# Copyright (c) 2020 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.

from __future__ import print_function

import math
import time
import unittest

import numpy as np

import paddle
import paddle.fluid as fluid
from paddle.fluid.dygraph import declarative, ProgramTranslator
from paddle.fluid.dygraph.nn import BatchNorm, Conv2D, Linear, Pool2D
from paddle.fluid.dygraph.io import VARIABLE_FILENAME

from predictor_utils import PredictorTools

SEED = 2020
IMAGENET1000 = 1281167
base_lr = 0.001
momentum_rate = 0.9
l2_decay = 1e-4
# NOTE: Reduce batch_size from 8 to 2 to avoid unittest timeout.
batch_size = 2
epoch_num = 1
place = fluid.CUDAPlace(0) if fluid.is_compiled_with_cuda() \
    else fluid.CPUPlace()
MODEL_SAVE_PATH = "./resnet.inference.model"
DY_STATE_DICT_SAVE_PATH = "./resnet.dygraph"
program_translator = ProgramTranslator()

if fluid.is_compiled_with_cuda():
    fluid.set_flags({'FLAGS_cudnn_deterministic': True})


def optimizer_setting(parameter_list=None):
    optimizer = fluid.optimizer.Momentum(
        learning_rate=base_lr,
        momentum=momentum_rate,
        regularization=fluid.regularizer.L2Decay(l2_decay),
        parameter_list=parameter_list)

    return optimizer


class ConvBNLayer(fluid.dygraph.Layer):
    def __init__(self,
                 num_channels,
                 num_filters,
                 filter_size,
                 stride=1,
                 groups=1,
                 act=None):
        super(ConvBNLayer, self).__init__()

        self._conv = Conv2D(
            num_channels=num_channels,
            num_filters=num_filters,
            filter_size=filter_size,
            stride=stride,
            padding=(filter_size - 1) // 2,
            groups=groups,
            act=None,
            bias_attr=False)

        self._batch_norm = BatchNorm(num_filters, act=act)

    def forward(self, inputs):
        y = self._conv(inputs)
        y = self._batch_norm(y)

        return y


class BottleneckBlock(fluid.dygraph.Layer):
    def __init__(self, num_channels, num_filters, stride, shortcut=True):
        super(BottleneckBlock, self).__init__()

        self.conv0 = ConvBNLayer(
            num_channels=num_channels,
            num_filters=num_filters,
            filter_size=1,
            act='relu')
        self.conv1 = ConvBNLayer(
            num_channels=num_filters,
            num_filters=num_filters,
            filter_size=3,
            stride=stride,
            act='relu')
        self.conv2 = ConvBNLayer(
            num_channels=num_filters,
            num_filters=num_filters * 4,
            filter_size=1,
            act=None)

        if not shortcut:
            self.short = ConvBNLayer(
                num_channels=num_channels,
                num_filters=num_filters * 4,
                filter_size=1,
                stride=stride)

        self.shortcut = shortcut

        self._num_channels_out = num_filters * 4

    def forward(self, inputs):
        y = self.conv0(inputs)
        conv1 = self.conv1(y)
        conv2 = self.conv2(conv1)

        if self.shortcut:
            short = inputs
        else:
            short = self.short(inputs)

        y = fluid.layers.elementwise_add(x=short, y=conv2)

        layer_helper = fluid.layer_helper.LayerHelper(
            self.full_name(), act='relu')
        return layer_helper.append_activation(y)


class ResNet(fluid.dygraph.Layer):
    def __init__(self, layers=50, class_dim=102):
        super(ResNet, self).__init__()

        self.layers = layers
        supported_layers = [50, 101, 152]
        assert layers in supported_layers, \
            "supported layers are {} but input layer is {}".format(supported_layers, layers)

        if layers == 50:
            depth = [3, 4, 6, 3]
        elif layers == 101:
            depth = [3, 4, 23, 3]
        elif layers == 152:
            depth = [3, 8, 36, 3]
        num_channels = [64, 256, 512, 1024]
        num_filters = [64, 128, 256, 512]

        self.conv = ConvBNLayer(
            num_channels=3, num_filters=64, filter_size=7, stride=2, act='relu')
        self.pool2d_max = Pool2D(
            pool_size=3, pool_stride=2, pool_padding=1, pool_type='max')

        self.bottleneck_block_list = []
        for block in range(len(depth)):
            shortcut = False
            for i in range(depth[block]):
                bottleneck_block = self.add_sublayer(
                    'bb_%d_%d' % (block, i),
                    BottleneckBlock(
                        num_channels=num_channels[block]
                        if i == 0 else num_filters[block] * 4,
                        num_filters=num_filters[block],
                        stride=2 if i == 0 and block != 0 else 1,
                        shortcut=shortcut))
                self.bottleneck_block_list.append(bottleneck_block)
                shortcut = True

        self.pool2d_avg = Pool2D(
            pool_size=7, pool_type='avg', global_pooling=True)

        self.pool2d_avg_output = num_filters[len(num_filters) - 1] * 4 * 1 * 1

        stdv = 1.0 / math.sqrt(2048 * 1.0)

        self.out = Linear(
            self.pool2d_avg_output,
            class_dim,
            act='softmax',
            param_attr=fluid.param_attr.ParamAttr(
                initializer=fluid.initializer.Uniform(-stdv, stdv)))

