import torch.nn as nn
from torch.nn import functional as F
import torchvision.transforms as transforms

from detr.main import build_ACT_model_and_optimizer, build_CNNMLP_model_and_optimizer
from models.text_encoder import DistilBERTTextEncoder
import IPython
e = IPython.embed

class ACTPolicy(nn.Module):
    def __init__(self, args_override):
        super().__init__()
        model, optimizer = build_ACT_model_and_optimizer(args_override)
        self.model = model # CVAE decoder
        self.optimizer = optimizer
        self.kl_weight = args_override['kl_weight']
        self.use_text = args_override.get('use_text', False)
        self.text_encoder = None
        if self.use_text:
            text_encoder_type = args_override.get('text_encoder_type', 'distilbert')
            if text_encoder_type != 'distilbert':
                raise NotImplementedError(f'Unsupported text encoder: {text_encoder_type}')
            self.text_encoder = DistilBERTTextEncoder(
                model_name=args_override.get('text_tokenizer_name', 'distilbert-base-uncased'),
                output_dim=args_override.get('text_feature_dim', 768),
                freeze=args_override.get('freeze_text_encoder', True),
            )
        print(f'KL Weight {self.kl_weight}')

    def __call__(self, qpos, image, text_input_ids=None, text_attention_mask=None, text_features=None, actions=None, is_pad=None):
        env_state = None
        normalize = transforms.Normalize(mean=[0.485, 0.456, 0.406],
                                         std=[0.229, 0.224, 0.225])
        image = normalize(image)

        if self.use_text and text_features is None and text_input_ids is not None and text_attention_mask is not None:
            if self.text_encoder is None:
                raise RuntimeError('Text encoder is not initialized while use_text=True.')
            text_features = self.text_encoder(text_input_ids, text_attention_mask)

        if actions is not None: # training time
            if is_pad is None:
                raise ValueError('`is_pad` must be provided during training when `actions` is not None.')
            actions = actions[:, :self.model.num_queries]
            is_pad = is_pad[:, :self.model.num_queries]

            a_hat, is_pad_hat, (mu, logvar) = self.model(
                qpos,
                image,
                env_state,
                text_features=text_features,
                actions=actions,
                is_pad=is_pad,
            )
            total_kld, dim_wise_kld, mean_kld = kl_divergence(mu, logvar)
            loss_dict = dict()
            all_l1 = F.l1_loss(actions, a_hat, reduction='none')
            l1 = (all_l1 * ~is_pad.unsqueeze(-1)).mean()
            loss_dict['l1'] = l1
            loss_dict['kl'] = total_kld[0]
            loss_dict['loss'] = loss_dict['l1'] + loss_dict['kl'] * self.kl_weight
            return loss_dict
        else: # inference time
            a_hat, _, (_, _) = self.model(qpos, image, env_state, text_features=text_features) # no action, sample from prior
            return a_hat

    def configure_optimizers(self):
        return self.optimizer


class CNNMLPPolicy(nn.Module):
    def __init__(self, args_override):
        super().__init__()
        model, optimizer = build_CNNMLP_model_and_optimizer(args_override)
        self.model = model # decoder
        self.optimizer = optimizer

    def __call__(self, qpos, image, text_input_ids=None, text_attention_mask=None, text_features=None, actions=None, is_pad=None):
        env_state = None # TODO
        normalize = transforms.Normalize(mean=[0.485, 0.456, 0.406],
                                         std=[0.229, 0.224, 0.225])
        image = normalize(image)
        if actions is not None: # training time
            actions = actions[:, 0]
            a_hat = self.model(qpos, image, env_state, actions)
            mse = F.mse_loss(actions, a_hat)
            loss_dict = dict()
            loss_dict['mse'] = mse
            loss_dict['loss'] = loss_dict['mse']
            return loss_dict
        else: # inference time
            a_hat = self.model(qpos, image, env_state) # no action, sample from prior
            return a_hat

    def configure_optimizers(self):
        return self.optimizer

def kl_divergence(mu, logvar):
    batch_size = mu.size(0)
    assert batch_size != 0
    if mu.data.ndimension() == 4:
        mu = mu.view(mu.size(0), mu.size(1))
    if logvar.data.ndimension() == 4:
        logvar = logvar.view(logvar.size(0), logvar.size(1))

    klds = -0.5 * (1 + logvar - mu.pow(2) - logvar.exp())
    total_kld = klds.sum(1).mean(0, True)
    dimension_wise_kld = klds.mean(0)
    mean_kld = klds.mean(1).mean(0, True)

    return total_kld, dimension_wise_kld, mean_kld