"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
import helper
import problem_unittests as tests

source_path = 'data/small_vocab_en'
target_path = 'data/small_vocab_fr'
source_text = helper.load_data(source_path)
target_text = helper.load_data(target_path)

"""
Explanation: Language Translation
In this project, you’re going to take a peek into the realm of neural network machine translation.  You’ll be training a sequence to sequence model on a dataset of English and French sentences that can translate new sentences from English to French.
Get the Data
Since translating the whole language of English to French will take lots of time to train, we have provided you with a small portion of the English corpus.
End of explanation
"""


view_sentence_range = (0, 10)

"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
import numpy as np

print('Dataset Stats')
print('Roughly the number of unique words: {}'.format(len({word: None for word in source_text.split()})))

sentences = source_text.split('\n')
word_counts = [len(sentence.split()) for sentence in sentences]
print('Number of sentences: {}'.format(len(sentences)))
print('Average number of words in a sentence: {}'.format(np.average(word_counts)))

print()
print('English sentences {} to {}:'.format(*view_sentence_range))
print('\n'.join(source_text.split('\n')[view_sentence_range[0]:view_sentence_range[1]]))
print()
print('French sentences {} to {}:'.format(*view_sentence_range))
print('\n'.join(target_text.split('\n')[view_sentence_range[0]:view_sentence_range[1]]))

"""
Explanation: Explore the Data
Play around with view_sentence_range to view different parts of the data.
End of explanation
"""


def text_to_ids(source_text, target_text, source_vocab_to_int, target_vocab_to_int):
    """
    Convert source and target text to proper word ids
    :param source_text: String that contains all the source text.
    :param target_text: String that contains all the target text.
    :param source_vocab_to_int: Dictionary to go from the source words to an id
    :param target_vocab_to_int: Dictionary to go from the target words to an id
    :return: A tuple of lists (source_id_text, target_id_text)
    """
    # TODO: Implement Function
    source_id_text = [[source_vocab_to_int.get(word, source_vocab_to_int['<UNK>']) for word in line.split(' ')]
                       for line in source_text.split('\n')]
                     
    target_id_text = [[target_vocab_to_int.get(word, target_vocab_to_int['<UNK>']) for word in line.split(' ')]
                     + [target_vocab_to_int['<EOS>']] for line in target_text.split('\n')]
    return source_id_text, target_id_text

"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
tests.test_text_to_ids(text_to_ids)

"""
Explanation: Implement Preprocessing Function
Text to Word Ids
As you did with other RNNs, you must turn the text into a number so the computer can understand it. In the function text_to_ids(), you'll turn source_text and target_text from words to ids.  However, you need to add the &lt;EOS&gt; word id at the end of target_text.  This will help the neural network predict when the sentence should end.
You can get the &lt;EOS&gt; word id by doing:
python
target_vocab_to_int['&lt;EOS&gt;']
You can get other word ids using source_vocab_to_int and target_vocab_to_int.
End of explanation
"""


"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
helper.preprocess_and_save_data(source_path, target_path, text_to_ids)

"""
Explanation: Preprocess all the data and save it
Running the code cell below will preprocess all the data and save it to file.
End of explanation
"""


"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
import numpy as np
import helper
import problem_unittests as tests

(source_int_text, target_int_text), (source_vocab_to_int, target_vocab_to_int), _ = helper.load_preprocess()

"""
Explanation: Check Point
This is your first checkpoint. If you ever decide to come back to this notebook or have to restart the notebook, you can start from here. The preprocessed data has been saved to disk.
End of explanation
"""


"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
from distutils.version import LooseVersion
import warnings
import tensorflow as tf
from tensorflow.python.layers.core import Dense

# Check TensorFlow Version
assert LooseVersion(tf.__version__) >= LooseVersion('1.1'), 'Please use TensorFlow version 1.1 or newer'
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()))

