# Copyright 2019 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# ==============================================================================
"""Script to pre-process classification data into tfrecords."""
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import collections
import csv
import os

from absl import app
from absl import flags
from absl import logging
import numpy as np
import tensorflow as tf

import sentencepiece as spm
from official.nlp.xlnet import classifier_utils
from official.nlp.xlnet import preprocess_utils


flags.DEFINE_bool(
    "overwrite_data",
    default=False,
    help="If False, will use cached data if available.")
flags.DEFINE_string("output_dir", default="", help="Output dir for TF records.")
flags.DEFINE_string(
    "spiece_model_file", default="", help="Sentence Piece model path.")
flags.DEFINE_string("data_dir", default="", help="Directory for input data.")

# task specific
flags.DEFINE_string("eval_split", default="dev", help="could be dev or test")
flags.DEFINE_string("task_name", default=None, help="Task name")
flags.DEFINE_integer(
    "eval_batch_size", default=64, help="batch size for evaluation")
flags.DEFINE_integer("max_seq_length", default=128, help="Max sequence length")
flags.DEFINE_integer(
    "num_passes",
    default=1,
    help="Num passes for processing training data. "
    "This is use to batch data without loss for TPUs.")
flags.DEFINE_bool("uncased", default=False, help="Use uncased.")
flags.DEFINE_bool(
    "is_regression", default=False, help="Whether it's a regression task.")
flags.DEFINE_bool(
    "use_bert_format",
    default=False,
    help="Whether to use BERT format to arrange input data.")

FLAGS = flags.FLAGS


class InputExample(object):
  """A single training/test example for simple sequence classification."""

  def __init__(self, guid, text_a, text_b=None, label=None):
    """Constructs a InputExample.

    Args:
      guid: Unique id for the example.
      text_a: string. The untokenized text of the first sequence. For single
        sequence tasks, only this sequence must be specified.
      text_b: (Optional) string. The untokenized text of the second sequence.
        Only must be specified for sequence pair tasks.
      label: (Optional) string. The label of the example. This should be
        specified for train and dev examples, but not for test examples.
    """
    self.guid = guid
    self.text_a = text_a
    self.text_b = text_b
    self.label = label


class DataProcessor(object):
  """Base class for data converters for sequence classification data sets."""

  def get_train_examples(self, data_dir):
    """Gets a collection of `InputExample`s for the train set."""
    raise NotImplementedError()

  def get_dev_examples(self, data_dir):
    """Gets a collection of `InputExample`s for the dev set."""
    raise NotImplementedError()

  def get_test_examples(self, data_dir):
    """Gets a collection of `InputExample`s for prediction."""
    raise NotImplementedError()

  def get_labels(self):
    """Gets the list of labels for this data set."""
    raise NotImplementedError()

  @classmethod
  def _read_tsv(cls, input_file, quotechar=None):
    """Reads a tab separated value file."""
    with tf.io.gfile.GFile(input_file, "r") as f:
      reader = csv.reader(f, delimiter="\t", quotechar=quotechar)
      lines = []
      for line in reader:
        # pylint: disable=g-explicit-length-test
        if len(line) == 0:
          continue
        lines.append(line)
      return lines


class GLUEProcessor(DataProcessor):
  """GLUEProcessor."""

  def __init__(self):
    self.train_file = "train.tsv"
    self.dev_file = "dev.tsv"
    self.test_file = "test.tsv"
    self.label_column = None
    self.text_a_column = None
    self.text_b_column = None
    self.contains_header = True
    self.test_text_a_column = None
    self.test_text_b_column = None
    self.test_contains_header = True

  def get_train_examples(self, data_dir):
    """See base class."""
    return self._create_examples(
        self._read_tsv(os.path.join(data_dir, self.train_file)), "train")

  def get_dev_examples(self, data_dir):
    """See base class."""
    return self._create_examples(
        self._read_tsv(os.path.join(data_dir, self.dev_file)), "dev")

  def get_test_examples(self, data_dir):
    """See base class."""
    if self.test_text_a_column is None:
      self.test_text_a_column = self.text_a_column
    if self.test_text_b_column is None:
      self.test_text_b_column = self.text_b_column

    return self._create_examples(
        self._read_tsv(os.path.join(data_dir, self.test_file)), "test")

  def get_labels(self):
    """See base class."""
    return ["0", "1"]

  def _create_examples(self, lines, set_type):
    """Creates examples for the training and dev sets."""
    examples = []
    for (i, line) in enumerate(lines):
      if i == 0 and self.contains_header and set_type != "test":
        continue
      if i == 0 and self.test_contains_header and set_type == "test":
        continue
      guid = "%s-%s" % (set_type, i)

      a_column = (
          self.text_a_column if set_type != "test" else self.test_text_a_column)
      b_column = (
          self.text_b_column if set_type != "test" else self.test_text_b_column)

