#   Copyright (c) 2019 PaddlePaddle 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.
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from __future__ import unicode_literals
from __future__ import absolute_import

import sys
import os
import json
import random
import logging
import numpy as np
import six
from io import open
from collections import namedtuple

import tokenization
from batching import pad_batch_data


log = logging.getLogger(__name__)

if six.PY3:
    import io
    sys.stdout = io.TextIOWrapper(sys.stdout.buffer, encoding='utf-8')
    sys.stderr = io.TextIOWrapper(sys.stderr.buffer, encoding='utf-8')


def csv_reader(fd, delimiter='\t'):
    def gen():
        for i in fd:
            slots = i.rstrip('\n').split(delimiter)
            if len(slots) == 1:
                yield slots,
            else:
                yield slots
    return gen()


class BaseReader(object):
    def __init__(self,
                 vocab_path,
                 label_map_config=None,
                 max_seq_len=512,
                 do_lower_case=True,
                 in_tokens=False,
                 is_inference=False,
                 random_seed=None,
                 tokenizer="FullTokenizer",
                 is_classify=True,
                 is_regression=False,
                 for_cn=True,
                 task_id=0):
        self.max_seq_len = max_seq_len
        self.tokenizer = tokenization.FullTokenizer(
            vocab_file=vocab_path, do_lower_case=do_lower_case)
        self.vocab = self.tokenizer.vocab
        self.pad_id = self.vocab["[PAD]"]
        self.cls_id = self.vocab["[CLS]"]
        self.sep_id = self.vocab["[SEP]"]
        self.in_tokens = in_tokens
        self.is_inference = is_inference
        self.for_cn = for_cn
        self.task_id = task_id

        np.random.seed(random_seed)

        self.is_classify = is_classify
        self.is_regression = is_regression
        self.current_example = 0
        self.current_epoch = 0
        self.num_examples = 0

        if label_map_config:
            with open(label_map_config, encoding='utf8') as f:
                self.label_map = json.load(f)
        else:
            self.label_map = None

    def get_train_progress(self):
        """Gets progress for training phase."""
        return self.current_example, self.current_epoch

    def _read_tsv(self, input_file, quotechar=None):
        """Reads a tab separated value file."""
        with open(input_file, 'r', encoding='utf8') as f:
            reader = csv_reader(f)
            headers = next(reader)
            Example = namedtuple('Example', headers)

            examples = []
            for line in reader:
                example = Example(*line)
                examples.append(example)
            return examples

    def _truncate_seq_pair(self, tokens_a, tokens_b, max_length):
        """Truncates a sequence pair in place to the maximum length."""

        # This is a simple heuristic which will always truncate the longer sequence
        # one token at a time. This makes more sense than truncating an equal percent
        # of tokens from each, since if one sequence is very short then each token
        # that's truncated likely contains more information than a longer sequence.
        while True:
            total_length = len(tokens_a) + len(tokens_b)
            if total_length <= max_length:
                break
            if len(tokens_a) > len(tokens_b):
                tokens_a.pop()
            else:
                tokens_b.pop()

    def _convert_example_to_record(self, example, max_seq_length, tokenizer):
        """Converts a single `Example` into a single `Record`."""

        text_a = tokenization.convert_to_unicode(example.text_a)
        tokens_a = tokenizer.tokenize(text_a)
        tokens_b = None

        has_text_b = False
        if isinstance(example, dict):
            has_text_b = "text_b" in example.keys()
        else:
            has_text_b = "text_b" in example._fields

        if has_text_b:
            text_b = tokenization.convert_to_unicode(example.text_b)
            tokens_b = tokenizer.tokenize(text_b)

        if tokens_b:
            # Modifies `tokens_a` and `tokens_b` in place so that the total
            # length is less than the specified length.
            # Account for [CLS], [SEP], [SEP] with "- 3"
            self._truncate_seq_pair(tokens_a, tokens_b, max_seq_length - 3)
        else:
            # Account for [CLS] and [SEP] with "- 2"
            if len(tokens_a) > max_seq_length - 2:
                tokens_a = tokens_a[0:(max_seq_length - 2)]