"""
Explanation: Check the Version of TensorFlow and Access to GPU
This will check to make sure you have the correct version of TensorFlow and access to a GPU
End of explanation
"""


def model_inputs():
    """
    Create TF Placeholders for input, targets, learning rate, and lengths of source and target sequences.
    :return: Tuple (input, targets, learning rate, keep probability, target sequence length,
    max target sequence length, source sequence length)
    """
    # TODO: Implement Function
    input_data = tf.placeholder(tf.int32, [None, None], name='input')
    targets = tf.placeholder(tf.int32, [None, None], name='targets')
    learning_rate = tf.placeholder(tf.float32, name='learning_rate')
    keep_prob = tf.placeholder(tf.float32, name='keep_prob')
    target_sequence_length = tf.placeholder(tf.int32, (None,), name='target_sequence_length')
    max_target_sequence_length = tf.reduce_max(target_sequence_length,name='max_target_len')
    source_sequence_length = tf.placeholder(tf.int32, (None,), name='source_sequence_length')
    
    return input_data, targets, learning_rate, keep_prob, target_sequence_length, max_target_sequence_length, source_sequence_length


"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
tests.test_model_inputs(model_inputs)

"""
Explanation: Build the Neural Network
You'll build the components necessary to build a Sequence-to-Sequence model by implementing the following functions below:
- model_inputs
- process_decoder_input
- encoding_layer
- decoding_layer_train
- decoding_layer_infer
- decoding_layer
- seq2seq_model
Input
Implement the model_inputs() function to create TF Placeholders for the Neural Network. It should create the following placeholders:

Input text placeholder named "input" using the TF Placeholder name parameter with rank 2.
Targets placeholder with rank 2.
Learning rate placeholder with rank 0.
Keep probability placeholder named "keep_prob" using the TF Placeholder name parameter with rank 0.
Target sequence length placeholder named "target_sequence_length" with rank 1
Max target sequence length tensor named "max_target_len" getting its value from applying tf.reduce_max on the target_sequence_length placeholder. Rank 0.
Source sequence length placeholder named "source_sequence_length" with rank 1

Return the placeholders in the following the tuple (input, targets, learning rate, keep probability, target sequence length, max target sequence length, source sequence length)
End of explanation
"""


def process_decoder_input(target_data, target_vocab_to_int, batch_size):
    """
    Preprocess target data for encoding
    :param target_data: Target Placehoder
    :param target_vocab_to_int: Dictionary to go from the target words to an id
    :param batch_size: Batch Size
    :return: Preprocessed target data
    """
    # TODO: Implement Function
    ending = tf.strided_slice(target_data, [0,0], [batch_size,-1], [1,1])
    dec_input = tf.concat([tf.fill([batch_size,1], target_vocab_to_int['<GO>']), ending],1)
    return dec_input

"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
tests.test_process_encoding_input(process_decoder_input)

"""
Explanation: Process Decoder Input
Implement process_decoder_input by removing the last word id from each batch in target_data and concat the GO ID to the begining of each batch.
End of explanation
"""



def encoding_layer(rnn_inputs, rnn_size, num_layers, keep_prob, 
                   source_sequence_length, source_vocab_size, 
                   encoding_embedding_size):
    """
    Create encoding layer
    :param rnn_inputs: Inputs for the RNN
    :param rnn_size: RNN Size
    :param num_layers: Number of layers
    :param keep_prob: Dropout keep probability
    :param source_sequence_length: a list of the lengths of each sequence in the batch
    :param source_vocab_size: vocabulary size of source data
    :param encoding_embedding_size: embedding size of source data
    :return: tuple (RNN output, RNN state)
    """
    # TODO: Implement Function
    enc_embed_input = tf.contrib.layers.embed_sequence(rnn_inputs, source_vocab_size, encoding_embedding_size)
    #RNN cell
    def make_cell(rnn_size):
        enc_cell = tf.contrib.rnn.LSTMCell(rnn_size,
                                          initializer=tf.random_uniform_initializer(-0.1,0.1,seed=2))
        return enc_cell
    
    #enc_cell = tf.contrib.rnn.MultiRNNCell([tf.contrib.rnn.DropoutWrapper(make_cell(rnn_size),
    #                                                                     output_keep_prob=keep_prob)
      #                                      for _ in range(num_layers)])
    enc_cell = tf.contrib.rnn.MultiRNNCell([make_cell(rnn_size) for _ in range(num_layers)])
   #enc_cell = tf.contrib.rnn.DropoutWrapper(enc_cell,keep_prob)
    enc_output, enc_state = tf.nn.dynamic_rnn(enc_cell, enc_embed_input, 
                                             sequence_length=source_sequence_length,
                                             dtype=tf.float32)
    
    return enc_cell, enc_state

"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
tests.test_encoding_layer(encoding_layer)

