
# coding: utf-8

# In[3]:

import os.path
import tensorflow as tf
import helper
import warnings
from distutils.version import LooseVersion
import project_tests as tests

# Check TensorFlow Version
assert LooseVersion(tf.__version__) >= LooseVersion('1.0'), 'Please use TensorFlow version 1.0 or newer.  You are using {}'.format(tf.__version__)
print('TensorFlow Version: {}'.format(tf.__version__))

# Check for a GPU
if not tf.test.gpu_device_name():
    warnings.warn('No GPU found. Please use a GPU to train your neural network.')
else:
    print('Default GPU Device: {}'.format(tf.test.gpu_device_name()))

def load_vgg(sess, vgg_path):
    """
    Load Pretrained VGG Model into TensorFlow.
    :param sess: TensorFlow Session
    :param vgg_path: Path to vgg folder, containing "variables/" and "saved_model.pb"
    :return: Tuple of Tensors from VGG model (image_input, keep_prob, layer3_out, layer4_out, layer7_out)
    """
    # TODO: Implement function
    #   Use tf.saved_model.loader.load to load the model and weights
    vgg_tag = 'vgg16'
    vgg_input_tensor_name = 'image_input:0'
    vgg_keep_prob_tensor_name = 'keep_prob:0'
    vgg_layer3_out_tensor_name = 'layer3_out:0'
    vgg_layer4_out_tensor_name = 'layer4_out:0'
    vgg_layer7_out_tensor_name = 'layer7_out:0'
    
    tf.saved_model.loader.load(sess,[vgg_tag],vgg_path)
    graph = tf.get_default_graph()
    input_image = graph.get_tensor_by_name(vgg_input_tensor_name)
    keep_prob = graph.get_tensor_by_name(vgg_keep_prob_tensor_name)
    vgg_layer3_out = graph.get_tensor_by_name(vgg_layer3_out_tensor_name)
    vgg_layer4_out = graph.get_tensor_by_name(vgg_layer4_out_tensor_name)
    vgg_layer7_out = graph.get_tensor_by_name(vgg_layer7_out_tensor_name)
    
    return input_image, keep_prob, vgg_layer3_out, vgg_layer4_out, vgg_layer7_out

#tests.test_load_vgg(load_vgg, tf)

def layers(vgg_layer3_out, vgg_layer4_out, vgg_layer7_out, num_classes):
    """
    Create the layers for a fully convolutional network.  Build skip-layers using the vgg layers.
    :param vgg_layer7_out: TF Tensor for VGG Layer 3 output
    :param vgg_layer4_out: TF Tensor for VGG Layer 4 output
    :param vgg_layer3_out: TF Tensor for VGG Layer 7 output
    :param num_classes: Number of classes to classify
    :return: The Tensor for the last layer of output
    """
    # TODO: Implement function
    #resample vgg_layer7_out by 1x1 Convolution: To go from ?x5x18x4096 to ?x5x18x2
    vgg_layer7_out_resampled = tf.layers.conv2d(vgg_layer7_out,num_classes,1,padding="same",
                                kernel_initializer=tf.truncated_normal_initializer(stddev=0.01),
                                kernel_regularizer=tf.contrib.layers.l2_regularizer(1e-3))
    
    #upscale vgg_layer7_out_resampled: by factor of 2 in order to go from ?x5x18x2 to ?x10x36x2
    vgg_layer7_out_upscaled = tf.layers.conv2d_transpose(vgg_layer7_out_resampled,num_classes,4,2,padding="same",
                                       kernel_initializer=tf.truncated_normal_initializer(stddev=0.01),
                                       kernel_regularizer=tf.contrib.layers.l2_regularizer(1e-3))
    
    #resample vgg_layer4_out out by 1x1 Convolution: To go from ?x10x36x512 to ?x10x36x2
    vgg_layer4_out_resampled = tf.layers.conv2d(vgg_layer4_out,num_classes,1,padding="same",
                                kernel_initializer=tf.truncated_normal_initializer(stddev=0.01),
                                kernel_regularizer=tf.contrib.layers.l2_regularizer(1e-3))
    
    #add these two layers together  
    combined_layer1 = tf.add(vgg_layer7_out_upscaled, vgg_layer4_out_resampled)
    
    #upscale combined_layer1 by factor of 2 in order to go from ?x10x36x2 to ?x20x72x2
    fcn_layer2 = tf.layers.conv2d_transpose(combined_layer1,num_classes,4,2,padding="same",
                                       kernel_regularizer=tf.contrib.layers.l2_regularizer(1e-3),
                                       kernel_initializer=tf.truncated_normal_initializer(stddev=0.01))
    
    #resample vgg_layer3_out out by 1x1 Convolution: To go from ?x20x72x256 to ?x20x72x2
    vgg_layer3_out_resampled = tf.layers.conv2d(vgg_layer3_out,num_classes,1,padding="same",
                                kernel_regularizer=tf.contrib.layers.l2_regularizer(1e-3),
                                kernel_initializer=tf.truncated_normal_initializer(stddev=0.01))
    
    #add these two layers together
    combined_layer2 = tf.add(vgg_layer3_out_resampled, fcn_layer2)
    