        # The convention in BERT/ERNIE is:
        # (a) For sequence pairs:
        #  tokens:   [CLS] is this jack ##son ##ville ? [SEP] no it is not . [SEP]
        #  type_ids: 0     0  0    0    0     0       0 0     1  1  1  1   1 1
        # (b) For single sequences:
        #  tokens:   [CLS] the dog is hairy . [SEP]
        #  type_ids: 0     0   0   0  0     0 0
        #
        # Where "type_ids" are used to indicate whether this is the first
        # sequence or the second sequence. The embedding vectors for `type=0` and
        # `type=1` were learned during pre-training and are added to the wordpiece
        # embedding vector (and position vector). This is not *strictly* necessary
        # since the [SEP] token unambiguously separates the sequences, but it makes
        # it easier for the model to learn the concept of sequences.
        #
        # For classification tasks, the first vector (corresponding to [CLS]) is
        # used as as the "sentence vector". Note that this only makes sense because
        # the entire model is fine-tuned.
        tokens = []
        text_type_ids = []
        tokens.append("[CLS]")
        text_type_ids.append(0)
        for token in tokens_a:
            tokens.append(token)
            text_type_ids.append(0)
        tokens.append("[SEP]")
        text_type_ids.append(0)

        if tokens_b:
            for token in tokens_b:
                tokens.append(token)
                text_type_ids.append(1)
            tokens.append("[SEP]")
            text_type_ids.append(1)

        token_ids = tokenizer.convert_tokens_to_ids(tokens)
        position_ids = list(range(len(token_ids)))

        if self.is_inference:
            Record = namedtuple('Record',
                                ['token_ids', 'text_type_ids', 'position_ids'])
            record = Record(
                token_ids=token_ids,
                text_type_ids=text_type_ids,
                position_ids=position_ids)
        else:
            if self.label_map:
                label_id = self.label_map[example.label]
            else:
                label_id = example.label

            Record = namedtuple('Record', [
                'token_ids', 'text_type_ids', 'position_ids', 'label_id', 'qid'
            ])

            qid = None
            if "qid" in example._fields:
                qid = example.qid

            record = Record(
                token_ids=token_ids,
                text_type_ids=text_type_ids,
                position_ids=position_ids,
                label_id=label_id,
                qid=qid)
        return record

    def _prepare_batch_data(self, examples, batch_size, phase=None):
        """generate batch records"""
        batch_records, max_len = [], 0
        for index, example in enumerate(examples):
            if phase == "train":
                self.current_example = index
            record = self._convert_example_to_record(example, self.max_seq_len,
                                                     self.tokenizer)
            max_len = max(max_len, len(record.token_ids))
            if self.in_tokens:
                to_append = (len(batch_records) + 1) * max_len <= batch_size
            else:
                to_append = len(batch_records) < batch_size
            if to_append:
                batch_records.append(record)
            else:
                yield self._pad_batch_records(batch_records)
                batch_records, max_len = [record], len(record.token_ids)

        if batch_records:
            yield self._pad_batch_records(batch_records)

    def get_num_examples(self, input_file):
        examples = self._read_tsv(input_file)
        return len(examples)

    def data_generator(self,
                       input_file,
                       batch_size,
                       epoch,
                       dev_count=1,
                       shuffle=True,
                       phase=None):
        examples = self._read_tsv(input_file)

        if phase == 'train':
            trainer_id = int(os.getenv("PADDLE_TRAINER_ID", "0"))
            trainer_num = int(os.getenv("PADDLE_TRAINERS_NUM", "1"))
            examples = examples[trainer_id: (len(examples) //trainer_num) * trainer_num : trainer_num]
            log.info('apply sharding %d/%d' % (trainer_id, trainer_num))