      # there are some incomplete lines in QNLI
      if len(line) <= a_column:
        logging.warning("Incomplete line, ignored.")
        continue
      text_a = line[a_column]

      if b_column is not None:
        if len(line) <= b_column:
          logging.warning("Incomplete line, ignored.")
          continue
        text_b = line[b_column]
      else:
        text_b = None

      if set_type == "test":
        label = self.get_labels()[0]
      else:
        if len(line) <= self.label_column:
          logging.warning("Incomplete line, ignored.")
          continue
        label = line[self.label_column]
      examples.append(
          InputExample(guid=guid, text_a=text_a, text_b=text_b, label=label))
    return examples


class Yelp5Processor(DataProcessor):
  """Yelp5Processor."""

  def get_train_examples(self, data_dir):
    return self._create_examples(os.path.join(data_dir, "train.csv"))

  def get_dev_examples(self, data_dir):
    return self._create_examples(os.path.join(data_dir, "test.csv"))

  def get_labels(self):
    """See base class."""
    return ["1", "2", "3", "4", "5"]

  def _create_examples(self, input_file):
    """Creates examples for the training and dev sets."""
    examples = []
    with tf.io.gfile.GFile(input_file) as f:
      reader = csv.reader(f)
      for i, line in enumerate(reader):

        label = line[0]
        text_a = line[1].replace('""', '"').replace('\\"', '"')
        examples.append(
            InputExample(guid=str(i), text_a=text_a, text_b=None, label=label))
    return examples


class ImdbProcessor(DataProcessor):
  """ImdbProcessor."""

  def get_labels(self):
    return ["neg", "pos"]

  def get_train_examples(self, data_dir):
    return self._create_examples(os.path.join(data_dir, "train"))

  def get_dev_examples(self, data_dir):
    return self._create_examples(os.path.join(data_dir, "test"))

  def _create_examples(self, data_dir):
    """Creates examples."""
    examples = []
    for label in ["neg", "pos"]:
      cur_dir = os.path.join(data_dir, label)
      for filename in tf.io.gfile.listdir(cur_dir):
        if not filename.endswith("txt"):
          continue

        if len(examples) % 1000 == 0:
          logging.info("Loading dev example %d", len(examples))

        path = os.path.join(cur_dir, filename)
        with tf.io.gfile.GFile(path) as f:
          text = f.read().strip().replace("<br />", " ")
        examples.append(
            InputExample(
                guid="unused_id", text_a=text, text_b=None, label=label))
    return examples


class MnliMatchedProcessor(GLUEProcessor):
  """MnliMatchedProcessor."""

  def __init__(self):
    super(MnliMatchedProcessor, self).__init__()
    self.dev_file = "dev_matched.tsv"
    self.test_file = "test_matched.tsv"
    self.label_column = -1
    self.text_a_column = 8
    self.text_b_column = 9

  def get_labels(self):
    return ["contradiction", "entailment", "neutral"]


class MnliMismatchedProcessor(MnliMatchedProcessor):

  def __init__(self):
    super(MnliMismatchedProcessor, self).__init__()
    self.dev_file = "dev_mismatched.tsv"
    self.test_file = "test_mismatched.tsv"


class StsbProcessor(GLUEProcessor):
  """StsbProcessor."""

  def __init__(self):
    super(StsbProcessor, self).__init__()
    self.label_column = 9
    self.text_a_column = 7
    self.text_b_column = 8

  def get_labels(self):
    return [0.0]

  def _create_examples(self, lines, set_type):
    """Creates examples for the training and dev sets."""
    examples = []
    for (i, line) in enumerate(lines):
      if i == 0 and self.contains_header and set_type != "test":
        continue
      if i == 0 and self.test_contains_header and set_type == "test":
        continue
      guid = "%s-%s" % (set_type, i)

      a_column = (
          self.text_a_column if set_type != "test" else self.test_text_a_column)
      b_column = (
          self.text_b_column if set_type != "test" else self.test_text_b_column)

      # there are some incomplete lines in QNLI
      if len(line) <= a_column:
        logging.warning("Incomplete line, ignored.")
        continue
      text_a = line[a_column]

      if b_column is not None:
        if len(line) <= b_column:
          logging.warning("Incomplete line, ignored.")
          continue
        text_b = line[b_column]
      else:
        text_b = None

      if set_type == "test":
        label = self.get_labels()[0]
      else:
        if len(line) <= self.label_column:
          logging.warning("Incomplete line, ignored.")
          continue
        label = float(line[self.label_column])
      examples.append(
          InputExample(guid=guid, text_a=text_a, text_b=text_b, label=label))

    return examples


def file_based_convert_examples_to_features(examples,
                                            label_list,
                                            max_seq_length,
                                            tokenize_fn,
                                            output_file,
                                            num_passes=1):
  """Convert a set of `InputExample`s to a TFRecord file."""

