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# Copyright (c) Xuanyi Dong [GitHub D-X-Y], 2019 #
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import math, torch
from collections import OrderedDict
from bisect import bisect_right
import torch.nn as nn
from ..initialization import initialize_resnet
from ..SharedUtils    import additive_func
from .SoftSelect      import select2withP, ChannelWiseInter
from .SoftSelect      import linear_forward
from .SoftSelect      import get_width_choices


def get_depth_choices(nDepth, return_num):
  if nDepth == 2:
    choices = (1, 2)
  elif nDepth == 3:
    choices = (1, 2, 3)
  elif nDepth > 3:
    choices = list(range(1, nDepth+1, 2))
    if choices[-1] < nDepth: choices.append(nDepth)
  else:
    raise ValueError('invalid nDepth : {:}'.format(nDepth))
  if return_num: return len(choices)
  else         : return choices



class ConvBNReLU(nn.Module):
  num_conv  = 1
  def __init__(self, nIn, nOut, kernel, stride, padding, bias, has_avg, has_bn, has_relu):
    super(ConvBNReLU, self).__init__()
    self.InShape  = None
    self.OutShape = None
    self.choices  = get_width_choices(nOut)
    self.register_buffer('choices_tensor', torch.Tensor( self.choices ))

    if has_avg : self.avg = nn.AvgPool2d(kernel_size=2, stride=2, padding=0)
    else       : self.avg = None
    self.conv = nn.Conv2d(nIn, nOut, kernel_size=kernel, stride=stride, padding=padding, dilation=1, groups=1, bias=bias)
    if has_bn  : self.bn  = nn.BatchNorm2d(nOut)
    else       : self.bn  = None
    if has_relu: self.relu = nn.ReLU(inplace=False)
    else       : self.relu = None
    self.in_dim   = nIn
    self.out_dim  = nOut

  def get_flops(self, divide=1):
    iC, oC = self.in_dim, self.out_dim
    assert iC <= self.conv.in_channels and oC <= self.conv.out_channels, '{:} vs {:}  |  {:} vs {:}'.format(iC, self.conv.in_channels, oC, self.conv.out_channels)
    assert isinstance(self.InShape, tuple) and len(self.InShape) == 2, 'invalid in-shape : {:}'.format(self.InShape)
    assert isinstance(self.OutShape, tuple) and len(self.OutShape) == 2, 'invalid out-shape : {:}'.format(self.OutShape)
    #conv_per_position_flops = self.conv.kernel_size[0] * self.conv.kernel_size[1] * iC * oC / self.conv.groups
    conv_per_position_flops = (self.conv.kernel_size[0] * self.conv.kernel_size[1] * 1.0 / self.conv.groups)
    all_positions = self.OutShape[0] * self.OutShape[1]
    flops = (conv_per_position_flops * all_positions / divide) * iC * oC
    if self.conv.bias is not None: flops += all_positions / divide
    return flops

  def forward(self, inputs):
    if self.avg : out = self.avg( inputs )
    else        : out = inputs
    conv = self.conv( out )
    if self.bn  : out = self.bn( conv )
    else        : out = conv
    if self.relu: out = self.relu( out )
    else        : out = out
    if self.InShape is None:
      self.InShape  = (inputs.size(-2), inputs.size(-1))
      self.OutShape = (out.size(-2)   , out.size(-1))
    return out


class ResNetBasicblock(nn.Module):
  expansion = 1
  num_conv  = 2
  def __init__(self, inplanes, planes, stride):
    super(ResNetBasicblock, self).__init__()
    assert stride == 1 or stride == 2, 'invalid stride {:}'.format(stride)
    self.conv_a = ConvBNReLU(inplanes, planes, 3, stride, 1, False, has_avg=False, has_bn=True, has_relu=True)
    self.conv_b = ConvBNReLU(  planes, planes, 3,      1, 1, False, has_avg=False, has_bn=True, has_relu=False)
    if stride == 2:
      self.downsample = ConvBNReLU(inplanes, planes, 1, 1, 0, False, has_avg=True, has_bn=False, has_relu=False)
    elif inplanes != planes:
      self.downsample = ConvBNReLU(inplanes, planes, 1, 1, 0, False, has_avg=False,has_bn=True , has_relu=False)
    else:
      self.downsample = None
    self.out_dim     = planes
    self.search_mode = 'basic'

