import torch
import torch.nn as nn

__all__ = ['OPS', 'ResNetBasicblock', 'SearchSpaceNames']

OPS = {
  'noise'        : lambda C_in, C_out, stride, affine, track_running_stats: NoiseOp(stride, 0., 1.), # C_in, C_out not needed
  'none'         : lambda C_in, C_out, stride, affine, track_running_stats: Zero(C_in, C_out, stride),
  'avg_pool_3x3' : lambda C_in, C_out, stride, affine, track_running_stats: POOLING(C_in, C_out, stride, 'avg', affine, track_running_stats),
  'max_pool_3x3' : lambda C_in, C_out, stride, affine, track_running_stats: POOLING(C_in, C_out, stride, 'max', affine, track_running_stats),
  'nor_conv_7x7' : lambda C_in, C_out, stride, affine, track_running_stats: ReLUConvBN(C_in, C_out, (7,7), (stride,stride), (3,3), (1,1), affine, track_running_stats),
  'nor_conv_3x3' : lambda C_in, C_out, stride, affine, track_running_stats: ReLUConvBN(C_in, C_out, (3,3), (stride,stride), (1,1), (1,1), affine, track_running_stats),
  'nor_conv_1x1' : lambda C_in, C_out, stride, affine, track_running_stats: ReLUConvBN(C_in, C_out, (1,1), (stride,stride), (0,0), (1,1), affine, track_running_stats),
  'dua_sepc_3x3' : lambda C_in, C_out, stride, affine, track_running_stats: DualSepConv(C_in, C_out, (3,3), (stride,stride), (1,1), (1,1), affine, track_running_stats),
  'dua_sepc_5x5' : lambda C_in, C_out, stride, affine, track_running_stats: DualSepConv(C_in, C_out, (5,5), (stride,stride), (2,2), (1,1), affine, track_running_stats),
  'dil_sepc_3x3' : lambda C_in, C_out, stride, affine, track_running_stats: SepConv(C_in, C_out, (3,3), (stride,stride), (2,2), (2,2), affine, track_running_stats),
  'dil_sepc_5x5' : lambda C_in, C_out, stride, affine, track_running_stats: SepConv(C_in, C_out, (5,5), (stride,stride), (4,4), (2,2), affine, track_running_stats),
  'skip_connect' : lambda C_in, C_out, stride, affine, track_running_stats: Identity() if stride == 1 and C_in == C_out else FactorizedReduce(C_in, C_out, stride, affine, track_running_stats),
}

CONNECT_NAS_BENCHMARK = ['none', 'skip_connect', 'nor_conv_3x3']
NAS_BENCH_201         = ['none', 'skip_connect', 'nor_conv_1x1', 'nor_conv_3x3', 'avg_pool_3x3']
DARTS_SPACE           = ['none', 'skip_connect', 'dua_sepc_3x3', 'dua_sepc_5x5', 'dil_sepc_3x3', 'dil_sepc_5x5', 'avg_pool_3x3', 'max_pool_3x3']
#### wrc modified
NAS_BENCH_201_SKIP    = ['none', 'skip_connect', 'nor_conv_1x1_skip', 'nor_conv_3x3_skip', 'avg_pool_3x3']
NAS_BENCH_201_SIMPLE  = ['skip_connect', 'nor_conv_1x1', 'nor_conv_3x3', 'avg_pool_3x3']
NAS_BENCH_201_S2      = ['skip_connect', 'nor_conv_3x3']
NAS_BENCH_201_S4      = ['noise', 'nor_conv_3x3']
NAS_BENCH_201_S10     = ['none', 'nor_conv_3x3']

SearchSpaceNames = {'connect-nas'  : CONNECT_NAS_BENCHMARK,
                    'nas-bench-201': NAS_BENCH_201,
                    'nas-bench-201-simple': NAS_BENCH_201_SIMPLE,
                    'nas-bench-201-s2': NAS_BENCH_201_S2,
                    'nas-bench-201-s4': NAS_BENCH_201_S4,
                    'nas-bench-201-s10': NAS_BENCH_201_S10,
                    'darts'        : DARTS_SPACE}

class NoiseOp(nn.Module):
    def __init__(self, stride, mean, std):
        super(NoiseOp, self).__init__()
        self.stride = stride
        self.mean = mean
        self.std = std

    def forward(self, x):
        if self.stride != 1:
            x_new = x[:,:,::self.stride,::self.stride]
        else:
            x_new = x
        noise = x_new.data.new(x_new.size()).normal_(self.mean, self.std)
        return noise

class ReLUConvBN(nn.Module):

  def __init__(self, C_in, C_out, kernel_size, stride, padding, dilation, affine, track_running_stats=True):
    super(ReLUConvBN, self).__init__()
    self.op = nn.Sequential(
      nn.ReLU(inplace=False),
      nn.Conv2d(C_in, C_out, kernel_size, stride=stride, padding=padding, dilation=dilation, bias=False),
      nn.BatchNorm2d(C_out, affine=affine, track_running_stats=track_running_stats)
    )

  def forward(self, x):
    return self.op(x)

