"""
FGSM demos on mnist using advbox tool.
"""
import paddle.v2 as paddle
import paddle.v2.fluid as fluid
import matplotlib.pyplot as plt
import numpy as np

from advbox.models.paddle import PaddleModel
from advbox.attacks.gradientsign import GradientSignAttack

def cnn_model(img):
    """
    Mnist cnn model
    Args:
        img(Varaible): the input image to be recognized
    Returns:
        Variable: the label prediction
    """
    #conv1 = fluid.nets.conv2d()
    conv_pool_1 = fluid.nets.simple_img_conv_pool(
            input=img,
            num_filters=20,
            filter_size=5,
            pool_size=2,
            pool_stride=2,
            act='relu')

    conv_pool_2 = fluid.nets.simple_img_conv_pool(
            input=conv_pool_1,
            num_filters=50,
            filter_size=5,
            pool_size=2,
            pool_stride=2,
            act='relu')

    logits = fluid.layers.fc(
            input=conv_pool_2,
            size=10,
            act='softmax')
    return logits


def main():
    """
    Advbox demo which demonstrate how to use advbox.
    """
    IMG_NAME = 'img'
    LABEL_NAME = 'label'

    img = fluid.layers.data(name=IMG_NAME, shape=[1, 28, 28], dtype='float32')
    # gradient should flow
    img.stop_gradient = False
    label = fluid.layers.data(name=LABEL_NAME, shape=[1], dtype='int64')
    logits = cnn_model(img)
    cost = fluid.layers.cross_entropy(input=logits, label=label)
    avg_cost = fluid.layers.mean(x=cost)

    place = fluid.CPUPlace()
    exe = fluid.Executor(place)

    BATCH_SIZE = 1
    train_reader = paddle.batch(
        paddle.reader.shuffle(
            paddle.dataset.mnist.train(), buf_size=500),
        batch_size=BATCH_SIZE)
    feeder = fluid.DataFeeder(
        feed_list=[IMG_NAME, LABEL_NAME], 
        place=place, 
        program=fluid.default_main_program()
    )

    fluid.io.load_params(exe, "./mnist/", main_program=fluid.default_main_program())

    # advbox demo
    m = PaddleModel(
        fluid.default_main_program(), 
        IMG_NAME,
        LABEL_NAME, 
        logits.name, 
        avg_cost.name, 
        (-1, 1)
    )
    att = GradientSignAttack(m)
    for data in train_reader():
        # fgsm attack
        adv_img = att(data)
        plt.imshow(n[0][0], cmap='Greys_r')
        plt.show()
        #np.save('adv_img', adv_img)
        break
    
if __name__ == '__main__':
    main()