  def get_flops(self, divide=1):
    flop_A = self.conv_a.get_flops(divide)
    flop_B = self.conv_b.get_flops(divide)
    if hasattr(self.downsample, 'get_flops'):
      flop_C = self.downsample.get_flops(divide)
    else:
      flop_C = 0
    return flop_A + flop_B + flop_C

  def forward(self, inputs):
    basicblock = self.conv_a(inputs)
    basicblock = self.conv_b(basicblock)
    if self.downsample is not None: residual = self.downsample(inputs)
    else                          : residual = inputs
    out = additive_func(residual, basicblock)
    return nn.functional.relu(out, inplace=True)



class ResNetBottleneck(nn.Module):
  expansion = 4
  num_conv  = 3
  def __init__(self, inplanes, planes, stride):
    super(ResNetBottleneck, self).__init__()
    assert stride == 1 or stride == 2, 'invalid stride {:}'.format(stride)
    self.conv_1x1 = ConvBNReLU(inplanes, planes, 1,      1, 0, False, has_avg=False, has_bn=True, has_relu=True)
    self.conv_3x3 = ConvBNReLU(  planes, planes, 3, stride, 1, False, has_avg=False, has_bn=True, has_relu=True)
    self.conv_1x4 = ConvBNReLU(planes, planes*self.expansion, 1, 1, 0, False, has_avg=False, has_bn=True, has_relu=False)
    if stride == 2:
      self.downsample = ConvBNReLU(inplanes, planes*self.expansion, 1, 1, 0, False, has_avg=True, has_bn=False, has_relu=False)
    elif inplanes != planes*self.expansion:
      self.downsample = ConvBNReLU(inplanes, planes*self.expansion, 1, 1, 0, False, has_avg=False,has_bn=True , has_relu=False)
    else:
      self.downsample = None
    self.out_dim     = planes * self.expansion
    self.search_mode = 'basic'

  def get_range(self):
    return self.conv_1x1.get_range() + self.conv_3x3.get_range() + self.conv_1x4.get_range()

  def get_flops(self, divide):
    flop_A = self.conv_1x1.get_flops(divide)
    flop_B = self.conv_3x3.get_flops(divide)
    flop_C = self.conv_1x4.get_flops(divide)
    if hasattr(self.downsample, 'get_flops'):
      flop_D = self.downsample.get_flops(divide)
    else:
      flop_D = 0
    return flop_A + flop_B + flop_C + flop_D

  def forward(self, inputs):
    bottleneck = self.conv_1x1(inputs)
    bottleneck = self.conv_3x3(bottleneck)
    bottleneck = self.conv_1x4(bottleneck)
    if self.downsample is not None: residual = self.downsample(inputs)
    else                          : residual = inputs
    out = additive_func(residual, bottleneck)
    return nn.functional.relu(out, inplace=True)


class SearchDepthCifarResNet(nn.Module):

  def __init__(self, block_name, depth, num_classes):
    super(SearchDepthCifarResNet, self).__init__()

    #Model type specifies number of layers for CIFAR-10 and CIFAR-100 model
    if block_name == 'ResNetBasicblock':
      block = ResNetBasicblock
      assert (depth - 2) % 6 == 0, 'depth should be one of 20, 32, 44, 56, 110'
      layer_blocks = (depth - 2) // 6
    elif block_name == 'ResNetBottleneck':
      block = ResNetBottleneck
      assert (depth - 2) % 9 == 0, 'depth should be one of 164'
      layer_blocks = (depth - 2) // 9
    else:
      raise ValueError('invalid block : {:}'.format(block_name))