"""
Explanation: Encoding
Implement encoding_layer() to create a Encoder RNN layer:
 * Embed the encoder input using tf.contrib.layers.embed_sequence
 * Construct a stacked tf.contrib.rnn.LSTMCell wrapped in a tf.contrib.rnn.DropoutWrapper
 * Pass cell and embedded input to tf.nn.dynamic_rnn()
End of explanation
"""



def decoding_layer_train(encoder_state, dec_cell, dec_embed_input, 
                         target_sequence_length, max_summary_length, 
                         output_layer, keep_prob):
    """
    Create a decoding layer for training
    :param encoder_state: Encoder State
    :param dec_cell: Decoder RNN Cell
    :param dec_embed_input: Decoder embedded input
    :param target_sequence_length: The lengths of each sequence in the target batch
    :param max_summary_length: The length of the longest sequence in the batch
    :param output_layer: Function to apply the output layer
    :param keep_prob: Dropout keep probability
    :return: BasicDecoderOutput containing training logits and sample_id
    """
    # TODO: Implement Function
    
    # Helper for the training process. Used by BasicDecoder to read inputs
    with tf.variable_scope("decode"):
        training_helper = tf.contrib.seq2seq.TrainingHelper(inputs=dec_embed_input,
                                                           sequence_length=target_sequence_length,
                                                           time_major=False)
    # Basic Decoder
        training_decoder = tf.contrib.seq2seq.BasicDecoder(dec_cell, training_helper,
                                       encoder_state, output_layer)
        
    #Perform dynamic decoding using the decoder
        training_decoder_output = tf.contrib.seq2seq.dynamic_decode(training_decoder,
                                                                   impute_finished=True,
                                                                   maximum_iterations=max_summary_length)[0]
        return training_decoder_output



"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
tests.test_decoding_layer_train(decoding_layer_train)

"""
Explanation: Decoding - Training
Create a training decoding layer:
* Create a tf.contrib.seq2seq.TrainingHelper 
* Create a tf.contrib.seq2seq.BasicDecoder
* Obtain the decoder outputs from tf.contrib.seq2seq.dynamic_decode
End of explanation
"""


def decoding_layer_infer(encoder_state, dec_cell, dec_embeddings, start_of_sequence_id,
                         end_of_sequence_id, max_target_sequence_length,
                         vocab_size, output_layer, batch_size, keep_prob):
    """
    Create a decoding layer for inference
    :param encoder_state: Encoder state
    :param dec_cell: Decoder RNN Cell
    :param dec_embeddings: Decoder embeddings
    :param start_of_sequence_id: GO ID
    :param end_of_sequence_id: EOS Id
    :param max_target_sequence_length: Maximum length of target sequences
    :param vocab_size: Size of decoder/target vocabulary
    :param decoding_scope: TenorFlow Variable Scope for decoding
    :param output_layer: Function to apply the output layer
    :param batch_size: Batch size
    :param keep_prob: Dropout keep probability
    :return: BasicDecoderOutput containing inference logits and sample_id
    """
    # TODO: Implement Function
    #with tf.variable_scope("decode", reuse=True):
    start_tokens = tf.tile(tf.constant([start_of_sequence_id], dtype=tf.int32), 
                              [batch_size], name='start_tokens')
    # Helper for inference process
    inference_helper = tf.contrib.seq2seq.GreedyEmbeddingHelper(dec_embeddings,
                                                                   start_tokens,
                                                                   end_of_sequence_id)
    #Basic decoder
    inference_decoder = tf.contrib.seq2seq.BasicDecoder(dec_cell, inference_helper,
                                                           encoder_state, output_layer)
        
    #Perform dynamic decoding using the decoder
    inference_decoder_output = tf.contrib.seq2seq.dynamic_decode(inference_decoder,
                                                                    impute_finished=True,
                                                                    maximum_iterations=max_target_sequence_length)[0]
    return inference_decoder_output



