import torch
import torch.nn as nn
import torch.nn.functional as F
import pdb
import math
from maskrcnn_benchmark.modeling.utils import cat, concat_box_prediction_layers, permute_and_flatten
from timm.models.layers import DropPath

from transformers.activations import ACT2FN
class BertPredictionHeadTransform(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.dense = nn.Linear(config.hidden_size, config.hidden_size)
        if isinstance(config.hidden_act, str):
            self.transform_act_fn = ACT2FN[config.hidden_act]
        else:
            self.transform_act_fn = config.hidden_act
        self.LayerNorm = nn.LayerNorm(config.hidden_size, eps=config.layer_norm_eps)

    def forward(self, hidden_states):
        hidden_states = self.dense(hidden_states)
        hidden_states = self.transform_act_fn(hidden_states)
        hidden_states = self.LayerNorm(hidden_states)
        return hidden_states


class BertLMPredictionHead(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.transform = BertPredictionHeadTransform(config)

        # The output weights are the same as the input embeddings, but there is
        # an output-only bias for each token.
        self.decoder = nn.Linear(config.hidden_size, config.vocab_size, bias=False)

        self.bias = nn.Parameter(torch.zeros(config.vocab_size))

        # Need a link between the two variables so that the bias is correctly resized with `resize_token_embeddings`
        self.decoder.bias = self.bias

    def forward(self, hidden_states):
        hidden_states = self.transform(hidden_states)
        hidden_states = self.decoder(hidden_states)
        return hidden_states

class FeatureResizer(nn.Module):
    """
    This class takes as input a set of embeddings of dimension C1 and outputs a set of
    embedding of dimension C2, after a linear transformation, dropout and normalization (LN).
    """

    def __init__(self, input_feat_size, output_feat_size, dropout, do_ln=True):
        super().__init__()
        self.do_ln = do_ln
        # Object feature encoding
        self.fc = nn.Linear(input_feat_size, output_feat_size, bias=True)
        self.layer_norm = nn.LayerNorm(output_feat_size, eps=1e-12)
        self.dropout = nn.Dropout(dropout)

    def forward(self, encoder_features):
        x = self.fc(encoder_features)
        if self.do_ln:
            x = self.layer_norm(x)
        output = self.dropout(x)
        return output


def _make_conv(input_dim, output_dim, k, stride=1):
    pad = (k - 1) // 2
    return nn.Sequential(
        nn.Conv2d(input_dim, output_dim, (k, k), padding=(pad, pad), stride=(stride, stride)),
        nn.BatchNorm2d(output_dim),
        nn.ReLU(inplace=True)
    )


def _make_mlp(input_dim, output_dim, drop):
    return nn.Sequential(nn.Linear(input_dim, output_dim),
                         nn.BatchNorm1d(output_dim),
                         nn.ReLU(inplace=True),
                         nn.Dropout(drop),
                         nn.Linear(output_dim, output_dim),
                         nn.BatchNorm1d(output_dim),
                         nn.ReLU(inplace=True))


def _make_coord(batch, height, width):
    # relative position encoding
    xv, yv = torch.meshgrid([torch.arange(0, height), torch.arange(0, width)])
    xv_min = (xv.float() * 2 - width) / width
    yv_min = (yv.float() * 2 - height) / height
    xv_max = ((xv + 1).float() * 2 - width) / width
    yv_max = ((yv + 1).float() * 2 - height) / height
    xv_ctr = (xv_min + xv_max) / 2
    yv_ctr = (yv_min + yv_max) / 2
    hmap = torch.ones(height, width) * (1. / height)
    wmap = torch.ones(height, width) * (1. / width)
    coord = torch.autograd.Variable(torch.cat([xv_min.unsqueeze(0), yv_min.unsqueeze(0), \
                                               xv_max.unsqueeze(0), yv_max.unsqueeze(0), \
                                               xv_ctr.unsqueeze(0), yv_ctr.unsqueeze(0), \
                                               hmap.unsqueeze(0), wmap.unsqueeze(0)], dim=0))
    coord = coord.unsqueeze(0).repeat(batch, 1, 1, 1)
    return coord


