import torch
import torch.nn as nn
import typing
import transformers

from .config import MLPConfig


class Backbone(nn.Module):
    def __init__(self, config):
        super().__init__()
        self.model = nn.Sequential(
            nn.Linear(config.input_dim, config.hidden_dim),
            nn.ReLU(),
            nn.Linear(config.hidden_dim, config.hidden_dim),
            nn.ReLU(),
            nn.Linear(config.hidden_dim, config.output_dim)
        )

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


class MLP(transformers.PreTrainedModel):
  """HF-compatible model."""
  config_class = MLPConfig
  base_model_prefix = 'mlp'

  def __init__(self, config: MLPConfig):
    super().__init__(config)
    self.config = config
    self.backbone = Backbone(config)