from .bases import _ScandinavianStemmer


class SwedishStemmer(_ScandinavianStemmer):

    """
    The Swedish Snowball stemmer.

    :cvar __vowels: The Swedish vowels.
    :type __vowels: unicode
    :cvar __s_ending: Letters that may directly appear before a word final 's'.
    :type __s_ending: unicode
    :cvar __step1_suffixes: Suffixes to be deleted in step 1 of the algorithm.
    :type __step1_suffixes: tuple
    :cvar __step2_suffixes: Suffixes to be deleted in step 2 of the algorithm.
    :type __step2_suffixes: tuple
    :cvar __step3_suffixes: Suffixes to be deleted in step 3 of the algorithm.
    :type __step3_suffixes: tuple
    :note: A detailed description of the Swedish
           stemming algorithm can be found under
           http://snowball.tartarus.org/algorithms/swedish/stemmer.html
    """

    __vowels = "aeiouy\xE4\xE5\xF6"
    __s_ending = "bcdfghjklmnoprtvy"
    __step1_suffixes = (
        "heterna",
        "hetens",
        "heter",
        "heten",
        "anden",
        "arnas",
        "ernas",
        "ornas",
        "andes",
        "andet",
        "arens",
        "arna",
        "erna",
        "orna",
        "ande",
        "arne",
        "aste",
        "aren",
        "ades",
        "erns",
        "ade",
        "are",
        "ern",
        "ens",
        "het",
        "ast",
        "ad",
        "en",
        "ar",
        "er",
        "or",
        "as",
        "es",
        "at",
        "a",
        "e",
        "s",
    )
    __step2_suffixes = ("dd", "gd", "nn", "dt", "gt", "kt", "tt")
    __step3_suffixes = ("fullt", "l\xF6st", "els", "lig", "ig")

    def stem(self, word):
        """
        Stem a Swedish word and return the stemmed form.

        :param word: The word that is stemmed.
        :type word: str or unicode
        :return: The stemmed form.
        :rtype: unicode

        """
        word = word.lower()

        r1 = self._r1_scandinavian(word, self.__vowels)

        # STEP 1
        for suffix in self.__step1_suffixes:
            if r1.endswith(suffix):
                if suffix == "s":
                    if word[-2] in self.__s_ending:
                        word = word[:-1]
                        r1 = r1[:-1]
                else:
                    word = word[: -len(suffix)]
                    r1 = r1[: -len(suffix)]
                break

        # STEP 2
        for suffix in self.__step2_suffixes:
            if r1.endswith(suffix):
                word = word[:-1]
                r1 = r1[:-1]
                break

        # STEP 3
        for suffix in self.__step3_suffixes:
            if r1.endswith(suffix):
                if suffix in ("els", "lig", "ig"):
                    word = word[: -len(suffix)]
                elif suffix in ("fullt", "l\xF6st"):
                    word = word[:-1]
                break

        return word