def l1norm(X, dim, eps=1e-8):
    """L1-normalize columns of X
    """
    norm = torch.abs(X).sum(dim=dim, keepdim=True) + eps
    X = torch.div(X, norm)
    return X


def l2norm(X, dim, eps=1e-8):
    """L2-normalize columns of X
    """
    norm = torch.pow(X, 2).sum(dim=dim, keepdim=True).sqrt() + eps
    X = torch.div(X, norm)
    return X


def func_attention(query, context, smooth=1, raw_feature_norm="softmax", eps=1e-8):
    """
    query: (n_context, queryL, d)
    context: (n_context, sourceL, d)
    """
    batch_size_q, queryL = query.size(0), query.size(1)
    batch_size, sourceL = context.size(0), context.size(1)

    # Get attention
    # --> (batch, d, queryL)
    queryT = torch.transpose(query, 1, 2)

    # (batch, sourceL, d)(batch, d, queryL)
    # --> (batch, sourceL, queryL)
    attn = torch.bmm(context, queryT)
    if raw_feature_norm == "softmax":
        # --> (batch*sourceL, queryL)
        attn = attn.view(batch_size * sourceL, queryL)
        attn = nn.Softmax()(attn)
        # --> (batch, sourceL, queryL)
        attn = attn.view(batch_size, sourceL, queryL)
    elif raw_feature_norm == "l2norm":
        attn = l2norm(attn, 2)
    elif raw_feature_norm == "clipped_l2norm":
        attn = nn.LeakyReLU(0.1)(attn)
        attn = l2norm(attn, 2)
    else:
        raise ValueError("unknown first norm type:", raw_feature_norm)
    # --> (batch, queryL, sourceL)
    attn = torch.transpose(attn, 1, 2).contiguous()
    # --> (batch*queryL, sourceL)
    attn = attn.view(batch_size * queryL, sourceL)
    attn = nn.Softmax()(attn * smooth)
    # --> (batch, queryL, sourceL)
    attn = attn.view(batch_size, queryL, sourceL)
    # --> (batch, sourceL, queryL)
    attnT = torch.transpose(attn, 1, 2).contiguous()

    # --> (batch, d, sourceL)
    contextT = torch.transpose(context, 1, 2)
    # (batch x d x sourceL)(batch x sourceL x queryL)
    # --> (batch, d, queryL)
    weightedContext = torch.bmm(contextT, attnT)
    # --> (batch, queryL, d)
    weightedContext = torch.transpose(weightedContext, 1, 2)

    return weightedContext, attnT


class BiMultiHeadAttention(nn.Module):
    def __init__(self, v_dim, l_dim, embed_dim, num_heads, dropout=0.1, cfg=None):
        super(BiMultiHeadAttention, self).__init__()

        self.embed_dim = embed_dim
        self.num_heads = num_heads
        self.head_dim = embed_dim // num_heads
        self.v_dim = v_dim
        self.l_dim = l_dim

        assert (
                self.head_dim * self.num_heads == self.embed_dim
        ), f"embed_dim must be divisible by num_heads (got `embed_dim`: {self.embed_dim} and `num_heads`: {self.num_heads})."
        self.scale = self.head_dim ** (-0.5)
        self.dropout = dropout

        self.v_proj = nn.Linear(self.v_dim, self.embed_dim)
        self.l_proj = nn.Linear(self.l_dim, self.embed_dim)
        self.values_v_proj = nn.Linear(self.v_dim, self.embed_dim)
        self.values_l_proj = nn.Linear(self.l_dim, self.embed_dim)

        self.out_v_proj = nn.Linear(self.embed_dim, self.v_dim)
        self.out_l_proj = nn.Linear(self.embed_dim, self.l_dim)

        self.stable_softmax_2d = cfg.MODEL.DYHEAD.FUSE_CONFIG.STABLE_SOFTMAX_2D
        self.clamp_min_for_underflow = cfg.MODEL.DYHEAD.FUSE_CONFIG.CLAMP_MIN_FOR_UNDERFLOW
        self.clamp_max_for_overflow = cfg.MODEL.DYHEAD.FUSE_CONFIG.CLAMP_MAX_FOR_OVERFLOW