"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
tests.test_decoding_layer_infer(decoding_layer_infer)

"""
Explanation: Decoding - Inference
Create inference decoder:
* Create a tf.contrib.seq2seq.GreedyEmbeddingHelper
* Create a tf.contrib.seq2seq.BasicDecoder
* Obtain the decoder outputs from tf.contrib.seq2seq.dynamic_decode
End of explanation
"""



def decoding_layer(dec_input, encoder_state,
                   target_sequence_length, max_target_sequence_length,
                   rnn_size,
                   num_layers, target_vocab_to_int, target_vocab_size,
                   batch_size, keep_prob, decoding_embedding_size):
    """
    Create decoding layer
    :param dec_input: Decoder input
    :param encoder_state: Encoder state
    :param target_sequence_length: The lengths of each sequence in the target batch
    :param max_target_sequence_length: Maximum length of target sequences
    :param rnn_size: RNN Size
    :param num_layers: Number of layers
    :param target_vocab_to_int: Dictionary to go from the target words to an id
    :param target_vocab_size: Size of target vocabulary
    :param batch_size: The size of the batch
    :param keep_prob: Dropout keep probability
    :param decoding_embedding_size: Decoding embedding size
    :return: Tuple of (Training BasicDecoderOutput, Inference BasicDecoderOutput)
    """
    # TODO: Implement Function
    
    target_vocab_size = len(target_vocab_to_int)
    dec_embeddings = tf.Variable(tf.random_uniform([target_vocab_size, decoding_embedding_size]))
    dec_embed_input=tf.nn.embedding_lookup(dec_embeddings, dec_input)
    
    #Construct decoder cell
    def make_cell(rnn_size):
        dec_cell = tf.contrib.rnn.LSTMCell(rnn_size,
                                          initializer=tf.random_uniform_initializer(-0.1,0.1, seed=2))
                                        #reuse=tf.get_variable_scope().reuse)
        return dec_cell
    
   # dec_cell = tf.contrib.rnn.MultiRNNCell([tf.contrib.rnn.DropoutWrapper(make_cell(rnn_size),
           #                                                               output_keep_prob=keep_prob)
  #                                          for _ in range(num_layers)])
    
    dec_cell = tf.contrib.rnn.MultiRNNCell([make_cell(rnn_size) for _ in range(num_layers)])
                                           
                                     
    output_layer=Dense(target_vocab_size,
                      kernel_initializer=tf.truncated_normal_initializer(mean=0.0, stddev=0.1))
    
    with tf.variable_scope("decode"):
        training_decoder_output = decoding_layer_train(encoder_state, dec_cell, dec_embed_input, 
                         target_sequence_length, max_target_sequence_length, 
                         output_layer, keep_prob)
    with tf.variable_scope("decoder",reuse=True):
        
        inference_decoder_output = decoding_layer_infer(encoder_state, dec_cell, dec_embeddings, target_vocab_to_int['<GO>'],
                         target_vocab_to_int['<EOS>'], max_target_sequence_length,
                         target_vocab_size, output_layer, batch_size, keep_prob)
    return training_decoder_output, inference_decoder_output



"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
tests.test_decoding_layer(decoding_layer)

"""
Explanation: Build the Decoding Layer
Implement decoding_layer() to create a Decoder RNN layer.

Embed the target sequences
Construct the decoder LSTM cell (just like you constructed the encoder cell above)
Create an output layer to map the outputs of the decoder to the elements of our vocabulary
Use the your decoding_layer_train(encoder_state, dec_cell, dec_embed_input, target_sequence_length, max_target_sequence_length, output_layer, keep_prob) function to get the training logits.
Use your decoding_layer_infer(encoder_state, dec_cell, dec_embeddings, start_of_sequence_id, end_of_sequence_id, max_target_sequence_length, vocab_size, output_layer, batch_size, keep_prob) function to get the inference logits.

