#!/usr/bin/env python
# -*- coding: utf-8 -*-
#
# GuessIt - A library for guessing information from filenames
# Copyright (c) 2011 Nicolas Wack <wackou@gmail.com>
#
# GuessIt is free software; you can redistribute it and/or modify it under
# the terms of the Lesser GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# GuessIt is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# Lesser GNU General Public License for more details.
#
# You should have received a copy of the Lesser GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#

from __future__ import unicode_literals
from guessit import UnicodeMixin, base_text_type, u, s
from guessit.fileutils import load_file_in_same_dir
from guessit.textutils import find_words
from guessit.country import Country
import re
import logging

__all__ = [ 'is_iso_language', 'is_language', 'lang_set', 'Language',
            'ALL_LANGUAGES', 'ALL_LANGUAGES_NAMES', 'UNDETERMINED',
            'search_language', 'guess_language' ]


log = logging.getLogger(__name__)


# downloaded from http://www.loc.gov/standards/iso639-2/ISO-639-2_utf-8.txt
#
# Description of the fields:
# "An alpha-3 (bibliographic) code, an alpha-3 (terminologic) code (when given),
# an alpha-2 code (when given), an English name, and a French name of a language
# are all separated by pipe (|) characters."
_iso639_contents = load_file_in_same_dir(__file__, 'ISO-639-2_utf-8.txt')

# drop the BOM from the beginning of the file
_iso639_contents = _iso639_contents[1:]

language_matrix = [ l.strip().split('|')
                    for l in _iso639_contents.strip().split('\n') ]


# update information in the language matrix
language_matrix += [['mol', '', 'mo', 'Moldavian', 'moldave'],
                    ['ass', '', '', 'Assyrian', 'assyrien']]

for lang in language_matrix:
    # remove unused languages that shadow other common ones with a non-official form
    if (lang[2] == 'se' or # Northern Sami shadows Swedish
        lang[2] == 'br'):  # Breton shadows Brazilian
        lang[2] = ''
    # add missing information
    if lang[0] == 'und':
        lang[2] = 'un'
    if lang[0] == 'srp':
        lang[1] = 'scc' # from OpenSubtitles


lng3        = frozenset(l[0] for l in language_matrix if l[0])
lng3term    = frozenset(l[1] for l in language_matrix if l[1])
lng2        = frozenset(l[2] for l in language_matrix if l[2])
lng_en_name = frozenset(lng for l in language_matrix
                        for lng in l[3].lower().split('; ') if lng)
lng_fr_name = frozenset(lng for l in language_matrix
                        for lng in l[4].lower().split('; ') if lng)
lng_all_names = lng3 | lng3term | lng2 | lng_en_name | lng_fr_name

lng3_to_lng3term = dict((l[0], l[1]) for l in language_matrix if l[1])
lng3term_to_lng3 = dict((l[1], l[0]) for l in language_matrix if l[1])

lng3_to_lng2 = dict((l[0], l[2]) for l in language_matrix if l[2])
lng2_to_lng3 = dict((l[2], l[0]) for l in language_matrix if l[2])

# we only return the first given english name, hoping it is the most used one
lng3_to_lng_en_name = dict((l[0], l[3].split('; ')[0])
                           for l in language_matrix if l[3])
lng_en_name_to_lng3 = dict((en_name.lower(), l[0])
                           for l in language_matrix if l[3]
                           for en_name in l[3].split('; '))

# we only return the first given french name, hoping it is the most used one
lng3_to_lng_fr_name = dict((l[0], l[4].split('; ')[0])
                           for l in language_matrix if l[4])
lng_fr_name_to_lng3 = dict((fr_name.lower(), l[0])
                           for l in language_matrix if l[4]
                           for fr_name in l[4].split('; '))