        def wrapper():
            all_dev_batches = []
            for epoch_index in range(epoch):
                if phase == "train":
                    self.current_example = 0
                    self.current_epoch = epoch_index
                if shuffle:
                    np.random.shuffle(examples)

                for batch_data in self._prepare_batch_data(
                        examples, batch_size, phase=phase):
                    if len(all_dev_batches) < dev_count:
                        all_dev_batches.append(batch_data)
                    if len(all_dev_batches) == dev_count:
                        for batch in all_dev_batches:
                            yield batch
                        all_dev_batches = []
        def f():
            try:
                for i in wrapper():
                    yield i
            except Exception as e:
                import traceback
                traceback.print_exc()
        return f


class ClassifyReader(BaseReader):
    def _read_tsv(self, input_file, quotechar=None):
        """Reads a tab separated value file."""
        with open(input_file, 'r', encoding='utf8') as f:
            reader = csv_reader(f)
            headers = next(reader)
            text_indices = [
                index for index, h in enumerate(headers) if h != "label"
            ]
            Example = namedtuple('Example', headers)

            examples = []
            for line in reader:
                for index, text in enumerate(line):
                    if index in text_indices:
                        if self.for_cn:
                            line[index] = text.replace(' ', '')
                        else:
                            line[index] = text
                example = Example(*line)
                examples.append(example)
            return examples

    def _pad_batch_records(self, batch_records):
        batch_token_ids = [record.token_ids for record in batch_records]
        batch_text_type_ids = [record.text_type_ids for record in batch_records]
        batch_position_ids = [record.position_ids for record in batch_records]

        if not self.is_inference:
            batch_labels = [record.label_id for record in batch_records]
            if self.is_classify:
                batch_labels = np.array(batch_labels).astype("int64").reshape(
                    [-1, 1])
            elif self.is_regression:
                batch_labels = np.array(batch_labels).astype("float32").reshape(
                    [-1, 1])

            if batch_records[0].qid:
                batch_qids = [record.qid for record in batch_records]
                batch_qids = np.array(batch_qids).astype("int64").reshape(
                    [-1, 1])
            else:
                batch_qids = np.array([]).astype("int64").reshape([-1, 1])

        # padding
        padded_token_ids, input_mask = pad_batch_data(
            batch_token_ids, pad_idx=self.pad_id, return_input_mask=True)
        padded_text_type_ids = pad_batch_data(
            batch_text_type_ids, pad_idx=self.pad_id)
        padded_position_ids = pad_batch_data(
            batch_position_ids, pad_idx=self.pad_id)
        padded_task_ids = np.ones_like(
            padded_token_ids, dtype="int64") * self.task_id

        return_list = [
            padded_token_ids, padded_text_type_ids, padded_position_ids,
            padded_task_ids, input_mask
        ]
        if not self.is_inference:
            return_list += [batch_labels, batch_qids]

        return return_list


class SequenceLabelReader(BaseReader):
    def _pad_batch_records(self, batch_records):
        batch_token_ids = [record.token_ids for record in batch_records]
        batch_text_type_ids = [record.text_type_ids for record in batch_records]
        batch_position_ids = [record.position_ids for record in batch_records]
        batch_label_ids = [record.label_ids for record in batch_records]

