import torch
import torch.nn as nn


class VirtualCell(nn.Module):
    def __init__(self, expr_dim, emb_dim, hidden_dim):
        super(VirtualCell, self).__init__()
        self.delta_net = nn.Sequential(
            nn.Linear(emb_dim, hidden_dim),
            nn.LayerNorm(hidden_dim),
            nn.GELU(),
            nn.Linear(hidden_dim, expr_dim),
        )
        nn.init.zeros_(self.delta_net[-1].weight)
        nn.init.zeros_(self.delta_net[-1].bias)

    def forward(self, ctrl_expr, pert_emb):
        pred_delta = self.delta_net(pert_emb)

        return ctrl_expr + pred_delta