import tensorflow as tf
from tensorflow.keras import layers


def selective_kernel_feature_fusion(
    multi_scale_feature_1, multi_scale_feature_2, multi_scale_feature_3
):
    channels = list(multi_scale_feature_1.shape)[-1]
    combined_feature = layers.Add()(
        [multi_scale_feature_1, multi_scale_feature_2, multi_scale_feature_3]
    )
    gap = layers.GlobalAveragePooling2D()(combined_feature)
    channel_wise_statistics = tf.reshape(gap, shape=(-1, 1, 1, channels))
    compact_feature_representation = layers.Conv2D(
        filters=channels // 8, kernel_size=(1, 1), activation="relu"
    )(channel_wise_statistics)
    feature_descriptor_1 = layers.Conv2D(
        channels, kernel_size=(1, 1), activation="softmax"
    )(compact_feature_representation)
    feature_descriptor_2 = layers.Conv2D(
        channels, kernel_size=(1, 1), activation="softmax"
    )(compact_feature_representation)
    feature_descriptor_3 = layers.Conv2D(
        channels, kernel_size=(1, 1), activation="softmax"
    )(compact_feature_representation)
    feature_1 = multi_scale_feature_1 * feature_descriptor_1
    feature_2 = multi_scale_feature_2 * feature_descriptor_2
    feature_3 = multi_scale_feature_3 * feature_descriptor_3
    aggregated_feature = layers.Add()([feature_1, feature_2, feature_3])
    return aggregated_feature