# The implementation is based on HRNET, available at https://github.com/HRNet/HigherHRNet-Human-Pose-Estimation.

import os

import numpy as np
import torch
import torch.nn as nn
import torch.nn.functional as F

from modelscope.metainfo import Models
from modelscope.models.base.base_torch_model import TorchModel
from modelscope.models.builder import MODELS
from modelscope.models.cv.body_2d_keypoints.hrnet_basic_modules import (
    BN_MOMENTUM, BasicBlock, Bottleneck, HighResolutionModule, blocks_dict)
from modelscope.models.cv.body_2d_keypoints.w48 import cfg_128x128_15
from modelscope.utils.constant import Tasks


@MODELS.register_module(
    Tasks.body_2d_keypoints, module_name=Models.body_2d_keypoints)
class PoseHighResolutionNetV2(TorchModel):

    def __init__(self, cfg=None, **kwargs):
        if cfg is None:
            cfg = cfg_128x128_15
        self.inplanes = 64
        extra = cfg['MODEL']['EXTRA']
        super(PoseHighResolutionNetV2, self).__init__(**kwargs)

        # stem net
        self.conv1 = nn.Conv2d(
            3, 64, kernel_size=3, stride=2, padding=1, bias=False)
        self.bn1 = nn.BatchNorm2d(64, momentum=BN_MOMENTUM)
        self.conv2 = nn.Conv2d(
            64, 64, kernel_size=3, stride=2, padding=1, bias=False)
        self.bn2 = nn.BatchNorm2d(64, momentum=BN_MOMENTUM)
        self.relu = nn.ReLU(inplace=True)
        self.layer1 = self._make_layer(Bottleneck, 64, 4)

        self.stage2_cfg = cfg['MODEL']['EXTRA']['STAGE2']
        num_channels = self.stage2_cfg['NUM_CHANNELS']
        block = blocks_dict[self.stage2_cfg['BLOCK']]
        num_channels = [
            num_channels[i] * block.expansion
            for i in range(len(num_channels))
        ]
        self.transition1 = self._make_transition_layer([256], num_channels)
        self.stage2, pre_stage_channels = self._make_stage(
            self.stage2_cfg, num_channels)

        self.stage3_cfg = cfg['MODEL']['EXTRA']['STAGE3']
        num_channels = self.stage3_cfg['NUM_CHANNELS']
        block = blocks_dict[self.stage3_cfg['BLOCK']]
        num_channels = [
            num_channels[i] * block.expansion
            for i in range(len(num_channels))
        ]
        self.transition2 = self._make_transition_layer(pre_stage_channels,
                                                       num_channels)
        self.stage3, pre_stage_channels = self._make_stage(
            self.stage3_cfg, num_channels)

        self.stage4_cfg = cfg['MODEL']['EXTRA']['STAGE4']
        num_channels = self.stage4_cfg['NUM_CHANNELS']
        block = blocks_dict[self.stage4_cfg['BLOCK']]
        num_channels = [
            num_channels[i] * block.expansion
            for i in range(len(num_channels))
        ]
        self.transition3 = self._make_transition_layer(pre_stage_channels,
                                                       num_channels)
        self.stage4, pre_stage_channels = self._make_stage(
            self.stage4_cfg, num_channels, multi_scale_output=True)
        """final four layers"""
        last_inp_channels = np.int(np.sum(pre_stage_channels))
        self.final_layer = nn.Sequential(
            nn.Conv2d(
                in_channels=last_inp_channels,
                out_channels=last_inp_channels,
                kernel_size=1,
                stride=1,
                padding=0),
            nn.BatchNorm2d(last_inp_channels, momentum=BN_MOMENTUM),
            nn.ReLU(inplace=False),
            nn.Conv2d(
                in_channels=last_inp_channels,
                out_channels=cfg['MODEL']['NUM_JOINTS'],
                kernel_size=extra['FINAL_CONV_KERNEL'],
                stride=1,
                padding=1 if extra['FINAL_CONV_KERNEL'] == 3 else 0))

        self.pretrained_layers = cfg['MODEL']['EXTRA']['PRETRAINED_LAYERS']

    def _make_transition_layer(self, num_channels_pre_layer,
                               num_channels_cur_layer):
        num_branches_cur = len(num_channels_cur_layer)
        num_branches_pre = len(num_channels_pre_layer)