# contains a list of exceptions: strings that should be parsed as a language
# but which are not in an ISO form
lng_exceptions = { 'unknown': ('und', None),
                   'inconnu': ('und', None),
                   'unk': ('und', None),
                   'un': ('und', None),
                   'gr': ('gre', None),
                   'greek': ('gre', None),
                   'esp': ('spa', None),
                   'español': ('spa', None),
                   'se': ('swe', None),
                   'po': ('pt', 'br'),
                   'pb': ('pt', 'br'),
                   'pob': ('pt', 'br'),
                   'br': ('pt', 'br'),
                   'brazilian': ('pt', 'br'),
                   'català': ('cat', None),
                   'cz': ('cze', None),
                   'ua': ('ukr', None),
                   'cn': ('chi', None),
                   'chs': ('chi', None),
                   'jp': ('jpn', None),
                   'scr': ('hrv', None)
                   }


def is_iso_language(language):
    return language.lower() in lng_all_names

def is_language(language):
    return is_iso_language(language) or language in lng_exceptions

def lang_set(languages, strict=False):
    """Return a set of guessit.Language created from their given string
    representation.

    if strict is True, then this will raise an exception if any language
    could not be identified.
    """
    return set(Language(l, strict=strict) for l in languages)


class Language(UnicodeMixin):
    """This class represents a human language.

    You can initialize it with pretty much anything, as it knows conversion
    from ISO-639 2-letter and 3-letter codes, English and French names.

    You can also distinguish languages for specific countries, such as
    Portuguese and Brazilian Portuguese.

    There are various properties on the language object that give you the
    representation of the language for a specific usage, such as .alpha3
    to get the ISO 3-letter code, or .opensubtitles to get the OpenSubtitles
    language code.

    >>> Language('fr')
    Language(French)

    >>> s(Language('eng').french_name)
    'anglais'

    >>> s(Language('pt(br)').country.english_name)
    'Brazil'

    >>> s(Language('Español (Latinoamérica)').country.english_name)
    'Latin America'

    >>> Language('Spanish (Latin America)') == Language('Español (Latinoamérica)')
    True

    >>> s(Language('zz', strict=False).english_name)
    'Undetermined'

    >>> s(Language('pt(br)').opensubtitles)
    'pob'
    """

    _with_country_regexp = re.compile('(.*)\((.*)\)')
    _with_country_regexp2 = re.compile('(.*)-(.*)')

    def __init__(self, language, country=None, strict=False, scheme=None):
        language = u(language.strip().lower())
        with_country = (Language._with_country_regexp.match(language) or
                        Language._with_country_regexp2.match(language))
        if with_country:
            self.lang = Language(with_country.group(1)).lang
            self.country = Country(with_country.group(2))
            return

        self.lang = None
        self.country = Country(country) if country else None

        # first look for scheme specific languages
        if scheme == 'opensubtitles':
            if language == 'br':
                self.lang = 'bre'
                return
            elif language == 'se':
                self.lang = 'sme'
                return
        elif scheme is not None:
            log.warning('Unrecognized scheme: "%s" - Proceeding with standard one' % scheme)

        # look for ISO language codes
        if len(language) == 2:
            self.lang = lng2_to_lng3.get(language)
        elif len(language) == 3:
            self.lang = (language
                         if language in lng3
                         else lng3term_to_lng3.get(language))
        else:
            self.lang = (lng_en_name_to_lng3.get(language) or
                         lng_fr_name_to_lng3.get(language))

        # general language exceptions
        if self.lang is None and language in lng_exceptions:
            lang, country = lng_exceptions[language]
            self.lang = Language(lang).alpha3
            self.country = Country(country) if country else None

        msg = 'The given string "%s" could not be identified as a language' % language

        if self.lang is None and strict:
            raise ValueError(msg)

        if self.lang is None:
            log.debug(msg)
            self.lang = 'und'

    @property
    def alpha2(self):
        return lng3_to_lng2[self.lang]

    @property
    def alpha3(self):
        return self.lang

    @property
    def alpha3term(self):
        return lng3_to_lng3term[self.lang]

    @property
    def english_name(self):
        return lng3_to_lng_en_name[self.lang]

    @property
    def french_name(self):
        return lng3_to_lng_fr_name[self.lang]

    @property
    def opensubtitles(self):
        if self.lang == 'por' and self.country and self.country.alpha2 == 'br':
            return 'pob'
        elif self.lang in ['gre', 'srp']:
            return self.alpha3term
        return self.alpha3