        self._reset_parameters()

    def _shape(self, tensor: torch.Tensor, seq_len: int, bsz: int):
        return tensor.view(bsz, seq_len, self.num_heads, self.head_dim).transpose(1, 2).contiguous()

    def _reset_parameters(self):
        nn.init.xavier_uniform_(self.v_proj.weight)
        self.v_proj.bias.data.fill_(0)
        nn.init.xavier_uniform_(self.l_proj.weight)
        self.l_proj.bias.data.fill_(0)
        nn.init.xavier_uniform_(self.values_v_proj.weight)
        self.values_v_proj.bias.data.fill_(0)
        nn.init.xavier_uniform_(self.values_l_proj.weight)
        self.values_l_proj.bias.data.fill_(0)
        nn.init.xavier_uniform_(self.out_v_proj.weight)
        self.out_v_proj.bias.data.fill_(0)
        nn.init.xavier_uniform_(self.out_l_proj.weight)
        self.out_l_proj.bias.data.fill_(0)

    def forward(self, v, l, attention_mask_l=None):
        bsz, tgt_len, embed_dim = v.size()

        query_states = self.v_proj(v) * self.scale
        key_states = self._shape(self.l_proj(l), -1, bsz)
        value_v_states = self._shape(self.values_v_proj(v), -1, bsz)
        value_l_states = self._shape(self.values_l_proj(l), -1, bsz)

        proj_shape = (bsz * self.num_heads, -1, self.head_dim)
        query_states = self._shape(query_states, tgt_len, bsz).view(*proj_shape)
        key_states = key_states.view(*proj_shape)
        value_v_states = value_v_states.view(*proj_shape)
        value_l_states = value_l_states.view(*proj_shape)

        src_len = key_states.size(1)
        attn_weights = torch.bmm(query_states, key_states.transpose(1, 2))

        if attn_weights.size() != (bsz * self.num_heads, tgt_len, src_len):
            raise ValueError(
                f"Attention weights should be of size {(bsz * self.num_heads, tgt_len, src_len)}, but is {attn_weights.size()}"
            )

        # attn_weights_l = nn.functional.softmax(attn_weights.transpose(1, 2), dim=-1)

        if self.stable_softmax_2d:
            attn_weights = attn_weights - attn_weights.max()
        
        if self.clamp_min_for_underflow:
            attn_weights = torch.clamp(attn_weights, min=-50000) # Do not increase -50000, data type half has quite limited range
        if self.clamp_max_for_overflow:
            attn_weights = torch.clamp(attn_weights, max=50000) # Do not increase 50000, data type half has quite limited range

        attn_weights_T = attn_weights.transpose(1, 2)
        attn_weights_l = (attn_weights_T - torch.max(attn_weights_T, dim=-1, keepdim=True)[
            0])
        if self.clamp_min_for_underflow:
            attn_weights_l = torch.clamp(attn_weights_l, min=-50000) # Do not increase -50000, data type half has quite limited range
        if self.clamp_max_for_overflow:
            attn_weights_l = torch.clamp(attn_weights_l, max=50000) # Do not increase 50000, data type half has quite limited range

        attn_weights_l = attn_weights_l.softmax(dim=-1)

        if attention_mask_l is not None:
            assert (attention_mask_l.dim() == 2)
            attention_mask = attention_mask_l.unsqueeze(1).unsqueeze(1)
            attention_mask = attention_mask.expand(bsz, 1, tgt_len, src_len)
            attention_mask = attention_mask.masked_fill(attention_mask == 0, -9e15)

            if attention_mask.size() != (bsz, 1, tgt_len, src_len):
                raise ValueError(
                    f"Attention mask should be of size {(bsz, 1, tgt_len, src_len)}"
                )
            attn_weights = attn_weights.view(bsz, self.num_heads, tgt_len, src_len) + attention_mask
            attn_weights = attn_weights.view(bsz * self.num_heads, tgt_len, src_len)