        # padding
        padded_token_ids, input_mask, batch_seq_lens = pad_batch_data(
            batch_token_ids,
            pad_idx=self.pad_id,
            return_input_mask=True,
            return_seq_lens=True)
        padded_text_type_ids = pad_batch_data(
            batch_text_type_ids, pad_idx=self.pad_id)
        padded_position_ids = pad_batch_data(
            batch_position_ids, pad_idx=self.pad_id)
        padded_label_ids = pad_batch_data(
            batch_label_ids, pad_idx=len(self.label_map) - 1)
        padded_task_ids = np.ones_like(
            padded_token_ids, dtype="int64") * self.task_id

        return_list = [
            padded_token_ids, padded_text_type_ids, padded_position_ids,
            padded_task_ids, input_mask, padded_label_ids, batch_seq_lens
        ]
        return return_list

    def _reseg_token_label(self, tokens, labels, tokenizer):
        assert len(tokens) == len(labels)
        ret_tokens = []
        ret_labels = []
        for token, label in zip(tokens, labels):
            sub_token = tokenizer.tokenize(token)
            if len(sub_token) == 0:
                continue
            ret_tokens.extend(sub_token)
            if len(sub_token) == 1:
                ret_labels.append(label)
                continue

            if label == "O" or label.startswith("I-"):
                ret_labels.extend([label] * len(sub_token))
            elif label.startswith("B-"):
                i_label = "I-" + label[2:]
                ret_labels.extend([label] + [i_label] * (len(sub_token) - 1))
            elif label.startswith("S-"):
                b_laebl = "B-" + label[2:]
                e_label = "E-" + label[2:]
                i_label = "I-" + label[2:]
                ret_labels.extend([b_laebl] + [i_label] * (len(sub_token) - 2) + [e_label])
            elif label.startswith("E-"):
                i_label = "I-" + label[2:]
                ret_labels.extend([i_label] * (len(sub_token) - 1) + [label])

        assert len(ret_tokens) == len(ret_labels)
        return ret_tokens, ret_labels

    def _convert_example_to_record(self, example, max_seq_length, tokenizer):
        tokens = tokenization.convert_to_unicode(example.text_a).split(u"")
        labels = tokenization.convert_to_unicode(example.label).split(u"")
        tokens, labels = self._reseg_token_label(tokens, labels, tokenizer)

        if len(tokens) > max_seq_length - 2:
            tokens = tokens[0:(max_seq_length - 2)]
            labels = labels[0:(max_seq_length - 2)]

        tokens = ["[CLS]"] + tokens + ["[SEP]"]
        token_ids = tokenizer.convert_tokens_to_ids(tokens)
        position_ids = list(range(len(token_ids)))
        text_type_ids = [0] * len(token_ids)
        no_entity_id = len(self.label_map) - 1
        label_ids = [no_entity_id] + [
            self.label_map[label] for label in labels
        ] + [no_entity_id]

        Record = namedtuple(
            'Record',
            ['token_ids', 'text_type_ids', 'position_ids', 'label_ids'])
        record = Record(
            token_ids=token_ids,
            text_type_ids=text_type_ids,
            position_ids=position_ids,
            label_ids=label_ids)
        return record


class ExtractEmbeddingReader(BaseReader):
    def _pad_batch_records(self, batch_records):
        batch_token_ids = [record.token_ids for record in batch_records]
        batch_text_type_ids = [record.text_type_ids for record in batch_records]
        batch_position_ids = [record.position_ids for record in batch_records]

        # padding
        padded_token_ids, input_mask, seq_lens = pad_batch_data(
            batch_token_ids,
            pad_idx=self.pad_id,
            return_input_mask=True,
            return_seq_lens=True)
        padded_text_type_ids = pad_batch_data(
            batch_text_type_ids, pad_idx=self.pad_id)
        padded_position_ids = pad_batch_data(
            batch_position_ids, pad_idx=self.pad_id)
        padded_task_ids = np.ones_like(
            padded_token_ids, dtype="int64") * self.task_id

        return_list = [
            padded_token_ids, padded_text_type_ids, padded_position_ids,
            padded_task_ids, input_mask, seq_lens
        ]

