import importlib
from copy import deepcopy
from os import path as osp

from basicsr.utils import get_root_logger, scandir
from basicsr.utils.registry import LOSS_REGISTRY
from .gan_loss import g_path_regularize, gradient_penalty_loss, r1_penalty
from .rebalance_loss import Rebalance_L1

__all__ = [
    "build_loss",
    "gradient_penalty_loss",
    "r1_penalty",
    "g_path_regularize",
    "Rebalance_L1",
]

# automatically scan and import loss modules for registry
# scan all the files under the 'losses' folder and collect files ending with '_loss.py'
loss_folder = osp.dirname(osp.abspath(__file__))
loss_filenames = [
    osp.splitext(osp.basename(v))[0]
    for v in scandir(loss_folder)
    if v.endswith("_loss.py")
]
# import all the loss modules
_model_modules = [
    importlib.import_module(f"basicsr.losses.{file_name}")
    for file_name in loss_filenames
]


def build_loss(opt):
    """Build loss from options.

    Args:
        opt (dict): Configuration. It must contain:
            type (str): Model type.
    """
    opt = deepcopy(opt)
    loss_type = opt.pop("type")
    loss = LOSS_REGISTRY.get(loss_type)(**opt)
    logger = get_root_logger()
    logger.info(f"Loss [{loss.__class__.__name__}] is created.")
    return loss
