#  Copyright 2015-present The Scikit Flow Authors. All Rights Reserved.
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#  Licensed under the Apache License, Version 2.0 (the "License");
#  you may not use this file except in compliance with the License.
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#   http://www.apache.org/licenses/LICENSE-2.0
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"""
This is an example of using recurrent neural networks over characters
for DBpedia dataset to predict class from description of an entity.

This model is similar to one described in this paper:
   "Character-level Convolutional Networks for Text Classification"
   http://arxiv.org/abs/1509.01626

and is somewhat alternative to the Lua code from here:
   https://github.com/zhangxiangxiao/Crepe
"""

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import numpy as np
from sklearn import metrics
import pandas

import tensorflow as tf
from tensorflow.contrib import learn

FLAGS = tf.app.flags.FLAGS
tf.app.flags.DEFINE_bool('test_with_fake_data', False,
                         'Test the example code with fake data.')

MAX_DOCUMENT_LENGTH = 100
HIDDEN_SIZE = 20


def char_rnn_model(x, y):
  """Character level recurrent neural network model to predict classes."""
  y = tf.one_hot(y, 15, 1, 0)
  byte_list = learn.ops.one_hot_matrix(x, 256)
  byte_list = learn.ops.split_squeeze(1, MAX_DOCUMENT_LENGTH, byte_list)

  cell = tf.nn.rnn_cell.GRUCell(HIDDEN_SIZE)
  _, encoding = tf.nn.rnn(cell, byte_list, dtype=tf.float32)

  prediction, loss = learn.models.logistic_regression(encoding, y)

  train_op = tf.contrib.layers.optimize_loss(
      loss, tf.contrib.framework.get_global_step(),
      optimizer='Adam', learning_rate=0.01)

  return {'class': tf.argmax(prediction, 1), 'prob': prediction}, loss, train_op


def main(unused_argv):
  # Prepare training and testing data
  dbpedia = learn.datasets.load_dataset(
      'dbpedia', test_with_fake_data=FLAGS.test_with_fake_data)
  x_train = pandas.DataFrame(dbpedia.train.data)[1]
  y_train = pandas.Series(dbpedia.train.target)
  x_test = pandas.DataFrame(dbpedia.test.data)[1]
  y_test = pandas.Series(dbpedia.test.target)

  # Process vocabulary
  char_processor = learn.preprocessing.ByteProcessor(MAX_DOCUMENT_LENGTH)
  x_train = np.array(list(char_processor.fit_transform(x_train)))
  x_test = np.array(list(char_processor.transform(x_test)))

  # Build model
  classifier = learn.Estimator(model_fn=char_rnn_model)

  # Train and predict
  classifier.fit(x_train, y_train, steps=100)
  y_predicted = classifier.predict(x_test)
  score = metrics.accuracy_score(y_test, y_predicted['class'])
  print('Accuracy: {0:f}'.format(score))


if __name__ == '__main__':
  tf.app.run()
