import logging
import os
import re
import xml.etree.ElementTree as ET
from typing import Optional

import datasets

_CITATION = """\
@misc{solar3.0,
    title = {Developmental corpus {\v S}olar 3.0},
    author = {Arhar Holdt, {\v S}pela and Rozman, Tadeja and Stritar Ku{\v c}uk, Mojca and Krek, Simon and Krap{\v s} Vodopivec, Irena and Stabej, Marko and Pori, Eva and Goli, Teja and Lavri{\v c}, Polona and Laskowski, Cyprian and Kocjan{\v c}i{\v c}, Polonca and Klemenc, Bojan and Krsnik, Luka and Kosem, Iztok},
    url = {http://hdl.handle.net/11356/1589},
    note = {Slovenian language resource repository {CLARIN}.{SI}},
    year = {2022}
}
"""

_DESCRIPTION = """\
Šolar is a developmental corpus of 5485 school texts (e.g., essays), written by students in Slovenian secondary schools 
(age 15-19) and pupils in the 7th-9th grade of primary school (13-15), with a small percentage also from the 6th grade. 
Part of the corpus (2,094 texts) is annotated with teachers' corrections using a system of labels described in the 
document available at https://www.clarin.si/repository/xmlui/bitstream/handle/11356/1589/Smernice-za-oznacevanje-korpusa-Solar_V1.1.pdf (in Slovenian).
"""

_HOMEPAGE = "http://hdl.handle.net/11356/1589"

_LICENSE = "Creative Commons - Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)"

_URLS = {
    "solar_tei": "https://www.clarin.si/repository/xmlui/bitstream/handle/11356/1589/Solar.TEI.zip"
}

XML_NAMESPACE = "{http://www.w3.org/XML/1998/namespace}"


def namespace(element):
    # https://stackoverflow.com/a/12946675
    m = re.match(r'\{.*\}', element.tag)
    return m.group(0) if m else ''


def resolve_element(tag_el, ne_tag: Optional[str] = "O"):
    if not tag_el.tag.endswith(("w", "pc", "seg")):
        logging.info(f"Skipping tag {tag_el.tag}")
        return []

    if tag_el.tag.endswith(("w", "pc")):
        form = tag_el.text.strip()
        lemma = tag_el.text.strip() if tag_el.tag.endswith("pc") else tag_el.attrib["lemma"]
        msd = tag_el.attrib["ana"]
        ret_ne_tag = ne_tag
        id_tag = tag_el.attrib[f"{XML_NAMESPACE}id"]

        return [(id_tag, form, lemma, msd, ret_ne_tag)]
    # Named entities: words and punctuation nested directly below current element
    elif tag_el.tag.endswith("seg"):
        anns = []
        ret_ne_tag = tag_el.attrib["subtype"].upper()
        for curr_child in tag_el:
            anns.extend(resolve_element(curr_child, ne_tag=ret_ne_tag))

        return anns


def read_data(data_path):
    data = {}  # ID_sent -> sentence_metadata
    tree = ET.parse(data_path)
    root = tree.getroot()
    NAMESPACE = namespace(root)

    for curr_text in root.iterfind(f".//{NAMESPACE}div"):
        id_text = curr_text.attrib[f"{XML_NAMESPACE}id"]
        bibl_el = curr_text.find(f"{NAMESPACE}bibl")
        if bibl_el is None:
            text_title = "Unknown_title"
            logging.warning(f"The following text does not have a 'bibl' element: {curr_text.attrib}. "
                            f"Setting title to 'Unknown_title'")
            is_manually_validated = False
        else:
            text_title = bibl_el.attrib["n"]
            note_el = bibl_el.find(f"{NAMESPACE}note")
            is_manually_validated = note_el.text == "DA"

        for idx_par, curr_par in enumerate(curr_text.iterfind(f".//{NAMESPACE}p")):
            for idx_sent, curr_sent in enumerate(curr_par.iterfind(f".//{NAMESPACE}s")):
                id_sent = curr_sent.attrib[f"{XML_NAMESPACE}id"]
                ids, forms, lemmas, msds, nes = [], [], [], [], []
                for curr_el in curr_sent:
                    curr_annotations = resolve_element(curr_el)
                    for curr_ann in curr_annotations:
                        ids.append(curr_ann[0])
                        forms.append(curr_ann[1])
                        lemmas.append(curr_ann[2])
                        msds.append(curr_ann[3])
                        nes.append(curr_ann[4])

                data[id_sent] = {
                    "id_doc": id_text,
                    "doc_title": text_title,
                    "idx_par": idx_par,
                    "idx_sent": idx_sent,
                    "id_token": ids, "form": forms, "lemma": lemmas, "msd": msds, "ne_tag": nes,
                    "is_manually_validated": is_manually_validated
                }

    return data


class Solar3(datasets.GeneratorBasedBuilder):
    """Šolar is a developmental corpus of school texts (e.g., essays), annotated with metadata and (partially)
    with teachers' corrections. """