        attn_weights_v = nn.functional.softmax(attn_weights, dim=-1)

        attn_probs_v = F.dropout(attn_weights_v, p=self.dropout, training=self.training)
        attn_probs_l = F.dropout(attn_weights_l, p=self.dropout, training=self.training)

        attn_output_v = torch.bmm(attn_probs_v, value_l_states)
        attn_output_l = torch.bmm(attn_probs_l, value_v_states)


        if attn_output_v.size() != (bsz * self.num_heads, tgt_len, self.head_dim):
            raise ValueError(
                f"`attn_output_v` should be of size {(bsz, self.num_heads, tgt_len, self.head_dim)}, but is {attn_output_v.size()}"
            )

        if attn_output_l.size() != (bsz * self.num_heads, src_len, self.head_dim):
            raise ValueError(
                f"`attn_output_l` should be of size {(bsz, self.num_heads, src_len, self.head_dim)}, but is {attn_output_l.size()}"
            )

        attn_output_v = attn_output_v.view(bsz, self.num_heads, tgt_len, self.head_dim)
        attn_output_v = attn_output_v.transpose(1, 2)
        attn_output_v = attn_output_v.reshape(bsz, tgt_len, self.embed_dim)

        attn_output_l = attn_output_l.view(bsz, self.num_heads, src_len, self.head_dim)
        attn_output_l = attn_output_l.transpose(1, 2)
        attn_output_l = attn_output_l.reshape(bsz, src_len, self.embed_dim)

        attn_output_v = self.out_v_proj(attn_output_v)
        attn_output_l = self.out_l_proj(attn_output_l)

        return attn_output_v, attn_output_l


# Bi-Direction MHA (text->image, image->text)
class BiAttentionBlock(nn.Module):
    def __init__(self, v_dim, l_dim, embed_dim, num_heads, hidden_dim=None, dropout=0.1,
                 drop_path=.0, init_values=1e-4, cfg=None):
        """
        Inputs:
            embed_dim - Dimensionality of input and attention feature vectors
            hidden_dim - Dimensionality of hidden layer in feed-forward network
                         (usually 2-4x larger than embed_dim)
            num_heads - Number of heads to use in the Multi-Head Attention block
            dropout - Amount of dropout to apply in the feed-forward network
        """
        super(BiAttentionBlock, self).__init__()

        # pre layer norm
        self.layer_norm_v = nn.LayerNorm(v_dim)
        self.layer_norm_l = nn.LayerNorm(l_dim)
        self.attn = BiMultiHeadAttention(v_dim=v_dim,
                                         l_dim=l_dim,
                                         embed_dim=embed_dim,
                                         num_heads=num_heads,
                                         dropout=dropout,
                                         cfg=cfg)

        # add layer scale for training stability
        self.drop_path = DropPath(drop_path) if drop_path > 0. else nn.Identity()
        self.gamma_v = nn.Parameter(init_values * torch.ones((v_dim)), requires_grad=True)
        self.gamma_l = nn.Parameter(init_values * torch.ones((l_dim)), requires_grad=True)

    def forward(self, v, l, attention_mask_l=None, dummy_tensor=None):
        v = self.layer_norm_v(v)
        l = self.layer_norm_l(l)
        delta_v, delta_l = self.attn(v, l, attention_mask_l=attention_mask_l)
        # v, l = v + delta_v, l + delta_l
        v = v + self.drop_path(self.gamma_v * delta_v)
        l = l + self.drop_path(self.gamma_l * delta_l)
        return v, l

class BiAttentionBlockForCheckpoint(nn.Module):
    def __init__(self, v_dim, l_dim, embed_dim, num_heads, hidden_dim=None, dropout=0.1,
                 drop_path=.0, init_values=1e-4, cfg=None):
        """
        Inputs:
            embed_dim - Dimensionality of input and attention feature vectors
            hidden_dim - Dimensionality of hidden layer in feed-forward network
                         (usually 2-4x larger than embed_dim)
            num_heads - Number of heads to use in the Multi-Head Attention block
            dropout - Amount of dropout to apply in the feed-forward network
        """
        super(BiAttentionBlockForCheckpoint, self).__init__()

