# coding=utf-8
# Copyright 2018 The Google AI Language Team Authors and The HuggingFace Inc. team.
# Copyright (c) 2018, NVIDIA CORPORATION.  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.
""" BERT multiple choice fine-tuning: utilities to work with multiple choice tasks of reading comprehension  """

from __future__ import absolute_import, division, print_function


import logging
import os
import sys
from io import open
import json
import csv
import glob
import tqdm


logger = logging.getLogger(__name__)


class InputExample(object):
    """A single training/test example for multiple choice"""

    def __init__(self, example_id, question,  contexts, endings, label=None):
        """Constructs a InputExample.

        Args:
            example_id: Unique id for the example.
            contexts: list of str. The untokenized text of the first sequence (context of corresponding question).
            question: string. The untokenized text of the second sequence (qustion).
            endings: list of str. multiple choice's options. Its length must be equal to contexts' length.
            label: (Optional) string. The label of the example. This should be
            specified for train and dev examples, but not for test examples.
        """
        self.example_id = example_id
        self.question = question
        self.contexts = contexts
        self.endings = endings
        self.label = label


class InputFeatures(object):
    def __init__(self,
                 example_id,
                 choices_features,
                 label

    ):
        self.example_id = example_id
        self.choices_features = [
            {
                'input_ids': input_ids,
                'input_mask': input_mask,
                'segment_ids': segment_ids
            }
            for _, input_ids, input_mask, segment_ids in choices_features
        ]
        self.label = label


class DataProcessor(object):
    """Base class for data converters for multiple choice 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 the test set."""
        raise NotImplementedError()

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


class RaceProcessor(DataProcessor):
    """Processor for the RACE data set."""

    def get_train_examples(self, data_dir):
        """See base class."""
        logger.info("LOOKING AT {} train".format(data_dir))
        high = os.path.join(data_dir, 'train/high')
        middle = os.path.join(data_dir, 'train/middle')
        high = self._read_txt(high)
        middle = self._read_txt(middle)
        return self._create_examples(high + middle, 'train')

    def get_dev_examples(self, data_dir):
        """See base class."""
        logger.info("LOOKING AT {} dev".format(data_dir))
        high = os.path.join(data_dir, 'dev/high')
        middle = os.path.join(data_dir, 'dev/middle')
        high = self._read_txt(high)
        middle = self._read_txt(middle)
        return self._create_examples(high + middle, 'dev')

    def get_test_examples(self, data_dir):
        """See base class."""
        logger.info("LOOKING AT {} test".format(data_dir))
        high = os.path.join(data_dir, 'test/high')
        middle = os.path.join(data_dir, 'test/middle')
        high = self._read_txt(high)
        middle = self._read_txt(middle)
        return self._create_examples(high + middle, 'test')

    def get_labels(self):
        """See base class."""
        return ["0", "1", "2", "3"]

    def _read_txt(self, input_dir):
        lines = []
        files = glob.glob(input_dir + "/*txt")
        for file in tqdm.tqdm(files, desc="read files"):
            with open(file, 'r', encoding='utf-8') as fin:
                data_raw = json.load(fin)
                data_raw["race_id"] = file
                lines.append(data_raw)
        return lines


    def _create_examples(self, lines, set_type):
        """Creates examples for the training and dev sets."""
        examples = []
        for (_, data_raw) in enumerate(lines):
            race_id = "%s-%s" % (set_type, data_raw["race_id"])
            article = data_raw["article"]
            for i in range(len(data_raw["answers"])):
                truth = str(ord(data_raw['answers'][i]) - ord('A'))
                question = data_raw['questions'][i]
                options = data_raw['options'][i]

                examples.append(
                    InputExample(
                        example_id=race_id,
                        question=question,
                        contexts=[article, article, article, article], # this is not efficient but convenient
                        endings=[options[0], options[1], options[2], options[3]],
                        label=truth))
        return examples

class SwagProcessor(DataProcessor):
    """Processor for the SWAG data set."""

