import torch
import numpy as np
from collections import namedtuple
from .detectors import build_detector


def build_network(model_cfg, num_class, dataset):
    model = build_detector(
        model_cfg=model_cfg, num_class=num_class, dataset=dataset
    )
    return model


def model_fn_decorator():
    ModelReturn = namedtuple('ModelReturn', ['loss', 'tb_dict', 'disp_dict'])

    def model_func(model, batch_dict):
        for key, val in batch_dict.items():
            if not isinstance(val, np.ndarray):
                continue
            if key in ['frame_id']:
                continue
            batch_dict[key] = torch.from_numpy(val).float().cuda()
        ret_dict, tb_dict, disp_dict = model(batch_dict)

        loss = ret_dict['loss'].mean()
        if hasattr(model, 'update_global_step'):
            model.update_global_step()
        else:
            model.module.update_global_step()

        return ModelReturn(loss, tb_dict, disp_dict)

    return model_func