        # pre layer norm
        self.layer_norm_v = nn.LayerNorm(v_dim)
        self.layer_norm_l = nn.LayerNorm(l_dim)
        self.attn = BiMultiHeadAttention(v_dim=v_dim,
                                         l_dim=l_dim,
                                         embed_dim=embed_dim,
                                         num_heads=num_heads,
                                         dropout=dropout,
                                         cfg=cfg)

        # add layer scale for training stability
        self.drop_path = DropPath(drop_path) if drop_path > 0. else nn.Identity()
        self.gamma_v = nn.Parameter(init_values * torch.ones((v_dim)), requires_grad=True)
        self.gamma_l = nn.Parameter(init_values * torch.ones((l_dim)), requires_grad=True)

        self.cfg = cfg
        if self.cfg.MODEL.DYHEAD.FUSE_CONFIG.SEPARATE_BIDIRECTIONAL:
            if not self.cfg.MODEL.DYHEAD.FUSE_CONFIG.DO_LANG_PROJ_OUTSIDE_CHECKPOINT:
                self.shrink_lang = FeatureResizer(l_dim * 5, l_dim, 0.1)

    def forward(self, q0, q1, q2, q3, q4, l, attention_mask_l=None, dummy_tensor=None, cache=None, attention_mask_cache=None):

        if self.cfg.MODEL.DYHEAD.FUSE_CONFIG.SEPARATE_BIDIRECTIONAL:
            visu_feat = []
            lang_feat = []
            for ii, feat in enumerate([q0, q1, q2, q3, q4]):
                bs, _, h, w = feat.shape
                q = feat.flatten(2).transpose(1, 2)
                
                new_v, new_l = self.single_attention_call(q, l, attention_mask_l=attention_mask_l)
                new_v = new_v.transpose(1, 2).contiguous().view(bs, -1, h, w)
                lang_feat.append(new_l)
                visu_feat.append(new_v)
            if self.cfg.MODEL.DYHEAD.FUSE_CONFIG.DO_LANG_PROJ_OUTSIDE_CHECKPOINT:
                pass
            else:
                lang_feat = self.shrink_lang(torch.cat(lang_feat, dim = -1)) # From multiple dimensions
                lang_feat = [lang_feat, None, None, None, None]
        else:
            visu_feat = []
            size_per_level, visual_features_flatten = [], []
            for ii, feat_per_level in enumerate([q0, q1, q2, q3, q4]):
                bs, c, h, w = feat_per_level.shape
                size_per_level.append([h, w])
                feat = permute_and_flatten(feat_per_level, bs, 1, c, h, w)
                visual_features_flatten.append(feat)
            visual_features_flatten = cat(visual_features_flatten, dim=1)
            new_v, new_l = self.single_attention_call(visual_features_flatten, l, attention_mask_l=attention_mask_l)
            # [bs, N, C] -> [bs, C, N]
            new_v = new_v.transpose(1, 2).contiguous()

            start = 0
            for (h, w) in size_per_level:
                new_v_per_level = new_v[:, :, start:start + h * w].view(bs, -1, h, w).contiguous()
                visu_feat.append(new_v_per_level)
                start += h * w
            
            lang_feat = [new_l, None, None, None, None]

        return visu_feat[0], visu_feat[1], visu_feat[2], visu_feat[3], visu_feat[4], lang_feat[0], lang_feat[1], lang_feat[2], lang_feat[3], lang_feat[4]

    
    def single_attention_call(self, v, l, attention_mask_l=None, dummy_tensor=None):
        v = self.layer_norm_v(v)
        l = self.layer_norm_l(l)
        delta_v, delta_l = self.attn(v, l, attention_mask_l=attention_mask_l)
        # v, l = v + delta_v, l + delta_l
        v = v + self.drop_path(self.gamma_v * delta_v)
        l = l + self.drop_path(self.gamma_l * delta_l)
        return v, l