Note: You'll need to use tf.variable_scope to share variables between training and inference.
End of explanation
"""


def seq2seq_model(input_data, target_data, keep_prob, batch_size,
                  source_sequence_length, target_sequence_length,
                  max_target_sentence_length,
                  source_vocab_size, target_vocab_size,
                  enc_embedding_size, dec_embedding_size,
                  rnn_size, num_layers, target_vocab_to_int):
    """
    Build the Sequence-to-Sequence part of the neural network
    :param input_data: Input placeholder
    :param target_data: Target placeholder
    :param keep_prob: Dropout keep probability placeholder
    :param batch_size: Batch Size
    :param source_sequence_length: Sequence Lengths of source sequences in the batch
    :param target_sequence_length: Sequence Lengths of target sequences in the batch
    :param source_vocab_size: Source vocabulary size
    :param target_vocab_size: Target vocabulary size
    :param enc_embedding_size: Decoder embedding size
    :param dec_embedding_size: Encoder embedding size
    :param rnn_size: RNN Size
    :param num_layers: Number of layers
    :param target_vocab_to_int: Dictionary to go from the target words to an id
    :return: Tuple of (Training BasicDecoderOutput, Inference BasicDecoderOutput)
    """
    # TODO: Implement Function
    _, enc_state = encoding_layer(input_data, 
                                  rnn_size,
                                  num_layers,
                                  keep_prob,
                                  source_sequence_length,
                                  source_vocab_size,
                                  enc_embedding_size)
    dec_input = process_decoder_input(target_data, 
                                     target_vocab_to_int,
                                     batch_size)
    
    training_decoder_output, inference_decoder_output = decoding_layer(dec_input, 
                                                                       enc_state,
                                                                       target_sequence_length, 
                                                                       max_target_sentence_length,
                                                                       rnn_size,
                                                                       num_layers, 
                                                                       target_vocab_to_int, 
                                                                       target_vocab_size,
                                                                       batch_size, 
                                                                       keep_prob, 
                                                                       dec_embedding_size)
    return training_decoder_output, inference_decoder_output


"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
tests.test_seq2seq_model(seq2seq_model)

"""
Explanation: Build the Neural Network
Apply the functions you implemented above to:

Encode the input using your encoding_layer(rnn_inputs, rnn_size, num_layers, keep_prob,  source_sequence_length, source_vocab_size, encoding_embedding_size).
Process target data using your process_decoder_input(target_data, target_vocab_to_int, batch_size) function.
Decode the encoded input using your decoding_layer(dec_input, enc_state, target_sequence_length, max_target_sentence_length, rnn_size, num_layers, target_vocab_to_int, target_vocab_size, batch_size, keep_prob, dec_embedding_size) function.
End of explanation
"""


# Number of Epochs
epochs = 10
# Batch Size
batch_size = 128
# RNN Size
rnn_size = 50
# Number of Layers
num_layers = 2
# Embedding Size
encoding_embedding_size = 15
decoding_embedding_size = 15
# Learning Rate
learning_rate = 0.001
# Dropout Keep Probability
keep_probability = 0.9
display_step =1

"""
Explanation: Neural Network Training
Hyperparameters
Tune the following parameters:

Set epochs to the number of epochs.
Set batch_size to the batch size.
Set rnn_size to the size of the RNNs.
Set num_layers to the number of layers.
Set encoding_embedding_size to the size of the embedding for the encoder.
Set decoding_embedding_size to the size of the embedding for the decoder.
Set learning_rate to the learning rate.
Set keep_probability to the Dropout keep probability
Set display_step to state how many steps between each debug output statement
End of explanation
"""


"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
save_path = 'checkpoints/dev'
(source_int_text, target_int_text), (source_vocab_to_int, target_vocab_to_int), _ = helper.load_preprocess()
max_target_sentence_length = max([len(sentence) for sentence in source_int_text])

train_graph = tf.Graph()
with train_graph.as_default():
    input_data, targets, lr, keep_prob, target_sequence_length, max_target_sequence_length, source_sequence_length = model_inputs()

