"""Europarl Monolingual Dataset."""

from __future__ import absolute_import, division, print_function
from dataclasses import dataclass

import json
import os
import re

import datasets


_CITATION = """\
@inproceedings{koehn2005europarl,
  title={Europarl: A parallel corpus for statistical machine translation},
  author={Koehn, Philipp},
  booktitle={MT summit},
  volume={5},
  pages={79--86},
  year={2005},
  organization={Citeseer}
}
"""

_DESCRIPTION = """\
Europarl Monolingual Dataset.

The Europarl parallel corpus is extracted from the proceedings of the
European Parliament (from 2000 to 2011). It includes versions in 21 European
languages: Romanic (French, Italian, Spanish, Portuguese, Romanian),
Germanic (English, Dutch, German, Danish, Swedish), Slavik (Bulgarian,
Czech, Polish, Slovak, Slovene), Finni-Ugric (Finnish, Hungarian, Estonian),
Baltic (Latvian, Lithuanian), and Greek.

Upstream url: https://www.statmt.org/europarl/
"""

_HOMEPAGE = "https://www.statmt.org/europarl/"

_AVAILABLE_LANGUAGES = [
    ("bg", "Bulgarian"), ("cs", "Czech"), ("da", "Danish"), ("de", "German"),
    ("el", "Greek"), ("en", "English"), ("es", "Spanish"), ("et", "Estonian"),
    ("fi", "Finnish"), ("fr", "French"), ("hu", "Hungarian"), ("it", "Italian"),
    ("lt", "Lithuanian"), ("lv", "Latvian"), ("nl", "Dutch"), ("pl", "Polish"),
    ("pt", "Portuguese"), ("ro", "Romanian"), ("sk", "Slovak"),
    ("sl", "Slovene"), ("sv", "Swedish")
]

@dataclass
class EuroparlMonoConfig(datasets.BuilderConfig):
    """BuilderConfig for Europarl Monolingual."""
    language: str = None


class EuroparlMonoDataset(datasets.GeneratorBasedBuilder):
    """Europarl Monolingual Dataset."""

    _TRAIN_FILE = "train.jsonl"
    _VAL_FILE = "val.jsonl"
    _TEST_FILE = "test.jsonl"

    BUILDER_CONFIGS = [
        EuroparlMonoConfig(
            name="europarl-%s" % langISO2,
            language=langISO2,
            version=datasets.Version("7.0.0"),
            description="Europarl %s Dataset." % langEnglish,
        ) for langISO2, langEnglish in _AVAILABLE_LANGUAGES
    ]

    def _info(self):
        return datasets.DatasetInfo(
            description=_DESCRIPTION,
            features=datasets.Features(
                {
                    "paragraph": datasets.Value("string"),
                    "date": datasets.Value("string"),
                    "chapter": datasets.Value("string"),
                    "speaker": datasets.Value("int16"),
                    "speaker_name": datasets.Value("string")
                }
            ),
            supervised_keys=None,
            homepage=_HOMEPAGE,
            citation=_CITATION,
        )

    def _split_generators(self, dl_manager):
        arch_path = dl_manager.download_and_extract(os.path.join(_HOMEPAGE, "v%d" % self.config.version.major, "europarl.tgz"))
        path_dir = os.path.join(arch_path, os.path.join("txt", self.config.language))
        paths = [os.path.join(path_dir, file) for file in os.listdir(path_dir)]
        return [
            datasets.SplitGenerator(
                name=datasets.Split.TRAIN, gen_kwargs={"filepath": paths}
            )
        ]

    def _generate_examples(self, filepath):
        """Generate Europarl Monolingual examples."""

        id_ = 0
        for file in filepath:
            with open(file, "r") as f:
                current_date = "-".join(os.path.basename(file).strip(".txt").split("-")[-4:-1])
                current_paragraph = ""
                current_paragraph_id = 0
                current_chapter = 0
                current_speaker_id = 0
                current_speaker_name = ""
                for line in f:
                    if not line.startswith("<"):
                        current_paragraph += line.strip("\n")
                    else:
                        if len(current_paragraph) != 0:
                            yield id_, {
                                "paragraph": current_paragraph,
                                "date": current_date,
                                "chapter": current_chapter,
                                "speaker": current_speaker_id,
                                "speaker_name": current_speaker_name,
                            }
                            current_paragraph = ""
                            id_ += 1
                        if line.startswith("<P>"):
                            current_paragraph_id += 1
                        if line.startswith("<CHAPTER"):
                            current_chapter = line.lstrip("<CHAPTER ID=").rstrip(">\n").strip("\"")
                        if line.startswith("<SPEAKER"):
                            current_speaker_id = "0"
                            current_speaker_name = ""
                            grps = re.findall("([^<\s]+)=([^\s\">]+|\"[^\">]+\")", line)
                            for attr, value in grps:
                                value = value.strip("\"")
                                if attr == "ID":
                                    current_speaker_id = int(value)
                                elif attr == "NAME":
                                    current_speaker_name = value