import re
from typing import Union

from ebooklib.epub import Section, Link
from src.livecarta_config import LiveCartaConfig


class NavPoint:
    """
    Class - Navigation Point, - every html|xhtml from epub
    These are data structures which form mapping from NCX to python data structures.
    """

    def __init__(self, obj: Union[Link, Section] = None, ):
        self.href, self.id = self.parse_href_id(obj)
        self.title = obj.title

    @staticmethod
    def parse_href_id(item: Union[Link, Section]):
        """Function parses href & id from item.href"""
        reg = r'(.+\..+\#)(.+)'
        match = re.search(reg, item.href)
        href, div_id = None, None
        if match:
            div_id = match.group(2)
            if match.group(1):
                href = match.group(1)[:-1]
        else:
            reg2 = r'(.+\..+)'
            match2 = re.search(reg2, item.href)
            if match2 and match2.group(1):
                href = match2.group(1)

        return href, div_id

    def __str__(self):
        return '<NavPoint: %s, %s>' % (self.href, self.id)


def flatten(x):
    """magic function from stackoverflow for list flattening"""
    atom = lambda i: not isinstance(i, list)
    nil = lambda i: not i
    car = lambda i: i[0]
    cdr = lambda i: i[1:]
    cons = lambda i, y: i + y

    res = [x] if atom(x) else x if nil(x) else cons(*map(flatten, [car(x), cdr(x)]))
    return res


class ChapterItem:
    """
    Class of Chapter that could have subchapters
    These are data structures which form mapping to livecarta json structure.
    """

    def __init__(self, title, content, sub_items):
        self.title = title
        self.content = content
        self.sub_items = sub_items

    def to_dict(self, lvl=1):
        """Function returns dictionary of chapter"""
        sub_dicts = []
        if self.sub_items:
            for i in self.sub_items:
                sub_dicts.append(i.to_dict(lvl + 1))

        if lvl > LiveCartaConfig.SUPPORTED_LEVELS:
            return {
                "title": self.title,
                "contents": [self.content] + [x['contents'] for x in sub_dicts],
                "sub_items": []
            }

        if (lvl == LiveCartaConfig.SUPPORTED_LEVELS) and sub_dicts:
            return {
                "title": self.title,
                "contents": [self.content] + flatten([x['contents'] for x in sub_dicts]),
                "sub_items": []
            }

        return {
            "title": self.title,
            "contents": [self.content],
            "sub_items": sub_dicts
        }

    def __str__(self):
        return '<Chapter: %s>' % self.title