    @declarative
    def forward(self, inputs):
        y = self.conv(inputs)
        y = self.pool2d_max(y)
        for bottleneck_block in self.bottleneck_block_list:
            y = bottleneck_block(y)
        y = self.pool2d_avg(y)
        y = fluid.layers.reshape(y, shape=[-1, self.pool2d_avg_output])
        pred = self.out(y)

        return pred


def reader_decorator(reader):
    def __reader__():
        for item in reader():
            img = np.array(item[0]).astype('float32').reshape(3, 224, 224)
            label = np.array(item[1]).astype('int64').reshape(1)
            yield img, label

    return __reader__


def train(to_static):
    """
    Tests model decorated by `dygraph_to_static_output` in static mode. For users, the model is defined in dygraph mode and trained in static mode.
    """
    with fluid.dygraph.guard(place):
        np.random.seed(SEED)
        paddle.manual_seed(SEED)
        paddle.framework.random._manual_program_seed(SEED)

        train_reader = paddle.batch(
            reader_decorator(paddle.dataset.flowers.train(use_xmap=False)),
            batch_size=batch_size,
            drop_last=True)
        data_loader = fluid.io.DataLoader.from_generator(
            capacity=5, iterable=True)
        data_loader.set_sample_list_generator(train_reader)

        resnet = ResNet()
        optimizer = optimizer_setting(parameter_list=resnet.parameters())

        for epoch in range(epoch_num):
            total_loss = 0.0
            total_acc1 = 0.0
            total_acc5 = 0.0
            total_sample = 0

            for batch_id, data in enumerate(data_loader()):
                start_time = time.time()
                img, label = data

                pred = resnet(img)
                loss = fluid.layers.cross_entropy(input=pred, label=label)
                avg_loss = fluid.layers.mean(x=loss)
                acc_top1 = fluid.layers.accuracy(input=pred, label=label, k=1)
                acc_top5 = fluid.layers.accuracy(input=pred, label=label, k=5)

                avg_loss.backward()
                optimizer.minimize(avg_loss)
                resnet.clear_gradients()

                total_loss += avg_loss
                total_acc1 += acc_top1
                total_acc5 += acc_top5
                total_sample += 1

                end_time = time.time()
                if batch_id % 2 == 0:
                    print( "epoch %d | batch step %d, loss %0.3f, acc1 %0.3f, acc5 %0.3f, time %f" % \
                        ( epoch, batch_id, total_loss.numpy() / total_sample, \
                            total_acc1.numpy() / total_sample, total_acc5.numpy() / total_sample, end_time-start_time))
                if batch_id == 10:
                    if to_static:
                        fluid.dygraph.jit.save(resnet, MODEL_SAVE_PATH)
                    else:
                        fluid.dygraph.save_dygraph(resnet.state_dict(),
                                                   DY_STATE_DICT_SAVE_PATH)
                    # avoid dataloader throw abort signaal
                    data_loader._reset()
                    break

    return total_loss.numpy()


def predict_dygraph(data):
    program_translator.enable(False)
    with fluid.dygraph.guard(place):
        resnet = ResNet()

        model_dict, _ = fluid.dygraph.load_dygraph(DY_STATE_DICT_SAVE_PATH)
        resnet.set_dict(model_dict)
        resnet.eval()

        pred_res = resnet(fluid.dygraph.to_variable(data))

        return pred_res.numpy()


def predict_static(data):
    exe = fluid.Executor(place)
    [inference_program, feed_target_names,
     fetch_targets] = fluid.io.load_inference_model(
         MODEL_SAVE_PATH, executor=exe, params_filename=VARIABLE_FILENAME)

    pred_res = exe.run(inference_program,
                       feed={feed_target_names[0]: data},
                       fetch_list=fetch_targets)

    return pred_res[0]


def predict_dygraph_jit(data):
    with fluid.dygraph.guard(place):
        resnet = fluid.dygraph.jit.load(MODEL_SAVE_PATH)
        resnet.eval()

        pred_res = resnet(data)

        return pred_res.numpy()


def predict_analysis_inference(data):
    output = PredictorTools(MODEL_SAVE_PATH, VARIABLE_FILENAME, [data])
    out = output()
    return out


class TestResnet(unittest.TestCase):
    def train(self, to_static):
        program_translator.enable(to_static)
        return train(to_static)

    def verify_predict(self):
        image = np.random.random([1, 3, 224, 224]).astype('float32')
        dy_pre = predict_dygraph(image)
        st_pre = predict_static(image)
        dy_jit_pre = predict_dygraph_jit(image)
        predictor_pre = predict_analysis_inference(image)
        self.assertTrue(
            np.allclose(dy_pre, st_pre),
            msg="dy_pre:\n {}\n, st_pre: \n{}.".format(dy_pre, st_pre))
        self.assertTrue(
            np.allclose(dy_jit_pre, st_pre),
            msg="dy_jit_pre:\n {}\n, st_pre: \n{}.".format(dy_jit_pre, st_pre))
        self.assertTrue(
            np.allclose(predictor_pre, st_pre),
            msg="predictor_pre:\n {}\n, st_pre: \n{}.".format(predictor_pre,
                                                              st_pre))

    def test_resnet(self):
        static_loss = self.train(to_static=True)
        dygraph_loss = self.train(to_static=False)
        self.assertTrue(
            np.allclose(static_loss, dygraph_loss),
            msg="static_loss: {} \n dygraph_loss: {}".format(static_loss,
                                                             dygraph_loss))
        self.verify_predict()

    def test_in_static_mode_mkldnn(self):
        fluid.set_flags({'FLAGS_use_mkldnn': True})
        try:
            train(to_static=True)
        finally:
            fluid.set_flags({'FLAGS_use_mkldnn': False})


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