1], shape[2], shape[3]
            if data_layout == "NHWC":
                x_shape = [n, h, w, c]
            elif data_layout == "NCHW":
                x_shape = [n, c, h, w]
            else:
                raise ValueError("Unknown data layout.")
        scale_shape = [c]

        x_val = np.random.random_sample(x_shape).astype(dtype)
        scale_val = np.random.random_sample(scale_shape).astype(np.float32)
        bias_val = np.random.random_sample(scale_shape).astype(np.float32)

        mean = np.zeros(scale_shape).astype(np.float32)
        variance = np.ones(scale_shape).astype(np.float32)

        y_out = _reference_testing(x_val, scale_val, bias_val, mean, variance,
                                   epsilon, data_layout).astype(dtype)

        scope = core.Scope()

        # create input
        x_tensor = create_or_get_tensor(scope, "x_val",
                                        OpTest.np_dtype_to_fluid_dtype(x_val),
                                        place)
        scale_tensor = create_or_get_tensor(
            scope, "scale_val",
            OpTest.np_dtype_to_fluid_dtype(scale_val), place)
        bias_tensor = create_or_get_tensor(
            scope, "bias_val", OpTest.np_dtype_to_fluid_dtype(bias_val), place)
        mean_tensor = create_or_get_tensor(scope, "mean",
                                           OpTest.np_dtype_to_fluid_dtype(mean),
                                           place)
        variance_tensor = create_or_get_tensor(
            scope, "variance", OpTest.np_dtype_to_fluid_dtype(variance), place)

        # create output
        y_tensor = create_or_get_tensor(scope, "y_out", None, place)
        saved_mean_tensor = create_or_get_tensor(scope, "saved_mean", None,
                                                 place)
        saved_variance_tensor = create_or_get_tensor(scope, "saved_variance",
                                                     None, place)
        mean_out_tensor = mean_tensor
        variance_out_tensor = variance_tensor

        batch_norm_op = Operator(
            "batch_norm",
            # inputs
            X="x_val",
            Scale="scale_val",
            Bias="bias_val",
            Mean="mean",
            Variance="variance",
            # outputs
            Y="y_out",
            MeanOut="mean",
            VarianceOut="variance",
            SavedMean="saved_mean",
            SavedVariance="saved_variance",
            # attrs
            is_test=True,
            data_layout=data_layout,
            use_mkldnn=self.use_mkldnn,
            epsilon=epsilon)

        batch_norm_op.run(scope, place)

        # check inference result
        self.__assert_close(
            y_tensor,
            y_out,
            "inference output are different at " + str(place) + ", " +
            data_layout + ", " + str(np.dtype(dtype)) +
            str(np.array(y_tensor)) + str(y_out),
            atol=1e-3)

    def test_check_output(self):
        places = [core.CPUPlace()]
        if core.is_compiled_with_cuda() and core.op_support_gpu("batch_norm"):
            places.append(core.CUDAPlace(0))

        for place in places:
            for data_format in ["NCHW", "NHWC"]:
                self.check_with_place(place, data_format, self.dtype,
                                      [2, 3, 4, 5])
                self.check_with_place(place, data_format, self.dtype, [2, 3])

    def init_kernel_type(self):
        pass


class TestFP16BatchNormOpInference(TestBatchNormOpInference):
    def setUp(self):
        self.dtype = np.float16
        self.use_mkldnn = False
        self.init_kernel_type()

    def test_check_output(self):
        places = []
        if core.is_compiled_with_cuda() and core.op_support_gpu("batch_norm"):
            place = core.CUDAPlace(0)
            if core.is_float16_supported(place):
                places.append(place)

        for place in places:
            for data_format in ["NCHW", "NHWC"]:
                self.check_with_place(place, data_format, self.dtype,
                                      [2, 3, 4, 5])
                self.check_with_place(place, data_format, self.dtype, [2, 3])


class TestBatchNormOpTraining(unittest.TestCase):
    def setUp(self):
        self.use_mkldnn = False
        self.data_formats = ["NCHW", "NHWC"]
        self.init_kernel_type()

    def __assert_close(self, tensor, np_array, msg, atol=1e-4):
        np.allclose(np.array(tensor), np_array, atol=atol)

    def ref_forward_backward(self, x, y_grad, scale, bias, mean, variance,
                             epsilon, momentum, shape, data_layout):
        # run forward
        y, saved_mean, var_ref = _reference_training(x, scale, bias, epsilon,
                                                     data_layout)
        mean_out = saved_mean * (1. - momentum) + momentum * mean
        variance_out = var_ref * (1. - momentum) + momentum * variance
        saved_variance = 1. / np.sqrt(var_ref + epsilon)
        # run backward
        x_grad, scale_grad, bias_grad = _reference_grad(
            x, y_grad, scale, saved_mean, var_ref, epsilon, data_layout)