    self.message      = 'SearchShapeCifarResNet : Depth : {:} , Layers for each block : {:}'.format(depth, layer_blocks)
    self.num_classes  = num_classes
    self.channels     = [16]
    self.layers       = nn.ModuleList( [ ConvBNReLU(3, 16, 3, 1, 1, False, has_avg=False, has_bn=True, has_relu=True) ] )
    self.InShape      = None
    self.depth_info   = OrderedDict()
    self.depth_at_i   = OrderedDict()
    for stage in range(3):
      cur_block_choices = get_depth_choices(layer_blocks, False)
      assert cur_block_choices[-1] == layer_blocks, 'stage={:}, {:} vs {:}'.format(stage, cur_block_choices, layer_blocks)
      self.message += "\nstage={:} ::: depth-block-choices={:} for {:} blocks.".format(stage, cur_block_choices, layer_blocks)
      block_choices, xstart = [], len(self.layers)
      for iL in range(layer_blocks):
        iC     = self.channels[-1]
        planes = 16 * (2**stage)
        stride = 2 if stage > 0 and iL == 0 else 1
        module = block(iC, planes, stride)
        self.channels.append( module.out_dim )
        self.layers.append  ( module )
        self.message += "\nstage={:}, ilayer={:02d}/{:02d}, block={:03d}, iC={:3d}, oC={:3d}, stride={:}".format(stage, iL, layer_blocks, len(self.layers)-1, iC, module.out_dim, stride)
        # added for depth
        layer_index = len(self.layers) - 1
        if iL + 1 in cur_block_choices: block_choices.append( layer_index )
        if iL + 1 == layer_blocks:
          self.depth_info[layer_index] = {'choices': block_choices,
                                          'stage'  : stage,
                                          'xstart' : xstart}
    self.depth_info_list = []
    for xend, info in self.depth_info.items():
      self.depth_info_list.append( (xend, info) )
      xstart, xstage = info['xstart'], info['stage']
      for ilayer in range(xstart, xend+1):
        idx = bisect_right(info['choices'], ilayer-1)
        self.depth_at_i[ilayer] = (xstage, idx)

    self.avgpool     = nn.AvgPool2d(8)
    self.classifier  = nn.Linear(module.out_dim, num_classes)
    self.InShape     = None
    self.tau         = -1
    self.search_mode = 'basic'
    #assert sum(x.num_conv for x in self.layers) + 1 == depth, 'invalid depth check {:} vs {:}'.format(sum(x.num_conv for x in self.layers)+1, depth)
    

    self.register_parameter('depth_attentions', nn.Parameter(torch.Tensor(3, get_depth_choices(layer_blocks, True))))
    nn.init.normal_(self.depth_attentions, 0, 0.01)
    self.apply(initialize_resnet)

  def arch_parameters(self):
    return [self.depth_attentions]

  def base_parameters(self):
    return list(self.layers.parameters()) + list(self.avgpool.parameters()) + list(self.classifier.parameters())

  def get_flop(self, mode, config_dict, extra_info):
    if config_dict is not None: config_dict = config_dict.copy()
    # select depth
    if mode == 'genotype':
      with torch.no_grad():
        depth_probs = nn.functional.softmax(self.depth_attentions, dim=1)
        choices = torch.argmax(depth_probs, dim=1).cpu().tolist()
    elif mode == 'max':
      choices = [depth_probs.size(1)-1 for _ in range(depth_probs.size(0))]
    elif mode == 'random':
      with torch.no_grad():
        depth_probs = nn.functional.softmax(self.depth_attentions, dim=1)
        choices = torch.multinomial(depth_probs, 1, False).cpu().tolist()
    else:
      raise ValueError('invalid mode : {:}'.format(mode))
    selected_layers = []
    for choice, xvalue in zip(choices, self.depth_info_list):
      xtemp = xvalue[1]['choices'][choice] - xvalue[1]['xstart'] + 1
      selected_layers.append(xtemp)
    flop = 0
    for i, layer in enumerate(self.layers):
      if i in self.depth_at_i:
        xstagei, xatti = self.depth_at_i[i]
        if xatti <= choices[xstagei]: # leave this depth
          flop+= layer.get_flops()
        else:
          flop+= 0 # do not use this layer
      else:
        flop+= layer.get_flops()
    # the last fc layer
    flop += self.classifier.in_features * self.classifier.out_features
    if config_dict is None:
      return flop / 1e6
    else:
      config_dict['xblocks']    = selected_layers
      config_dict['super_type'] = 'infer-depth'
      config_dict['estimated_FLOP'] = flop / 1e6
      return flop / 1e6, config_dict