    @property
    def tmdb(self):
        if self.country:
            return '%s-%s' % (self.alpha2, self.country.alpha2.upper())
        return self.alpha2

    def __hash__(self):
        return hash(self.lang)

    def __eq__(self, other):
        if isinstance(other, Language):
            return self.lang == other.lang

        if isinstance(other, base_text_type):
            try:
                return self == Language(other)
            except ValueError:
                return False

        return False

    def __ne__(self, other):
        return not self == other

    def __nonzero__(self):
        return self.lang != 'und'

    def __unicode__(self):
        if self.country:
            return '%s(%s)' % (self.english_name, self.country.alpha2)
        else:
            return self.english_name

    def __repr__(self):
        if self.country:
            return 'Language(%s, country=%s)' % (self.english_name, self.country)
        else:
            return 'Language(%s)' % self.english_name


UNDETERMINED = Language('und')
ALL_LANGUAGES = frozenset(Language(lng) for lng in lng_all_names) - frozenset([UNDETERMINED])
ALL_LANGUAGES_NAMES = lng_all_names

def search_language(string, lang_filter=None, skip=None):
    """Looks for language patterns, and if found return the language object,
    its group span and an associated confidence.

    you can specify a list of allowed languages using the lang_filter argument,
    as in lang_filter = [ 'fr', 'eng', 'spanish' ]

    >>> search_language('movie [en].avi')
    (Language(English), (7, 9), 0.8)

    >>> search_language('the zen fat cat and the gay mad men got a new fan', lang_filter = ['en', 'fr', 'es'])
    (None, None, None)
    """

    # list of common words which could be interpreted as languages, but which
    # are far too common to be able to say they represent a language in the
    # middle of a string (where they most likely carry their commmon meaning)
    lng_common_words = frozenset([
        # english words
        'is', 'it', 'am', 'mad', 'men', 'man', 'run', 'sin', 'st', 'to',
        'no', 'non', 'war', 'min', 'new', 'car', 'day', 'bad', 'bat', 'fan',
        'fry', 'cop', 'zen', 'gay', 'fat', 'cherokee', 'got', 'an', 'as',
        'cat', 'her', 'be', 'hat', 'sun', 'may', 'my', 'mr', 'rum', 'pi',
        # french words
        'bas', 'de', 'le', 'son', 'vo', 'vf', 'ne', 'ca', 'ce', 'et', 'que',
        'mal', 'est', 'vol', 'or', 'mon', 'se',
        # spanish words
        'la', 'el', 'del', 'por', 'mar',
        # other
        'ind', 'arw', 'ts', 'ii', 'bin', 'chan', 'ss', 'san', 'oss', 'iii',
        'vi', 'ben', 'da', 'lt'
        ])
    sep = r'[](){} \._-+'

    if lang_filter:
        lang_filter = lang_set(lang_filter)

    slow = ' %s ' % string.lower()
    confidence = 1.0 # for all of them

    for lang in set(find_words(slow)) & lng_all_names:

        if lang in lng_common_words:
            continue

        pos = slow.find(lang)

        if pos != -1:
            end = pos + len(lang)
            
            # skip if span in in skip list
            while skip and (pos - 1, end - 1) in skip:
                pos = slow.find(lang, end)
                if pos == -1:
                    continue
                end = pos + len(lang)                
            if pos == -1:
                continue
                            
            # make sure our word is always surrounded by separators
            if slow[pos - 1] not in sep or slow[end] not in sep:
                continue

            language = Language(slow[pos:end])
            if lang_filter and language not in lang_filter:
                continue

            # only allow those languages that have a 2-letter code, those that
            # don't are too esoteric and probably false matches
            if language.lang not in lng3_to_lng2:
                continue

            # confidence depends on lng2, lng3, english name, ...
            if len(lang) == 2:
                confidence = 0.8
            elif len(lang) == 3:
                confidence = 0.9
            else:
                # Note: we could either be really confident that we found a
                #       language or assume that full language names are too
                #       common words and lower their confidence accordingly
                confidence = 0.3 # going with the low-confidence route here

            return language, (pos - 1, end - 1), confidence

    return None, None, None


def guess_language(text):
    """Guess the language in which a body of text is written.

    This uses the external guess-language python module, and will fail and return
    Language(Undetermined) if it is not installed.
    """
    try:
        from guess_language import guessLanguage
        return Language(guessLanguage(text))

    except ImportError:
        log.error('Cannot detect the language of the given text body, missing dependency: guess-language')
        log.error('Please install it from PyPI, by doing eg: pip install guess-language')
        return UNDETERMINED