    #sequence_length = tf.placeholder_with_default(max_target_sentence_length, None, name='sequence_length')
    input_shape = tf.shape(input_data)

    train_logits, inference_logits = seq2seq_model(tf.reverse(input_data, [-1]),
                                                   targets,
                                                   keep_prob,
                                                   batch_size,
                                                   source_sequence_length,
                                                   target_sequence_length,
                                                   max_target_sequence_length,
                                                   len(source_vocab_to_int),
                                                   len(target_vocab_to_int),
                                                   encoding_embedding_size,
                                                   decoding_embedding_size,
                                                   rnn_size,
                                                   num_layers,
                                                   target_vocab_to_int)


    training_logits = tf.identity(train_logits.rnn_output, name='logits')
    inference_logits = tf.identity(inference_logits.sample_id, name='predictions')

    masks = tf.sequence_mask(target_sequence_length, max_target_sequence_length, dtype=tf.float32, name='masks')

    with tf.name_scope("optimization"):
        # Loss function
        cost = tf.contrib.seq2seq.sequence_loss(
            training_logits,
            targets,
            masks)

        # Optimizer
        optimizer = tf.train.AdamOptimizer(lr)

        # Gradient Clipping
        gradients = optimizer.compute_gradients(cost)
        capped_gradients = [(tf.clip_by_value(grad, -1., 1.), var) for grad, var in gradients if grad is not None]
        train_op = optimizer.apply_gradients(capped_gradients)


"""
Explanation: Build the Graph
Build the graph using the neural network you implemented.
End of explanation
"""


"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
def pad_sentence_batch(sentence_batch, pad_int):
    """Pad sentences with <PAD> so that each sentence of a batch has the same length"""
    max_sentence = max([len(sentence) for sentence in sentence_batch])
    return [sentence + [pad_int] * (max_sentence - len(sentence)) for sentence in sentence_batch]


def get_batches(sources, targets, batch_size, source_pad_int, target_pad_int):
    """Batch targets, sources, and the lengths of their sentences together"""
    for batch_i in range(0, len(sources)//batch_size):
        start_i = batch_i * batch_size

        # Slice the right amount for the batch
        sources_batch = sources[start_i:start_i + batch_size]
        targets_batch = targets[start_i:start_i + batch_size]

        # Pad
        pad_sources_batch = np.array(pad_sentence_batch(sources_batch, source_pad_int))
        pad_targets_batch = np.array(pad_sentence_batch(targets_batch, target_pad_int))

        # Need the lengths for the _lengths parameters
        pad_targets_lengths = []
        for target in pad_targets_batch:
            pad_targets_lengths.append(len(target))

        pad_source_lengths = []
        for source in pad_sources_batch:
            pad_source_lengths.append(len(source))

        yield pad_sources_batch, pad_targets_batch, pad_source_lengths, pad_targets_lengths


"""
Explanation: Batch and pad the source and target sequences
End of explanation
"""


"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
def get_accuracy(target, logits):
    """
    Calculate accuracy
    """
    max_seq = max(target.shape[1], logits.shape[1])
    if max_seq - target.shape[1]:
        target = np.pad(
            target,
            [(0,0),(0,max_seq - target.shape[1])],
            'constant')
    if max_seq - logits.shape[1]:
        logits = np.pad(
            logits,
            [(0,0),(0,max_seq - logits.shape[1])],
            'constant')

    return np.mean(np.equal(target, logits))

# Split data to training and validation sets
train_source = source_int_text[batch_size:]
train_target = target_int_text[batch_size:]
valid_source = source_int_text[:batch_size]
valid_target = target_int_text[:batch_size]
(valid_sources_batch, valid_targets_batch, valid_sources_lengths, valid_targets_lengths ) = next(get_batches(valid_source,
                                                                                                             valid_target,
                                                                                                             batch_size,
                                                                                                             source_vocab_to_int['<PAD>'],
                                                                                                             target_vocab_to_int['<PAD>']))                                                                                                  
with tf.Session(graph=train_graph) as sess:
    sess.run(tf.global_variables_initializer())

    for epoch_i in range(epochs):
        for batch_i, (source_batch, target_batch, sources_lengths, targets_lengths) in enumerate(
                get_batches(train_source, train_target, batch_size,
                            source_vocab_to_int['<PAD>'],
                            target_vocab_to_int['<PAD>'])):

