"""
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)
    """
    target_text = target_text.replace("\n"," <EOS>\n") + " <EOS>" #last line does not have an line break
    source_lines = source_text.split("\n")
    target_lines = target_text.split("\n")
    
    source_ids = []
    target_ids = []
    
    for s in source_lines:
        source_ids.append(list(map(lambda x: source_vocab_to_int[x], s.split())))
    for t in target_lines:
        target_ids.append(list(map(lambda x: target_vocab_to_int[x], t.split())))
        
    return source_ids, target_ids

"""
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 each sentence from 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

(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

# Check TensorFlow Version
assert LooseVersion(tf.__version__) in [LooseVersion('1.0.0'), LooseVersion('1.0.1')], 'This project requires TensorFlow version 1.0  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()))

"""
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, and learning rate.
    :return: Tuple (input, targets, learning rate, keep probability)
    """
    inputs = tf.placeholder(tf.int32, [None, None], name="input")
    targets = tf.placeholder(tf.int32, [None, None])
    learning_rate = tf.placeholder(tf.float32)
    keep_probablility = tf.placeholder(tf.float32, name="keep_prob")
    return inputs, targets, learning_rate, keep_probablility

"""
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_decoding_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.

Return the placeholders in the following the tuple (Input, Targets, Learing Rate, Keep Probability)
End of explanation
"""


def process_decoding_input(target_data, target_vocab_to_int, batch_size):
    """
    Preprocess target data for dencoding
    :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
    """
    target_data_minus_last_word = tf.strided_slice(target_data, [0, 0], [batch_size, -1], [1, 1])
    return tf.concat([tf.fill([batch_size, 1], target_vocab_to_int['<GO>']), target_data_minus_last_word], 1)

"""
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"""
tests.test_process_decoding_input(process_decoding_input)

"""
Explanation: Process Decoding Input
Implement process_decoding_input using TensorFlow to remove the last word id from each batch in target_data and concat the GO ID to the beginning of each batch.
End of explanation
"""


def encoding_layer(rnn_inputs, rnn_size, num_layers, keep_prob):
    """
    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
    :return: RNN state
    """
    encoding_cell = tf.contrib.rnn.MultiRNNCell([tf.contrib.rnn.BasicLSTMCell(rnn_size)] * num_layers)
    outputs, state = tf.nn.dynamic_rnn(encoding_cell, rnn_inputs, dtype=tf.float32)
    return 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 using tf.nn.dynamic_rnn().
End of explanation
"""


def decoding_layer_train(encoder_state, dec_cell, dec_embed_input, sequence_length, decoding_scope,
                         output_fn, 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 sequence_length: Sequence Length
    :param decoding_scope: TenorFlow Variable Scope for decoding
    :param output_fn: Function to apply the output layer
    :param keep_prob: Dropout keep probability
    :return: Train Logits
    """
    train_decoder_function = tf.contrib.seq2seq.simple_decoder_fn_train(encoder_state)
    train_decoder_predictions, _, _ = tf.contrib.seq2seq.dynamic_rnn_decoder(
        dec_cell, train_decoder_function, dec_embed_input, sequence_length, scope=decoding_scope)
    return output_fn(train_decoder_predictions)


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

"""
Explanation: Decoding - Training
Create training logits using tf.contrib.seq2seq.simple_decoder_fn_train() and tf.contrib.seq2seq.dynamic_rnn_decoder().  Apply the output_fn to the tf.contrib.seq2seq.dynamic_rnn_decoder() outputs.
End of explanation
"""


def decoding_layer_infer(encoder_state, dec_cell, dec_embeddings, start_of_sequence_id, end_of_sequence_id,
                         maximum_length, vocab_size, decoding_scope, output_fn, 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 maximum_length: The maximum allowed time steps to decode
    :param vocab_size: Size of vocabulary
    :param decoding_scope: TensorFlow Variable Scope for decoding
    :param output_fn: Function to apply the output layer
    :param keep_prob: Dropout keep probability
    :return: Inference Logits
    """
    inference_decoder_function = tf.contrib.seq2seq.simple_decoder_fn_inference(
        output_fn, encoder_state, dec_embeddings, start_of_sequence_id, end_of_sequence_id,
        maximum_length - 1, vocab_size)
    outputs, state, context_state = tf.contrib.seq2seq.dynamic_rnn_decoder(
        dec_cell, inference_decoder_function, scope=decoding_scope)
    return outputs