        return y, mean_out, variance_out, saved_mean, saved_variance, x_grad, scale_grad, bias_grad

    def test_forward_backward(self):
        def test_with_place(place, data_layout, shape):
            # attr
            epsilon = 0.00001
            momentum = 0.9
            if data_layout == "NCHW":
                n, c, h, w = shape[0], shape[1], shape[2], shape[3]
            else:
                n, h, w, c = shape[0], shape[1], shape[2], shape[3]
            scale_shape = [c]

            np.random.seed(123)
            x = np.random.random_sample(shape).astype(np.float32)
            scale = np.random.random_sample(scale_shape).astype(np.float32)
            bias = np.random.random_sample(scale_shape).astype(np.float32)
            mean = np.zeros(scale_shape).astype(np.float32)
            variance = np.ones(scale_shape).astype(np.float32)

            y_grad = np.random.random_sample(shape).astype(np.float32)

            y, mean_out, variance_out, saved_mean, saved_variance, x_grad, scale_grad, bias_grad = self.ref_forward_backward(
                x, y_grad, scale, bias, mean, variance, epsilon, momentum,
                shape, data_layout)

            var_dict = locals()
            var_dict['y@GRAD'] = y_grad

            var_names = [
                'x', 'scale', 'bias', 'mean', 'variance', 'y', 'saved_mean',
                'saved_variance'
            ]
            ground_truth = {name: var_dict[name] for name in var_names}

            program = fluid.Program()
            with fluid.program_guard(program):
                block = program.global_block()
                for name in ground_truth:
                    block.create_var(
                        name=name,
                        dtype='float32',
                        shape=ground_truth[name].shape)
                bn_op = block.append_op(
                    type="batch_norm",
                    inputs={
                        "X": block.var('x'),
                        "Scale": block.var('scale'),
                        "Bias": block.var('bias'),
                        "Mean": block.var('mean'),
                        "Variance": block.var('variance')
                    },
                    outputs={
                        "Y": block.var('y'),
                        "MeanOut": block.var('mean'),  # share the same memory
                        "VarianceOut":
                        block.var('variance'),  # share the same memory
                        "SavedMean": block.var('saved_mean'),
                        "SavedVariance": block.var('saved_variance')
                    },
                    attrs={
                        "momentum": momentum,
                        "epsilon": epsilon,
                        "is_test": False,
                        "data_layout": data_layout,
                        "use_mkldnn": self.use_mkldnn
                    })
                block.create_var(name='y@GRAD', dtype='float32', shape=y.shape)

                # generate backward op_desc
                grad_op_desc_list, op_grad_to_var = core.get_grad_op_desc(
                    bn_op.desc, set(), [])
                grad_op_desc = grad_op_desc_list[0]
                new_op_desc = block.desc.append_op()
                new_op_desc.copy_from(grad_op_desc)
                for var_name in grad_op_desc.output_arg_names():
                    block.desc.var(var_name.encode("ascii"))
                grad_op_desc.infer_var_type(block.desc)
                grad_op_desc.infer_shape(block.desc)
                for arg in grad_op_desc.output_arg_names():
                    grad_var = block.desc.find_var(arg.encode("ascii"))
                    grad_var.set_dtype(core.VarDesc.VarType.FP32)

                exe = fluid.Executor(place)
                out = exe.run(
                    program,
                    feed={
                        name: var_dict[name]
                        for name in
                        ['x', 'scale', 'bias', 'mean', 'variance', 'y@GRAD']
                    },
                    fetch_list=[
                        'y', 'mean', 'variance', 'saved_mean', 'saved_variance',
                        'x@GRAD', 'scale@GRAD', 'bias@GRAD'
                    ])

            self.__assert_close(y, out[0], "y")
            self.__assert_close(mean_out, out[1], "mean")
            self.__assert_close(variance_out, out[2], "variance", 1e-3)
            self.__assert_close(saved_mean, out[3], "saved_mean")
            self.__assert_close(saved_variance, out[4], "saved_variance", 1e-3)
            self.__assert_close(x_grad, out[5], "x_grad")
            self.__assert_close(scale_grad, out[6], "scale_grad")
            self.__assert_close(bias_grad, out[7], "bias_grad")

            print "op test forward passed: ", str(place), data_layout

        places = [core.CPUPlace()]

        if core.is_compiled_with_cuda() and core.op_support_gpu("batch_norm"):
            places.append(core.CUDAPlace(0))

        for place in places:
            for data_format in self.data_formats:
                test_with_place(place, data_format, [2, 3, 4, 5])

    def init_kernel_type(self):
        pass


if __name__ == '__main__':
    unittest.main()