        return return_list


class MRCReader(BaseReader):
    def __init__(self,
                 vocab_path,
                 label_map_config=None,
                 max_seq_len=512,
                 do_lower_case=True,
                 in_tokens=False,
                 random_seed=None,
                 tokenizer="FullTokenizer",
                 is_classify=True,
                 is_regression=False,
                 for_cn=True,
                 task_id=0,
                 doc_stride=128,
                 max_query_length=64):
        self.max_seq_len = max_seq_len
        self.tokenizer = tokenization.FullTokenizer(
            vocab_file=vocab_path, do_lower_case=do_lower_case)
        self.vocab = self.tokenizer.vocab
        self.pad_id = self.vocab["[PAD]"]
        self.cls_id = self.vocab["[CLS]"]
        self.sep_id = self.vocab["[SEP]"]
        self.in_tokens = in_tokens
        self.for_cn = for_cn
        self.task_id = task_id
        self.doc_stride = doc_stride
        self.max_query_length = max_query_length
        self.examples = {}
        self.features = {}

        if random_seed is not None:
            np.random.seed(random_seed)

        self.current_example = 0
        self.current_epoch = 0
        self.num_examples = 0

        self.Example = namedtuple('Example',
                ['qas_id', 'question_text', 'doc_tokens', 'orig_answer_text',
                'start_position', 'end_position'])
        self.Feature = namedtuple("Feature", ["unique_id", "example_index", "doc_span_index",
                "tokens", "token_to_orig_map", "token_is_max_context",
                "token_ids", "position_ids", "text_type_ids",
                "start_position", "end_position"])
        self.DocSpan = namedtuple("DocSpan", ["start", "length"])

    def _read_json(self, input_file, is_training):
        examples = []
        with open(input_file, "r", encoding='utf8') as f:
            input_data = json.load(f)["data"]
            for entry in input_data:
                for paragraph in entry["paragraphs"]:
                    paragraph_text = paragraph["context"]
                    for qa in paragraph["qas"]:
                        qas_id = qa["id"]
                        question_text = qa["question"]
                        start_pos = None
                        end_pos = None
                        orig_answer_text = None

                        if is_training:
                            if len(qa["answers"]) != 1:
                                raise ValueError(
                                    "For training, each question should have exactly 1 answer."
                                )

                            answer = qa["answers"][0]
                            orig_answer_text = answer["text"]
                            answer_offset = answer["answer_start"]
                            answer_length = len(orig_answer_text)
                            doc_tokens = [
                                paragraph_text[:answer_offset],
                                paragraph_text[answer_offset:answer_offset +
                                               answer_length],
                                paragraph_text[answer_offset + answer_length:]
                            ]

                            start_pos = 1
                            end_pos = 1

                            actual_text = " ".join(doc_tokens[start_pos:(end_pos
                                                                         + 1)])
                            if actual_text.find(orig_answer_text) == -1:
                                log.info("Could not find answer: '%s' vs. '%s'",
                                      actual_text, orig_answer_text)
                                continue
                        else:
                            doc_tokens = tokenization.tokenize_chinese_chars(
                                paragraph_text)

                        example = self.Example(
                            qas_id=qas_id,
                            question_text=question_text,
                            doc_tokens=doc_tokens,
                            orig_answer_text=orig_answer_text,
                            start_position=start_pos,
                            end_position=end_pos)
                        examples.append(example)

        return examples

    def _improve_answer_span(self, doc_tokens, input_start, input_end,
                             tokenizer, orig_answer_text):
        tok_answer_text = " ".join(tokenizer.tokenize(orig_answer_text))

        for new_start in range(input_start, input_end + 1):
            for new_end in range(input_end, new_start - 1, -1):
                text_span = " ".join(doc_tokens[new_start:(new_end + 1)])
                if text_span == tok_answer_text:
                    return (new_start, new_end)

        return (input_start, input_end)

    def _check_is_max_context(self, doc_spans, cur_span_index, position):
        best_score = None
        best_span_index = None
        for (span_index, doc_span) in enumerate(doc_spans):
            end = doc_span.start + doc_span.length - 1
            if position < doc_span.start:
                continue
            if position > end:
                continue
            num_left_context = position - doc_span.start
            num_right_context = end - position
            score = min(num_left_context,
                        num_right_context) + 0.01 * doc_span.length
            if best_score is None or score > best_score:
                best_score = score
                best_span_index = span_index