  def get_arch_info(self):
    string = "for depth, there are {:} attention probabilities.".format(len(self.depth_attentions))
    string+= '\n{:}'.format(self.depth_info)
    discrepancy = []
    with torch.no_grad():
      for i, att in enumerate(self.depth_attentions):
        prob = nn.functional.softmax(att, dim=0)
        prob = prob.cpu() ; selc = prob.argmax().item() ; prob = prob.tolist()
        prob = ['{:.3f}'.format(x) for x in prob]
        xstring = '{:03d}/{:03d}-th : {:}'.format(i, len(self.depth_attentions), ' '.join(prob))
        logt = ['{:.4f}'.format(x) for x in att.cpu().tolist()]
        xstring += '  ||  {:17s}'.format(' '.join(logt))
        prob = sorted( [float(x) for x in prob] )
        disc = prob[-1] - prob[-2]
        xstring += '  || discrepancy={:.2f} || select={:}/{:}'.format(disc, selc, len(prob))
        discrepancy.append( disc )
        string += '\n{:}'.format(xstring)
    return string, discrepancy

  def set_tau(self, tau_max, tau_min, epoch_ratio):
    assert epoch_ratio >= 0 and epoch_ratio <= 1, 'invalid epoch-ratio : {:}'.format(epoch_ratio)
    tau = tau_min + (tau_max-tau_min) * (1 + math.cos(math.pi * epoch_ratio)) / 2
    self.tau = tau

  def get_message(self):
    return self.message

  def forward(self, inputs):
    if self.search_mode == 'basic':
      return self.basic_forward(inputs)
    elif self.search_mode == 'search':
      return self.search_forward(inputs)
    else:
      raise ValueError('invalid search_mode = {:}'.format(self.search_mode))

  def search_forward(self, inputs):
    flop_depth_probs = nn.functional.softmax(self.depth_attentions, dim=1)
    flop_depth_probs = torch.flip( torch.cumsum( torch.flip(flop_depth_probs, [1]), 1 ), [1] )
    selected_depth_probs = select2withP(self.depth_attentions, self.tau, True)

    x, flops = inputs, []
    feature_maps = []
    for i, layer in enumerate(self.layers):
      layer_i = layer( x )
      feature_maps.append( layer_i )
      if i in self.depth_info: # aggregate the information
        choices = self.depth_info[i]['choices']
        xstagei = self.depth_info[i]['stage']
        possible_tensors = []
        for tempi, A in enumerate(choices):
          xtensor = feature_maps[A]
          possible_tensors.append( xtensor )
        weighted_sum = sum( xtensor * W for xtensor, W in zip(possible_tensors, selected_depth_probs[xstagei]) )
        x = weighted_sum
      else:
        x = layer_i
       
      if i in self.depth_at_i:
        xstagei, xatti = self.depth_at_i[i]
        #print ('layer-{:03d}, stage={:}, att={:}, prob={:}, flop={:}'.format(i, xstagei, xatti, flop_depth_probs[xstagei, xatti].item(), layer.get_flops(1e6)))
        x_expected_flop = flop_depth_probs[xstagei, xatti] * layer.get_flops(1e6)
      else:
        x_expected_flop = layer.get_flops(1e6)
      flops.append( x_expected_flop )
    flops.append( (self.classifier.in_features * self.classifier.out_features*1.0/1e6) )

    features = self.avgpool(x)
    features = features.view(features.size(0), -1)
    logits   = linear_forward(features, self.classifier)
    return logits, torch.stack( [sum(flops)] )

  def basic_forward(self, inputs):
    if self.InShape is None: self.InShape = (inputs.size(-2), inputs.size(-1))
    x = inputs
    for i, layer in enumerate(self.layers):
      x = layer( x )
    features = self.avgpool(x)
    features = features.view(features.size(0), -1)
    logits   = self.classifier(features)
    return features, logits