  # do not create duplicated records
  if tf.io.gfile.exists(output_file) and not FLAGS.overwrite_data:
    logging.info("Do not overwrite tfrecord %s exists.", output_file)
    return

  logging.info("Create new tfrecord %s.", output_file)

  writer = tf.io.TFRecordWriter(output_file)

  examples *= num_passes

  for (ex_index, example) in enumerate(examples):
    if ex_index % 10000 == 0:
      logging.info("Writing example %d of %d", ex_index, len(examples))

    feature = classifier_utils.convert_single_example(ex_index, example,
                                                      label_list,
                                                      max_seq_length,
                                                      tokenize_fn,
                                                      FLAGS.use_bert_format)

    def create_int_feature(values):
      f = tf.train.Feature(int64_list=tf.train.Int64List(value=list(values)))
      return f

    def create_float_feature(values):
      f = tf.train.Feature(float_list=tf.train.FloatList(value=list(values)))
      return f

    features = collections.OrderedDict()
    features["input_ids"] = create_int_feature(feature.input_ids)
    features["input_mask"] = create_float_feature(feature.input_mask)
    features["segment_ids"] = create_int_feature(feature.segment_ids)
    if label_list is not None:
      features["label_ids"] = create_int_feature([feature.label_id])
    else:
      features["label_ids"] = create_float_feature([float(feature.label_id)])
    features["is_real_example"] = create_int_feature(
        [int(feature.is_real_example)])

    tf_example = tf.train.Example(features=tf.train.Features(feature=features))
    writer.write(tf_example.SerializeToString())
  writer.close()


def main(_):
  logging.set_verbosity(logging.INFO)
  processors = {
      "mnli_matched": MnliMatchedProcessor,
      "mnli_mismatched": MnliMismatchedProcessor,
      "sts-b": StsbProcessor,
      "imdb": ImdbProcessor,
      "yelp5": Yelp5Processor
  }

  task_name = FLAGS.task_name.lower()

  if task_name not in processors:
    raise ValueError("Task not found: %s" % (task_name))

  processor = processors[task_name]()
  label_list = processor.get_labels() if not FLAGS.is_regression else None

  sp = spm.SentencePieceProcessor()
  sp.Load(FLAGS.spiece_model_file)

  def tokenize_fn(text):
    text = preprocess_utils.preprocess_text(text, lower=FLAGS.uncased)
    return preprocess_utils.encode_ids(sp, text)

  spm_basename = os.path.basename(FLAGS.spiece_model_file)

  train_file_base = "{}.len-{}.train.tf_record".format(spm_basename,
                                                       FLAGS.max_seq_length)
  train_file = os.path.join(FLAGS.output_dir, train_file_base)
  logging.info("Use tfrecord file %s", train_file)

  train_examples = processor.get_train_examples(FLAGS.data_dir)
  np.random.shuffle(train_examples)
  logging.info("Num of train samples: %d", len(train_examples))

  file_based_convert_examples_to_features(train_examples, label_list,
                                          FLAGS.max_seq_length, tokenize_fn,
                                          train_file, FLAGS.num_passes)
  if FLAGS.eval_split == "dev":
    eval_examples = processor.get_dev_examples(FLAGS.data_dir)
  else:
    eval_examples = processor.get_test_examples(FLAGS.data_dir)

  logging.info("Num of eval samples: %d", len(eval_examples))

  # TPU requires a fixed batch size for all batches, therefore the number
  # of examples must be a multiple of the batch size, or else examples
  # will get dropped. So we pad with fake examples which are ignored
  # later on. These do NOT count towards the metric (all tf.metrics
  # support a per-instance weight, and these get a weight of 0.0).
  #
  # Modified in XL: We also adopt the same mechanism for GPUs.
  while len(eval_examples) % FLAGS.eval_batch_size != 0:
    eval_examples.append(classifier_utils.PaddingInputExample())

  eval_file_base = "{}.len-{}.{}.eval.tf_record".format(spm_basename,
                                                        FLAGS.max_seq_length,
                                                        FLAGS.eval_split)
  eval_file = os.path.join(FLAGS.output_dir, eval_file_base)

  file_based_convert_examples_to_features(eval_examples, label_list,
                                          FLAGS.max_seq_length, tokenize_fn,
                                          eval_file)


if __name__ == "__main__":
  app.run(main)
