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# SPDX-License-Identifier: AGPL-3.0-or-later
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# lint: pylint
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"""Plugin to detect the search language from the search query.
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The language detection is done by using the fastText_ library (`python
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fasttext`_). fastText_ distributes the `language identification model`_, for
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reference:
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- `FastText.zip: Compressing text classification models`_
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- `Bag of Tricks for Efficient Text Classification`_
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The `language identification model`_ support the language codes (ISO-639-3)::
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af als am an ar arz as ast av az azb ba bar bcl be bg bh bn bo bpy br bs bxr
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ca cbk ce ceb ckb co cs cv cy da de diq dsb dty dv el eml en eo es et eu fa
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fi fr frr fy ga gd gl gn gom gu gv he hi hif hr hsb ht hu hy ia id ie ilo io
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is it ja jbo jv ka kk km kn ko krc ku kv kw ky la lb lez li lmo lo lrc lt lv
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mai mg mhr min mk ml mn mr mrj ms mt mwl my myv mzn nah nap nds ne new nl nn
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no oc or os pa pam pfl pl pms pnb ps pt qu rm ro ru rue sa sah sc scn sco sd
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sh si sk sl so sq sr su sv sw ta te tg th tk tl tr tt tyv ug uk ur uz vec vep
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vi vls vo wa war wuu xal xmf yi yo yue zh
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The `language identification model`_ is harmonized with the SearXNG's language
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(locale) model. General conditions of SearXNG's locale model are:
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a. SearXNG's locale of a query is passed to the
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:py:obj:`searx.locales.get_engine_locale` to get a language and/or region
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code that is used by an engine.
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b. SearXNG and most of the engines do not support all the languages from
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language model and there might be also a discrepancy in the ISO-639-3 and
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ISO-639-2 handling (:py:obj:`searx.locales.get_engine_locale`). Further
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more, in SearXNG the locales like ``zh-TH`` (``zh-CN``) are mapped to
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``zh_Hant`` (``zh_Hans``).
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Conclusion: This plugin does only auto-detect the languages a user can select in
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the language menu (:py:obj:`supported_langs`).
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SearXNG's locale of a query comes from (*highest wins*):
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1. The ``Accept-Language`` header from user's HTTP client.
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2. The user select a locale in the preferences.
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3. The user select a locale from the menu in the query form (e.g. ``:zh-TW``)
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4. This plugin is activated in the preferences and the locale (only the language
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code / none region code) comes from the fastText's language detection.
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Conclusion: There is a conflict between the language selected by the user and
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the language from language detection of this plugin. For example, the user
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explicitly selects the German locale via the search syntax to search for a term
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that is identified as an English term (try ``:de-DE thermomix``, for example).
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.. hint::
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To SearXNG maintainers; please take into account: under some circumstances
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the auto-detection of the language of this plugin could be detrimental to
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users expectations. Its not recommended to activate this plugin by
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default. It should always be the user's decision whether to activate this
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plugin or not.
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.. _fastText: https://fasttext.cc/
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.. _python fasttext: https://pypi.org/project/fasttext/
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.. _language identification model: https://fasttext.cc/docs/en/language-identification.html
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.. _Bag of Tricks for Efficient Text Classification: https://arxiv.org/abs/1607.01759
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.. _`FastText.zip: Compressing text classification models`: https://arxiv.org/abs/1612.03651
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"""
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from flask_babel import gettext
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import babel
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from searx.utils import detect_language
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from searx.languages import language_codes
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name = gettext('Autodetect search language')
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description = gettext('Automatically detect the query search language and switch to it.')
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preference_section = 'general'
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default_on = False
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supported_langs = set()
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"""Languages supported by most searxng engines (:py:obj:`searx.languages.language_codes`)."""
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def pre_search(request, search): # pylint: disable=unused-argument
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lang = detect_language(search.search_query.query, min_probability=0)
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if lang in supported_langs:
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search.search_query.lang = lang
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try:
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search.search_query.locale = babel.Locale.parse(lang)
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except babel.core.UnknownLocaleError:
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pass
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return True
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def init(app, settings): # pylint: disable=unused-argument
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for searxng_locale in language_codes:
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supported_langs.add(searxng_locale[0].split('-')[0])
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return True
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