        return cur_span_index == best_span_index

    def _convert_example_to_feature(self, examples, max_seq_length, tokenizer,
                                    is_training):
        features = []
        unique_id = 1000000000

        for (example_index, example) in enumerate(examples):
            query_tokens = tokenizer.tokenize(example.question_text)
            if len(query_tokens) > self.max_query_length:
                query_tokens = query_tokens[0:self.max_query_length]
            tok_to_orig_index = []
            orig_to_tok_index = []
            all_doc_tokens = []
            for (i, token) in enumerate(example.doc_tokens):
                orig_to_tok_index.append(len(all_doc_tokens))
                sub_tokens = tokenizer.tokenize(token)
                for sub_token in sub_tokens:
                    tok_to_orig_index.append(i)
                    all_doc_tokens.append(sub_token)

            tok_start_position = None
            tok_end_position = None
            if is_training:
                tok_start_position = orig_to_tok_index[example.start_position]
                if example.end_position < len(example.doc_tokens) - 1:
                    tok_end_position = orig_to_tok_index[example.end_position +
                                                         1] - 1
                else:
                    tok_end_position = len(all_doc_tokens) - 1
                (tok_start_position,
                 tok_end_position) = self._improve_answer_span(
                     all_doc_tokens, tok_start_position, tok_end_position,
                     tokenizer, example.orig_answer_text)

            max_tokens_for_doc = max_seq_length - len(query_tokens) - 3
            doc_spans = []
            start_offset = 0
            while start_offset < len(all_doc_tokens):
                length = len(all_doc_tokens) - start_offset
                if length > max_tokens_for_doc:
                    length = max_tokens_for_doc
                doc_spans.append(self.DocSpan(start=start_offset, length=length))
                if start_offset + length == len(all_doc_tokens):
                    break
                start_offset += min(length, self.doc_stride)

            for (doc_span_index, doc_span) in enumerate(doc_spans):
                tokens = []
                token_to_orig_map = {}
                token_is_max_context = {}
                text_type_ids = []
                tokens.append("[CLS]")
                text_type_ids.append(0)
                for token in query_tokens:
                    tokens.append(token)
                    text_type_ids.append(0)
                tokens.append("[SEP]")
                text_type_ids.append(0)

                for i in range(doc_span.length):
                    split_token_index = doc_span.start + i
                    token_to_orig_map[len(tokens)] = tok_to_orig_index[
                        split_token_index]

                    is_max_context = self._check_is_max_context(
                        doc_spans, doc_span_index, split_token_index)
                    token_is_max_context[len(tokens)] = is_max_context
                    tokens.append(all_doc_tokens[split_token_index])
                    text_type_ids.append(1)
                tokens.append("[SEP]")
                text_type_ids.append(1)

                token_ids = tokenizer.convert_tokens_to_ids(tokens)
                position_ids = list(range(len(token_ids)))
                start_position = None
                end_position = None
                if is_training:
                    doc_start = doc_span.start
                    doc_end = doc_span.start + doc_span.length - 1
                    out_of_span = False
                    if not (tok_start_position >= doc_start and
                            tok_end_position <= doc_end):
                        out_of_span = True
                    if out_of_span:
                        start_position = 0
                        end_position = 0
                    else:
                        doc_offset = len(query_tokens) + 2
                        start_position = tok_start_position - doc_start + doc_offset
                        end_position = tok_end_position - doc_start + doc_offset

                feature = self.Feature(
                    unique_id=unique_id,
                    example_index=example_index,
                    doc_span_index=doc_span_index,
                    tokens=tokens,
                    token_to_orig_map=token_to_orig_map,
                    token_is_max_context=token_is_max_context,
                    token_ids=token_ids,
                    position_ids=position_ids,
                    text_type_ids=text_type_ids,
                    start_position=start_position,
                    end_position=end_position)
                features.append(feature)

