annas_archive.py

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# SPDX-License-Identifier: AGPL-3.0-or-later
"""`Anna's Archive`_ is a free non-profit online shadow library metasearch
engine providing access to a variety of book resources (also via IPFS), created
by a team of anonymous archivists (AnnaArchivist_).
 
.. _Anna's Archive: https://annas-archive.org/
.. _AnnaArchivist: https://annas-software.org/AnnaArchivist/annas-archive
 
Configuration
=============
 
The engine has the following additional settings:
 
- :py:obj:`aa_content`
- :py:obj:`aa_ext`
- :py:obj:`aa_sort`
 
With this options a SearXNG maintainer is able to configure **additional**
engines for specific searches in Anna's Archive.  For example a engine to search
for *newest* articles and journals (PDF) / by shortcut ``!aaa <search-term>``.
 
.. code:: yaml
 
  - name: annas articles
    engine: annas_archive
    shortcut: aaa
    aa_content: 'magazine'
    aa_ext: 'pdf'
    aa_sort: 'newest'
 
Implementations
===============
 
"""
 
from typing import List, Dict, Any, Optional
from urllib.parse import urlencode
from lxml import html
 
from searx.utils import extract_text, eval_xpath, eval_xpath_getindex, eval_xpath_list
from searx.enginelib.traits import EngineTraits
from searx.data import ENGINE_TRAITS
 
# about
about: Dict[str, Any] = {
    "website": "https://annas-archive.org/",
    "wikidata_id": "Q115288326",
    "official_api_documentation": None,
    "use_official_api": False,
    "require_api_key": False,
    "results": "HTML",
}
 
# engine dependent config
categories: List[str] = ["files"]
paging: bool = True
 
# search-url
base_url: str = "https://annas-archive.org"
aa_content: str = ""
"""Anan's search form field **Content** / possible values::
 
    book_fiction, book_unknown, book_nonfiction,
    book_comic, magazine, standards_document
 
To not filter use an empty string (default).
"""
aa_sort: str = ''
"""Sort Anna's results, possible values::
 
    newest, oldest, largest, smallest
 
To sort by *most relevant* use an empty string (default)."""
 
aa_ext: str = ''
"""Filter Anna's results by a file ending.  Common filters for example are
``pdf`` and ``epub``.
 
.. note::
 
   Anna's Archive is a beta release: Filter results by file extension does not
   really work on Anna's Archive.
 
"""
 
 
def init(engine_settings=None):  # pylint: disable=unused-argument
    """Check of engine's settings."""
    traits = EngineTraits(**ENGINE_TRAITS['annas archive'])
 
    if aa_content and aa_content not in traits.custom['content']:
        raise ValueError(f'invalid setting content: {aa_content}')
 
    if aa_sort and aa_sort not in traits.custom['sort']:
        raise ValueError(f'invalid setting sort: {aa_sort}')
 
    if aa_ext and aa_ext not in traits.custom['ext']:
        raise ValueError(f'invalid setting ext: {aa_ext}')
 
 
def request(query, params: Dict[str, Any]) -> Dict[str, Any]:
    lang = traits.get_language(params["language"], traits.all_locale)  # type: ignore
    args = {
        'lang': lang,
        'content': aa_content,
        'ext': aa_ext,
        'sort': aa_sort,
        'q': query,
        'page': params['pageno'],
    }
    # filter out None and empty values
    filtered_args = dict((k, v) for k, v in args.items() if v)
    params["url"] = f"{base_url}/search?{urlencode(filtered_args)}"
    return params
 
 
def response(resp) -> List[Dict[str, Optional[str]]]:
    results: List[Dict[str, Optional[str]]] = []
    dom = html.fromstring(resp.text)
 
    for item in eval_xpath_list(dom, '//main//div[contains(@class, "h-[125]")]/a'):
        results.append(_get_result(item))
 
    # The rendering of the WEB page is very strange; except the first position
    # all other positions of Anna's result page are enclosed in SGML comments.
    # These comments are *uncommented* by some JS code, see query of class
    # '.js-scroll-hidden' in Anna's HTML template:
    #   https://annas-software.org/AnnaArchivist/annas-archive/-/blob/main/allthethings/templates/macros/md5_list.html
 
    for item in eval_xpath_list(dom, '//main//div[contains(@class, "js-scroll-hidden")]'):
        item = html.fromstring(item.xpath('./comment()')[0].text)
        results.append(_get_result(item))
 
    return results
 
 
def _get_result(item):
    return {
        'template': 'paper.html',
        'url': base_url + extract_text(eval_xpath_getindex(item, './@href', 0)),
        'title': extract_text(eval_xpath(item, './/h3/text()[1]')),
        'publisher': extract_text(eval_xpath(item, './/div[contains(@class, "text-sm")]')),
        'authors': [extract_text(eval_xpath(item, './/div[contains(@class, "italic")]'))],
        'content': extract_text(eval_xpath(item, './/div[contains(@class, "text-xs")]')),
        'thumbnail': extract_text(eval_xpath_getindex(item, './/img/@src', 0, default=None), allow_none=True),
    }
 
 
def fetch_traits(engine_traits: EngineTraits):
    """Fetch languages and other search arguments from Anna's search form."""
    # pylint: disable=import-outside-toplevel
 
    import babel
    from searx.network import get  # see https://github.com/searxng/searxng/issues/762
    from searx.locales import language_tag
 
    engine_traits.all_locale = ''
    engine_traits.custom['content'] = []
    engine_traits.custom['ext'] = []
    engine_traits.custom['sort'] = []
 
    resp = get(base_url + '/search')
    if not resp.ok:  # type: ignore
        raise RuntimeError("Response from Anna's search page is not OK.")
    dom = html.fromstring(resp.text)  # type: ignore
 
    # supported language codes
 
    lang_map = {}
    for x in eval_xpath_list(dom, "//form//input[@name='lang']"):
        eng_lang = x.get("value")
        if eng_lang in ('', '_empty', 'nl-BE', 'und'):
            continue
        try:
            locale = babel.Locale.parse(lang_map.get(eng_lang, eng_lang), sep='-')
        except babel.UnknownLocaleError:
            # silently ignore unknown languages
            # print("ERROR: %s -> %s is unknown by babel" % (x.get("data-name"), eng_lang))
            continue
        sxng_lang = language_tag(locale)
        conflict = engine_traits.languages.get(sxng_lang)
        if conflict:
            if conflict != eng_lang:
                print("CONFLICT: babel %s --> %s, %s" % (sxng_lang, conflict, eng_lang))
            continue
        engine_traits.languages[sxng_lang] = eng_lang
 
    for x in eval_xpath_list(dom, "//form//input[@name='content']"):
        engine_traits.custom['content'].append(x.get("value"))
 
    for x in eval_xpath_list(dom, "//form//input[@name='ext']"):
        engine_traits.custom['ext'].append(x.get("value"))
 
    for x in eval_xpath_list(dom, "//form//select[@name='sort']//option"):
        engine_traits.custom['sort'].append(x.get("value"))
 
    # for better diff; sort the persistence of these traits
    engine_traits.custom['content'].sort()
    engine_traits.custom['ext'].sort()
    engine_traits.custom['sort'].sort()