        transition_layers = []
        for i in range(num_branches_cur):
            if i < num_branches_pre:
                if num_channels_cur_layer[i] != num_channels_pre_layer[i]:
                    transition_layers.append(
                        nn.Sequential(
                            nn.Conv2d(
                                num_channels_pre_layer[i],
                                num_channels_cur_layer[i],
                                3,
                                1,
                                1,
                                bias=False),
                            nn.BatchNorm2d(num_channels_cur_layer[i]),
                            nn.ReLU(inplace=True)))
                else:
                    transition_layers.append(None)
            else:
                conv3x3s = []
                for j in range(i + 1 - num_branches_pre):
                    inchannels = num_channels_pre_layer[-1]
                    outchannels = num_channels_cur_layer[
                        i] if j == i - num_branches_pre else inchannels
                    conv3x3s.append(
                        nn.Sequential(
                            nn.Conv2d(
                                inchannels, outchannels, 3, 2, 1, bias=False),
                            nn.BatchNorm2d(outchannels),
                            nn.ReLU(inplace=True)))
                transition_layers.append(nn.Sequential(*conv3x3s))

        return nn.ModuleList(transition_layers)

    def _make_layer(self, block, planes, blocks, stride=1):
        downsample = None
        if stride != 1 or self.inplanes != planes * block.expansion:
            downsample = nn.Sequential(
                nn.Conv2d(
                    self.inplanes,
                    planes * block.expansion,
                    kernel_size=1,
                    stride=stride,
                    bias=False),
                nn.BatchNorm2d(planes * block.expansion, momentum=BN_MOMENTUM),
            )

        layers = []
        layers.append(block(self.inplanes, planes, stride, downsample))
        self.inplanes = planes * block.expansion
        for i in range(1, blocks):
            layers.append(block(self.inplanes, planes))

        return nn.Sequential(*layers)

    def _make_stage(self,
                    layer_config,
                    num_inchannels,
                    multi_scale_output=True):
        num_modules = layer_config['NUM_MODULES']
        num_branches = layer_config['NUM_BRANCHES']
        num_blocks = layer_config['NUM_BLOCKS']
        num_channels = layer_config['NUM_CHANNELS']
        block = blocks_dict[layer_config['BLOCK']]
        fuse_method = layer_config['FUSE_METHOD']

        modules = []
        for i in range(num_modules):
            if not multi_scale_output and i == num_modules - 1:
                reset_multi_scale_output = False
            else:
                reset_multi_scale_output = True

            modules.append(
                HighResolutionModule(num_branches, block, num_blocks,
                                     num_inchannels, num_channels, fuse_method,
                                     reset_multi_scale_output))
            num_inchannels = modules[-1].get_num_inchannels()

        return nn.Sequential(*modules), num_inchannels

    def forward(self, x):
        x = self.conv1(x)
        x = self.bn1(x)
        x = self.relu(x)
        x = self.conv2(x)
        x = self.bn2(x)
        x = self.relu(x)
        x = self.layer1(x)

        x_list = []
        for i in range(self.stage2_cfg['NUM_BRANCHES']):
            if self.transition1[i] is not None:
                x_list.append(self.transition1[i](x))
            else:
                x_list.append(x)

        y_list = self.stage2(x_list)

        x_list = []
        for i in range(self.stage3_cfg['NUM_BRANCHES']):
            if self.transition2[i] is not None:
                x_list.append(self.transition2[i](y_list[-1]))
            else:
                x_list.append(y_list[i])

        y_list = self.stage3(x_list)

        x_list = []
        for i in range(self.stage4_cfg['NUM_BRANCHES']):
            if self.transition3[i] is not None:
                x_list.append(self.transition3[i](y_list[-1]))
            else:
                x_list.append(y_list[i])

        y_list = self.stage4(x_list)

        y0_h, y0_w = y_list[0].size(2), y_list[0].size(3)
        y1 = F.upsample(y_list[1], size=(y0_h, y0_w), mode='bilinear')
        y2 = F.upsample(y_list[2], size=(y0_h, y0_w), mode='bilinear')
        y3 = F.upsample(y_list[3], size=(y0_h, y0_w), mode='bilinear')

        y = torch.cat([y_list[0], y1, y2, y3], 1)
        output = self.final_layer(y)

        return output