    def get_train_examples(self, data_dir):
        """See base class."""
        logger.info("LOOKING AT {} train".format(data_dir))
        return self._create_examples(self._read_csv(os.path.join(data_dir, "train.csv")), "train")

    def get_dev_examples(self, data_dir):
        """See base class."""
        logger.info("LOOKING AT {} dev".format(data_dir))
        return self._create_examples(self._read_csv(os.path.join(data_dir, "val.csv")), "dev")

    def get_test_examples(self, data_dir):
        """See base class."""
        logger.info("LOOKING AT {} dev".format(data_dir))
        raise ValueError(
            "For swag testing, the input file does not contain a label column. It can not be tested in current code"
            "setting!"
        )
        return self._create_examples(self._read_csv(os.path.join(data_dir, "test.csv")), "test")
    def get_labels(self):
        """See base class."""
        return ["0", "1", "2", "3"]

    def _read_csv(self, input_file):
        with open(input_file, 'r', encoding='utf-8') as f:
            reader = csv.reader(f)
            lines = []
            for line in reader:
                if sys.version_info[0] == 2:
                    line = list(unicode(cell, 'utf-8') for cell in line)
                lines.append(line)
            return lines


    def _create_examples(self, lines, type):
        """Creates examples for the training and dev sets."""
        if type == "train" and lines[0][-1] != 'label':
            raise ValueError(
                "For training, the input file must contain a label column."
            )

        examples = [
            InputExample(
                example_id=line[2],
                question=line[5],  # in the swag dataset, the
                # common beginning of each
                # choice is stored in "sent2".
                contexts = [line[4], line[4], line[4], line[4]],
                endings = [line[7], line[8], line[9], line[10]],
                label=line[11]
            ) for line in lines[1:]  # we skip the line with the column names
        ]

        return examples


class ArcProcessor(DataProcessor):
    """Processor for the ARC data set (request from allennlp)."""

    def get_train_examples(self, data_dir):
        """See base class."""
        logger.info("LOOKING AT {} train".format(data_dir))
        return self._create_examples(self._read_json(os.path.join(data_dir, "train.jsonl")), "train")

    def get_dev_examples(self, data_dir):
        """See base class."""
        logger.info("LOOKING AT {} dev".format(data_dir))
        return self._create_examples(self._read_json(os.path.join(data_dir, "dev.jsonl")), "dev")

    def get_test_examples(self, data_dir):
        logger.info("LOOKING AT {} test".format(data_dir))
        return self._create_examples(self._read_json(os.path.join(data_dir, "test.jsonl")), "test")

    def get_labels(self):
        """See base class."""
        return ["0", "1", "2", "3"]

    def _read_json(self, input_file):
        with open(input_file, 'r', encoding='utf-8') as fin:
            lines = fin.readlines()
            return lines


    def _create_examples(self, lines, type):
        """Creates examples for the training and dev sets."""

        #There are two types of labels. They should be normalized
        def normalize(truth):
            if truth in "ABCD":
                return ord(truth) - ord("A")
            elif truth in "1234":
                return int(truth) - 1
            else:
                logger.info("truth ERROR! %s", str(truth))
                return None

        examples = []
        three_choice = 0
        four_choice = 0
        five_choice = 0
        other_choices = 0
        # we deleted example which has more than or less than four choices
        for line in tqdm.tqdm(lines, desc="read arc data"):
            data_raw = json.loads(line.strip("\n"))
            if len(data_raw["question"]["choices"]) == 3:
                three_choice += 1
                continue
            elif len(data_raw["question"]["choices"]) == 5:
                five_choice += 1
                continue
            elif len(data_raw["question"]["choices"]) != 4:
                other_choices += 1
                continue
            four_choice += 1
            truth = str(normalize(data_raw["answerKey"]))
            assert truth != "None"
            question_choices = data_raw["question"]
            question = question_choices["stem"]
            id = data_raw["id"]
            options = question_choices["choices"]
            if len(options) == 4:
                examples.append(
                    InputExample(
                        example_id = id,
                        question=question,
                        contexts=[options[0]["para"].replace("_", ""), options[1]["para"].replace("_", ""),
                                  options[2]["para"].replace("_", ""), options[3]["para"].replace("_", "")],
                        endings=[options[0]["text"], options[1]["text"], options[2]["text"], options[3]["text"]],
                        label=truth))

        if type == "train":
            assert len(examples) > 1
            assert examples[0].label is not None
        logger.info("len examples: %s}", str(len(examples)))
        logger.info("Three choices: %s", str(three_choice))
        logger.info("Five choices: %s", str(five_choice))
        logger.info("Other choices: %s", str(other_choices))
        logger.info("four choices: %s", str(four_choice))

        return examples


def convert_examples_to_features(examples, label_list, max_seq_length,
                                 tokenizer,
                                 cls_token_at_end=False,
                                 cls_token='[CLS]',
                                 cls_token_segment_id=1,
                                 sep_token='[SEP]',
                                 sequence_a_segment_id=0,
                                 sequence_b_segment_id=1,
                                 sep_token_extra=False,
                                 pad_token_segment_id=0,
                                 pad_on_left=False,
                                 pad_token=0,
                                 mask_padding_with_zero=True):
    """ Loads a data file into a list of `InputBatch`s
        `cls_token_at_end` define the location of the CLS token:
            - False (Default, BERT/XLM pattern): [CLS] + A + [SEP] + B + [SEP]
            - True (XLNet/GPT pattern): A + [SEP] + B + [SEP] + [CLS]
        `cls_token_segment_id` define the segment id associated to the CLS token (0 for BERT, 2 for XLNet)
    """