                unique_id += 1

        return features

    def _prepare_batch_data(self, records, batch_size, phase=None):
        """generate batch records"""
        batch_records, max_len = [], 0

        for index, record in enumerate(records):
            if phase == "train":
                self.current_example = index
            max_len = max(max_len, len(record.token_ids))
            if self.in_tokens:
                to_append = (len(batch_records) + 1) * max_len <= batch_size
            else:
                to_append = len(batch_records) < batch_size
            if to_append:
                batch_records.append(record)
            else:
                yield self._pad_batch_records(batch_records, phase == "train")
                batch_records, max_len = [record], len(record.token_ids)

        if batch_records:
            yield self._pad_batch_records(batch_records, phase == "train")

    def _pad_batch_records(self, batch_records, is_training):
        batch_token_ids = [record.token_ids for record in batch_records]
        batch_text_type_ids = [record.text_type_ids for record in batch_records]
        batch_position_ids = [record.position_ids for record in batch_records]
        if is_training:
            batch_start_position = [
                record.start_position for record in batch_records
            ]
            batch_end_position = [
                record.end_position for record in batch_records
            ]
            batch_start_position = np.array(batch_start_position).astype(
                "int64").reshape([-1, 1])
            batch_end_position = np.array(batch_end_position).astype(
                "int64").reshape([-1, 1])

        else:
            batch_size = len(batch_token_ids)
            batch_start_position = np.zeros(
                shape=[batch_size, 1], dtype="int64")
            batch_end_position = np.zeros(shape=[batch_size, 1], dtype="int64")

        batch_unique_ids = [record.unique_id for record in batch_records]
        batch_unique_ids = np.array(batch_unique_ids).astype("int64").reshape(
            [-1, 1])

        # padding
        padded_token_ids, input_mask = pad_batch_data(
            batch_token_ids, pad_idx=self.pad_id, return_input_mask=True)
        padded_text_type_ids = pad_batch_data(
            batch_text_type_ids, pad_idx=self.pad_id)
        padded_position_ids = pad_batch_data(
            batch_position_ids, pad_idx=self.pad_id)
        padded_task_ids = np.ones_like(
            padded_token_ids, dtype="int64") * self.task_id

        return_list = [
            padded_token_ids, padded_text_type_ids, padded_position_ids,
            padded_task_ids, input_mask, batch_start_position,
            batch_end_position, batch_unique_ids
        ]

        return return_list

    def get_num_examples(self, phase):
        return len(self.features[phase])

    def get_features(self, phase):
        return self.features[phase]

    def get_examples(self, phase):
        return self.examples[phase]

    def data_generator(self,
                       input_file,
                       batch_size,
                       epoch,
                       dev_count=1,
                       shuffle=True,
                       phase=None):

        examples = self.examples.get(phase, None)
        features = self.features.get(phase, None)
        if not examples:
            examples = self._read_json(input_file, phase == "train")
            features = self._convert_example_to_feature(
                examples, self.max_seq_len, self.tokenizer, phase == "train")
            self.examples[phase] = examples
            self.features[phase] = features

        def wrapper():
            all_dev_batches = []
            for epoch_index in range(epoch):
                if phase == "train":
                    self.current_example = 0
                    self.current_epoch = epoch_index
                if phase == "train" and shuffle:
                    np.random.shuffle(features)

                for batch_data in self._prepare_batch_data(
                        features, batch_size, phase=phase):
                    if len(all_dev_batches) < dev_count:
                        all_dev_batches.append(batch_data)
                    if len(all_dev_batches) == dev_count:
                        for batch in all_dev_batches:
                            yield batch
                        all_dev_batches = []

        return wrapper


if __name__ == '__main__':
    pass