            _, loss = sess.run(
                [train_op, cost],
                {input_data: source_batch,
                 targets: target_batch,
                 lr: learning_rate,
                 target_sequence_length: targets_lengths,
                 source_sequence_length: sources_lengths,
                 keep_prob: keep_probability})


            if batch_i % display_step == 0 and batch_i > 0:


                batch_train_logits = sess.run(
                    inference_logits,
                    {input_data: source_batch,
                     source_sequence_length: sources_lengths,
                     target_sequence_length: targets_lengths,
                     keep_prob: 1.0})


                batch_valid_logits = sess.run(
                    inference_logits,
                    {input_data: valid_sources_batch,
                     source_sequence_length: valid_sources_lengths,
                     target_sequence_length: valid_targets_lengths,
                     keep_prob: 1.0})

                train_acc = get_accuracy(target_batch, batch_train_logits)

                valid_acc = get_accuracy(valid_targets_batch, batch_valid_logits)

                print('Epoch {:>3} Batch {:>4}/{} - Train Accuracy: {:>6.4f}, Validation Accuracy: {:>6.4f}, Loss: {:>6.4f}'
                      .format(epoch_i, batch_i, len(source_int_text) // batch_size, train_acc, valid_acc, loss))

    # Save Model
    saver = tf.train.Saver()
    saver.save(sess, save_path)
    print('Model Trained and Saved')

"""
Explanation: Train
Train the neural network on the preprocessed data. If you have a hard time getting a good loss, check the forms to see if anyone is having the same problem.
End of explanation
"""


"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
# Save parameters for checkpoint
helper.save_params(save_path)

"""
Explanation: Save Parameters
Save the batch_size and save_path parameters for inference.
End of explanation
"""


"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
import tensorflow as tf
import numpy as np
import helper
import problem_unittests as tests

_, (source_vocab_to_int, target_vocab_to_int), (source_int_to_vocab, target_int_to_vocab) = helper.load_preprocess()
load_path = helper.load_params()

"""
Explanation: Checkpoint
End of explanation
"""


def sentence_to_seq(sentence, vocab_to_int):
    """
    Convert a sentence to a sequence of ids
    :param sentence: String
    :param vocab_to_int: Dictionary to go from the words to an id
    :return: List of word ids
    """
    # TODO: Implement Function
    return None


"""
DON'T MODIFY ANYTHING IN THIS CELL THAT IS BELOW THIS LINE
"""
tests.test_sentence_to_seq(sentence_to_seq)

"""
Explanation: Sentence to Sequence
To feed a sentence into the model for translation, you first need to preprocess it.  Implement the function sentence_to_seq() to preprocess new sentences.

Convert the sentence to lowercase
Convert words into ids using vocab_to_int
Convert words not in the vocabulary, to the &lt;UNK&gt; word id.
End of explanation
"""


translate_sentence = 'he saw a old yellow truck .'


"""
DON'T MODIFY ANYTHING IN THIS CELL
"""
translate_sentence = sentence_to_seq(translate_sentence, source_vocab_to_int)

loaded_graph = tf.Graph()
with tf.Session(graph=loaded_graph) as sess:
    # Load saved model
    loader = tf.train.import_meta_graph(load_path + '.meta')
    loader.restore(sess, load_path)

    input_data = loaded_graph.get_tensor_by_name('input:0')
    logits = loaded_graph.get_tensor_by_name('predictions:0')
    target_sequence_length = loaded_graph.get_tensor_by_name('target_sequence_length:0')
    source_sequence_length = loaded_graph.get_tensor_by_name('source_sequence_length:0')
    keep_prob = loaded_graph.get_tensor_by_name('keep_prob:0')

    translate_logits = sess.run(logits, {input_data: [translate_sentence]*batch_size,
                                         target_sequence_length: [len(translate_sentence)*2]*batch_size,
                                         source_sequence_length: [len(translate_sentence)]*batch_size,
                                         keep_prob: 1.0})[0]

print('Input')
print('  Word Ids:      {}'.format([i for i in translate_sentence]))
print('  English Words: {}'.format([source_int_to_vocab[i] for i in translate_sentence]))

print('\nPrediction')
print('  Word Ids:      {}'.format([i for i in translate_logits]))
print('  French Words: {}'.format(" ".join([target_int_to_vocab[i] for i in translate_logits])))


"""
Explanation: Translate
This will translate translate_sentence from English to French.
End of explanation
"""