    label_map = {label : i for i, label in enumerate(label_list)}

    features = []
    for (ex_index, example) in tqdm.tqdm(enumerate(examples), desc="convert examples to features"):
        if ex_index % 10000 == 0:
            logger.info("Writing example %d of %d" % (ex_index, len(examples)))
        choices_features = []
        for ending_idx, (context, ending) in enumerate(zip(example.contexts, example.endings)):
            tokens_a = tokenizer.tokenize(context)
            tokens_b = None
            if example.question.find("_") != -1:
                #this is for cloze question
                tokens_b = tokenizer.tokenize(example.question.replace("_", ending))
            else:
                tokens_b = tokenizer.tokenize(example.question + " " + ending)
                # you can add seq token between quesiotn and ending. This does not make too much difference.
                # tokens_b = tokenizer.tokenize(example.question)
                # tokens_b += [sep_token]
                # if sep_token_extra:
                #     tokens_b += [sep_token]
                # tokens_b += tokenizer.tokenize(ending)

            special_tokens_count = 4 if sep_token_extra else 3
            _truncate_seq_pair(tokens_a, tokens_b, max_seq_length - special_tokens_count)

            # The convention in BERT 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 = tokens_a + [sep_token]
            if sep_token_extra:
                # roberta uses an extra separator b/w pairs of sentences
                tokens += [sep_token]

            segment_ids = [sequence_a_segment_id] * len(tokens)

            if tokens_b:
                tokens += tokens_b + [sep_token]
                segment_ids += [sequence_b_segment_id] * (len(tokens_b) + 1)

            if cls_token_at_end:
                tokens = tokens + [cls_token]
                segment_ids = segment_ids + [cls_token_segment_id]
            else:
                tokens = [cls_token] + tokens
                segment_ids = [cls_token_segment_id] + segment_ids

            input_ids = tokenizer.convert_tokens_to_ids(tokens)

            # The mask has 1 for real tokens and 0 for padding tokens. Only real
            # tokens are attended to.
            input_mask = [1 if mask_padding_with_zero else 0] * len(input_ids)

            # Zero-pad up to the sequence length.
            padding_length = max_seq_length - len(input_ids)
            if pad_on_left:
                input_ids = ([pad_token] * padding_length) + input_ids
                input_mask = ([0 if mask_padding_with_zero else 1] * padding_length) + input_mask
                segment_ids = ([pad_token_segment_id] * padding_length) + segment_ids
            else:
                input_ids = input_ids + ([pad_token] * padding_length)
                input_mask = input_mask + ([0 if mask_padding_with_zero else 1] * padding_length)
                segment_ids = segment_ids + ([pad_token_segment_id] * padding_length)

            assert len(input_ids) == max_seq_length
            assert len(input_mask) == max_seq_length
            assert len(segment_ids) == max_seq_length
            choices_features.append((tokens, input_ids, input_mask, segment_ids))
        label = label_map[example.label]

        if ex_index < 2:
            logger.info("*** Example ***")
            logger.info("race_id: {}".format(example.example_id))
            for choice_idx, (tokens, input_ids, input_mask, segment_ids) in enumerate(choices_features):
                logger.info("choice: {}".format(choice_idx))
                logger.info("tokens: {}".format(' '.join(tokens)))
                logger.info("input_ids: {}".format(' '.join(map(str, input_ids))))
                logger.info("input_mask: {}".format(' '.join(map(str, input_mask))))
                logger.info("segment_ids: {}".format(' '.join(map(str, segment_ids))))
                logger.info("label: {}".format(label))

        features.append(
            InputFeatures(
                example_id = example.example_id,
                choices_features = choices_features,
                label = label
            )
        )

    return features


def _truncate_seq_pair(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.

    # However, since we'd better not to remove tokens of options and questions, you can choose to use a bigger
    # length or only pop from context
    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:
            logger.info('Attention! you are removing from token_b (swag task is ok). '
                        'If you are training ARC and RACE (you are poping question + options), '
                        'you need to try to use a bigger max seq length!')
            tokens_b.pop()


processors = {
    "race": RaceProcessor,
    "swag": SwagProcessor,
    "arc": ArcProcessor
}


GLUE_TASKS_NUM_LABELS = {
    "race", 4,
    "swag", 4,
    "arc", 4
}