import random 
import os
import re

import datasets

from datasets.tasks import TextClassification

_DESCRIPTION = """\
Common Crawl - Malayalam.
"""

_CITATION = """\
@article{qburst,
    title={Common Crawl - Malayalam},
    author={n.d},
    year={2020},
    journal={n.d},
}
"""

_URLs = {
    "malayalam_wiki_1": "https://calicut.qburst.in/commoncrawl/malayalam/2020-10/malayalam_filtered_html_body.tar.gz",
    "malayalam_wiki_2": "https://calicut.qburst.in/commoncrawl/malayalam/2020-10/unfiltered_heading_and_para.tar.gz"
}


class MalayalamWikiConfig(datasets.BuilderConfig):
    """BuilderConfig for MalayalamWiki."""

    def __init__(self, **kwargs):
        """BuilderConfig for MalayalamWiki.

        Args:
            **kwargs: keyword arguments forwarded to super.
        """
        super(MalayalamWikiConfig, self).__init__(**kwargs)

class MalayalamWiki(datasets.GeneratorBasedBuilder):
    """Malayalam News topic classification dataset."""

    VERSION = datasets.Version("1.0.0")

    BUILDER_CONFIGS = [
        MalayalamWikiConfig(
            name="malayalam_wiki", version=VERSION, description="Common Crawl - Malayalam."
        ),
    ]


    def partition (self, list_in, n):
        random.shuffle(list_in)
        return [list_in[i::n] for i in range(n)]

    def remove_special_characters(self, txt):
        chars_to_ignore_regex = '[\,\?\.\!\-\;\:\"\“\%\‘\”\�Utrnle\_]'
        unicode_ignore_regex = r'[\u200e\u200c\u200d]'
        english_ignore_regex = r'[a-zA-Z]'
        
        txt = txt.strip()
        txt = re.sub(chars_to_ignore_regex, '',txt)
        txt = re.sub(unicode_ignore_regex, '',txt) + " "
        txt = re.sub(english_ignore_regex, '',txt) + " "
        return txt

    def _info(self):
        return datasets.DatasetInfo(
            description=_DESCRIPTION,
            features=datasets.Features(
                {
                    "text": datasets.Value("string")
                }
            ),
            supervised_keys=None,
            homepage="https://github.com/qburst/common-crawl-malayalam",
            citation=_CITATION
        )

    def _split_generators(self, dl_manager):
        """Returns SplitGenerators."""
        # TODO:  implement iter_archive() instead of download_and_extract
        dl_path = dl_manager.download_and_extract(_URLs)
        files = sorted(os.listdir(os.path.join(dl_path["malayalam_wiki_1"],"malayalam_filtered_html_body")))
        file_paths = [os.path.join(dl_path["malayalam_wiki_1"], "malayalam_filtered_html_body" , file) for file in files]
        files = sorted(os.listdir(os.path.join(dl_path["malayalam_wiki_2"],"unfiltered_heading_and_para")))
        wiki_2 = [os.path.join(dl_path["malayalam_wiki_2"],"unfiltered_heading_and_para",  file) for file in files]
        file_paths.extend(wiki_2)
        filepaths_splice = self.partition(file_paths,3)
        return [
            datasets.SplitGenerator(
                name=datasets.Split.TRAIN,
                gen_kwargs={
                    "filepath": filepaths_splice[0],
                    "split": "train",
                },
            ),
            datasets.SplitGenerator(
                name=datasets.Split.VALIDATION,
                gen_kwargs={
                    "filepath": filepaths_splice[1],
                    "split": "validation",
                },
            ),
            datasets.SplitGenerator(
                name=datasets.Split.TEST,
                gen_kwargs={
                    "filepath": filepaths_splice[2],
                    "split": "test",
                },
            )
        ]

    def _generate_examples(self, filepath):
        for file_id, file in enumerate(filepath):
            with open(file, encoding="utf-8") as f:
                for row_id, row in enumerate(f):
                    yield  f"{file_id}_{row_id}", {"text": self.remove_special_characters(row).strip()}