  
#### wrc modified
class ReLUConvBNSkip(nn.Module):

  def __init__(self, C_in, C_out, kernel_size, stride, padding, dilation, affine, track_running_stats=True):
    super(ReLUConvBNSkip, self).__init__()
    self.op = nn.Sequential(
      nn.ReLU(inplace=False),
      nn.Conv2d(C_in, C_out, kernel_size, stride=stride, padding=padding, dilation=dilation, bias=False),
      nn.BatchNorm2d(C_out, affine=affine, track_running_stats=track_running_stats)
    )

  def forward(self, x):
    return self.op(x) + x
####

class SepConv(nn.Module):
    
  def __init__(self, C_in, C_out, kernel_size, stride, padding, dilation, affine, track_running_stats=True):
    super(SepConv, self).__init__()
    self.op = nn.Sequential(
      nn.ReLU(inplace=False),
      nn.Conv2d(C_in, C_in, kernel_size=kernel_size, stride=stride, padding=padding, dilation=dilation, groups=C_in, bias=False),
      nn.Conv2d(C_in, C_out, kernel_size=1, padding=0, bias=False),
      nn.BatchNorm2d(C_out, affine=affine, track_running_stats=track_running_stats),
      )

  def forward(self, x):
    return self.op(x)


class DualSepConv(nn.Module):
    
  def __init__(self, C_in, C_out, kernel_size, stride, padding, dilation, affine, track_running_stats=True):
    super(DualSepConv, self).__init__()
    self.op_a = SepConv(C_in, C_in , kernel_size, stride, padding, dilation, affine, track_running_stats)
    self.op_b = SepConv(C_in, C_out, kernel_size, 1, padding, dilation, affine, track_running_stats)

  def forward(self, x):
    x = self.op_a(x)
    x = self.op_b(x)
    return x


class ResNetBasicblock(nn.Module):

  def __init__(self, inplanes, planes, stride, affine=True):
    super(ResNetBasicblock, self).__init__()
    assert stride == 1 or stride == 2, 'invalid stride {:}'.format(stride)
    self.conv_a = ReLUConvBN(inplanes, planes, 3, stride, 1, 1, affine)
    self.conv_b = ReLUConvBN(  planes, planes, 3,      1, 1, 1, affine)
    if stride == 2:
      self.downsample = nn.Sequential(
                           nn.AvgPool2d(kernel_size=2, stride=2, padding=0),
                           nn.Conv2d(inplanes, planes, kernel_size=1, stride=1, padding=0, bias=False))
    elif inplanes != planes:
      self.downsample = ReLUConvBN(inplanes, planes, 1, 1, 0, 1, affine)
    else:
      self.downsample = None
    self.in_dim  = inplanes
    self.out_dim = planes
    self.stride  = stride
    self.num_conv = 2

  def extra_repr(self):
    string = '{name}(inC={in_dim}, outC={out_dim}, stride={stride})'.format(name=self.__class__.__name__, **self.__dict__)
    return string

  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
    return residual + basicblock


class POOLING(nn.Module):

  def __init__(self, C_in, C_out, stride, mode, affine=True, track_running_stats=True):
    super(POOLING, self).__init__()
    if C_in == C_out:
      self.preprocess = None
    else:
      self.preprocess = ReLUConvBN(C_in, C_out, 1, 1, 0, affine, track_running_stats)
    if mode == 'avg'  : self.op = nn.AvgPool2d(3, stride=stride, padding=1, count_include_pad=False)
    elif mode == 'max': self.op = nn.MaxPool2d(3, stride=stride, padding=1)
    else              : raise ValueError('Invalid mode={:} in POOLING'.format(mode))

  def forward(self, inputs):
    if self.preprocess: x = self.preprocess(inputs)
    else              : x = inputs
    return self.op(x)


class Identity(nn.Module):

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

  def forward(self, x):
    return x


class Zero(nn.Module):

  def __init__(self, C_in, C_out, stride):
    super(Zero, self).__init__()
    self.C_in   = C_in
    self.C_out  = C_out
    self.stride = stride
    self.is_zero = True

  def forward(self, x):
    if self.C_in == self.C_out:
      if self.stride == 1: return x.mul(0.)
      else               : return x[:,:,::self.stride,::self.stride].mul(0.)
    else: ## this is never called in nasbench201
      shape = list(x.shape)
      shape[1] = self.C_out
      zeros = x.new_zeros(shape, dtype=x.dtype, device=x.device)
      return zeros

  def extra_repr(self):
    return 'C_in={C_in}, C_out={C_out}, stride={stride}'.format(**self.__dict__)


class FactorizedReduce(nn.Module):

  def __init__(self, C_in, C_out, stride, affine, track_running_stats):
    super(FactorizedReduce, self).__init__()
    self.stride = stride
    self.C_in   = C_in
    self.C_out  = C_out
    self.relu   = nn.ReLU(inplace=False)
    if stride == 2:
      #assert C_out % 2 == 0, 'C_out : {:}'.format(C_out)
      C_outs = [C_out // 2, C_out - C_out // 2]
      self.convs = nn.ModuleList()
      for i in range(2):
        self.convs.append( nn.Conv2d(C_in, C_outs[i], 1, stride=stride, padding=0, bias=False) )
      self.pad = nn.ConstantPad2d((0, 1, 0, 1), 0)
    elif stride == 1:
      self.conv = nn.Conv2d(C_in, C_out, 1, stride=stride, padding=0, bias=False)
    else:
      raise ValueError('Invalid stride : {:}'.format(stride))
    self.bn = nn.BatchNorm2d(C_out, affine=affine, track_running_stats=track_running_stats)

  def forward(self, x):
    if self.stride == 2:
      x = self.relu(x)
      y = self.pad(x)
      out = torch.cat([self.convs[0](x), self.convs[1](y[:,:,1:,1:])], dim=1)
    else:
      out = self.conv(x)
    out = self.bn(out)
    return out

  def extra_repr(self):
    return 'C_in={C_in}, C_out={C_out}, stride={stride}'.format(**self.__dict__)