"""
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 logits using tf.contrib.seq2seq.simple_decoder_fn_inference() and tf.contrib.seq2seq.dynamic_rnn_decoder().
End of explanation
"""


def decoding_layer(dec_embed_input, dec_embeddings, encoder_state, vocab_size, sequence_length, rnn_size,
                   num_layers, target_vocab_to_int, keep_prob):
    """
    Create decoding layer
    :param dec_embed_input: Decoder embedded input
    :param dec_embeddings: Decoder embeddings
    :param encoder_state: The encoded state
    :param vocab_size: Size of vocabulary
    :param sequence_length: Sequence Length
    :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 keep_prob: Dropout keep probability
    :return: Tuple of (Training Logits, Inference Logits)
    """
    decoder_cell = tf.contrib.rnn.MultiRNNCell([tf.contrib.rnn.BasicLSTMCell(rnn_size)] * num_layers)
    with tf.variable_scope("decoding") as decoding_scope:
        output_function = lambda fn: tf.contrib.layers.fully_connected(fn, vocab_size, None, scope=decoding_scope)
        training_logits = decoding_layer_train(
            encoder_state, decoder_cell, dec_embed_input, sequence_length, decoding_scope, output_function, keep_prob)
        decoding_scope.reuse_variables()
        inference_logits = decoding_layer_infer(
            encoder_state, decoder_cell, dec_embeddings, target_vocab_to_int['<GO>'], target_vocab_to_int['<EOS>'],
            sequence_length, vocab_size, decoding_scope, output_function, keep_prob)
    return training_logits, inference_logits


"""
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.

Create RNN cell for decoding using rnn_size and num_layers.
Create the output fuction using lambda to transform it's input, logits, to class logits.
Use the your decoding_layer_train(encoder_state, dec_cell, dec_embed_input, sequence_length, decoding_scope, output_fn, 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, maximum_length, vocab_size, decoding_scope, output_fn, 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, sequence_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 sequence_length: Sequence Length
    :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 Logits, Inference Logits)
    """
    encoding_embedded_input = tf.contrib.layers.embed_sequence(input_data, source_vocab_size, enc_embedding_size)
    encoder_state = encoding_layer(encoding_embedded_input, rnn_size, num_layers, keep_prob)
    processed_decoding_input = process_decoding_input(target_data, target_vocab_to_int, batch_size)
    decoding_embeddings = tf.Variable(tf.random_uniform([target_vocab_size, dec_embedding_size]))
    decoding_embeded_input = tf.nn.embedding_lookup(decoding_embeddings, processed_decoding_input)
    return decoding_layer(decoding_embeded_input, decoding_embeddings, encoder_state, target_vocab_size,
                         sequence_length, rnn_size, num_layers, target_vocab_to_int, keep_prob)


"""
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:

Apply embedding to the input data for the encoder.
Encode the input using your encoding_layer(rnn_inputs, rnn_size, num_layers, keep_prob).
Process target data using your process_decoding_input(target_data, target_vocab_to_int, batch_size) function.
Apply embedding to the target data for the decoder.
Decode the encoded input using your decoding_layer(dec_embed_input, dec_embeddings, encoder_state, vocab_size, sequence_length, rnn_size, num_layers, target_vocab_to_int, keep_prob).
End of explanation
"""


# Number of Epochs
epochs = 10
# Batch Size
batch_size = 256
# RNN Size
rnn_size = 100
# Number of Layers
num_layers = 2
# Embedding Size
encoding_embedding_size = 13
decoding_embedding_size = 13
# Learning Rate
learning_rate = .01
# Dropout Keep Probability
keep_probability = .5

"""
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
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_source_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 = model_inputs()
    sequence_length = tf.placeholder_with_default(max_source_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, 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)

    tf.identity(inference_logits, 'logits')
    with tf.name_scope("optimization"):
        # Loss function
        cost = tf.contrib.seq2seq.sequence_loss(
            train_logits,
            targets,
            tf.ones([input_shape[0], sequence_length]))

        # 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
"""
import time

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]), (0,0)],
            'constant')

    return np.mean(np.equal(target, np.argmax(logits, 2)))

train_source = source_int_text[batch_size:]
train_target = target_int_text[batch_size:]

valid_source = helper.pad_sentence_batch(source_int_text[:batch_size])
valid_target = helper.pad_sentence_batch(target_int_text[:batch_size])

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) in enumerate(
                helper.batch_data(train_source, train_target, batch_size)):
            start_time = time.time()
            
            _, loss = sess.run(
                [train_op, cost],
                {input_data: source_batch,
                 targets: target_batch,
                 lr: learning_rate,
                 sequence_length: target_batch.shape[1],
                 keep_prob: keep_probability})
            
            batch_train_logits = sess.run(
                inference_logits,
                {input_data: source_batch, keep_prob: 1.0})
            batch_valid_logits = sess.run(
                inference_logits,
                {input_data: valid_source, keep_prob: 1.0})
                
            train_acc = get_accuracy(target_batch, batch_train_logits)
            valid_acc = get_accuracy(np.array(valid_target), batch_valid_logits)
            end_time = time.time()
            print('Epoch {:>3} Batch {:>4}/{} - Train Accuracy: {:>6.3f}, Validation Accuracy: {:>6.3f}, Loss: {:>6.3f}'
                  .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
    """
    sentence = sentence.lower()
    words = sentence.split()
    word_ids = []
    
    for word in words:
        if word in vocab_to_int:
            word_ids.append(vocab_to_int[word])
        else:
            word_ids.append(vocab_to_int['<UNK>'])
    return word_ids


"""
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('logits:0')
    keep_prob = loaded_graph.get_tensor_by_name('keep_prob:0')

    translate_logits = sess.run(logits, {input_data: [translate_sentence], 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 np.argmax(translate_logits, 1)]))
print('  French Words: {}'.format([target_int_to_vocab[i] for i in np.argmax(translate_logits, 1)]))

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


