# The implementation is based on openpose, available at https://github.com/Hzzone/pytorch-openpose.

from collections import OrderedDict

import torch
import torch.nn as nn


def make_layers(block, no_relu_layers):
    layers = []
    for layer_name, v in block.items():
        if 'pool' in layer_name:
            layer = nn.MaxPool2d(kernel_size=v[0], stride=v[1], padding=v[2])
            layers.append((layer_name, layer))
        else:
            conv2d = nn.Conv2d(
                in_channels=v[0],
                out_channels=v[1],
                kernel_size=v[2],
                stride=v[3],
                padding=v[4])
            layers.append((layer_name, conv2d))
            if layer_name not in no_relu_layers:
                layers.append(('relu_' + layer_name, nn.ReLU(inplace=True)))

    return nn.Sequential(OrderedDict(layers))


class BodyposeModel(nn.Module):

    def __init__(self):
        super(BodyposeModel, self).__init__()

        # these layers have no relu layer
        no_relu_layers = [
            'conv5_5_CPM_L1', 'conv5_5_CPM_L2', 'Mconv7_stage2_L1',
            'Mconv7_stage2_L2', 'Mconv7_stage3_L1', 'Mconv7_stage3_L2',
            'Mconv7_stage4_L1', 'Mconv7_stage4_L2', 'Mconv7_stage5_L1',
            'Mconv7_stage5_L2', 'Mconv7_stage6_L1', 'Mconv7_stage6_L1'
        ]
        blocks = {}
        block0 = OrderedDict([('conv1_1', [3, 64, 3, 1, 1]),
                              ('conv1_2', [64, 64, 3, 1, 1]),
                              ('pool1_stage1', [2, 2, 0]),
                              ('conv2_1', [64, 128, 3, 1, 1]),
                              ('conv2_2', [128, 128, 3, 1, 1]),
                              ('pool2_stage1', [2, 2, 0]),
                              ('conv3_1', [128, 256, 3, 1, 1]),
                              ('conv3_2', [256, 256, 3, 1, 1]),
                              ('conv3_3', [256, 256, 3, 1, 1]),
                              ('conv3_4', [256, 256, 3, 1, 1]),
                              ('pool3_stage1', [2, 2, 0]),
                              ('conv4_1', [256, 512, 3, 1, 1]),
                              ('conv4_2', [512, 512, 3, 1, 1]),
                              ('conv4_3_CPM', [512, 256, 3, 1, 1]),
                              ('conv4_4_CPM', [256, 128, 3, 1, 1])])

        # Stage 1
        block1_1 = OrderedDict([('conv5_1_CPM_L1', [128, 128, 3, 1, 1]),
                                ('conv5_2_CPM_L1', [128, 128, 3, 1, 1]),
                                ('conv5_3_CPM_L1', [128, 128, 3, 1, 1]),
                                ('conv5_4_CPM_L1', [128, 512, 1, 1, 0]),
                                ('conv5_5_CPM_L1', [512, 38, 1, 1, 0])])

        block1_2 = OrderedDict([('conv5_1_CPM_L2', [128, 128, 3, 1, 1]),
                                ('conv5_2_CPM_L2', [128, 128, 3, 1, 1]),
                                ('conv5_3_CPM_L2', [128, 128, 3, 1, 1]),
                                ('conv5_4_CPM_L2', [128, 512, 1, 1, 0]),
                                ('conv5_5_CPM_L2', [512, 19, 1, 1, 0])])
        blocks['block1_1'] = block1_1
        blocks['block1_2'] = block1_2

        self.model0 = make_layers(block0, no_relu_layers)

        # Stages 2 - 6
        for i in range(2, 7):
            blocks['block%d_1' % i] = OrderedDict([
                ('Mconv1_stage%d_L1' % i, [185, 128, 7, 1, 3]),
                ('Mconv2_stage%d_L1' % i, [128, 128, 7, 1, 3]),
                ('Mconv3_stage%d_L1' % i, [128, 128, 7, 1, 3]),
                ('Mconv4_stage%d_L1' % i, [128, 128, 7, 1, 3]),
                ('Mconv5_stage%d_L1' % i, [128, 128, 7, 1, 3]),
                ('Mconv6_stage%d_L1' % i, [128, 128, 1, 1, 0]),
                ('Mconv7_stage%d_L1' % i, [128, 38, 1, 1, 0])
            ])

            blocks['block%d_2' % i] = OrderedDict([
                ('Mconv1_stage%d_L2' % i, [185, 128, 7, 1, 3]),
                ('Mconv2_stage%d_L2' % i, [128, 128, 7, 1, 3]),
                ('Mconv3_stage%d_L2' % i, [128, 128, 7, 1, 3]),
                ('Mconv4_stage%d_L2' % i, [128, 128, 7, 1, 3]),
                ('Mconv5_stage%d_L2' % i, [128, 128, 7, 1, 3]),
                ('Mconv6_stage%d_L2' % i, [128, 128, 1, 1, 0]),
                ('Mconv7_stage%d_L2' % i, [128, 19, 1, 1, 0])
            ])

        for k in blocks.keys():
            blocks[k] = make_layers(blocks[k], no_relu_layers)

        self.model1_1 = blocks['block1_1']
        self.model2_1 = blocks['block2_1']
        self.model3_1 = blocks['block3_1']
        self.model4_1 = blocks['block4_1']
        self.model5_1 = blocks['block5_1']
        self.model6_1 = blocks['block6_1']

        self.model1_2 = blocks['block1_2']
        self.model2_2 = blocks['block2_2']
        self.model3_2 = blocks['block3_2']
        self.model4_2 = blocks['block4_2']
        self.model5_2 = blocks['block5_2']
        self.model6_2 = blocks['block6_2']

    def forward(self, x):

        out1 = self.model0(x)

        out1_1 = self.model1_1(out1)
        out1_2 = self.model1_2(out1)
        out2 = torch.cat([out1_1, out1_2, out1], 1)

        out2_1 = self.model2_1(out2)
        out2_2 = self.model2_2(out2)
        out3 = torch.cat([out2_1, out2_2, out1], 1)

        out3_1 = self.model3_1(out3)
        out3_2 = self.model3_2(out3)
        out4 = torch.cat([out3_1, out3_2, out1], 1)

        out4_1 = self.model4_1(out4)
        out4_2 = self.model4_2(out4)
        out5 = torch.cat([out4_1, out4_2, out1], 1)

        out5_1 = self.model5_1(out5)
        out5_2 = self.model5_2(out5)
        out6 = torch.cat([out5_1, out5_2, out1], 1)

        out6_1 = self.model6_1(out6)
        out6_2 = self.model6_2(out6)

        return out6_1, out6_2
