# Copyright 2020 Huy Le Nguyen (@usimarit)
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import tensorflow as tf


class GLU(tf.keras.layers.Layer):
    def __init__(self,
                 axis=-1,
                 name="glu_activation",
                 **kwargs):
        super(GLU, self).__init__(name=name, **kwargs)
        self.axis = axis

    def call(self, inputs, **kwargs):
        a, b = tf.split(inputs, 2, axis=self.axis)
        b = tf.nn.sigmoid(b)
        return tf.multiply(a, b)

    def get_config(self):
        conf = super(GLU, self).get_config()
        conf.update({"axis": self.axis})
        return conf