from tensorflow.examples.tutorials.mnist import input_data
import tensorflow as tf

mnist = input_data.read_data_sets("MNIST_data/", one_hot=True)

learning_rate = 0.001
training_iters = 200000
batch_size = 64
display_step = 10

n_input = 784
n_classes = 10
dropout = 0.8

x = tf.placeholder(tf.float32,[None,n_input])
y = tf.placeholder(tf.float32,[None,n_classes])
keep_prob = tf.placeholder(tf.float32)

def conv2d(name, l_input, w, b):
    return tf.nn.relu(tf.nn.bias_add(tf.nn.conv2d(l_input, w, strides = [1,1,1,1], padding = 'SAME'), b), name = name)

def max_pool(name ,l_input, k):
    return tf.nn.max_pool(l_input, ksize = [1,k,k,1], strides = [1,k,k,1], padding = 'SAME', name = name)

def norm(name, l_input, lsize = 4):
    return tf.nn.lrn(l_input, lsize, bias = 1.0, alpha = 0.001 / 9.0, beta = 0.75, name = name)

def alex_net(_X, _weights, _biases, _dropout):
    _X = tf.reshape(_X, shape = [-1,28,28,1])

    conv1 = conv2d('conv1', _X, _weights['wc1'], _biases['bc1'])

    pool1 = max_pool('pool1', conv1, k = 2)

    norm1 = norm('norm1', pool1, lsize = 4)

    norm1 = tf.nn.dropout(norm1, _dropout)


    conv2 = conv2d('conv2', norm1, _weights['wc2'], _biases['bc2'])
    
    pool2 = max_pool('pool2', conv2, k=2)
    
    norm2 = norm('norm2', pool2, lsize=4)
    
    norm2 = tf.nn.dropout(norm2, _dropout)

    
    conv3 = conv2d('conv3', norm2, _weights['wc3'], _biases['bc3'])
    
    pool3 = max_pool('pool3', conv3, k=2)
    
    norm3 = norm('norm3', pool3, lsize=4)
    
    norm3 = tf.nn.dropout(norm3, _dropout)


    dense1 = tf.reshape(norm3, [-1,_weights['wd1'].get_shape().as_list()[0]])
    dense1 = tf.nn.relu(tf.matmul(dense1, _weights['wd1']) + _biases['bd1'], name = 'fc1')

    dense2 = tf.nn.relu(tf.matmul(dense1, _weights['wd2']) + _biases['bd2'], name = 'fc2')

    out = tf.matmul(dense2, _weights['out'] + _biases['out'])

    return out

weights = {
    'wc1': tf.Variable(tf.random_normal([3, 3, 1, 64])),
    'wc2': tf.Variable(tf.random_normal([3, 3, 64, 128])),
    'wc3': tf.Variable(tf.random_normal([3, 3, 128, 256])),
    'wd1': tf.Variable(tf.random_normal([4*4*256, 1024])),
    'wd2': tf.Variable(tf.random_normal([1024, 1024])),
    'out': tf.Variable(tf.random_normal([1024, 10]))
}

biases = {
    'bc1': tf.Variable(tf.random_normal([64])),
    'bc2': tf.Variable(tf.random_normal([128])),
    'bc3': tf.Variable(tf.random_normal([256])),
    'bd1': tf.Variable(tf.random_normal([1024])),
    'bd2': tf.Variable(tf.random_normal([1024])),
    'out': tf.Variable(tf.random_normal([n_classes]))
}

pred = alex_net(x,weights,biases,keep_prob)

cost = tf.reduce_mean(tf.nn.softmax_cross_entropy_with_logits(logits = pred, labels = y))
optimizer = tf.train.AdamOptimizer(learning_rate = learning_rate).minimize(cost)

correct_pred = tf.equal(tf.argmax(pred, 1), tf.argmax(y, 1))
accuracy = tf.reduce_mean(tf.cast(correct_pred, tf.float32))

init = tf.initialize_all_variables()

with tf.Session() as sess:
    sess.run(init)
    step = 1
    while step * batch_size < training_iters:
        batch_xs, batch_ys = mnist.train.next_batch(batch_size)

        sess.run(optimizer, feed_dict = {x : batch_xs, y : batch_ys, keep_prob : dropout})
        if step % display_step == 0:
            acc = sess.run(accuracy, feed_dict = {x: batch_xs, y: batch_ys, keep_prob: 1.})
            
            loss = sess.run(cost, feed_dict = {x: batch_xs, y: batch_ys, keep_prob: 1.})

            print ("Iter " + str(step*batch_size) + ", Minibatch Loss= " + "{:.6f}".format(loss) + ", Training Accuracy= " + "{:.5f}".format(acc))

        step += 1
    print ("Optimization Finished!")
    print ("Testing Accuracy:", sess.run(accuracy, feed_dict={x: mnist.test.images[:256], y: mnist.test.labels[:256], keep_prob: 1.}))