import gzip
import logging
import re
import requests
import urllib.request
from typing import Optional
from warcio.archiveiterator import ArchiveIterator
from selectolax.parser import HTMLParser

import datasets
from datasets import (
    BuilderConfig, Version, DownloadManager, SplitGenerator, Split, Features, Value
)


COMMON = "https://data.commoncrawl.org/"

LANGUAGES = ['af', 'ar', 'bg', 'bn', 'ca', 'cs', 'cy', 'da', 'de', 'el', 'en', 'es', 'et', 'fa', 'fi', 'fr', 'gu',
             'he,\nhi', 'hr', 'hu', 'id', 'it', 'ja', 'kn', 'ko', 'lt', 'lv', 'mk', 'ml', 'mr', 'ne', 'nl', 'no', 'pa',
             'pl,\npt', 'ro', 'ru', 'sk', 'sl', 'so', 'sq', 'sv', 'sw', 'ta', 'te', 'th', 'tl', 'tr', 'uk', 'ur', 'vi',
             'zh-cn', 'zh-tw']


URL = "https://data.commoncrawl.org/crawl-data/CC-MAIN-2022-49/warc.paths.gz"


logger = logging.getLogger(__name__)
VERSION = Version("1.0.0")


def get_common_crawl_url(url: str):
    with urllib.request.urlopen(url) as req:
        with gzip.GzipFile(fileobj=req) as uncomp:
            return [COMMON+data for data in uncomp.read().decode().splitlines()]


def _decode_text(_bytes):
    try:
        return _bytes.decode('utf-8')
    except:
        return None


def _preprocessing(text):
    tree = HTMLParser(text)

    if tree.body is None:
        return None

    for tag in tree.css('script'):
        tag.decompose()
    for tag in tree.css('style'):
        tag.decompose()

    text = tree.body.text(separator='\n')
    text = re.sub("\n{2,}", "\n\n", text)
    text = re.sub("\t{2,}", "\t\t", text)
    return text


class CommonCrawlConfig(BuilderConfig):
    def __init__(self, features, data_url, citation, url, version, label_classes: Optional[tuple] = None, **kwargs):
        super(CommonCrawlConfig, self).__init__(version=version, **kwargs)
        self.features = features
        self.label_classes = label_classes
        self.data_url = data_url
        self.citation = citation
        self.url = url


class CommonCrawl(datasets.GeneratorBasedBuilder):
    BUILDER_CONFIG_CLASS = CommonCrawlConfig
    BUILDER_CONFIGS = [
        CommonCrawlConfig(name=f"{i+1}", description="", features="text", data_url=url, citation="", url="", version=VERSION)
        for i, url in enumerate(get_common_crawl_url(URL))
    ]

    def _info(self):
        return datasets.DatasetInfo(
            description="",
            features=Features(
                {
                    "id": Value("int32"),
                    "text": Value("string"),
                }
            ),
            supervised_keys=None,
            homepage="https://github.com/hkjeon13",
            citation="",
        )

    def _split_generators(self, dl_manager: DownloadManager):
        downloaded_files = dl_manager.download_and_extract({"train": self.config.data_url})
        return [SplitGenerator(Split.TRAIN, gen_kwargs={"filepath": downloaded_files["train"]})]

    def _generate_examples(self, filepath):
        logger.info("generating examples from = %s", filepath)
        filepath = filepath.split("::")[-1]
        _open = requests.get(filepath, stream=True).raw if filepath.startswith("http") else open(filepath, "rb")
        number = 0
        for record in ArchiveIterator(_open, arc2warc=True):
            if record.rec_type == 'response' and record.http_headers.get_header('Content-Type') == 'text/html':
                text = _preprocessing(record.content_stream().read())
                if text is not None:
                    yield number, {"id": number, "text": text}
                    number += 1