"""EU Wikipedias"""

import json

import datasets
from huggingface_hub.file_download import hf_hub_url

try:
    import lzma as xz
except ImportError:
    import pylzma as xz

datasets.logging.set_verbosity_info()
logger = datasets.logging.get_logger(__name__)

_CITATION = """\
@ONLINE {wikidump,
    author = {Wikimedia Foundation},
    title  = {Wikimedia Downloads},
    url    = {https://dumps.wikimedia.org}
}
"""

_DESCRIPTION = """\
Wikipedia dataset containing cleaned articles of all languages.
The datasets are built from the Wikipedia dump
(https://dumps.wikimedia.org/) with one split per language. Each example
contains the content of one full Wikipedia article with cleaning to strip
markdown and unwanted sections (references, etc.).
"""

_LICENSE = (
    "This work is licensed under the Creative Commons Attribution-ShareAlike "
    "3.0 Unported License. To view a copy of this license, visit "
    "http://creativecommons.org/licenses/by-sa/3.0/ or send a letter to "
    "Creative Commons, PO Box 1866, Mountain View, CA 94042, USA."
)

_URL = "https://huggingface.co/datasets/joelito/EU_Wikipedias"

_LANGUAGES = ["bg", "cs", "da", "de", "el", "en", "es", "et", "fi", "fr", "ga", "hr",
              "hu", "it", "lt", "lv", "mt", "nl", "pl", "pt", "ro", "sk", "sl", "sv"]

_DATES = ["20221120"]  # one can add more in the future with the file prepare_wikipedias.py

# IMPORTANT: Increase this once larger datasets are available (English has 11 in 20221120)
_HIGHEST_NUMBER_OF_SHARDS = 11

class EUWikipediasConfig(datasets.BuilderConfig):
    """BuilderConfig for EUWikipedias."""

    def __init__(self, date=None, language=None, **kwargs):
        """BuilderConfig for EUWikipedias.
        Args:
          language: string, the language code for the Wikipedia dump to use:
            One of bg,cs,da,de,el,en,es,et,fi,fr,ga,hr,hu,it,lt,lv,mt,nl,pl,pt,ro,sk,sl,sv or all
          date: string, date of the Wikipedia dump in YYYYMMDD format. A list of
            available dates can be found at https://dumps.wikimedia.org/enwiki/.
          **kwargs: keyword arguments forwarded to super.
        """
        if date not in _DATES:
            raise ValueError(f"date must be one of {_DATES} but was `{date}`")
        if language not in _LANGUAGES + ["all"]:
            raise ValueError(f"language must be one of {_LANGUAGES} but was `{language}`")

        super().__init__(
            name=f"{date}.{language}",
            description=f"Wikipedia dataset for {language}, parsed from {date} dump.",
            **kwargs,
        )
        self.date = date
        self.language = language


class EUWikipedias(datasets.GeneratorBasedBuilder):
    """EUWikipedias: A dataset of Wikipedias in the EU languages"""
    BUILDER_CONFIG_CLASS = EUWikipediasConfig

    BUILDER_CONFIGS = [EUWikipediasConfig(date=date, language=language)
                       for language in _LANGUAGES + ["all"]
                       for date in _DATES]

    def _info(self):
        return datasets.DatasetInfo(
            description=_DESCRIPTION,
            features=datasets.Features(
                {
                    "language": datasets.Value("string"),
                    "id": datasets.Value("string"),
                    "url": datasets.Value("string"),
                    "title": datasets.Value("string"),
                    "text": datasets.Value("string"),
                }
            ),
            supervised_keys=None,  # No default supervised_keys.
            homepage=_URL,
            citation=_CITATION,
        )

    def _split_generators(self, dl_manager):
        def download_url(dataset, file_name):
            url = hf_hub_url(repo_id=dataset, filename=f"data/{file_name}.jsonl.xz", repo_type="dataset")
            return dl_manager.download(url)

        data_infos = []
        languages = _LANGUAGES if self.config.language == "all" else [self.config.language]

        for language in languages:
            info = {"language": language}

            for shard in range(_HIGHEST_NUMBER_OF_SHARDS):
                try:
                    info["filepath"] = download_url("joelito/EU_Wikipedias", f"{self.config.date}/{language}_{shard}")
                    data_infos.append(info.copy())
                except:
                    break  # we found the last shard

        return [datasets.SplitGenerator(name=datasets.Split.TRAIN, gen_kwargs={"data_infos": data_infos})]

    def _generate_examples(self, data_infos):
        """This function returns the examples in the raw (text) form by iterating on all the files."""
        id_ = 0
        for data_info in data_infos:
            logger.info("Generating examples from = %s", data_info["filepath"])
            try:
                with xz.open(open(data_info["filepath"], "rb"), "rt", encoding="utf-8") as f:
                    for line in f:
                        if line:
                            example = json.loads(line)
                            if example is not None and isinstance(example, dict):
                                yield id_, {
                                    "language": data_info["language"],  # add the language
                                    **example,
                                }
                                id_ += 1
            except Exception:
                logger.exception("Error while processing file %s", data_info["filepath"])