# Single Direction MHA
class MultiHeadAttention(nn.Module):
    """
    Multi-head attention module for both image and text
    """

    def __init__(self, q_dim, k_dim, embed_dim, num_heads, dropout=0.1, 
        clamp_min_for_underflow = False, clamp_max_for_overflow = False):
        super(MultiHeadAttention, self).__init__()

        self.embed_dim = embed_dim
        self.num_heads = num_heads
        self.head_dim = embed_dim // num_heads
        self.q_dim = q_dim
        self.k_dim = k_dim

        assert (
                self.head_dim * self.num_heads == self.embed_dim
        ), f"embed_dim must be divisible by num_heads (got `embed_dim`: {self.embed_dim} and `num_heads`: {self.num_heads})."
        self.scale = self.head_dim ** (-0.5)
        self.dropout = dropout

        self.q_proj = nn.Linear(self.q_dim, self.embed_dim)
        self.k_proj = nn.Linear(self.k_dim, self.embed_dim)
        self.v_proj = nn.Linear(self.k_dim, self.embed_dim)
        self.out_proj = nn.Linear(self.embed_dim, self.q_dim)
        self.clamp_min_for_underflow = clamp_min_for_underflow
        self.clamp_max_for_overflow = clamp_max_for_overflow

        self._reset_parameters()

    def _shape(self, tensor: torch.Tensor, seq_len: int, bsz: int):
        return tensor.view(bsz, seq_len, self.num_heads, self.head_dim).transpose(1, 2).contiguous()

    def _reset_parameters(self):
        nn.init.xavier_uniform_(self.q_proj.weight)
        self.q_proj.bias.data.fill_(0)
        nn.init.xavier_uniform_(self.k_proj.weight)
        self.k_proj.bias.data.fill_(0)
        nn.init.xavier_uniform_(self.v_proj.weight)
        self.v_proj.bias.data.fill_(0)
        nn.init.xavier_uniform_(self.out_proj.weight)
        self.out_proj.bias.data.fill_(0)

    def forward(self, q, k, v, attention_mask=None, return_attention=False):
        bsz, tgt_len, embed_dim = q.size()

        query_states = self.q_proj(q) * self.scale
        key_states = self._shape(self.k_proj(k), -1, bsz)
        value_states = self._shape(self.v_proj(v), -1, bsz)

        proj_shape = (bsz * self.num_heads, -1, self.head_dim)
        query_states = self._shape(query_states, tgt_len, bsz).view(*proj_shape)
        key_states = key_states.view(*proj_shape)
        value_states = value_states.view(*proj_shape)

        src_len = key_states.size(1)
        attn_weights = torch.bmm(query_states, key_states.transpose(1, 2))

        if attn_weights.size() != (bsz * self.num_heads, tgt_len, src_len):
            raise ValueError(
                f"Attention weights should be of size {(bsz * self.num_heads, tgt_len, src_len)}, but is {attn_weights.size()}"
            )

        if self.clamp_min_for_underflow:
            attn_weights = torch.clamp(attn_weights, min=-50000) # Do not increase -50000, data type half has quite limited range
        if self.clamp_max_for_overflow:
            attn_weights = torch.clamp(attn_weights, max=50000) # Do not increase 50000, data type half has quite limited range

        if attention_mask is not None:
            # [bsz, src_len]
            assert (attention_mask.dim() == 2)
            attention_mask = attention_mask.unsqueeze(1).unsqueeze(1)
            attention_mask = attention_mask.expand(bsz, 1, tgt_len, src_len)
            attention_mask = attention_mask.masked_fill(attention_mask == 0, -9e15)

            if attention_mask.size() != (bsz, 1, tgt_len, src_len):
                raise ValueError(
                    f"Attention mask should be of size {(bsz, 1, tgt_len, src_len)}"
                )
            attn_weights = attn_weights.view(bsz, self.num_heads, tgt_len, src_len) + attention_mask
            attn_weights = attn_weights.view(bsz * self.num_heads, tgt_len, src_len)

        attn_weights = nn.functional.softmax(attn_weights, dim=-1)