    VERSION = datasets.Version("1.0.0")

    def _info(self):
        features = datasets.Features(
            {
                "id_doc": datasets.Value("string"),
                "doc_title": datasets.Value("string"),
                "is_manually_validated": datasets.Value("bool"),
                "idx_src_par": datasets.Value("int32"),
                "idx_src_sent": datasets.Value("int32"),
                "id_src_tokens": datasets.Sequence(datasets.Value("string")),
                "src_tokens": datasets.Sequence(datasets.Value("string")),
                "idx_tgt_par": datasets.Value("int32"),
                "idx_tgt_sent": datasets.Value("int32"),
                "id_tgt_tokens": datasets.Sequence(datasets.Value("string")),
                "tgt_tokens": datasets.Sequence(datasets.Value("string")),
                "corrections": [
                    {
                        "idx_src": datasets.Sequence(datasets.Value("int32")),
                        "idx_tgt": datasets.Sequence(datasets.Value("int32")),
                        "corr_types": datasets.Sequence(datasets.Value("string"))
                    }
                ]
            }
        )

        return datasets.DatasetInfo(
            description=_DESCRIPTION,
            features=features,
            homepage=_HOMEPAGE,
            license=_LICENSE,
            citation=_CITATION,
        )

    def _split_generators(self, dl_manager):
        urls = _URLS["solar_tei"]
        data_dir = dl_manager.download_and_extract(urls)

        return [
            datasets.SplitGenerator(
                name=datasets.Split.TRAIN,
                # These kwargs will be passed to _generate_examples
                gen_kwargs={
                    "source_path": os.path.join(data_dir, "Solar.TEI", "solar-orig.xml"),
                    "target_path": os.path.join(data_dir, "Solar.TEI", "solar-corr.xml"),
                    "links_path": os.path.join(data_dir, "Solar.TEI", "solar-errs.xml")
                }
            )
        ]

    def _generate_examples(self, source_path, target_path, links_path):
        source_data = read_data(source_path)
        target_data = read_data(target_path)

        data = ET.parse(links_path)
        root = data.getroot()
        NAMESPACE = namespace(root)

        for idx_corr, corrected_sent in enumerate(root.iterfind(f"{NAMESPACE}linkGrp")):
            involved_sents = corrected_sent.attrib["corresp"].split(" ")
            assert len(involved_sents) <= 2, f"The following correction has more than two sentences involved, " \
                                             f"which the script cannot handle: {corrected_sent.attrib}"
            if len(involved_sents) == 2:
                # not always ordered <source> <target>, sometimes reversed
                if "t" in involved_sents[0]:
                    id_src_sent, id_tgt_sent = list(map(lambda _s: _s[1:], involved_sents[::-1]))
                else:
                    id_src_sent, id_tgt_sent = list(map(lambda _s: _s[1:], involved_sents))
            else:  # one sentence: only source or only target (usually a sentence marked as redundant or as missing)
                id_src_sent, id_tgt_sent = None, None
                if "t" in involved_sents[0]:
                    id_tgt_sent = involved_sents[0][1:]
                else:
                    id_src_sent = involved_sents[0][1:]

            id_doc, doc_title, is_manually_validated = None, None, False
            src_sent_data, tgt_sent_data = {}, {}
            assert id_src_sent is not None or id_tgt_sent is not None
            if id_src_sent is not None:
                src_sent_data = source_data[id_src_sent]
                id_doc = src_sent_data["id_doc"]
                doc_title = src_sent_data["doc_title"]
                is_manually_validated |= src_sent_data["is_manually_validated"]
            if id_tgt_sent is not None:
                tgt_sent_data = target_data[id_tgt_sent]
                id_doc = tgt_sent_data["id_doc"]
                doc_title = tgt_sent_data["doc_title"]
                is_manually_validated |= tgt_sent_data["is_manually_validated"]

            corr_data = []
            for token_info in corrected_sent.findall(f"{NAMESPACE}link"):
                connections = token_info.attrib["target"].split(" ")

                corrections = token_info.attrib["type"]
                if corrections == "ID":
                    continue

                src_inds, tgt_inds = [], []
                corr_types = []
                for curr_corr in corrections.split("|"):
                    corr_types.append(curr_corr)

                for curr_tok in connections:
                    # Token IDs have an index at the end, but it is 1-based; convert it to 0-based
                    idx_tok = int(curr_tok.split(".")[-1]) - 1
                    if "t" in curr_tok:  # target token
                        tgt_inds.append(idx_tok)
                    else:  # source token
                        src_inds.append(idx_tok)

                corr_data.append({"idx_src": src_inds, "idx_tgt": tgt_inds, "corr_types": corr_types})

            yield idx_corr, {
                "id_doc": id_doc[:-1],  # doc ID without the "s" or "t" info
                "doc_title": doc_title,
                "is_manually_validated": is_manually_validated,
                "idx_src_par": src_sent_data.get("idx_par", -1),
                "idx_src_sent": src_sent_data.get("idx_sent", -1),
                "id_src_tokens": src_sent_data.get("id_token", []),
                "src_tokens": src_sent_data.get("form", []),
                "idx_tgt_par": tgt_sent_data.get("idx_par", -1),
                "idx_tgt_sent": tgt_sent_data.get("idx_sent", -1),
                "id_tgt_tokens": tgt_sent_data.get("id_token", []),
                "tgt_tokens": tgt_sent_data.get("form", []),
                "corrections": corr_data
            }