from einops import rearrange
import numpy as np
import torch
import torch.nn as nn


class Generator(nn.Module):

    def __init__(self,
                 in_features,
                 ffd_hidden_size,
                 num_classes,
                 attn_layer_num,
                 
                 ):
        super(Generator, self).__init__()
        
        self.attn = nn.ModuleList(
            [
                nn.MultiheadAttention(
                    embed_dim=in_features,
                    num_heads=8,
                    dropout=0.2,
                    batch_first=True,
                )
                for _ in range(attn_layer_num)
            ]
        )
        
        self.ffd = nn.Sequential(
            nn.Linear(in_features, ffd_hidden_size),
            nn.ReLU(),
            nn.Linear(ffd_hidden_size, in_features)
        )
        
        self.dropout = nn.Dropout(0.2)
        
        self.fc =  nn.Linear(in_features * 2, num_classes)
        
        self.proj = nn.Tanh()
        

    def forward(self, ssl_feature, judge_id=None):
        '''
        ssl_feature: [B, T, D]   
        output: [B, num_classes]
        '''
        
        B, T, D = ssl_feature.shape
        
        ssl_feature = self.ffd(ssl_feature)
        
        tmp_ssl_feature = ssl_feature
        
        for attn in self.attn:
            tmp_ssl_feature, _ = attn(tmp_ssl_feature, tmp_ssl_feature, tmp_ssl_feature)
    
        ssl_feature = self.dropout(torch.concat([torch.mean(tmp_ssl_feature, dim=1), torch.max(ssl_feature, dim=1)[0]], dim=1))  # B, 2D
        
        x = self.fc(ssl_feature)  # B, num_classes
        
        x = self.proj(x) * 2.0 + 3
        
        return x
    
    