        if return_attention:
            # this operation is a bit akward, but it's required to
            # make sure that attn_weights keeps its gradient.
            # In order to do so, attn_weights have to reshaped
            # twice and have to be reused in the following
            attn_weights_reshaped = attn_weights.view(bsz, self.num_heads, tgt_len, src_len)
            attn_weights = attn_weights_reshaped.view(bsz * self.num_heads, tgt_len, src_len)
        else:
            attn_weights_reshaped = None

        attn_probs = F.dropout(attn_weights, p=self.dropout, training=self.training)

        attn_output = torch.bmm(attn_probs, value_states)

        if attn_output.size() != (bsz * self.num_heads, tgt_len, self.head_dim):
            raise ValueError(
                f"`attn_output` should be of size {(bsz, self.num_heads, tgt_len, self.head_dim)}, but is {attn_output.size()}"
            )

        attn_output = attn_output.view(bsz, self.num_heads, tgt_len, self.head_dim)
        attn_output = attn_output.transpose(1, 2)
        attn_output = attn_output.reshape(bsz, tgt_len, self.embed_dim)

        attn_output = self.out_proj(attn_output)


        return attn_output, attn_weights


class AttentionMLP(nn.Module):
    def __init__(self, q_dim, hidden_dim, dropout=0.1):
        super(AttentionMLP, self).__init__()
        self.hidden_dim = hidden_dim
        self.activation_fn = nn.GELU()
        self.fc1 = nn.Linear(q_dim, hidden_dim)
        self.fc2 = nn.Linear(hidden_dim, q_dim)
        self.dropout = nn.Dropout(dropout)

    def forward(self, hidden_states):
        hidden_states = self.fc1(hidden_states)
        hidden_states = self.activation_fn(hidden_states)
        hidden_states = self.fc2(hidden_states)
        return hidden_states


class AttentionT2I(nn.Module):
    def __init__(self, q_dim, k_dim, embed_dim, num_heads, hidden_dim=None, dropout=0.1,
                 drop_path=.0, init_values=1e-4, mode="i2t", use_layer_scale = False,
                 clamp_min_for_underflow = False, clamp_max_for_overflow = False):
        """
        Inputs:
            embed_dim - Dimensionality of input and attention feature vectors
            hidden_dim - Dimensionality of hidden layer in feed-forward network
                         (usually 2-4x larger than embed_dim)
            num_heads - Number of heads to use in the Multi-Head Attention block
            dropout - Amount of dropout to apply in the feed-forward network
        """
        super(AttentionT2I, self).__init__()

        # pre_layer norm
        self.layer_norm_q_1 = nn.LayerNorm(q_dim)
        self.layer_norm_k_1 = nn.LayerNorm(k_dim)
        self.attn = MultiHeadAttention(q_dim=q_dim,
                                       k_dim=k_dim,
                                       embed_dim=embed_dim,
                                       num_heads=num_heads,
                                       clamp_min_for_underflow=clamp_min_for_underflow,
                                       clamp_max_for_overflow=clamp_max_for_overflow)
        self.mode = mode

        # add layer scale for training stability
        self.use_layer_scale = use_layer_scale
        if self.use_layer_scale:
            self.drop_path = DropPath(drop_path) if drop_path > 0. else nn.Identity()
            self.gamma = nn.Parameter(init_values * torch.ones((q_dim)), requires_grad=True)


    def forward(self, q0, q1, q2, q3, q4, k, v, attention_mask, dummy_arg=None):
        qs = []
        for q_index, q in enumerate([q0, q1, q2, q3, q4]):
            bs, _, h, w = q.shape
            # (batch, seq_len, embed_size)
            q = q.flatten(2).transpose(1, 2)
            q = self.layer_norm_q_1(q)
            k, v = self.layer_norm_k_1(k), self.layer_norm_k_1(v)
            delta_q = self.attn(q, k, v, attention_mask=attention_mask)[0]
            if self.use_layer_scale:
                q = q + self.drop_path(self.gamma * delta_q)
            else:
                q = q + delta_q
            q = q.transpose(1, 2).contiguous().view(bs, -1, h, w)
            qs.append(q)


        return qs[0], qs[1], qs[2], qs[3], qs[4]
