import numpy as np
import torch
from .monotonic_align.core import maximum_path_c


def maximum_path(value, mask):  
  """ Cython optimised version.
  value: [b, t_x, t_y]
  mask: [b, t_x, t_y]
  """
  value = value * mask
  device = value.device
  dtype = value.dtype
  value = value.data.cpu().numpy().astype(np.float32)
  path = np.zeros_like(value).astype(np.int32)
  mask = mask.data.cpu().numpy()

  t_x_max = mask.sum(1)[:, 0].astype(np.int32)
  t_y_max = mask.sum(2)[:, 0].astype(np.int32)
  maximum_path_c(path, value, t_x_max, t_y_max)
  return torch.from_numpy(path).to(device=device, dtype=dtype)