    #upscale combined_layer2 by factor of 8 in order to go from ?x20x72x2 to ?x160x576x2
    output_layer = tf.layers.conv2d_transpose(combined_layer2,num_classes,16,8,padding="same",
                                       kernel_regularizer=tf.contrib.layers.l2_regularizer(1e-3),
                                       kernel_initializer=tf.truncated_normal_initializer(stddev=0.01))
    
    return output_layer
#tests.test_layers(layers)

def optimize(nn_last_layer, correct_label, learning_rate, num_classes):
    """
    Build the TensorFLow loss and optimizer operations.
    :param nn_last_layer: TF Tensor of the last layer in the neural network
    :param correct_label: TF Placeholder for the correct label image
    :param learning_rate: TF Placeholder for the learning rate
    :param num_classes: Number of classes to classify
    :return: Tuple of (logits, train_op, cross_entropy_loss)
    """
    # TODO: Implement function
    logits = tf.reshape(nn_last_layer, (-1, num_classes))
    cross_entropy_loss = tf.reduce_mean(tf.nn.softmax_cross_entropy_with_logits(logits=logits, labels=correct_label))
    
    optimizer = tf.train.AdamOptimizer(learning_rate)   
    global_step = tf.Variable(0, name='global_step', trainable=False)
    train_op = optimizer.minimize(cross_entropy_loss, global_step=global_step)

    return logits, train_op, cross_entropy_loss
#tests.test_optimize(optimize)

def train_nn(sess, epochs, batch_size, get_batches_fn, train_op, cross_entropy_loss, input_image,
             correct_label, keep_prob, learning_rate):
    """
    Train neural network and print out the loss during training.
    :param sess: TF Session
    :param epochs: Number of epochs
    :param batch_size: Batch size
    :param get_batches_fn: Function to get batches of training data.  Call using get_batches_fn(batch_size)
    :param train_op: TF Operation to train the neural network
    :param cross_entropy_loss: TF Tensor for the amount of loss
    :param input_image: TF Placeholder for input images
    :param correct_label: TF Placeholder for label images
    :param keep_prob: TF Placeholder for dropout keep probability
    :param learning_rate: TF Placeholder for learning rate
    """
    # TODO: Implement function    
    sess.run(tf.global_variables_initializer())
    
    kp = 0.5
    lr = 0.001
    
    for epoch in range(epochs):
        print("Epoch " + str(epoch+1) + " running ...")
        epoch_loss = 0;
        batch_cnt = 0;
        
        for images, labels in get_batches_fn(batch_size):
            _, loss = sess.run([train_op, cross_entropy_loss],
                               feed_dict={input_image: images,
                                          correct_label: labels,
                                          keep_prob: kp,
                                          learning_rate: lr}
                              )
            epoch_loss += loss
            batch_cnt += 1
        print("Epoch Loss: " + str(epoch_loss/batch_cnt))    
    pass
#tests.test_train_nn(train_nn)


# In[4]:

def run():
    num_classes = 2
    image_shape = (160, 576)
    data_dir = './data'
    runs_dir = './runs'
    tests.test_for_kitti_dataset(data_dir)
    
    # Hyperparameters
    epochs = 30
    batch_size = 8

    # Placeholders
    correct_label = tf.placeholder(tf.float32, [None, image_shape[0], image_shape[1], num_classes])
    keep_prob = tf.placeholder(tf.float32)
    learning_rate = tf.placeholder(tf.float32)

    # Download pretrained vgg model
    helper.maybe_download_pretrained_vgg(data_dir)
    
    # Create function to get batches
    get_batches_fn = helper.gen_batch_function(os.path.join(data_dir, 'data_road/training'), image_shape)

    # OPTIONAL: Train and Inference on the cityscapes dataset instead of the Kitti dataset.
    # You'll need a GPU with at least 10 teraFLOPS to train on.
    #  https://www.cityscapes-dataset.com/

    with tf.Session() as sess:
        # Path to vgg model
        vgg_path = os.path.join(data_dir, 'vgg')
        
        # OPTIONAL: Augment Images for better results
        #  https://datascience.stackexchange.com/questions/5224/how-to-prepare-augment-images-for-neural-network

        # TODO: Build NN using load_vgg, layers, and optimize function
        input_image, keep_prob, vgg_layer3_out, vgg_layer4_out, vgg_layer7_out = load_vgg(sess,vgg_path)
        nn_last_layer = layers(vgg_layer3_out, vgg_layer4_out, vgg_layer7_out, num_classes)
        logits, train_operation, cross_entropy_loss = optimize(nn_last_layer, correct_label, learning_rate, num_classes)
        
        sess.run(tf.global_variables_initializer())
        sess.run(tf.local_variables_initializer())

        # TODO: Train NN using the train_nn function
        train_nn(sess, epochs, batch_size, get_batches_fn, train_operation, cross_entropy_loss, input_image, correct_label,
                 keep_prob, learning_rate)

        # TODO: Save inference data using helper.save_inference_samples
        helper.save_inference_samples(runs_dir, data_dir, sess, image_shape, logits, keep_prob, input_image)
                 
        # OPTIONAL: Apply the trained model to a video


# In[5]:

if __name__ == '__main__':
    run()


# In[ ]:



