language.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""
language and subtitle_language properties
"""
# pylint: disable=no-member
import copy
from collections import defaultdict, namedtuple

import babelfish
from rebulk import Rebulk, Rule, RemoveMatch, RenameMatch
from rebulk.remodule import re

from ..common import seps
from ..common.pattern import is_disabled
from ..common.words import iter_words
from ..common.validators import seps_surround


def language(config, common_words):
    """
    Builder for rebulk object.

    :param config: rule configuration
    :type config: dict
    :param common_words: common words
    :type common_words: set
    :return: Created Rebulk object
    :rtype: Rebulk
    """
    subtitle_both = config['subtitle_affixes']
    subtitle_prefixes = sorted(subtitle_both + config['subtitle_prefixes'], key=length_comparator)
    subtitle_suffixes = sorted(subtitle_both + config['subtitle_suffixes'], key=length_comparator)
    lang_both = config['language_affixes']
    lang_prefixes = sorted(lang_both + config['language_prefixes'], key=length_comparator)
    lang_suffixes = sorted(lang_both + config['language_suffixes'], key=length_comparator)
    weak_affixes = frozenset(config['weak_affixes'])

    rebulk = Rebulk(disabled=lambda context: (is_disabled(context, 'language') and
                                              is_disabled(context, 'subtitle_language')))

    rebulk.string(*subtitle_prefixes, name="subtitle_language.prefix", ignore_case=True, private=True,
                  validator=seps_surround, tags=['release-group-prefix'],
                  disabled=lambda context: is_disabled(context, 'subtitle_language'))
    rebulk.string(*subtitle_suffixes, name="subtitle_language.suffix", ignore_case=True, private=True,
                  validator=seps_surround,
                  disabled=lambda context: is_disabled(context, 'subtitle_language'))
    rebulk.string(*lang_suffixes, name="language.suffix", ignore_case=True, private=True,
                  validator=seps_surround, tags=['source-suffix'],
                  disabled=lambda context: is_disabled(context, 'language'))

    def find_languages(string, context=None):
        """Find languages in the string

        :return: list of tuple (property, Language, lang_word, word)
        """
        return LanguageFinder(context, subtitle_prefixes, subtitle_suffixes,
                              lang_prefixes, lang_suffixes, weak_affixes).find(string)

    rebulk.functional(find_languages,
                      properties={'language': [None]},
                      disabled=lambda context: not context.get('allowed_languages'))
    rebulk.rules(SubtitleExtensionRule,
                 SubtitlePrefixLanguageRule,
                 SubtitleSuffixLanguageRule,
                 RemoveLanguage,
                 RemoveInvalidLanguages(common_words))

    babelfish.language_converters['guessit'] = GuessitConverter(config['synonyms'])

    return rebulk


UNDETERMINED = babelfish.Language('und')


class GuessitConverter(babelfish.LanguageReverseConverter):  # pylint: disable=missing-docstring
    _with_country_regexp = re.compile(r'(.*)\((.*)\)')
    _with_country_regexp2 = re.compile(r'(.*)-(.*)')

    def __init__(self, synonyms):
        self.guessit_exceptions = {}
        for code, synlist in synonyms.items():
            if '_' in code:
                (alpha3, country) = code.split('_')
            else:
                (alpha3, country) = (code, None)
            for syn in synlist:
                self.guessit_exceptions[syn.lower()] = (alpha3, country, None)

    @property
    def codes(self):  # pylint: disable=missing-docstring
        return (babelfish.language_converters['alpha3b'].codes |
                babelfish.language_converters['alpha2'].codes |
                babelfish.language_converters['name'].codes |
                babelfish.language_converters['opensubtitles'].codes |
                babelfish.country_converters['name'].codes |
                frozenset(self.guessit_exceptions.keys()))

    def convert(self, alpha3, country=None, script=None):
        return str(babelfish.Language(alpha3, country, script))

    def reverse(self, name):  # pylint:disable=arguments-differ
        name = name.lower()
        # exceptions come first, as they need to override a potential match
        # with any of the other guessers
        try:
            return self.guessit_exceptions[name]
        except KeyError:
            pass

        for conv in [babelfish.Language,
                     babelfish.Language.fromalpha3b,
                     babelfish.Language.fromalpha2,
                     babelfish.Language.fromname,
                     babelfish.Language.fromopensubtitles,
                     babelfish.Language.fromietf]:
            try:
                reverse = conv(name)
                return reverse.alpha3, reverse.country, reverse.script
            except (ValueError, babelfish.LanguageReverseError):
                pass

        raise babelfish.LanguageReverseError(name)


def length_comparator(value):
    """
    Return value length.
    """
    return len(value)


_LanguageMatch = namedtuple('_LanguageMatch', ['property_name', 'word', 'lang'])


class LanguageWord(object):
    """
    Extension to the Word namedtuple in order to create compound words.

    E.g.: pt-BR, soft subtitles, custom subs
    """

    def __init__(self, start, end, value, input_string, next_word=None):
        self.start = start
        self.end = end
        self.value = value
        self.input_string = input_string
        self.next_word = next_word

    @property
    def extended_word(self):  # pylint:disable=inconsistent-return-statements
        """
        Return the extended word for this instance, if any.
        """
        if self.next_word:
            separator = self.input_string[self.end:self.next_word.start]
            next_separator = self.input_string[self.next_word.end:self.next_word.end + 1]

            if (separator == '-' and separator != next_separator) or separator in (' ', '.'):
                value = self.input_string[self.start:self.next_word.end].replace('.', ' ')

                return LanguageWord(self.start, self.next_word.end, value, self.input_string, self.next_word.next_word)

    def __repr__(self):
        return '<({start},{end}): {value}'.format(start=self.start, end=self.end, value=self.value)


def to_rebulk_match(language_match):
    """
    Convert language match to rebulk Match: start, end, dict
    """
    word = language_match.word
    start = word.start
    end = word.end
    name = language_match.property_name
    if language_match.lang == UNDETERMINED:
        return start, end, {
            'name': name,
            'value': word.value.lower(),
            'formatter': babelfish.Language,
            'tags': ['weak-language']
        }

    return start, end, {
        'name': name,
        'value': language_match.lang
    }


class LanguageFinder(object):
    """
    Helper class to search and return language matches: 'language' and 'subtitle_language' properties
    """

    def __init__(self, context,
                 subtitle_prefixes, subtitle_suffixes,
                 lang_prefixes, lang_suffixes, weak_affixes):
        allowed_languages = context.get('allowed_languages') if context else None
        self.allowed_languages = {l.lower() for l in allowed_languages or []}
        self.weak_affixes = weak_affixes
        self.prefixes_map = {}
        self.suffixes_map = {}

        if not is_disabled(context, 'subtitle_language'):
            self.prefixes_map['subtitle_language'] = subtitle_prefixes
            self.suffixes_map['subtitle_language'] = subtitle_suffixes

        self.prefixes_map['language'] = lang_prefixes
        self.suffixes_map['language'] = lang_suffixes

    def find(self, string):
        """
        Return all matches for language and subtitle_language.

        Undetermined language matches are removed if a regular language is found.
        Multi language matches are removed if there are only undetermined language matches
        """
        regular_lang_map = defaultdict(set)
        undetermined_map = defaultdict(set)
        multi_map = defaultdict(set)

        for match in self.iter_language_matches(string):
            key = match.property_name
            if match.lang == UNDETERMINED:
                undetermined_map[key].add(match)
            elif match.lang == 'mul':
                multi_map[key].add(match)
            else:
                regular_lang_map[key].add(match)

        for key, values in multi_map.items():
            if key in regular_lang_map or key not in undetermined_map:
                for value in values:
                    yield to_rebulk_match(value)

        for key, values in undetermined_map.items():
            if key not in regular_lang_map:
                for value in values:
                    yield to_rebulk_match(value)

        for values in regular_lang_map.values():
            for value in values:
                yield to_rebulk_match(value)

    def iter_language_matches(self, string):
        """
        Return language matches for the given string.
        """
        candidates = []
        previous = None
        for word in iter_words(string):
            language_word = LanguageWord(start=word.span[0], end=word.span[1], value=word.value, input_string=string)
            if previous:
                previous.next_word = language_word
                candidates.append(previous)
            previous = language_word
        if previous:
            candidates.append(previous)

        for candidate in candidates:
            for match in self.iter_matches_for_candidate(candidate):
                yield match

    def iter_matches_for_candidate(self, language_word):
        """
        Return language matches for the given candidate word.
        """
        tuples = [
            (language_word, language_word.next_word,
             self.prefixes_map,
             lambda string, prefix: string.startswith(prefix),
             lambda string, prefix: string[len(prefix):]),
            (language_word.next_word, language_word,
             self.suffixes_map,
             lambda string, suffix: string.endswith(suffix),
             lambda string, suffix: string[:len(string) - len(suffix)])
        ]

        for word, fallback_word, affixes, is_affix, strip_affix in tuples:
            if not word:
                continue

            match = self.find_match_for_word(word, fallback_word, affixes, is_affix, strip_affix)
            if match:
                yield match

        match = self.find_language_match_for_word(language_word)
        if match:
            yield match

    def find_match_for_word(self, word, fallback_word, affixes, is_affix, strip_affix):  # pylint:disable=inconsistent-return-statements
        """
        Return the language match for the given word and affixes.
        """
        for current_word in (word.extended_word, word):
            if not current_word:
                continue

            word_lang = current_word.value.lower()

            for key, parts in affixes.items():
                for part in parts:
                    if not is_affix(word_lang, part):
                        continue

                    match = None
                    value = strip_affix(word_lang, part)
                    if not value:
                        if fallback_word and (
                                abs(fallback_word.start - word.end) <= 1 or abs(word.start - fallback_word.end) <= 1):
                            match = self.find_language_match_for_word(fallback_word, key=key)

                        if not match and part not in self.weak_affixes:
                            match = self.create_language_match(key, LanguageWord(current_word.start, current_word.end,
                                                                                 'und', current_word.input_string))
                    else:
                        match = self.create_language_match(key, LanguageWord(current_word.start, current_word.end,
                                                                             value, current_word.input_string))

                    if match:
                        return match

    def find_language_match_for_word(self, word, key='language'):  # pylint:disable=inconsistent-return-statements
        """
        Return the language match for the given word.
        """
        for current_word in (word.extended_word, word):
            if current_word:
                match = self.create_language_match(key, current_word)
                if match:
                    return match

    def create_language_match(self, key, word):  # pylint:disable=inconsistent-return-statements
        """
        Create a LanguageMatch for a given word
        """
        lang = self.parse_language(word.value.lower())

        if lang is not None:
            return _LanguageMatch(property_name=key, word=word, lang=lang)

    def parse_language(self, lang_word):  # pylint:disable=inconsistent-return-statements
        """
        Parse the lang_word into a valid Language.

        Multi and Undetermined languages are also valid languages.
        """
        try:
            lang = babelfish.Language.fromguessit(lang_word)
            if ((hasattr(lang, 'name') and lang.name.lower() in self.allowed_languages) or
                    (hasattr(lang, 'alpha2') and lang.alpha2.lower() in self.allowed_languages) or
                    lang.alpha3.lower() in self.allowed_languages):
                return lang

        except babelfish.Error:
            pass


class SubtitlePrefixLanguageRule(Rule):
    """
    Convert language guess as subtitle_language if previous match is a subtitle language prefix
    """
    consequence = RemoveMatch

    properties = {'subtitle_language': [None]}

    def enabled(self, context):
        return not is_disabled(context, 'subtitle_language')

    def when(self, matches, context):
        to_rename = []
        to_remove = matches.named('subtitle_language.prefix')
        for lang in matches.named('language'):
            prefix = matches.previous(lang, lambda match: match.name == 'subtitle_language.prefix', 0)
            if not prefix:
                group_marker = matches.markers.at_match(lang, lambda marker: marker.name == 'group', 0)
                if group_marker:
                    # Find prefix if placed just before the group
                    prefix = matches.previous(group_marker, lambda match: match.name == 'subtitle_language.prefix',
                                              0)
                    if not prefix:
                        # Find prefix if placed before in the group
                        prefix = matches.range(group_marker.start, lang.start,
                                               lambda match: match.name == 'subtitle_language.prefix', 0)
            if prefix:
                to_rename.append((prefix, lang))
                to_remove.extend(matches.conflicting(lang))
                if prefix in to_remove:
                    to_remove.remove(prefix)
        return to_rename, to_remove

    def then(self, matches, when_response, context):
        to_rename, to_remove = when_response
        super(SubtitlePrefixLanguageRule, self).then(matches, to_remove, context)
        for prefix, match in to_rename:
            # Remove suffix equivalent of  prefix.
            suffix = copy.copy(prefix)
            suffix.name = 'subtitle_language.suffix'
            if suffix in matches:
                matches.remove(suffix)
            matches.remove(match)
            match.name = 'subtitle_language'
            matches.append(match)


class SubtitleSuffixLanguageRule(Rule):
    """
    Convert language guess as subtitle_language if next match is a subtitle language suffix
    """
    dependency = SubtitlePrefixLanguageRule
    consequence = RemoveMatch

    properties = {'subtitle_language': [None]}

    def enabled(self, context):
        return not is_disabled(context, 'subtitle_language')

    def when(self, matches, context):
        to_append = []
        to_remove = matches.named('subtitle_language.suffix')
        for lang in matches.named('language'):
            suffix = matches.next(lang, lambda match: match.name == 'subtitle_language.suffix', 0)
            if suffix:
                to_append.append(lang)
                if suffix in to_remove:
                    to_remove.remove(suffix)
        return to_append, to_remove

    def then(self, matches, when_response, context):
        to_rename, to_remove = when_response
        super(SubtitleSuffixLanguageRule, self).then(matches, to_remove, context)
        for match in to_rename:
            matches.remove(match)
            match.name = 'subtitle_language'
            matches.append(match)


class SubtitleExtensionRule(Rule):
    """
    Convert language guess as subtitle_language if next match is a subtitle extension.

    Since it's a strong match, it also removes any conflicting source with it.
    """
    consequence = [RemoveMatch, RenameMatch('subtitle_language')]

    properties = {'subtitle_language': [None]}

    def enabled(self, context):
        return not is_disabled(context, 'subtitle_language')

    def when(self, matches, context):  # pylint:disable=inconsistent-return-statements
        subtitle_extension = matches.named('container',
                                           lambda match: 'extension' in match.tags and 'subtitle' in match.tags,
                                           0)
        if subtitle_extension:
            subtitle_lang = matches.previous(subtitle_extension, lambda match: match.name == 'language', 0)
            if subtitle_lang:
                for weak in matches.named('subtitle_language', predicate=lambda m: 'weak-language' in m.tags):
                    weak.private = True

                return matches.conflicting(subtitle_lang, lambda m: m.name == 'source'), subtitle_lang


class RemoveLanguage(Rule):
    """Remove language matches that were not converted to subtitle_language when language is disabled."""

    consequence = RemoveMatch

    def enabled(self, context):
        return is_disabled(context, 'language')

    def when(self, matches, context):
        return matches.named('language')


class RemoveInvalidLanguages(Rule):
    """Remove language matches that matches the blacklisted common words."""

    consequence = RemoveMatch

    def __init__(self, common_words):
        """Constructor."""
        super(RemoveInvalidLanguages, self).__init__()
        self.common_words = common_words

    def when(self, matches, context):
        to_remove = []
        for match in matches.range(0, len(matches.input_string),
                                   predicate=lambda m: m.name in ('language', 'subtitle_language')):
            if match.raw.lower() not in self.common_words:
                continue

            group = matches.markers.at_match(match, index=0, predicate=lambda m: m.name == 'group')
            if group and (
                    not matches.range(
                        group.start, group.end, predicate=lambda m: m.name not in ('language', 'subtitle_language')
                    ) and (not matches.holes(group.start, group.end, predicate=lambda m: m.value.strip(seps)))):
                continue

            to_remove.append(match)

        return to_remove